In 2001, a self-administered questionnaire was sent to 1000 corn, Zea mays L., farmers in each of five states (Illinois, Indiana, Iowa, Minnesota, and Nebraska) to evaluate their perceptions of transgenic corn designed to control the European corn borer, Ostrinia nubilalis (Hübner), and corn rootworms, Diabrotica spp. Respondents returned 1,313 surveys (26.2%). Farmers with small acreages planted a greater portion of their corn (54.5%) with transgenic corn for control of European corn borer than farmers with large farms (39.2%). The majority (75.2%) of farmers use crop rotation to control the corn rootworm. Nine insecticides comprised 92.2% of the commercial soil insecticides used for control of corn rootworm larvae. More than one-third of the farmers in Illinois (33.5%) and Indiana (39.4%) treated first-year corn for corn rootworm, primarily due to western corn rootworm egg laying in soybean, Glycine max (L.). When asked whether they would plant transgenic corn protected against the corn rootworm, 35.0% of farmers responded they would, whereas 40.5% said they were unsure. The two greatest farmer concerns about transgenic corn were the ability to sell harvested grain (59.3%) and additional technology fees (54.8%). Respondents indicated that less farmer exposure to insecticide (69.9%) and less insecticide in the environment (68.5%) were the primary benefits of transgenic corn. Farmers who had no concerns about transgenic corn for rootworm control were more likely to purchase the product (46.8%). The most common refuge-planting options farmers favored were adjacent fields (30.9%) and split fields (29.9%). Farmers (21.1%) observed a yield increase (23.7 bu/ha [9.6 bu/acre]) when using transgenic corn for European corn borer control compared with nontransgenic corn. These data can help in understanding farmers’ knowledge and concerns regarding transgenic corn. This information may be of value to guide researchers, extension specialists, and policy makers in designing insect resistance management and integrated pest management programs.

The sterile insect technique (SIT) is currently being used for the control of many agricultural pests, including some lepidopteran species. The SIT relies on the rearing and release of large numbers of genetically sterile insects into a wild population. The holokinetic chromosomes of Lepidoptera respond differently to radiation than do species where there is a localized centromere. This difference has enabled a variation of the SIT to be developed for Lepidoptera where a substerilizing dose of radiation is given to the insects before their release with the result that a certain level of sterility is inherited by the F₁ offspring. The development of genetic sexing strains for fruit flies, enabling the release of males only, has resulted in enormous economic benefits in the mass rearing and has increased the efficiency of the field operations severalfold. This article outlines Mendelian approaches that are currently available to separate large numbers of males and females efficiently for different lepidopteran species and describes their difficulties and constraints. Successful transgenesis in several lepidopteran species opens up new possibilities to develop genetic sexing strains. The proposal to develop genetic sexing strains described in this article takes advantage of the fact that in Lepidoptera, the female is the heterogametic sex, with most species having a WZ sex chromosome pair, whereas the males are ZZ. This means that if a conditional lethal gene can be inserted into the W chromosome, then all females should die after the application of the restrictive condition. The assumptions made to accommodate this model are discussed, and the advantages to be gained for control programs are elucidated.

The Neotropical stingless bee Melipona quadrifasciata Lepeletier was evaluated for pollinating tomatoes (variety Rodas; long-life hybrid) in greenhouses under plastic and with a hydroponic system and “organic concepts” in Minas Gerais State, Brazil. Flowers not pollinated did not set any fruit. Pollination by bees plus manual pollination did not differ from either bee or manual pollination. Maximum fruit diameter, fruit height, and roundness (quotient between maximum fruit diameter and fruit height) were not significantly different between treatments, but fruit visited by M. quadrifasciata had 10.8% less seeds (dry mass) than manual pollination. This apparently low efficiency of M. quadrifasciata pollination was attributed to the overlap of only 30 min between highest bee foraging activity and highest flower stigma receptivity. Thus, it was concluded that M. quadrifasciata is a feasible pollinator of greenhouse tomatoes because of 1) the observed increase in fruit quality with lower mechanical injury than traditional manual pollination, 2) no significant decrease in fruit size, and 3) high price of such product in the market. Some considerations for sustainable use of M. quadrifasciata as greenhouse pollinator are presented. Although techniques for keeping captive colonies of M. quadrifasciata are currently available, the sole current method for acquiring new colonies is removing them from the forest, and if demand was created for large numbers of colonies for commercial use, techniques for captive rearing must be developed to prevent serious declines in wild populations.

RESUMO. A abelha-sem-ferrão Neotropical Melipona quadrifasciata Lepeletier foi avaliada para a polinização de tomates hidropônicos (híbrido longa-vida variedade Rodas) em casas-de-vegetação sob plástico e com ‘conceitos orgânicos’ em Minas Gerais, Brasil. As flores não polinizadas não produziram frutos. A polinização pelas abelhas juntamente com a polinização manual não diferiu da polinização somente pela abelha ou somente manual. O diâmetro máximo e a altura dos frutos e sua circunferência (quociente entre o diâmetro máximo e a altura dos frutos) não foram significativamente diferentes entre os tratamentos, mas os frutos visitados por M. quadrifasciata apresentaram 10,8% menos sementes (peso seco) do que os polinizados manualmente. Esta eficiência aparentemente baixa de M. quadrifasciata como polinizador foi atribuída à sobreposição de apenas 30 min entre o pico máximo de forrageamento das abelhas e a maior receptividade do estigma das flores. Concluiu-se ser possível usar M. quadrifasciata como polinizador de tomates cultivados em casa-de-vegetação porque (i) houve aumento na qualidade dos frutos, considerando-se a diminuição das injúrias mecânicas quando comparada à polinização manual tradicional, (ii) não houve diminuição do tamanho do fruto e (iii) pelo alto preço deste produto no mercado. Algumas considerações sobre o uso sustentável de M. quadrifasciata como polinizador em casas-de-vegetação são apresentadas. Apesar de existirem técnicas para manter colônias de M. quadrifasciata em cativeiro, o único método para aquisição de novas colônias e a retirada delas da mata e, criando-se demanda por grande número delas para uso comercial, técnicas de criação em cativeiro necessitam ser desenvolvidas, o que poderia prevenir grandes declínios das populações naturais desta abelha.

Two formic acid autumnal treatments, gel packets (BeeVar formulation) and impregnated paperwick (Liebig-Dispenser), were tested in apiary to evaluate their effectiveness against Varroa destructor Anderson & Trueman and their residues in honey in a Mediterranean region (Sardinia, Italy). Both treatments were efficient in the apiary control of the varroosis, with values of percentage of mite mortality ranging between 93.6 and 100%, without statistical differences between them. The more gradual release of formic acid from the gel application allowed a longer action (2 wk for each treatment) compared with the Liebig-Dispenser (≈3 d for each treatment). The rate of daily evaporation ranged between ≈5 and 9 g/d from BeeVar and ≈26 and 35 g/d from the Liebig-Dispenser, in the first and second treatment, respectively. The total amount of formic acid administered per hive during all the treatment period was ≈200 g for either treatment. A significantly higher adult bee mortality was recorded in the Liebig-Dispenser-treated hives compared with the BeeVar-treated group. On the contrary, BeeVar treatment produced an interruption of brood reared, whereas the extension of the sealed brood area of the Liebig-Dispenser-treated hives was not significantly different from that of the control hives. Neither queen mortality nor robbing activity was observed due to the treatments. Formic acid residues in honey collected in the nest were 3,855 ± 2,061 and 3,030 ± 1,624 mg/kg for the BeeVar- and the Liebig-Dispenser-treated hives, respectively. After 21 d from the end of the treatment, the residues fell to 1,261 ± 1,054 and 794 ± 518 mg/kg for the honey sampled from the BeeVar and Liebig-Dispenser groups, respectively.

Swarming is an important mechanism by which honey bee, Apis mellifera L., colonies reproduce, yet very little is known about the physiological changes in workers that are preparing to swarm. In this study, we determined the endocrine status of worker honey bees in preswarming colonies and in normal (nonswarming) colonies. Juvenile hormone (JH) titers in worker bees were similar in both groups before queen cells were present, but they became significantly lower in preswarming colonies compared with normal colonies when queen cells occurred in preswarming colonies. The lower JH titers in the preswarming colonies suggest that behavioral development is delayed in these colonies, consistent with previous reports that preswarming colonies have reduced foraging activities. Understanding the endocrine status of bees preparing for swarming will help us to better understand the biology of swarming.

At least 16 taxa of cicadellids and delphacids were tested by polymerase chain reaction (PCR) for the presence of a phytoplasma in the clover proliferation group, designated 16SrVI. Nucleic acid extracts from individual insects or groups of 5–10 were tested using PCR primers designed from the DNA sequence of 16S–23S rRNA or ribosomal protein genes of the pathogen. The beet leafhopper, Circulifer tenellus (Baker), was most often associated with the phytoplasma, with ≈16% of the insects testing positive. The phytoplasma was occasionally found associated with Ceratagallia spp. Leafhopper species that were not associated with the phytoplasma included Macrosteles spp., Dikraneura spp., Colladonus montanus (Van Duzee), Circulifer geminatus (Van Duzee), Ballana spp., Amplysellus spp., Paraphlepsius spp., Texananus spp., Balclutha spp., Latalus spp., Erythroneura spp., Exitianus exitiosus (Uhler), and unidentified delphacids. The detected phytoplasma was similar to, or synonymous with, the beet leafhopper-transmitted virescence agent that is associated with the potato purple top disease in the Columbia Basin region of Washington and Oregon. This is in contrast to the phytoplasma associated with potato purple top disease in Mexico that is related to aster yellows (group 16SrI). The association of the group 16SrVI phytoplasma almost exclusively with the beet leafhopper suggests that this insect is the major vector of the phytoplasma in this region.

Mealybug Maconellicoccus hirsutus (Green) adults, nymphs, crawlers, and eggs were tested for their susceptibility to hot water immersion at 47, 48, and 49°C. Eggs inside ovisacs were found most tolerant with prolonged survival compared with other stages at all temperatures. Ovisacs required an average of 1.38, 1.46, and 1.62 times longer treatment duration than adults, nymphs, and crawlers, respectively, for 99.9% predicted mortality at 47, 48, and 49°C. Lethal time estimations were calculated from inverse predictions of regressions derived from logit-transformed data as well as those created using a kinetic model. LT 99.9 estimations were 47.0, 21.2, and 11.9 min at 47, 48, and 49°C, respectively, by using regressions with logit transformations. The kinetic model predictions were 43.9, 19.6, and 11.1 min at 47, 48, and 49°C, respectively. During the study no emergence from eggs inside ovisacs was found after treatments of 52, 24, and 14 min at 47, 48, and 49°C, respectively. Results from this study provide efficacious temperature–time treatments.

Ozone (O₃) fumigation is a potential quarantine treatment alternative for controlling stored-product pests and surface insect pests on fresh agricultural commodities. We explored the effects of temperature, treatment time, controlled atmospheres, and vacuum in combination with O₃ to control two important pests of ornamental crops: western flower thrips, Frankliniella occidentalis (Pergande), and longtailed mealybug, Pseudococcus longispinus Targioni Tozzetti. Treatment parameters tested were O₃ concentrations from 0 to 3,800 ppm, treatment durations were from 30 to 120 min, vacuums were from 0 to 0.41 bar below ambient, temperatures were from 32.2 to 40.6°C, and controlled atmospheres were composed primarily of nitrogen, carbon dioxide, or breathing air [BA]. Treatment efficacy was enhanced by higher O₃ concentration and temperature, lower oxygen, and longer treatment times. Reduced pressure was not an important factor. Mealybugs were more difficult to kill than thrips. A 30-min treatment of O₃ at ≈200 ppm in 100% CO₂ at 37.8°C killed 47.9 and 98.0% of mealybugs and adult female thrips, respectively. All of the ornamentals tested were damaged to some degree by O₃ treatments. However, crops with thick leaves such as orchids exhibited little damage, and the waxy portions of certain flowers were not damaged. The results suggest that O₃ has potential as a quarantine treatment to control thrips and mealybugs on selected commodities.

A diagnostic polymerase chain reaction (PCR) method is presented for differentiating among the North American internal apple-feeding pests codling moth, Cydia pomonella (L.); oriental fruit moth, Grapholita molesta (Busck); lesser appleworm, Grapholita prunivora (Walsh); and cherry fruitworm, Grapholita packardi Zeller. An ≈470-bp fragment of mitochondrial cytochrome oxidase subunit I (COI) was sequenced in three to six specimens of each species. Consistent and diagnostic differences were observed among the species in two regions of COI from which forward and reverse primers were designed to amplify a 112–116-bp segment of the gene. The primer sets were used to selectively amplify DNA from specimens of diverse geographic origin for each corresponding target species. Protocols were adapted for conventional and quantitative PCR, the latter being substantially faster. The method was validated as a decision-making tool for quarantine identifications for Mexico by representatives of their phytosanitary agency (Sanidad Vegetal). The method can facilitate identification of intercepted internal feeding Lepidoptera in apple and pear for many other importing nations.

Earth mites are major winter pests of a variety of crops and pastures in southern Australia. Competition between four earth mite species was investigated using field and shadehouse experiments. The influence of different plant hosts on the frequency and intensity of competitive interactions also were examined. This information is important, because control attempts that eradicate one species of mite could be directly followed by an increase in abundance of another earth mite species. There were strong effects of intraspecific competition on the reproductive rate of species, while interspecific interactions between Halotydeus destructor (Tucker) and Penthaleus species and between the three Penthaleus species also were detected. Competitive abilities were altered on the different plant types. On pasture, the competitive advantage swayed between Penthaleus major (Dugés), H. destructor, and Penthaleus falcatus (Qin & Halliday). Penthaleus sp. x was the strongest competitor in a mixture of wheat, Triticum aestivum (L.), and oats, Avena sativa (L.), whereas on canola, Brassica napus (L.), and bristly ox-tongue, Picris echioides (L.), P. falcatus, and H. destructor were superior competitors. These results suggest that competition is a strong force influencing the abundance of earth mites in the field and that host plant factors are important in shaping the type of interactions. This highlights the importance of identifying mite species when considering control options and suggests that effective control recommendations need to be developed for each individual species.

Combined attracticide formulations targeting Oriental fruit moth, Grapholita molesta (Busck), and codling moth, Cydia pomonella (L.), were tested in a field trapping experiment. Capture of male codling moths in traps baited with the combined formulation was reduced compared with traps baited with the codling moth formulation alone, whereas capture of male Oriental fruit moth was increased compared with traps baited with the Oriental fruit moth formulation alone. Subsequent wind tunnel experiments showed that a single locus of the mixed attracticide formulation or close parallel presentation of the two formulations enhanced source contact by male Oriental fruit moths but did not influence earlier behaviors. However, the two formulations presented in a serial arrangement to Oriental fruit moth males in the wind tunnel resulted in enhanced lock-on, upwind flight, and source contact behaviors. In addition, male Oriental fruit moths remained on mixed pheromone droplets of the paste matrix longer than on droplets of the Oriental fruit moth formulation alone. The increased time spent on the mixed droplet was correlated with a more rapid poisoning and a greater proportion of poisoned males compared with males exposed to the Oriental fruit moth attracticide alone. These results demonstrate that a combined attracticide formulation will have different effects on each of the targeted species. It is anticipated that, due to decreased attractiveness, a combined formulation would be less effective against the codling moth. However, a mixed formulation, due to increased attractiveness and toxicity, could be more effective against the Oriental fruit moth under field conditions.

The Indianmeal moth, Plodia interpunctella (Hübner), was selected as a representative stored-product moth to test the validity of contour mapping of trap catch for pest monitoring in warehouses and retail stores. Three experiments, each replicated five times, were conducted in a 3.2 by 9.0-m aluminum shed. Each experiment involved placing pupae at a single release point (source) and recording the numbers of emerging adult males captured after 24, 48, and 72 h in each of four pheromone-baited sticky traps. The experiments differed only with respect to the point of release. Distribution of trap catch reflected the general distribution of moths in the shed; and consecutive contour maps tracked their dispersal from the source. As emergence and dispersal progressed, cumulative trap catch increased throughout the shed, but it remained highest near the source. The observed spatial patterns of trap catch relative to sources of infestation and the inverse relationship of trap catch to distance from a source support the validity of contour mapping as a means of monitoring stored-product moths and locating foci of infestation. The relationship between trap catch and distance from a source of infestation was well described by two-parameter exponential decay, both in P. interpunctella and in the previously studied Lasioderma serricorne (F.). Analysis of data from retail pet stores also showed exponential decline in trap catch of P. interpunctella with distance from centers of infestation.

The effect of exposure to both the pheromone and insecticide constituents of an attracticide formulation on subsequent pheromonal response of male oriental fruit moth, Grapholita molesta (Busck) (Lepidoptera: Tortricidae), was tested in several wind tunnel bioassays. Male response to the attracticide formulation was significantly reduced in all behavioral categories, including source contact 1 h after sublethal exposure (both by voluntary contact in the wind tunnel and forced application in the laboratory) to the attracticide formulation containing inert ingredients, pheromone, and insecticide. Sublethal exposure to the attracticide formulation in the laboratory (forced application) 24 h before the bioassay resulted in a significantly lower proportion of males subsequently responding to attracticide droplets in the wind tunnel. However, voluntary contact of male moths with the toxic formulation in the wind tunnel had no effect on subsequent response 24 h later. Exposure of males to different constituents of the attracticide formulation demonstrated that both pheromone and insecticide exerted effects on subsequent male pheromonal response. Exposure to the formulation containing the inert ingredients plus the pheromone (no insecticide) significantly reduced male behavioral responses to an attracticide droplet in the wind tunnel 1 h but not 24 h after exposure, compared with males treated with inert ingredients alone. Response to attracticide droplets was further reduced by exposure to the entire attracticide formulation containing inert ingredients, pheromone and insecticide at both 1 and 24 h postexposure. Similarly, males exposed to inert ingredients plus pheromone were less likely to orient to female-produced plumes 1 h but not 24 h after exposure than males treated with inert ingredients alone. Response to female-produced plumes was further reduced at 1 h but not at 24 h after exposure to the entire attracticide formulation. Mating success of males was significantly reduced by exposure to the entire attracticide formulation but not to the formulation without insecticide when placed with females 1 and 24 h postexposure. These findings suggest that sublethal poisoning of males exposed to the attracticide formulation will enhance the effectiveness of this formulation under field conditions.

Lycoriella mali Fitch (Diptera: Sciaridae) infests mushroom crops early in the crop cycle. Recent observations in mushroom houses indicated a difference in emergence time and size of adult L. mali developing on various strains of commercial mushrooms. Samples of adult flies from isolated mushroom houses growing Portabella mushrooms were significantly heavier then those from oyster mushroom houses, whereas flies from shiitake mushroom houses were lightest in weight. Flies collected from isolated Portabella mushroom houses were reared on four strains and species of Agaricus and Pleurotus mushrooms. After the adults emerged, females were weighed, mated, and allowed to oviposit. The number of eggs laid increased as the weight of the female increased. Flies collected from isolated Portabella mushroom houses were reared on eight strains and species of mushrooms. Flies were reared for four generations on each host mushroom mycelium then switched to different host mushrooms. Overall, the hybrid strain of Agaricus bisporus (Lange) Imbach (Agaricales: Agaricomycetideae) was the most favorable host for L. mali, whereas the wild strain of A. bisporus was the least favorable host. Mushroom hosts influence developmental time, survivorship, weight, and reproduction of L. mali.

In 1998 and 1999, pepper maggot flies, Zonosemata electa (Say), were excluded from pepper plants with row covers for 0–6 wk after initial oviposition was detected. The proportion of oviposition attempts (scars) and larval infestation that occurred each week and the cumulative oviposition and infestation over time were determined. Due to environmental factors, initial oviposition was delayed, and the numbers of oviposition scars on fruit and flies caught on traps were lower in 1998 than in 1999. The proportions of scarred or infested fruit were low (<8% of total) during the first 7 d after the pest was detected each year. Oviposition peaked 8–14 d after beginning in 1998, but not until 21–28 d after the initial scar was detected in 1999. Because systemic insecticides tend to provide control of adults and most hatching larvae, it may be possible to delay the initial insecticide application for up to a week after oviposition commences and still minimize fruit damage. There was no association with either year between the proportion of flies captured on traps and the proportion of oviposition scars on fruit the same week or 1 and 2 wk later.

Although acetylcholinesterase (AChE) is the primary target of organophosphorus insecticides (OPs), increasing evidence regarding their secondary effects suggests that OPs disturb homeostasis of insects by generating free radical intermediates that trigger lipid peroxidation. We therefore investigated alterations in lipid peroxidation product, malondialdehyde (MDA) content, and alanine aminotransferase (ALT) and aspartate aminotransferase (AST) activities, in conjunction with AChE activity as biochemical stress indicators in greater wax moth, Galleria mellonella (L.) larvae for OPs methyl parathion (MP) and ethyl parathion (EP). The effects of MP and EP were first investigated by rearing the young larvae on an artificial diet containing 0.01, 0.1, 1, 10, and 100 ppm of each insecticide. Second, the mature larvae were injected with 0.05, 0.5, 5, 50, and 500 ng of insecticides for determining the changes in biochemical stress responses. The diet with lowest level of MP significantly decreased the activities of all measured enzymes, whereas it increased MDA content. However ALT and AST were significantly higher in the larvae reared with the diet with high levels of MP than in control larvae. All tested levels of MP resulted in a decrease in AChE activity. The lowest level of EP in diet (0.01 ppm) significantly increased ALT activity, whereas it reduced that of AChE. This insecticide at 0.1 ppm resulted in reduced AST activity, but 1 ppm in diet elevated AST activity and MDA content. EP at 0.1 ppm and higher levels in the diet reduced ALT activity. All dietary EP levels significantly decreased AChE activity. ALT, AST, and AChE were lower in larvae fed with the diet containing 100 ppm ethyl parathion compared with larvae on control diet. MP at 50 ng per larva increased ALT and AST activities from 35.42 ± 0.74 and 26.34 ± 0.83 to 203.57 ± 1.09, and 122.90 ± 1.21 U/g, respectively, when the mature larvae were injected. All injected doses of EP dramatically reduced both ALT and AST activities, but only the lowest and highest levels of this insecticide decreased AChE activity. The lowest level of this insecticide also significantly increased MDA content in larvae. High levels of both insecticides increased MDA content. We observed a significant higher increase in MDA content in the larvae reared with 10 ppm EP (102.16 ± 1.57 nmol/g protein) than the control group (30.28 ± 1.42 nmol/g protein). These results suggest that OPs caused the metabolic and synaptic dysfunctions in greater wax moth and alter its biochemical physiology in response to oxidative stress.

Pollination is an essential step in the seed production of canola, Brassica napus L. It is achieved with the assistance of various pollen vectors, but particularly by the honey bee, Apis mellifera L. Although the importance of pollination has been shown for the production of seed crops, the need to introduce bee hives in canola fields during flowering to increase oil seed yield has not yet been proven. With the purpose of showing this, hives of A. mellifera were grouped and placed in various canola fields in the Chaudière-Appalaches and Capitale-Nationale regions (nine fields; three blocks with three treatments; 0, 1.5, and 3 hives per hectare). A cage was used to exclude pollinators and bee visitations were observed in each field. After the harvest, yield analyses were done in relation to the bee density gradient created, by using pod set, number of seeds per plant, and weight of 1000 seeds. Results showed an improvement in seed yield of 46% in the presence of three honey bee hives per hectare, compared with the absence of hives. The introduction of honey bees contributed to production and consequently, these pollinators represented a beneficial and important pollen vector for the optimal yield of canola.

The effect of aging on a commercial pheromone-based lure for attractiveness to male adult beet armyworms, Spodoptera exigua (Hübner), was assessed in terms of trapping efficiency and volatile emissions of two key components: (Z,E)-9,12-tetradecadienyl acetate and (Z)-9-tetradecen-1-ol. In field assays conducted in the Lower Rio Grande Valley, Texas, for 9 wk (June–August 2000) and for 8 wk (March–May) in Tamaulipas, Mexico, 0–1-wk-old lures collected greater than four-fold more male beet armyworm adults than lures that had been aged for 3–4 wk. Using solid phase microextraction and gas chromatographic analysis of the volatiles, mean (Z,E)-9,12-tetradecadienyl acetate emission declined by 32% after 5 wk of aging in a ventilated environmental chamber at 29.4°C, 35% RH, to simulate subtropical summers. Mean (Z)-9-tetradecen-1-ol emission was reduced by 62% after 4 wk of aging. Under the tropical and subtropical conditions of this study, the capacity of the lure to attract moths into the trap declined after aging for 3 wk. The blend ratio (Z,E)-9,12-tetradecadienyl acetate:(Z)-9-tetradecen-1-ol declined 29% when the lure was aged for 5 wk. This study will assist in the development of a standard trapping system for assessing adult beet armyworm populations in the tropical and subtropical conditions to which the species is endemic.

The dispersion of root injury to Zea mays L. by corn rootworm, Diabrotica spp., larvae was characterized using geostatistics to determine the appropriate sampling distance to obtain independent estimates of root injury. We also investigated the effect of the root injury levels on the spatial dependence of root injury at three different spatial scales: large-scale study with 25-m sampling distance in three, 8-ha fields; moderate-scale study with 0.2-m sampling distance in six, 2-ha fields; and small-scale study with exhaustive sampling in eight, 12-m² plots within cornfields. In the large-scale study, a nugget model best fit the semivariograms, indicating the dispersion of root injury exhibited a random pattern. In the moderate-scale study, all the semivariograms were best fit with an exponential model, and 68 to 96% of the variability was explained by spatial dependence, suggesting a high degree of spatial aggregation of corn root larval injury. The ranges of semivariograms fell within <4 m, except one field that had the range of 14.7 m. In the small-scale study, the Gaussian, exponential, or spherical models fit the semivariograms best and 50 to 89% of the variability was explained by spatial dependence, suggesting spatial aggregation of root injury. The ranges of semivariograms were from 0.35 to 1.04 m. In the small-scale study, the degree of spatial dependence increased significantly (P < 0.05) as the average root injury increased within the range of root injury observed in the study. These results suggest that the minimum distance between root samples in small-plot insecticide trials should be >1 m within a row to obtain unbiased estimates of root injury.

Lepidopterous stem borers seriously affect production of maize, Zea mays L., in sub-Saharan Africa. Intercropping maize with legumes such as lablab, Lablab purpurens (L.), is one of the effective systems to control stem borers. Sole culture maize and maize/lablab intercrop system of different lablab densities were planted at two locations to investigate the effects of intercrop system on incidence and severity of stem borers with particular reference to Chilo partellus (Swinhoe) (Lepidoptera: Pyralidae). Stem borer infestation was found to be more severe in sole culture maize than maize in maize/lablab intercrop. There was a significantly negative relationship between lablab densities and maize grain yields, suggesting a possible competition for resources between the two crops. It was concluded that density of lablab and date of planting of lablab in maize/lablab intercropping have significant affects on stem borer populations and maize grain yields.

A study to determine yield response to the Russian wheat aphid, Diuraphis noxia (Mordvilko), was conducted during the 1997–1998 and 1998–1999 growing seasons at three eastern Colorado locations, Akron, Fort Collins, and Lamar, with three wheat lines containing either Russian wheat aphid-resistant Dn4 gene, Dn6 gene, or resistance derived from PI 222668, and TAM 107 as the susceptible control. Russian wheat aphids per tiller were greater on TAM 107 than the resistant wheat lines at the 10× infestation level at Fort Collins and Akron in 1999. Yield, seed weight, and number of seeds per spike for each wheat line were somewhat affected by Russian wheat aphid per tiller mainly at Fort Collins. The infested resistant wheat lines harbored fewer Russian wheat aphids and yielded more than the infested susceptible wheat lines. Wheat lines containing the Dn4, Dn6, and PI 222668 genes contain different levels of antibiosis or antixenosis and tolerance. Although differences existed among sites and resistance, there is a benefit to planting resistant wheat when there is a potential for Russian wheat aphid infestations.

The European corn borer, Ostrinia nubilalis (Hübner) (Lepidoptera: Crambidae), is one of the most important pests of corn, Zea mays L., because it consistently causes high loss of yield. A study was conducted in 2000–2002 at field sites in central and western Kentucky to investigate whether infestation by O. nubilalis differentially affects the production of high-oil corn compared with traditional field corn. Statistical differences in grain weight and percentage of oil content between the five infestation levels were significant at both locations and for all years. Average grain yield was reduced by 0.40% and average oil concentration by 0.011% for each 1% of damaged plants, and there was a strong correlation (0.76) between leaf damage ratings (i.e., Guthrie scale) and yield reduction. In general, corn planted at the early planting date tended to have a higher yield (grain weight) and oil content.

In a 2-yr study, we investigated the efficacy of large-scale application of the biological insecticide Bacillus thuringiensis variety aizawai × kurstaki (Btk) in a Swedish spruce, Picea abies L. (Karst.), seed orchard for controlling damage caused by four lepidopteran species: Dioryctria abietella Den et. Schiff. (Pyralidae), Eupithecia abietaria Götze, E. analoga Djakonov (Geometridae), and Cydia strobilella (L.) (Tortricidae). The frequencies of these species, and Strobilomyia anthracina Czerny (Diptera: Anthomyiidae), were regularly monitored throughout the vegetative growth season to map their temporal distribution patterns and to quantify occurrences of species that may have been present in the cones at some stage during the season but migrated before the final sampling. This investigation revealed that E. abietaria occurred in similar numbers to D. abietella and has probably been overlooked as a potentially serious pest in spruce seed orchards in Sweden. To determine the number, timing, and rate of Btk required to control the lepidopterans, spraying was conducted at different phases of flowering and cone development, and three rates of Btk were applied. The Btk treatment reduced cone damage caused by D. abietella and Eupithecia spp. by one-half in 2002, a year with an intermediate number of cones, but the effect was weaker in 2003, when the cone crop was low. Damage caused by C. strobilella was not affected by the treatment. The different rates of Btk application did not affect the results, and repeated spraying seemed to be effective during 2002 but not in 2003.

A study was performed to evaluate the potential of the egg parasitoid Trichogramma exiguum Pinto and Platner (Hymenoptera: Trichogrammatidae), the newly registered insect growth regulator (IGR) tebufenozide (Confirm), and a modified spray technique (top whorl only pesticide application) for suppression of Nantucket pine tip moth, Rhyacionia frustrana (Comstock) (Lepidoptera: Tortricidae), damage in Virginia pine, Pinus virginiana Mill., Christmas trees. Augmentative releases of T. exiguum failed to increase parasitism levels in release plots compared with controls, and significant reduction in tip moth damage did not occur. High predation levels on released T. exiguum may have contributed to the failure of parasitoid augmentations. Whole-tree and top whorl tebufenozide treatments provided significantly greater damage control than corresponding applications of acephate (Orthene), a commonly used pesticide in Christmas trees. Damage to trees receiving whole-tree chemical applications did not differ significantly from trees receiving top whorl treatments for most measurements of damage. Top whorl chemical treatments resulted in a 67% reduction in time required for application and a 70% reduction in pesticide used.

The insect growth regulators (IGRs) tebufenozide and methoxyfenozide and the broad-spectrum insecticides azinphosmethyl, carbaryl, and fenpropathrin were compared for their activity against adult, egg, and larval stages of the grape berry moth, Endopiza viteana (Clemens) (Lepidoptera: Tortricidae), under laboratory and vineyard conditions. Adult mortality was not affected by exposure to field-equivalent rates of tebufenozide or methoxyfenozide on grape clusters, whereas all the broad-spectrum compounds significantly reduced adult survival, compared with the untreated controls. Surviving adult moths laid significantly more eggs on berries treated with the IGRs than on berries treated with any of the broad-spectrum insecticides. Survival of these eggs through to late larval and pupal stages was significantly lower on methoxyfenozide-treated grapes than on untreated grapes, and no pupae were found when grapes were treated with azinphosmethyl or fenpropathrin. Neither of the growth regulator insecticides limited egg eclosion or larval development by E. viteana when insecticides were applied before egg laying, whereas broad-spectrum insecticides were effective against both eggs and neonates at this timing. When applied after egg eclosion, all insecticide treatments significantly reduced survival of grape berry moth larvae. Under vineyard conditions, berries with 1-d-old residues of tebufenozide or methoxyfenozide received more E. viteana eggs than berries treated with broad-spectrum compounds. After aging for 7 or 14 d, no significant effects on E. viteana survival were detected among treatments. Whereas broad-spectrum insecticides provide control of multiple life stages of E. viteana, integration of tebufenozide or methoxyfenozide into vineyard management programs for control of this pest will be most successful if applications are timed for egg hatch.

The effect of prohexadione-calcium, a plant growth regulator that inhibits gibberellin metabolism, on Cacopsylla pyricoloa (Foerster) in pear trees, and Choristoneura rosaceana (Harris) and Aphis spireacola Patch, in apple trees was studied. C. pyricoloa and A. spireacola populations were significantly reduced in prohexadione-calcium-treated pear and apple, respectively. Insecticide control of both pests with imidacloprid was synergized in treatments with prohexadione-calcium. In apples treated with prohexadione-calcium, there was a significant reduction in the number of C. rosaceana shelters per tree and amount of fruit injury at harvest attributable to the C. rosaceana. There was an additive effect when tebufenozide was used to control C. rosaceana in trees treated with prohexadione-calcium. Prohexadione-calcium significantly reduced vegetative growth in both pears and apples. Synergistic and additive treatment effects of prohexadione-calcium and pesticides used in this study may be due to better penetration and coverage of pesticides due to reduced foliar growth or to changes in the nutritional quality of the host plants.

Two insecticide formulations containing the naturalyte insecticide spinosad, GF-120 Fruit Fly Bait and SpinTor 2 SC, were compared for control of apple maggot, Rhagoletis pomonella (Walsh), and blueberry maggot, Rhagoletis mendax Curran. In 2002 and 2003, larval infestation in blueberries and apples was significantly lower in plots treated with GF-120 (spinosad bait) or SpinTor than in untreated control plots. Fruit fly infestation in apples was reduced by 67% in 2002 after weekly application of GF-120 for 6 wk. Six weeks of GF-120 treatment reduced infestation in blueberries by 85% in 2002 and 98% in 2003. Plots treated weekly with the bait component of GF-120 for 6 wk had significantly higher infestation of blueberry maggot larvae compared with untreated plots in 2002. Observations of wild R. mendax flies revealed that similar numbers of flies landed on blueberry foliage treated with spinosad bait, the bait component alone, or water droplets. However, flies on spinosad bait and bait treated plants spent significantly more time within 5 cm of the treatment droplets compared with control (water) droplets. Overall, the results demonstrate a high degree of efficacy of baited spinosad formulations against these key pests of temperate fruit and suggest that GF-120 is an arrestant for foraging flies.

Toxicity of three biopesticides, i.e., two neem products and spinosad, was determined on foliage-dwelling life stages of Ceratothripoides claratris (Shumsher) (Thysanoptera: Thripidae), a major thrips pest on tomatoes, Lycopersicon spp., in central Thailand. Direct and residual contact toxicities of NeemAzal-TS (1% azadirachtin) and systemic activity of NeemAzal-MD 5 (5% azadirachtin) affected the survival of first larval stage (L1) in a concentration-dependent manner. However, neither second larval stage (L2) nor adult survival was influenced by both neem products. On the contrary, spinosad caused 100% mortality in both larval stages and adults of C. claratris regardless of the concentrations tested. No strong ovicidal effects were detected in three different age groups of eggs (i.e., 1, 2, and 3 d old) topically treated with both NeemAzal-TS and spinosad. Residual toxicity was highest with fresh residues of NeemAzal-TS compared with 1-, 3-, 5-, and 7-d-old residues and in general was higher under laboratory than greenhouse conditions. Irrespective of the age of the spray residues, spinosad always caused 100% mortality in larvae and adults. Strongest systemic effects were observed in L1 larvae 1 d after soil drenching with NeemAzal-MD 5 at the highest concentration tested. Foliar and soil applications of NeemAzal-TS and NeemAzal-MD 5, respectively, did not cause any oviposition deterrent effects.

Larvae of the diamondback moth, Plutella xylostella (L.) (Lepidoptera: Ypeunomutidae), cause severe economic damage to cabbage, Brassica oleracea L. variety capitata (Brassicaceae) and related vegetables in Thailand. Overuse of broad-spectrum insecticides for diamondback moth control is a serious problem and has obscured the contributions of indigenous parasitoids. Our objectives were to identify indigenous diamondback moth parasitoids in northern Thailand and to assess their potential for natural control. Six parasitoid species were reared from diamondback moth larvae and pupae collected in 1990 and in 2003–2004. These included the larval parasitoid Cotesia plutellae Kurdjumov (Braconidae), a larval-pupal parasitoid Macromalon orientale Kerrich (Ichneumonidae), and pupal parasitoids Diadromus collaris Gravenhorst (Ichneumonidae) and Brachymeria excarinata Gahan (Chalcididae). Single specimens of Isotima sp. Förster (Ichneumonidae) and Brachymeria lasus Walker (Chalcididae) also were reared from diamondback moth hosts. C. plutellae was the dominant larval parasitoid and was often reared from host larvae collected from fields sprayed regularly with insecticides; parasitism ranged from 14 to 78%. Average parasitism by M. orientale was only 0.5–6%. Parasitism of host pupae by D. collaris ranged from 9 to 31%, whereas B. excarinata pupal parasitism ranged from 9 to 25%. An integrated pest management (IPM) protocol using simple presence-absence sampling for lepidopterous larvae and the exclusive use of Bacillus thuringiensis (Bt) or neem resulted in the highest yields of undamaged cabbage compared with a control or weekly sprays of cypermethrin (local farmer practice). IPM programs focused on conservation of local diamondback moth parasitoids and on greater implementation of biological control will help alleviate growing public concerns regarding the effects of pesticides on vegetable growers and consumers.

Experiments were conducted to assess the damage of the glasshouse cucumber by twospotted spider mite, Tetranychus urticae Koch, and to investigate when the economic yield begins to decrease after T. urticae infestations. To assess the damage, dry matter partitioning in the cucumber plant was quantified and plant growth analyses were conducted at four different T. urticae infestation levels. T. urticae infestations decreased leaf productivity by reducing the total number of leaves per plant. Approximately 14% reductions of total leaf areas could result in significant yield loss. The decreased leaf productivity by T. urticae feeding caused biomass reductions and altered the pattern of dry matter partitioning in the plant; damaged plants accumulated more dry matter in the leaf, and partitioning of dry matter to fruits was hindered. The economic yield of cucumber began to significantly decrease as early as 4 wk after heavy mite infestations. This study also showed the seasonal differences in T. urticae–cucumber damage interactions among mite infestation levels.

In the Mediterranean Basin, developed diapausing larvae of the borer Sesamia nonagrioides Lefèbvre are found consistently during autumn in transgenic corn, Zea mays L., expressing Bacillus thuringiensis Berliner (Bt) toxins derived from event 176. These larvae can feed on sublethal concentrations of Bt toxins because the expression of this corn toxin declines after flowering. To evaluate the possible consequences of this phenomenon, the effect of sublethal concentrations of the natural toxin producer, B. thuringiensis variety kurstaki (Dipel DF) on the performance of S. nonagrioides in the laboratory was examined. Larvae treated with Dipel DF showed higher mortality, longer developmental time, extra molts, and higher sensitivity to critical daylength for diapause induction than the untreated larvae. Accordingly, diapausing larvae collected in October and February in a Bt cornfield exhibited a higher number of supernumerary molts before pupating and longer diapause development than larvae collected in a non-Bt field at the same time. These results demonstrate that deployment of Bt corn in the Mediterranean may affect both the borer performance and the development of Bt resistance in addition to direct mortality caused by the Bt toxin.

Wood discs decayed with brown rot fungi and polymer discs impregnated with acetone extract of decayed wood were embedded in sand of a two-dimensional foraging arena to evaluate their attractant potential in directing termite tunnels toward them. Termites were released near one arena corner and were guided to follow the physical guideline of the arena edges. In the absence of the attractants, termites generally formed a relatively linear tunnel along the edges. When decayed wood discs or treated polymer discs were placed in wet sand near one side of the arena, termite tunnels departed from the arena edges and were oriented toward them. The attraction distance ranged from 12 to 18 cm. The attractant properties were most likely water soluble and permeated through wet sand to cause termites to change their orientation. The results demonstrated that when such attractants are placed near a bait station in the field, they may be used to direct termite foraging toward the station.

Subterranean termites, Reticulitermes spp., were attracted to carbon dioxide (CO₂) in laboratory and field tests. In behavioral bioassays, Reticulitermes flavipes (Kollar), Reticulitermes tibialis Banks, and Reticulitermes virginicus Banks were attracted to CO₂ concentrations between 5 and 50 mmol/mol. In further bioassays, R. tibialis and R. virginicus were attracted to the headspace from polyisocyanurate construction foam that contained 10–12 mmol/mol CO₂. In soil bioassays in the laboratory, more termites foraged in chambers containing CO₂-generating formulations than in unbaited control chambers. In field tests, stations containing CO₂-generating baits attracted R. tibialis away from wooden fence posts at rangeland sites in Colorado. For all of the CO₂ formulations tested, termites foraged in significantly more bait stations at treatment fenceposts than in bait stations at the control fenceposts. By the end of the 8-wk study, the number of bait stations located by termites at treatment fenceposts ranged from 40 to 90%. At control fenceposts, termites foraged in only a single station and the one positive station was not located by termites until week 5 of the study. At treatment fenceposts, termites foraged equally in active stations (containing a CO₂-generating bait) and passive stations (with no CO₂-generating bait), indicating that bait stations may benefit passively from a proximal CO₂ source in the soil. CO₂ used as an attractant in current baiting systems could improve their effectiveness by allowing earlier exposure of termites to an insecticide.

Five selected insecticides were applied to four substrates and evaluated in laboratory studies for repellency and toxicity against the Pharaoh ant, Monomorium pharaonis (L.). We tested both repellent and nonrepellent formulations on outdoor (concrete and mulch) and indoor (ceramic and vinyl) substrates. Repellency was evaluated using a behavioral bioassay in which colonies were given a choice to leave the treated zone and move into empty nests provided in the untreated zone. We used a novel experimental design whereby ants walked on a Slinky coil suspended from a metal support frame, thus permitting a long foraging distance with a minimum use of space and resources. Cypermethrin, a repellent pyrethroid insecticide, resulted in colony budding, although the response was delayed. Toxicity of insecticides was evaluated as worker, queen, and brood mortality. The most effective treatment was fipronil, which provided 100% reduction in pretreatment activity by 2 d posttreatment on both concrete and mulch. Chlorfenapyr was highly effective on both outdoor and indoor substrates. Significant substrate effects were observed with insecticides applied to nonabsorbent substrates (ceramic tile), which performed better than insecticides applied to absorbent substrates (vinyl tile). Other highly absorbent materials (mulch and concrete), however, did not reduce insecticide efficacy. This is because ants relocated nests into and/or under these attractive nesting materials, thus increasing their exposure to toxic insecticide residues. Our results demonstrate efficacy of nonrepellent liquid insecticides as indoor treatments for the control of Pharaoh ants and possibly as exterior perimeter treatments.

We evaluated the effects of interspecific competition on ant bait performance with two urban pest ants, the Argentine ant, Linepithema humile (Mayr), and the little black ant, Monomorium minimum (Buckley). In a laboratory study, the impact of a solid sulfluramid bait on M. minimum was diminished when L. humile were present, whereas the presence of M. minimum reduced the performance of a liquid fipronil bait against L. humile. Argentine ants were not adversely affected by sulfluramid bait at any time, whereas M. minimum was unaffected by fipronil bait until 14 d of exposure. In field studies measuring diel foraging activity, M. minimum seemed to delay L. humile foraging to food stations by ≈30 min during summer 2001. However, L. humile subsequently recruited to food stations in very high numbers, thereby displacing M. minimum. L. humile visited food stations over an entire 24-h period, whereas M. minimum was only observed visiting food stations during daylight hours. Adjusting the timing of bait placement in the field may minimize any negative effects of interspecific competition between these two species on toxic bait performance.

This study evaluated the effect of Summon Preferred Food Source on feeding, tunneling, and bait station discovery by the Formosan subterranean termite, Coptotermes formosanus Shiraki. Bioassays were conducted to determine whether Summon disks affected the aggregation and feeding behavior of termites and to determine whether the presence of Summon disks caused increased recruitment of termites to wood blocks. When termites encountered the disk, they immediately clustered on top of the disk. Termites were observed aggregating on top of the disk throughout the experiment. Consumption of Summon disks was significantly greater than consumption of cardboard disks in paired choice tests. The presence of a Summon disk on top of a wood block caused a significant increase in consumption of the wood block. Bioassays also were conducted to determine whether water extracts of Summon disks affected termite behavior. Consumption of filter paper disks treated with a water extract of Summon disks was significantly greater than consumption of control filter paper disks. Termites tunneled through sand treated with a water extract of Summon disks faster than they tunneled through untreated sand. In a field test, the rate of infestation of monitoring stations with a Summon disk was 3 times greater than the rate of infestations of stations without a disk.

The efficacy and nonrepellency of indoxacarb (150 SC, 150 g [AI]/liter) and fipronil (Termidor SC, 9.1% [AI]) against field-collected eastern subterranean termite, Reticulitermes flavipes (Kollar), and the Formosan subterranean termite, Coptotermes formosanus Shiraki, were evaluated for mortality and penetration into treated soil in laboratory glass tube bioassays. Both insecticides were tested at five concentrations (0, 1, 10, 50, and 100 ppm) and two thicknesses (20 and 50 mm) of treated soil. Indoxacarb caused significantly greater mortality than controls at all treatment thicknesses of ≥10 ppm, but not at 1 ppm. Concentration and treatment thickness of indoxacarb significantly affected termite mortality. Eastern subterranean termites were significantly more susceptible to indoxacarb than Formosan subterranean termites, but there were no intercolony differences in either species. Termites completely penetrated through all treatment thickness of indoxacarb-treated soil at all concentrations, except one of the six Formosan subterranean termite replicates of 50 mm at 50 ppm, when all termites were killed before tunneling through the treated soil. Fipronil resulted in significantly faster and greater termite mortality than indoxacarb at corresponding concentrations. Concentration and treatment thickness of fipronil also significantly affected termite mortality. There was no intercolony difference in susceptibility to either insecticide in either termite. Both termite species completely penetrated 20-mm treatments of all tested fipronil concentrations, as well as 50-mm soil treated with fipronil at ≤10 ppm. At 50 and 100 ppm fipronil, termites tunneled only a mean of 87 ± 0.21 and 47 ± 0.18% deep into 50-mm treated soil, respectively, before death. Both insecticides demonstrated a delayed mode of activity and nonrepellency against the two termite species.

We expanded a simulation model of the population dynamics and genetics of the western corn rootworm for a landscape of corn, soybean, and other crops to study the simultaneous development of resistance to both crop rotation and transgenic corn. Transgenic corn effective against corn rootworm was recently approved in 2003 and may be a very effective new technology for control of western corn rootworm in areas with or without the rotation-resistant variant. In simulations of areas with rotation-resistant populations, planting transgenic corn to only rotated cornfields was a robust strategy to prevent resistance to both traits. In these areas, planting transgenic corn to only continuous fields was not an effective strategy for preventing adaptation to crop rotation or transgenic corn. In areas without rotation-resistant phenotypes, gene expression of the allele for resistance to transgenic corn was the most important factor affecting the development of resistance to transgenic corn. If the allele for resistance to transgenic corn is recessive, resistance can be delayed longer than 15 yr, but if the resistant allele is dominant then resistance usually developed within 15 yr. In a sensitivity analysis, among the parameters investigated, initial allele frequency and density dependence were the two most important factors affecting the evolution of resistance. We compared the results of this simulation model with a more complicated model and results between the two were similar. This indicates that results from a simpler model with a generational time-step can compare favorably with a more complex model with a daily time-step.

Western corn rootworm, Diabrotica virgifera virgifera LeConte, has overcome crop rotation in several areas of the north central United States. The effectiveness of crop rotation for management of corn rootworm has begun to fail in many areas of the midwestern United States, thus new management strategies need to be developed to control rotation-resistant populations. Transgenic corn, Zea mays L., effective against western corn rootworm, may be the most effective new technology for control of this pest in areas with or without populations adapted to crop rotation. We expanded a simulation model of the population dynamics and genetics of the western corn rootworm for a landscape of corn; soybean, Glycine max (L.); and other crops to study the simultaneous development of resistance to both crop rotation and transgenic corn. Results indicate that planting transgenic corn to first-year cornfields is a robust strategy to prevent resistance to both crop rotation and transgenic corn in areas where rotation-resistant populations are currently a problem or may be a problem in the future. In these areas, planting transgenic corn only in continuous cornfields is not an effective strategy to prevent resistance to either trait. In areas without rotation-resistant populations, gene expression of the allele for resistance to transgenic corn, R, is the most important factor affecting the evolution of resistance. If R is recessive, resistance can be delayed longer than 15 yr. If R is dominant, resistance may be difficult to prevent. In a sensitivity analysis, results indicate that density dependence, rotational level in the landscape, and initial allele frequency are the three most important factors affecting the results.

Susceptibility to carbaryl in six Mexican strains of the southern cattle tick, Boophilus microplus (Canestrini), was evaluated with the Food and Agricultural Organization larval packet test. Tick strains from the cattle fever tick quarantine zone in Texas were more susceptible to carbaryl than to coumaphos or diazinon. Compared with the susceptible reference (Gonzalez) strain, Mexican tick strains demonstrated 10.9–59.5-fold resistance to carbaryl. Significant cross-resistance was found between carbaryl and the organophosphate acaricides coumaphos and diazinon. Bioassay results with synergists suggested that metabolic detoxification mechanisms did not play a major role in carbaryl resistance. Resistance to carbaryl was likely conferred by insensitive acetylcholinesterase. The implications of carbaryl resistance in tick eradication and control also are discussed.

Bemisia tabaci (Gennadius) and Aphis gossypii Glover are devastating melon, Cucumis melo L., pests. The geographic areas where they occur overlap, and the same chemicals are used to control both of them. Therefore, to reduce pesticide use, it would be necessary to breed melon lines that simultaneously express a resistance to both insects. Female survival; the time when reproduction starts, peaks, and ends; the number of female offspring at the reproductive peak; and total reproduction (S) were determined under semicontrolled conditions for B. tabaci kept in clip-cages on a susceptible melon genotype Vedrantais, and 12 potential resistant accessions, particularly genotypes expressing the Vat gene controlling resistance to A. gossypii. By using the Lewontin triangular reproductive function and Bootstrapping, the intrinsic rate of increase (r) and its variance were calculated. Statistical analysis showed that the parameter S was as relevant as r for discriminating between the melon accessions. Three genotypes were potential genitors of resistance to the whitefly: PI 161375, PI 414723, and PI 532841. Those possessing the Vat gene were either resistant (PI 161375 and PI 414723) or susceptible (Margot, IsoVat R, and AR 5). This demonstrated the ineffectiveness of Vat against B. tabaci. In this article, we propose a strategy to breed lines that express resistance to aphids and whiteflies on the short term.

The noctuid Helicoverpa armigera (Hübner) is a major insect pest of chickpea Cicer arietinum L., pigeonpea Cajanus cajan (L.) Millsp., peanut Arachis hypogaea L., and cotton Gossypium spp., and host plant resistance is an important component for managing this pest in different crops. Because of variations in insect density and staggered flowering of the test material, it is difficult to identify cultivars with stable resistance to H. armigera across seasons and locations. To overcome these problems, we standardized the detached leaf assay to screen for resistance to this pest in chickpea, pigeonpea, peanut, and cotton under uniform insect pressure under laboratory conditions. Terminal branch (three to four fully expanded leaves) of chickpea, first fully expanded leaf of cotton, trifoliate of pigeonpea, or quadrifoliate of peanut, embedded in 3% agar-agar in a plastic cup/jar of appropriate size (250–500-ml capacity) infested with 10–20 neonate larvae can be used to screen for resistance to H. armigera. This technique keeps the leaves in a turgid condition for ≈1 wk. The experiments can be terminated when the larvae have caused >80% leaf damage in the susceptible check or when differences in leaf feeding between the resistant and susceptible checks are maximum. Detached leaf assay can be used as a rapid screening technique to evaluate germplasm, segregating breeding materials, and mapping populations for resistance to H. armigera in a short span of time with minimal cost, and under uniform insect infestation. It also provides useful information on antibiosis component of resistance to the target insect pest.

Transgenic lines of soybean, Glycine max (L.) Merrill, expressing a synthetic cry1A gene (tic107) from Bacillus thuringiensis (Bt), were evaluated in screenhouse and conventional field trials for efficacy against lepidopteran pests. In screenhouse trials, Bt soybean and negative checks (isogenic segregants and parental lines) were evaluated against Anticarsia gemmatalis Hübner and Pseudoplusia includens (Walker) in the United States and against A. gemmatalis, Epinotia aporema (Walsingham), Rachiplusia nu (Guenée), and Spilosoma virginica (F.) in Argentina. Bt soybean exhibited virtually complete efficacy against each of these pests, whereas negative checks suffered significant damage. Bt soybean and negative checks also were evaluated in conventional trials against native populations of A. gemmatalis and P. includens in the southeastern United States. Each of these insects caused significant damage to negative checks in one or more locations, whereas Bt soybean exhibited virtually complete efficacy against these pests. In the laboratory, lyophilized leaf tissues from Bt soybean incorporated in artificial diet at a concentration representing a 25-fold dilution of fresh tissue caused complete mortality of A. gemmatalis and near complete mortality of P. includens neonates after 11 d, whereas mortality on negative checks did not exceed 10% for either insect. Average TIC107 expression approached or exceeded 50 μg/g fresh weight at V3 stage of growth and 200 μg/g by R6 stage of growth. These results demonstrate that expression of TIC107 in soybean can not only achieve highly efficacious control of several lepidopterans under field conditions but also provide a high dose for effective insect resistance management.

RESUMEN Se evaluó resistencia a plagas lepidópteras de lineas de soja transgénicas, Glycine max (L.) Merrill, que expresan un gen cry1A sintético (tic107) de Bacillus thuringiensis (Bt), en ensayos a campo, con y sin jaulas. En ensayos con jaulas, las sojas Bt y los testigos negativos (segregantes isogénicos y líneas parentales) fueron evaluadas frente a Anticarsia gemmatalis Hübner y Pseudoplusia includens (Walker) en los EE.UU. de A. y frente a A. gemmatalis, Epinotia aporema (Walsingham), Rachiplusia nu (Guenée), y Spilosoma virginica (F.) en Argentina. La soja Bt exhibió una eficacia virtualmente total frente a cada una de las plagas, mientras que los testigos negativos sufrieron un significativo daño. La soja Bt y los testigos negativos también fueron evaluados en ensayos convencionales frente las poblaciones naturales de A. gemmatalis y P. includens en el sudeste de los EE.UU. de A. Cada uno de estos insectos causó daño significativo a los testigos negativos en una o más localidades, mientras que la soja Bt mostró una eficacia virtualmente total a dichas plagas. En el laboratorio, tejidos foliares liofilizados provenientes de soja Bt incorporados en dieta artificial a una concentración que representa una dilución de 25 veces la del tejido fresco, causó total mortalidad de neonatas de A. gemmatalis y casi completa mortalidad de neonatas de P. includens, luego de 11 días, mientras que la mortalidad en los testigos negativos no excedió el 10% en ambos insectos. La expresión de TIC107 promedió se aproximó o excedió los 50 μg/g de peso fresco en estado V3 de crecimiento y los 200 μg/g en estado R6. Estos resultados demuestran que la expresión de TIC107 en soja no sólo puede lograr un control altamente eficaz de varios lepidópteros en condiciones de campo, sino también proveer una alta dosis para un efectivo manejo de resistencia de insectos.

A field experiment was conducted to determine whether resistance to Russian wheat aphid, Diuraphis noxia (Mordvilko), conferred by the Dn4 gene is affected by genetic background. This was done by comparing the yield responses to Russian wheat aphid-resistant wheat containing Dn4, derived through the backcross method, to those of the corresponding recurrent parents. Infested resistant cultivars had fewer Russian wheat aphids per tiller than infested susceptible cultivars at the Lamar and Fort Collins, CO sites but not at the Akron, CO site. At the Lamar site, resistant cultivars yielded more than the susceptible cultivars. ‘Prairie Red’ and ‘Yumar’ were more resistant than ‘Prowers’, especially at the higher infestation level. Resistance in these cultivars was categorized in a laboratory experiment to confirm this differential expression of resistance. Resistance in Prairie Red, ‘Halt’, ‘Prowers 99’, and Yumar was categorized at three plant growth stages. Antibiosis was expressed as reductions in maximum number of nymphs produced per 24 h and intrinsic rate of increase. The maximum number of nymphs produced per 24 h was reduced in Halt and ‘Lamar’. Averaged over cultivars, the intrinsic rate of increase was less at jointing than at the seedling or tillering growth stages. Tolerance was expressed in the resistant cultivars as reduced chlorosis and leaf rolling. Growth reductions in infested Prowers 99 plants was less than the other cultivars. This study confirms that some cultivars containing Dn4 may express antibiosis and tolerance, whereas others may not show the same categories. Thus, expression is affected by genetic background.

Genetic linkage maps are fundamental for the localization of genes conferring tolerance to greenbug, Schizaphis graminum (Rondani), feeding damage in sorghum, Sorghum bicolor (L.) Moench. Thirteen linkage groups (LGs) containing 60 simple sequence repeat (SSR) loci were mapped by using a set of sorghum recombinant inbred lines (RILs) obtained from the cross ‘96-4121’ (greenbug-tolerant parent) × Redlan (greenbug-susceptible parent). The LG spanned a distance of 603.5 cM, with the number of loci per LG varying from 2 to 14. Seventeen additional SSR loci were unlinked at a log of odds value of 3.0. Based on chlorophyll loss occurring after greenbug feeding, visual damage ratings, and soil plant analysis development (SPAD), chlorophyll–loss indices were recorded for each RIL and for the parents used in the cross. Composite-interval mapping identified three quantitative trait loci (QTLs) associated with biotype I and five QTLs associated with biotype K. The amount of phenotypic variation explained by these QTLs ranged from 9 to 19.6%. The identification of QTLs that influence greenbug tolerance will not only facilitate the use of marker-assisted selection in sorghum breeding programs but also will provide a solid foundation for detailed characterization of individual loci implicated in greenbug tolerance in sorghum.

Experiments were conducted to identify and characterize host plant resistance to bird cherry-oat aphid, Rhopalosiphum padi (L.), in various wheat and wheat–grass hybrids. Initial tests screened for resistance to R. padi among 12 grass accessions (eight wheat [Triticum aestivum L.], three triticale [XTriticosecale Wittmack], and 1XElytricum [Elytrigia elongata [Host] Nevski × Triticum aestivum hybrid]). R. padi had less population growth on triticale accessions ‘8TA5L’ (PI 611760) and ‘Stniism 3’ (PI 386156) than on other accessions, but nymphiposition by R. padi did not differ among the 12 accessions. Follow-up experiments were conducted to characterize antibiosis, antixenosis, and tolerance to R. padi in three wheat and three triticale accessions. In antibiosis experiments, Stniism 3 and triticale ‘H7089-52’ (PI 611811) prolonged time to reproduction by R. padi compared with that on wheat accessions ‘Arapahoe’ (PI 518591), ‘KS92WGRC24’ (PI 574479), and ‘MV4’ (PI 435095), whereas time to reproduction on 8TA5L was intermediate and did not differ from that on the other five accessions. Also, R. padi produced fewest progeny on Stniism 3, and fewer progeny on 8TA5L than on H7089-52, Arapahoe, KS92WGRC24, and MV4. Stniism 3 showed antixenosis, because fewer winged R. padi selected Stniism 3 than Arapahoe, H7089-52, or MV4 in choice tests. In tolerance experiments, a 300 aphid-day infestation of R. padi limited shoot length of Arapahoe and KS92WGRC24 plants. Shoot lengths did not differ between infested and noninfested seedlings of MV4, 8TA5L, H7089-52, and Stniism 3, indicating tolerance to R. padi in these accessions. Triticale accessions 8TA5L, H7089-52, and Stniism 3 and MV4 wheat may be meaningful sources of R. padi resistance for small-grain breeding programs, and Stniism 3 may be particularly valuable, given reports of its additional resistance to the Russian wheat aphid, Diuraphis noxia (Mordvilko).

Large-scale screening of cassava, Manihot esculenta Crantz, genotypes for resistance to infestation by whitefly Bemisia tabaci Gennadius, the vector of cassava mosaic geminiviruses, is limited. A range of new cassava elite clones were therefore assessed for the whitefly infestation in the 1999/2000 and 2000/2001 cropping seasons in experimental fields of International Institute of Tropical Agriculture, Ibadan, Nigeria. On each scoring day, between 0600 and 0800 hours when the whiteflies were relatively immobile, adult whitefly populations on the five topmost expanded leaves of cassava cultivars were counted. All through the 6-mo scoring period, there was a highly significant difference in whitefly infestation among the new cassava elite clones. Vector population buildup was observed in Ibadan (forest–savanna transition zone) and Onne (humid forest), 2 mo after planting (MAP). Mean infestation across cassava genotypes was significantly highest (16.6 whiteflies per plant) in Ibadan and lowest in Zaria (0.2). Generally, whitefly infestation was very low in all locations at 5 and 6 MAP. During this period, cassava genotypes 96/1439 and 91/02324 significantly supported higher infestations than other genotypes. Plants of 96/1089A and TMS 30572 supported the lowest whitefly infestation across cassava genotypes in all locations. The preferential whitefly visitation, the differences between locations in relation to whitefly population, cassava mosaic disease, and the fresh root yield of cassava genotypes are discussed.

Indianmeal moth, Plodia interpunctella (Hübner), is classified as a freeze-intolerant organism and one of the most cold-tolerant stored-product pests. The objective of this study was to determine the relationship between mortality at low temperatures after minimum exposure and the supercooling point (SCP) for laboratory-reared P. interpunctella at different stages of development. This relationship also was analyzed for field-collected, cold-acclimated fifth instars. Mean SCP of laboratory-reared larvae (i.e., feeding stage) was consistently above ≈−16°C. Mean SCP of laboratory-reared pupae and adults (i.e., nonfeeding stages) and field-collected, cold-acclimated fifth instars was consistently below ≈−21°C. The SCP seemed to be the boundary between survival and death for larvae. However, it seemed that a 1-min exposure was not sufficient to cause larval mortality at the SCP. Alternatively, for both pupae and adults, the SCP seemed not to play an important role in their survival at low temperatures, with significant mortality observed at temperatures higher than the mean SCP. Adults were the most susceptible to low temperatures with no survival occurring at −20°C, >3°C above its mean SCP. Results of this investigation demonstrate that P. interpunctella has a different response to low temperatures depending on stage of development and cold acclimation. Classifying P. interpunctella only as a freeze-intolerant organism disregards the occurrence of prefreeze mortality in this species. Therefore, a reclassification of this species (e.g., chill tolerant or chill susceptible) based on the extent of prefreeze mortality and the temperature and time of exposure at which it occurs is suggested.

Managing stored-product insect pests by heating the ambient air of a food-processing facility to high temperatures (50–60°C), also referred to as heat treatment, is an effective technology that has been used since the early 1900s. The minimum temperature during heat treatment for effective disinfestation is 50°C. The effect of sublethal exposures to 50°C on the reproductive performance of stored-product insects associated with food-processing facilities is unknown. The red flour beetle, Tribolium castaneum (Herbst), is a pest commonly found in food-processing facilities worldwide. The adverse effects on fecundity, egg-to-adult survival, and progeny production of T. castaneum exposed as 1-d-old pupae and 2-wk-old adults to 50°C for 60 and 39 min, respectively, were determined in the laboratory. Pupae and adults exposed for the same time periods at 28°C served as the control treatment. Four possible reciprocal crosses were carried out among adults from the heat-treated (50°C) and control (28°C) treatments. The number of eggs produced during the first 2 wk of adult life, survival of these eggs to adulthood, and adult progeny production after 2 and 8 wk of oviposition in treatments representing all four reciprocal crosses were determined. Fecundity, egg-to-adult survival, and adult progeny production decreased by 17–63, 52–63, and 66–78%, respectively, when males, females, and both males and females were exposed to 50°C. These effects were relatively more pronounced in treatments in which pupae were exposed to the high temperature compared to adults, and in exposed females than in males. The impaired reproductive performance in T. castaneum pupae and adults surviving sublethal exposures to the minimum heat treatment temperature is valuable for understanding population rebound following a heat treatment intervention.