Indoor fumigation of honey bees, Apis mellifera L., with formic acid to control varroa mites, Varroa destructor Anderson & Trueman, allows simultaneous fumigation of multiple colonies with little labor input and good efficacy. Several experiments were designed to test the efficacy of formic acid as a treatment for honey bee mites, Acarapis woodi (Rennie) (Acari: Tarsonemidae), and nosema disease, Nosema sp., indoors in winter. The objectives of this study were 1) to determine the efficacy of formic acid fumigation for honey bee mite control by using both the thoracic slice and live dissection methods and 2) to determine whether indoor fumigation can reliably prevent the buildup of nosema disease in overwintering honey bee colonies. Indoor winter fumigation of honey bee colonies with formic acid was effective in killing a high percentage of honey bee mites but did not significantly reduce the proportion of bees with infested tracheae over the duration of the experiments. Thus, the method used to determine the efficacy of the treatment affected the results. Under conditions of relatively low or decreasing levels of nosema, fumigation tended to suppress the mean abundance of nosema spores relative to the controls. In three separate fumigation experiments using a range of formic acid concentrations, there was no statistical difference between the buildup or maintenance of nosema spore mean abundance over the winter in bees from formic acid fumigated colonies compared with untreated controls. However, fumigation with formic acid during winter at a low concentration for extended periods significantly suppressed spore buildup of mixed populations of nosema (Nosema apis and Nosema ceranae) in 1 yr.

Stingless bees are potential pollinators of commercial tropical crops and their use may increase in the short term. However, studies comparing the toxicity of pesticides to different individuals and species are lacking, making it difficult to evaluate their short- and long-term effects on colonies and populations of these insects. In this work, we tested the lethality of compounds from the main pesticide groups on stingless bees of the species Melipona beecheii Bennett, Trigona nigra Provancher, and Nannotrigona perilampoides Cresson. The LD₅₀ (in micrograms per bee) for each pesticide was calculated for callow workers and foragers of the three species as well as for gynes and drones of M. beecheii. The results showed that all species were highly susceptible to the evaluated compounds. Nicotinoid pesticides were the most toxic, followed in descending order by permethrin, diazinon, and methomyl. We found evidence of a relationship between the body weight of the species and their LD₅₀ for permethrin and methomyl (r = 0.91 and 0.90, respectively) but not for diazinon (r = -0.089). An analysis of contingency tables showed that within each species, callow workers had higher mortalities than foragers (P < 0.01). In M. beecheii at similar pesticide dose more males died compared with females [χ²_(0.01),1 = 10.16]. However, gynes were less resistant than workers [χ²_(0.01),1 = 8.11]. The potential negative consequences of pesticides to native stingless bees are discussed considering the reproductive biology of these insects. It is important to take actions to prevent damage to these key species for the ecology and agriculture of México and Latin America.

Yellow sticky traps were placed in six vineyards in central Texas from 2003 to 2006 and in locations outside the vineyards in 2004–2006. In total, 72 collections on 55 dates were examined. Xylem fluid-feeding insects were removed and identified to species and then analyzed by polymerase chain reaction to determine the presence or absence of Xylella fastidiosa Wells et al. Of the 1318 insects removed, 13 species were found, dominated by Homalodisca vitripennis (Germar), Clastoptera xanthocepahala Germar, and Graphocephala versuta (Say). Insects testing positive for X. fastidiosa were analyzed further using fluorescence resonance energy transfer probes to determine the genotype of the bacterium, which fell into four groups: subspecies fastidiosa, multiplex, sandyi, and unknown subspecies. Vineyards known to be affected by Pierce's disease had more insects that were contaminated by the bacterium than those that were not as affected. X. fastidiosa subsp. fastidiosa, the causative agent of Pierce's disease, was found more commonly in insects collected from vineyards than from insects collected outside the vineyards. Conversely, the subspecies multiplex and sandyi, which are not known to cause disease in grape, were more commonly found in insects collected outside the vineyard. The percentage of individuals contaminated with the bacterium increased over the course of the growing season, and the data suggest that vector insects acquired X. fastidiosa subsp. fastidiosa from infected grapevines, a necessary precursor for vine to vine transmission to occur. Management options, including the use of systemic insecticides and plant roguing, would be effective for this type of transmission model.

The rove beetle Atheta coriaria (Kraatz) (Coleoptera: Staphylinidae) is a natural enemy (biological control agent) commercially available for control of certain greenhouse insect pests, including fungus gnats, shore flies, and thrips. This study assessed the compatibility of pesticides (insecticides and fungicides) used in greenhouses with A. coriaria adults. Treatments were applied to 473-ml deli squat containers half-filled with a growing medium. We evaluated the effects of the pesticides when releases of A. coriaria adults were performed both before and after application of the designated pesticide solutions. All three of the neonicotinoid-based insecticides (clothianidin, dinotefuran, and thiamethoxam) were directly harmful to A. coriaria adults with ≤3.2 adults recovered (out of 20) among all three treatments across all experiments. In addition, the organophosphate insecticide chlorpyrifos at the low (0.25 fl oz/100 gal) and high (0.50 fl oz/100 gal) label rates; the plant-derived essential oil product (Indoor Pharm) containing soybean and rosemary oil; and the insecticide/miticide chlorfenpyr were directly harmful to A. coriaria adults with recovery rates ≤8.6 (out of 20) among all the treatments. The fungicides (azoxystrobin, fosetyl-aluminum, and mefenoxam) were not directly toxic to A. coriaria adults, with ≥17.7 adults recovered (out of 20) across all experiments. The insecticides (Bacillus thuringiensis subsp. israelensis, flonicamid, Metarhizium anisopliae strain52, and spinosad) and insect growth regulator azadirachtin were also not directly toxic to A. coriaria adults. Furthermore, many of these same treatments did not inhibit the ability of adult A. coriaria to consume fungus gnat (Bradysia sp. nr. coprophila) larvae in a feeding behavior experiment. Although the neonicotinoid-based insecticides were directly harmful to adult A. coriaria, when adults were released 48, 72, or 96 h after application, survival increased dramatically over time. This study has quantitatively demonstrated that certain pesticides (both insecticides and fungicides) are compatible with and can be used along with A. coriaria in systems that use this natural enemy to manage fungus gnat larvae.

Soyscreen oil was studied as a formulation ingredient to protect Beauveria bassiana (Balsamo) Vuillemin conidia from UV degradation. Feruloylated soy glycerides, referred to as Soyscreen oil, are biobased UV-absorbing molecules made by combining molecules of soybean oil with ferulic acid. Conidia stored in Soyscreen oil for 28 wk at 25, 30, and 35°C retained viability as well as conidia stored in sunflower oil, demonstrating that Soyscreen did not adversely affect viability with prolonged storage. For samples applied to glass and exposed to simulated sunlight (xenon light), conidia in sunflower oil with or without sunscreens (Soyscreen or oxyl methoxycinnimate) had similar conidia viability after exposure. These oil formulations retained conidia viability better than conidia applied as an aqueous treatment. However, the 10% Soyscreen oil formulation applied to field grown cabbage (Brassica oleracea L.) and bean (Phaseolus vulgaris L.) plants, did not improve residual insecticidal activity compared with aqueous applications of unformulated conidia or two commercial formulations when assayed against Trichoplusia ni (Hübner) larvae. Our results suggest that the oil applications lose UV protection because the oil was absorbed by the leaf. This conclusion was supported in subsequent laboratory exposures of conidia in oil-based formulations with UV screens applied to cabbage leaves or balsa wood, which lost protection as measured by decreased viability of conidia when exposed to simulated sunlight. As a result, additional formulation techniques such as encapsulation to prevent separation of the protective oil from the conidia may be required to extend protection when oil formulations are applied in the field.

The addition of 1% (wt:vol) aqueous extracts of cocoa (Theobroma cacao L.) (Malvales: Malvaceae), coffee (Coffea arabica L.) (Gentianales: Rubiaceae), and green and black tea (Camellia sinensis L.) (Ericales: Theaceae) provided excellent UV radiation protection for the beet armyworm, Spodoptera exigua (Hübner) (Lepidoptera: Noctuidae), nucleopolyhedrovirus under laboratory conditions. Aqueous extracts of coffee, green tea, and black tea at 0.5% provided 85–100% UV protection, whereas cocoa provided 50% UV protection. Epigallocatechin gallate (EGCG), a component of green tea, and caffeine, a component of tea and coffee, also were tested as UV protectants. Both compounds were ineffective when tested alone. When EGCG and caffeine were combined, UV protection increased in a synergistic manner, but <35% of the original virus activity was maintained. This study demonstrated that coffee was comparable to green tea and black tea as a UV protectant. Further studies should be conducted to optimize their use in biopesticide formulations.

Irradiation has been recognized and endorsed as a potential phytosanitary measure that could be an alternative to current quarantine treatments. Dosages of 50, 100, 150, 200, and 250 Gy were used to irradiate three different life stages (eggs, immatures, and adults) of Planococcus minor (Maskell) (Hemiptera: Pseudococcidae), focusing on females due to its parthenogenesis ability, with an aim to find the most tolerant stage and the most optimal dose to control P. minor. Cobalt 60 was the source of irradiation used. Irradiation of 150–250 Gy has a significant effect on all life stages of P. minor, decreasing its survival rate, percentage of adult reproduction, oviposition, and fertility rate. The adult was the most tolerant life stage in both mortality and fertility rate. All the different irradiated target life stage groups oviposited eggs, but none of the F₂ eggs hatched at the most optimal dosage of 150–250 Gy.

There have been relatively few attempts to model the distributions of the fruit flies Ceratitis capitata (Wiedemann), Ceratitis cosyra (Walker), and Ceratitis rosa Karsch in China, but the geographic distributions of these species are of considerable concern in terms of biosecurity. In this study, two different modeling methods (genetic algorithm for rule-set prediction [GARP] and maximum entropy species distribution modeling [Maxent]) were used to predict the potential distributions of these three fly species in China, by using distribution records and a set of environmental predictor variables. The results showed that Maxent performed well, compared with modeling by GARP, at each test threshold. For all three species, the results predicted by Maxent agreed with the observed distributions in Africa and in other parts of the world. In China, C. capitata seems to have the highest number of favorable habitat areas, relative to C. cosyra and C. rosa, i.e., Yunnan, Guizhou, Guangxi, Guangdong, Hainan, Fujian, Sichuan and Chongqing, whereas C. cosyra has the smallest range of suitable areas, i.e., Yunnan, some parts of Hainan and Sichuan. The suitable areas for C. rosa are mainly restricted to Yunnan, Hainan, southern Guangdong, and a few areas of Sichuan. The indications are that on the whole, Southwest and South China are the areas with the highest risk for establishment from these three fly species. Jackknife tests reveal that environmental variables associated with temperature have the strongest influence on the potential distributions of all three species relative to other variables.

The current study is an important step toward calibrating, validating, and improving irradiation methods used for Bactrocera tryoni (Froggatt) sterile insect technique (SIT). We used routine International Atomic Energy Agency/U.S. Department of Agriculture/Food and Agriculture Organization quality control tests assessing percentage of emergence, flight ability, sex ratio, mortality under stress, reproductive sterility, and sexual competitiveness, as well as a nonstandard test of longevity under nutritional stress to assess the impact of a range of target irradiation doses (60, 65, 70, 75, and 80 Gy) on the product quality of mass reared B. tryoni used in SIT. Sterility induction remained adequate (>99.5%) for sterile male-fertile female crosses, and 100% sterility was achieved in fertile male-sterile female crosses and sterile male-sterile female crosses for each irradiation doses tested. There was significant increase in mortality under stress as irradiation dose increased, and reduced participation in mating by males irradiated at higher doses. The current target-sterilizing dose for SIT of 70–75 Gy is associated with significant reduction in fly product “quality.” Our data suggest that adequate sterility and improved fly quality could be achieved through a small reduction in target sterilizing dose.

“Mal de Río Cuarto,” is the most important virus disease of corn, Zea mays L., in Argentina. It is caused by the Mal de Río Cuarto virus (family Reoviridae, genus Fijivirus. MRCV), which is a persistent virus transmitted by Delphacodes kuscheli (Fennah 1955) (Hemiptera: Delphacidae). Because corn is not a natural host of D. kuscheli, it has little protection from this pest. In contrast, wheat, Triticum aestivum L., is one of the main hosts of this vector and a reservoir of MRCV. The aim of this work was to identify genes involved in antixenosis, antibiosis, and tolerance of infestation by D. kuscheli in wheat, which might be used to reduce the population level of this vector on corn. A set of recombinant dihaploid (RDH) lines for chromosome 6A derived from the F₁ cross between ‘Chinese Spring’ (CS) × ‘Chinese Spring (Synthetic 6A)’ (S6A) substitution line, was used for mapping. The S6A parental line is resistant to the MRCV vector. Antixenosis, antibiosis, and tolerance were evaluated using conventional tests in controlled environmental conditions. Most of the RDH and S6A showed higher levels of antixenosis against D. kuscheli than the parental line CS. The RDH lines showed highly significant antibiosis in terms of the duration of first, third, and fifth nymphal instars, developmental time (days), survival and fecundity. There were highly significant differences in the tolerance to D. kuscheli based on the chlorophyll content of the first and second leaves, foliar area, and aboveground fresh and dry weights. The duration of the fifth nymphal instar and the developmental period were significantly associated with Xgwm1017 marker loci, located at 48 cM on 6AL. Another quantitative trait locus accounting for the variation in chlorophyll content of the first leaf was associated with the interval between loci Xgwm459 and Xgwm334a, located in the telomeric region of the 6AS chromosome arm. The alleles with positive effects came from S6A. Antibiotic resistance of RDH could be useful for controlling the population increase of the MRCV vector on wheat, because prolonging the duration of development increases the period between two subsequent generations, so reducing the abundance of infective populations colonizing corn.

The death of honey bees, Apis mellifera L., and the consequent colony collapse disorder causes major losses in agriculture and plant pollination worldwide. The phenomenon showed increasing rates in the past years, although its causes are still awaiting a clear answer. Although neonicotinoid systemic insecticides used for seed coating of agricultural crops were suspected as possible reason, studies so far have not shown the existence of unquestionable sources capable of delivering directly intoxicating doses in the fields. Guttation is a natural plant phenomenon causing the excretion of xylem fluid at leaf margins. Here, we show that leaf guttation drops of all the corn plants germinated from neonicotinoid-coated seeds contained amounts of insecticide constantly higher than 10 mg/1, with maxima up to 100 mg/1 for thiamethoxam and clothianidin, and up to 200 mg/1 for imidacloprid. The concentration of neonicotinoids in guttation drops can be near those of active ingredients commonly applied in field sprays for pest control, or even higher. When bees consume guttation drops, collected from plants grown from neonicotinoid-coated seeds, they encounter death within few minutes.

Insect predators in North America suppress Aphis glycines Matsumura (Hemiptera: Aphididae) populations; however, insecticides are required when populations reach economically damaging levels. Currently, insecticides used to manage A. glycines are broad-spectrum (pyrethroids and organophosphates), and probably reduce beneficial insect abundance in soybean, Glycine max (L.) Merr. Our goal was to determine whether insecticides considered reduced-risk by the Environmental Protection Agency could protect soybean yield from A. glycines herbivory while having a limited impact on the aphid's natural enemies. We compared three insecticides (imidacloprid, thiamethoxam, and pymetrozine,) to a broad-spectrum insecticide (λ-cyhalothrin) and an untreated control using two application methods. We applied neonicotinoid insecticides to seeds (imidacloprid and thiamethoxam) as well as foliage (imidacloprid); pymetrozine and λ-cyhalothrin were applied only to foliage. Foliage-applied insecticides had lower A. glycines populations and higher yields than the seed-applied insecticides. Among foliage-applied insecticides, pymetrozine and imidacloprid had an intermediate level of A. glycines population and yield protection compared with λ-cyhalothrin and the untreated control. We monitored natural enemies with yellow sticky cards, sweep-nets, and direct observation. Before foliar insecticides were applied (i.e., before aphid populations developed) seed treatments had no observable effect on the abundance of natural enemies. After foliar insecticides were applied, differences in natural enemy abundance were observed when sampled with sweep-nets and direct observation but not with yellow sticky cards. Based on the first two sampling methods, pymetrozine and the foliage-applied imidacloprid had intermediate abundances of natural enemies compared with the untreated control and λ-cyhalothrin.

The tarnished plant bug, Lygus lineolaris (Palisot de Beauvois) (Hemiptera: Miridae), has become the primary target of foliar insecticides in cotton, Gossypium hirsutum L., throughout the Midsouth over the past several years. This prompted a reevaluation of existing action thresholds for flowering cotton under current production practices and economics. A trial was conducted at 19 locations throughout the Midsouth during 2006 and 2007. Threshold treatments ranged from a weekly automatic insecticide application to a very high threshold of 10 tarnished plant bugs per 1.5 row-m on a black drop cloth. Individually, all locations reached the lowest threshold, and eight locations had a significant yield loss from tarnished plant bugs. Across all locations, lint yield decreased 0.85 to 1.72% for each threshold increase of one tarnished plant bug per 1.5 row-m. Yield loss was most closely correlated to pest density during the latter half of the flowering period. The relationship between plant bug density or damage and yield was similar for drop cloth, sweep net, and dirty square sampling methods, but the correlations among these sampling methods were not high. Incorporating actual insecticide application data from the trial and average production and economic factors for Midsouth cotton, the economic threshold, if monitoring once per week, should be between 1.6 and 2.6 tarnished plant bugs per 1.5 row-m during the flowering period. More frequent monitoring or situations where insecticide applications are more efficacious may alter this threshold.

The rice water weevil, Lissorhoptrus oryzophilus Kuschel, is the most widely distributed and destructive early season insect pest of rice, Oryza sativa L., in the United States. Economic losses result primarily from feeding by the larval stage of this insect on the roots of flooded rice plants. Prior studies suggest that infestations of rice water weevil larvae are more severe at low plant densities. Moreover, because feeding by the rice water weevil reduces rice plant tillering, a process particularly important to yield at low seeding rates, infestations by weevil larvae may have a greater impact on rice yields when rice is seeded at low rates. In total, six experiments were conducted over a 3-yr period in Louisiana and Missouri to investigate the impacts of rice seeding rate on levels of infestations by, and yield losses from, the rice water weevil. An inverse relationship between seeding rate and densities of rice water weevil larvae and pupae on a per area basis was found in two of the six experiments. Furthermore, in two of the three experiments conducted with ‘Bengal’ (a susceptible cultivar) in Louisiana, percentages of yield loss were significantly higher at lower seeding rates than at higher seeding rates. Overall, these results indicate that rice sown at low rates is more vulnerable to infestation by rice water weevils and more susceptible to yield losses from weevil injury. The significance of these findings in light of recent trends toward the use of lower seeding rates in drill-seeded rice is discussed.

The western pine beetle, Dendroctonus brevicomis LeConte (Coleoptera: Curculionidae: Scolytinae), is a major cause of ponderosa pine, Pinus ponderosa Dougl. ex Laws., mortality in much of western North America. Currently, techniques for managing D. brevicomis infestations are limited. Verbenone (4,6,6-trimethylbicyclo [3.1.1] hept-3-en-2-one) is an antiaggregation pheromone of several Dendroctonus spp., including D. brevicomis, and it has been registered as a biopesticide for control of mountain pine beetle, Dendroctonus ponderosae Hopkins, and southern pine beetle, Dendroctonus frontalis Zimmermann. We evaluated the efficacy of a 5-g verbenone pouch [82%-(-); 50 mg/d] applied at 125 U/ha for protecting P. ponderosa stands (2 ha) from D. brevicomis attack over a 3-yr period. No significant differences in levels of D. brevicomis-caused tree mortality or the percentage of unsuccessfully attacked trees were found between verbenone-treated and untreated plots during each year or cumulatively over the 3-yr period. Laboratory analyses of release rates and chemical composition of volatiles emanating from verbenone pouches after field exposure found no deterioration of the active ingredient or physical malfunction of the release device. The mean release rate of pouches from all locations and exposure periods was 44.5 mg/ d. In a trapping bioassay, the range of inhibition of the 5-g verbenone pouch was determined to be statistically constant 2 m from the release device. We discuss the implications of these and other results to the development of verbenone as a semiochemical-based tool for management of D. brevicomis infestations in P. ponderosa stands.

Forced infestation studies were conducted to determine whether northern or southern highbush blueberries, Vaccinium corymbosum L., are hosts for the invasive tephritid fruit flies in Hawaii. Fruit were exposed to gravid female flies of Bactrocera dorsalis Hendel (oriental fruit fly), Ceratitis capitata (Wiedemann) (Mediterranean fruit fly), or Bactrocera cucurbitae Coquilet (melon fly) in screen cages outdoors for 6 h and then held on sand in the laboratory for 2 wk for pupal and adult emergence. The number of puparia, number of puparia per gram, and percentage of adult emergence on ‘Bluecrop’ blueberry were significantly higher for B. dorsalis and C. capitata than B. cucurbitae; B. dorsalis, C. capitata, and B. cucurbitae produced an average of 1.06, 0.60, and 0.09 pupae per g fruit and had 50.8, 54.1, and 12.7% adult emergence, respectively. ‘Berkeley’ blueberries produced an average of only 0.06, 0.02, and 0.0 pupae per g fruit for B. dorsalis, C. capitata, and B. cucurbitae, respectively. Similarly, six blueberry cultivars were harvested weekly for 10 wk, exposed to Bactrocera latifrons (Hendel) in cages, and held for pupal and adult emergence on either sand or artificial diet. In total, 2,677 blueberries were exposed to 2,681 B. latifrons and held on sand, and no pupariation or adult emergence was observed. Small numbers of B. latifrons puparia and adults emerged from the artificial diet treatment in all cultivars. Results from rearing on sand and diet indicate that blueberry is an acceptable oviposition host for B. latifrons but not an adequate developmental host. These data suggest blueberry is potentially a good host for B. dorsalis and C. capitata, and an adequate host for Bactrocera cucurbitae, but that there may be significant variation in resistance among cultivars. Blueberry seems to be a nonhost for B. latifrons.

Tart cherry, Prunus cerasus L. variety Montmorency, fruit were infested with plum curculio, Conotrachelus nenuphar (Herbst) (Coleoptera: Curculionidae), and treated with insecticides to target late instars, neonates, and eggs. The organophosphates azinphos-methyl and phosmet and the neonicotinoid thiamethoxam reduced larval emergence rates by >90% for all life stage targets; after >30 d, few surviving larvae were found inside fruit. Acetamiprid and thiacloprid also had curative activity and yielded >75% reductions in emergence and few surviving larvae in the fruit after >30 d. The juvenile hormone analog pyriproxyfen reduced larval emergence, but 66% of fruit that was treated to target late-instars still had live larvae inside of them after >30 d. Novaluron, chlorantraniliprole, and esfenvalerate had no curative activity. Indoxacarb had limited curative activity, and all targeted life stages had larval emergence. Internal and external residues were analyzed and are discussed in relation to their penetration and curative potential. The curative activity of azinphos-methyl has played an important role in meeting federal standards for infestation-free tart cherries at processing. Regulatory changes are eliminating the use of this compound, and new integrated pest management programs for plum curculio will need to address the loss of azinphos-methyl's curative activity.

Populations of cabbage looper, Trichoplusia ni (Lepidoptera: Noctuidae), were sampled in experimental plots and commercial fields of cabbage (Brasicca spp.) in Minnesota during 1998–1999 as part of a larger effort to implement an integrated pest management program. Using a resampling approach and the Wald's sequential probability ratio test, sampling plans with different sampling parameters were evaluated using independent presence/absence and enumerative data. Evaluations and comparisons of the different sampling plans were made based on the operating characteristic and average sample number functions generated for each plan and through the use of a decision probability matrix. Values for upper and lower decision boundaries, sequential error rates (α, β), and tally threshold were modified to determine parameter influence on the operating characteristic and average sample number functions. The following parameters resulted in the most desirable operating characteristic and average sample number functions; action threshold of 0.1 proportion of plants infested, tally threshold of 1, α = β = 0.1, upper boundary of 0.15, lower boundary of 0.05, and resampling with replacement. We found that sampling parameters can be modified and evaluated using resampling software to achieve desirable operating characteristic and average sample number functions. Moreover, management of T. ni by using binomial sequential sampling should provide a good balance between cost and reliability by minimizing sample size and maintaining a high level of correct decisions (>95%) to treat or not treat.

Field-based experiments were used to determine the lethal activity of insecticides on apple maggot, Rhagoletis pomonella (Walsh) (Diptera: Tephritidae), eggs and larvae in apple (Malis spp.) fruit. The organophosphates azinphosmethyl and phosmet and the neonicotinoids thiacloprid, acetamiprid, clothianidin, and thiamethoxam showed significant curative activity on the apple maggot postinfestation, when applied topically to apple fruit 24 h postharvest. Of the compounds tested, only phosmet showed significant curative activity on apple maggot when applied 14 d postharvest. The pyrethroid esfenvalerate, oxadiazine indoxacarb, anthranilic diamide chlorantraniliprole, and spinosyns spinosad and spinetoram did not show activity on apple maggot eggs and larvae in fruit. Residue profiles showed that for most compounds, the majority (>85%) of residues were found in the skin and the outside 2 mm of the apple flesh. For the neonicotinoid compounds, however, substantial portions of residues were found to penetrate in and beyond the outer flesh regions, and the total flesh residue recoveries were generally greater than those from the skin. Residues of azinphosmethyl and phosmet were detected in all three flesh regions, with the largest proportions recovered from the skin.

Bacillus thuringiensis serovar japonensis strain Buibui has the potential to be an important control agent for pest scarabs. Bioassays were designed to test B. t. japonensis against two of the major turf and ornamental scarab pests infesting turfgrasses and ornamentals and to serve as a basis for further tests against other scarab pests. LC and LD₅₀ values of B. t. serovar japonensis strain Buibui toxin and spores were determined by four different bioassays for the oriental beetle, Anomala orientalis (Waterhouse), and northern masked chafer, Cyclocephala borealis Arrow. Oriental beetle larvae were bioassayed in autoclaved and nonautoclaved soil from where they were collected (Kingston, RI [native]), in nonautoclaved soil from where the northern masked chafer larvae were collected (Groton, CT [foreign]), and per os. Northern masked chafer larvae were bioassayed in autoclaved and nonautoclaved soil from where they were collected (Groton, CT [native]), in nonautoclaved soil from where the oriental beetle larvae were collected (Kingston, RI [foreign]) and per os. LC₅₀ values of 3.93 µg toxin/g autoclaved native soil, 1.80 µg toxin/g nonautoclaved native soil, and 0.42 µg toxin/g nonautoclaved foreign soil and an LD₅₀ value of 0.41 µg per os were determined at 14 d for A. orientalis. LC₅₀ values of 588.28 µg toxin/g autoclaved native soil, 155.10 µg toxin/g nonautoclaved native soil, 265.32 µg toxin/g nonautoclaved foreign soil, and LD₅₀ of 5.21 µg per os were determined at 14 d (soils) and 10 d (per os) for C. borealis. There were significant differences in LC₅₀ values for oriental beetles in autoclaved, nonautoclaved native soil and nonautoclaved foreign soil. There were significant differences in LC₅₀ values for northern masked chafers in autoclaved and nonautoclaved native soil. B. t. japonensis can be applied now for control of oriental beetles at rates that are economically competitive with synthetic chemicals. If we can determine the component of nonautoclaved soil that enhances the activity of toxin, it may be possible to lower the rates of toxin needed for control to more economical levels for more difficult to control species such as the northern masked chafer.

Fertilization reduction could be a useful pest management tactic for floriculture crops if it reduced pest populations with little loss in crop yield and quality. We evaluated the response of the twospotted spider mite, Tetranychus urticae Koch (Acari: Tetranychidae), to different fertilization levels for cut roses, Rosa hybrida L. ‘Tropicana’ and quantified fertilization effects on 1 ) management of T. urticae on roses, 2) abundance and distribution of T. urticae on roses, and 3) yield and quality of the cut rose crop. We tested two fertilization levels, 10% (15 ppm N) and 100% (150 ppm N) of the recommended level for commercial production, and three control methods: no control measure; a predatory mite, Phytoseiulus persimilis Athias-Henriot; and a miticide, bifenazate. Combinations of both bottom up (fertilization) and top down (biological or chemical control) tactics provided a greater degree of T. urticae control than either tactic alone. Rose productivity was reduced with fertilization at 10% of the recommended level; therefore, we conducted studies with T. urticae on roses fertilized with 33% (50 ppm N), 50% (75 ppm N), and 100% (150 ppm N) of the recommended level. Mean numbers of T. urticae and T. urticae eggs per flower shoot were twice as high on roses fertilized with 100 versus 33% or 50% of the recommended level. Number of rose leaves and total leaf area infested by T. urticae were similar at all fertilization levels. Cut rose yield and marketability were not compromised on plants fertilized with 50% of the recommended level.

Leptoglossus zonatus (Dallas) (Hemiptera: Coreidae) has recently emerged as a key pest of satsuma mandarin, Citrus unshiu Marcovitch, and other fruit crops in the Gulf Coast region of the United States. Studies were conducted under laboratory conditions (25 ± 2°C, 50 ± 10% RH, and a photoperiod of 14:10 [L:D] h) to investigate host preference and suitability of satsuma fruit as host for this pest. Three separate multiple choice experiments were performed to compare attraction of L. zonatus nymphs and adults to the fruit of tomato, Solanum lycopersicum L.; satsuma mandarin; peach, Prunus persica (L.) Batsch; kumquat (Fortunella spp.); and lemon, Citrus limon (L.) Burm. F. Results of all three experiments clearly showed that tomato was the most preferred by both the nymphs and adults, with satsuma a distant second. Attraction to tomato and satsuma fruit was not due mainly to color but mediated by host volatile semiochemicals (kairomones). Developmental experiments with L. zonatus on satsuma fruit suggest that it is a suitable host that can maintain modest to high populations of the pest. Approximately 39 eggs were deposited per female on satsuma fruit with a hatch rate of 98%. Total developmental time from egg through the fifth nymphal stage was ≈50 d. High survivorship was recorded for all stages and ranged from 100% for the fourth instars to ≈89.1% for second instars. Cumulative survivorship from eggs through the fifth stage was 75.6%. Sex ratio (female:male) of emerged adults was 1:1.03, and female longevity (≈73 d) was significantly greater than male longevity (57 d). Other aspects of the developmental biology of L. zonatus on satsuma are described, and the results are discussed in relation to the field ecology of the pest.

Experiments were conducted to evaluate the toxicity, feeding preference, repellency, and field efficacy associated with the organic insecticides azadirachtin, pyrethrins, and spinosad against two stink bug species, Acrosternum hilare, (Say) and Euschistus servus, (Say) (Hemiptera: Pentatomidae). Laboratory toxicity bioassays were conducted using treated green bean pods. The conventional pyrethroid λ-cyhalothrin was included for comparison. A. hilare, adults and nymphs were most susceptible to λ-cyhalothrin and to tank mixes of pyrethrins spinosad. E. servus, adults were susceptible to λ-cyhalothrin, spinosad, and all tank mixes, whereas E. servus, nymphs were susceptible to λ-cyhalothrin only. Feeding preference tests were conducted using insecticide-treated tomatoes and counting the number of feeding stylet sheaths on fruit after 24 h. All tomatoes treated with either azadirachtin, pyrethrins, or tank mixes resulted in fewer numbers of stylet sheaths than the untreated control, whereas treatment with spinosad alone did not. In filter paper repellency tests, both E. servus, and A. hilare, were repelled by pyrethrins and exhibited no response to azadirachtin. E. servus, was attracted to spinosad in comparison with a water-treated control; however, A. hilare, displayed no response. In field efficacy trials, each of the organic insecticides reduced the number of stink bugs in soybean, Glycine max, (L.) Merr., for up to 2 d after treatment; however, none of the insecticides reduced stink bug damage to fruit in tomatoes even after multiple applications. Implications for organic growers and integrated pest management programs are discussed.

A laboratory study was conducted to determine the toxicity of indoxacarb and chlorantraniliprole to Eastern subterranean termites, Reticulitermes flavipes (Kollar) (Isoptera: Rhinotermitidae) resulting from topical applications and exposure to treated soil. Soils with varying organic matter (0.57–3.64%) and chemical characteristics were used in termiticide bioassays. Lethal dose resulting from topical application indicated that chlorantraniliprole was two- to 11-fold more toxic than indoxacarb. Lethal concentration assays yielded opposite results where concentrations of indoxacarb in soil that caused either 50 or 90% mortality of R. flavipes workers at 48 and 144 h were two- to six-fold lower than chlorantraniliprole. The bioavailability of indoxacarb and chlorantraniliprole was negatively correlated with soil organic matter. Our results suggest that indoxacarb is more bioavailable to termites in soil than chlorantraniliprole based on calculated bioavailability ratios. However, how these laboratory results correlate to actual field application data and termite efficacy is unknown, and more research is needed. These compounds seem to have excellent activity on termites and have potential to provide new modes of action and new chemistry as liquid termiticides.

Pyrethroid resistance in Helicoverpa armigera (Hübner) field populations was investigated in Benin over several years by using third- and fourth-instar larval topical bioassays. H. armigera was resistant to pyrethroids tested as cypermethrin, deltamethrin, bifenthrin, and fenvalerate. Pretreatment with piperonyl butoxide significantly decreased the LD₅₀ value of cypermethrin and deltamethrin, and the resistance suppression by this synergist effect was observed. No significant decrease in the LD₅₀ value was obtained when S,S,S-tributyl phosphoro-trithioate was applied before deltamethrin. In the field, cypermethrin's LD₅₀ value varied, and the highest LD₅₀ values were observed during the rainy season, the cotton, Gossypium hirsutum L., crop period, when pyrethroids are extensively used. In the dry season when there was no cotton cultivation, the lowest LD₅₀ values were obtained. However, reversion was never total in the field; resistance did not revert to the level we observed in the susceptible strain. In the laboratory, when field populations were reared in insecticide-free conditions, resistance decreased and total reversion was observed. Results are discussed with regard to insecticide resistance fitness cost and resistance management strategies.

Field and laboratory colonies of Helicoverpa zea (Boddie) and Heliothis virescens (F.) were exposed to Cry1Ac and Cry2Ab2 toxins to compare different mortality and mortality stunting responses. Lethal concentrations for mortality (LC₅₀s), molt inhibitory concentrations for mortality surviving L1 larvae (MIC₅₀s), and inhibitory concentrations for mortality surviving L1 and L2 larvae (IC₅₀s) were established to describe the different responses across a range of test concentrations. MIC₅₀S and IC₅₀s at 7 d significantly correlated to LC₅₀s at 7 d, but MIC₅₀s were more closely correlated with MIC₅₀s than IC₅₀s. Experiments conducted to determine the fate of survivors (larval stage L1, L2, or L3 larvae) after 7 d of exposure of Bt toxin and transfer to untreated or Bt-treated diet revealed that significant numbers of stunted larvae recovered and survived to pupation. Percentage of survival was significantly higher for larvae fed untreated diet after 7 d on Bt-treated diet, but a few survivors also were found when larvae were fed only Bt diet. Survival to pupation of larvae classified as L1 at 7 d was significantly lower than those for L2 or L3 larvae at 7 d, indicating that many stunted larvae suffer chronic effects of the initial exposure to Bt and fail to reach the next life stage. Pupation of larvae classified as L1 at 7d was reduced and delayed in comparison with those for L2 and L3 larvae at 7d. Collectively, these data suggest that MIC₅₀ estimates at 7 d more accurately project total larval mortality from Bt exposure than do LC₅₀ or IC₅₀ at 7 d.

‘Hass’ avocado, Persea americana Mill., fruit imported into California from Mexico are infested with high levels of armored scale insects (Hemiptera: Diaspididae), constituting several species. The paucity and delicate nature of morphological characters traditionally used to diagnose armored scales often require careful preparation of slide-mounted specimens and expert knowledge of the group, for their accurate identification. Here, we present a simple, quick, and accurate means to identify armored scales on Mexican avocados, based on amplification of the internal transcribed spacer two of ribosomal DNA, by using the polymerase chain reaction (PCR). This region seems to show a high level of intraspecific conformity among scale specimens originating from different localities. A suite of species-specific reverse PCR primers are combined in a single reaction, with a universal forward primer, and produce a PCR product of a unique size, that after standard gel electrophoresis, allows the direct diagnosis of six diaspidid species: Abgrallaspis aguacatae Evans, Watson & Miller; Hemiberlesia lataniae (Signoret); Hemiberlesia sp. near latania; Hemiberlesia rapax (Comstock); Acutaspis albopicta (Cockerell); and Pinnaspis strachani (Cooley). Two additional species, Diaspis miranda (Cockerell) and Diaspis sp. near miranda, also are separated from the others by using this method and are subsequently diagnosed by secondary digestion of the PCR product with the restriction endonuclease smaI.

The Russian wheat aphid, Diuraphis noxia (Kurdjumov) (Hemiptera: Aphididae), is a serious wheat, Triticum aestivum L., and barley, Hordeum vulgare L., pest throughout the small grain-producing areas in the western United States. The virulency and classification of recently described Russian wheat aphid biotypes 1–7 (RWA1-7) were clarified using 24 plant differentials. These seven biotypes had been described previously using various methods and test environments; therefore, the purpose of this study was to test them all under uniform environmental conditions. RWA1 was the least virulent of the biotypes tested, with susceptible ratings observed in five plant differentials and intermediate ratings observed in four plant differentials. RWA4, RWA5, RWA6, and RWA7 had intermediate virulence. RWA4, RWA5, and RWA7 share similar responses, with susceptible responses in six plant differentials and intermediate responses in five plant differentials. Small differences within a few plant differentials separate RWA4, RWA5, and RWA7. RWA6 has susceptible responses with only four plant differentials, but 10 plant differentials had intermediate responses. RWA3 was highly virulent, with susceptible responses in 10 plant differentials and intermediate responses in five plant differentials. RWA2 was the most virulent strain tested with susceptible responses to 12 plant differentials and intermediate responses to five plant differentials. This study has demonstrated that RWA1-7 have different combinations of virulence to the plant differentials tested, thereby confirming previous Russian wheat aphid biotype designations.

Chinch bug, Blissus leucopterus leucopterus (Say) (Heteroptera: Blissidae), is one of the most important insect pests on forage pearl millet, Pennisetum glaucum L. R. Br., production in the southeastern United States. Twenty-nine forage pearl millet genotypes were assessed for chinch bug resistance by using stunt and necrosis ratings in combination with quantitative measurements of chlorophyll content and leaf photosynthetic rate. Plant stunt and leaf sheath necrosis ratings, and chlorophyll content in flag leaves differed among the 29 genotypes. Photosynthetic rate differed both among the noninfested control and among the chinch bug-infested plants. The chinch bug-infested plants had lower photosynthetic rate than the noninfested control plants. Inbreds with resistance superior to that of Tift 23DB were identified for hybrid development. When the 29 pearl millet genotypes were assessed by the six parameters by using cluster analysis, genotypes 07F-1226, 07F-1229, 07F-1231, 07F-1235, 07F-1238, 07F-1239, and 07F-1240 were the most resistant, whereas the genotypes 07F-1220, 07F-1221, 07F-1225, 07F-1227, 07F-1232, 07F-1246, and Tift 23DB were the most susceptible to chinch bug feeding. The rest of the genotypes expressed intermediate responses to the six parameters. To differentiate the physiological impact of chinch bug feeding on light and dark reactions of plant photosynthesis, photosynthesis capacity was assessed using light and CO₂ (A/Ci) response curves on noninfested and chinch bug-infested plants of genotypes 07F-1246, 07F-1223, and 07F-1245, which expressed low, intermediate, and high chlorophyll content, respectively. Based on the A/Ci curves, photosynthesis capacity of injured leaves was suppressed in 07F-1223 and 07F-1246, whereas the chinch bug-injured 07F-1245 leaves showed an increase of photosynthetic rate compared with the noninfested plants. In contrast, light response curves were suppressed in the chinch bug-injured plants compared with the noninfested plants of all three genotypes, irrespective of their variations in insect injury ratings. This research demonstrated that visual stunt and necrosis rating methods in combination with chlorophyll and photosynthesis measurements could be used in screening forage pearl millet for chinch bug resistance and deciphering the underlying resistance mechanisms.

Sequential hypothesis testing in pest management applications are usually carried out using Wald's procedure or Iwao's procedure. Both of these procedures are applicable for oneparameter pest count models. The current practice for handling nuisance parameters when using the Wald procedure is to assume they are equal to specified values based on historical experience, and in the case of Iwao's procedure to assume a known mean-variance relationship such as Taylor's power law. In this article, we discuss the weaknesses of these practices, and advocate the use of Bartlett's sequential procedure as a better way to handle nuisance parameters. We also show how Bartlett's procedure can be implemented within three-hypothesis testing scenarios, where differentiation between three levels of infestation is desired.

Many pest repellents are in household use, and a variety of procedures, indices, and statistical tests have been used to examine their effectiveness. However, the effect of action mechanism on these indices has not been adequately discussed. In addition, the interreplication variance of data have not been taken into account in some cases. This study considered the validity of tests used to evaluate repellents and proposed methods to statistically evaluate them. First, various repellents with different mechanisms of action were virtually assumed, and their repelling processes were formulated as differential equations. Numerical and analytical analyses of the formulae revealed that, in some action mechanisms, the indices could be altered by parameters other than the repellent effect and that the indices should be used only for repellents of a specific mechanism. Furthermore, the effect of an actual repellent, by using two different experimental designs and the maize weevil, Sitophilus zeamais Motschulsky (Coleoptera: Curculionidae), were evaluated. This demonstrated that the evaluated effectiveness could vary with experimental design and suggested that the design should reflect the situation in which repellents are actually used. Therefore, statistical methods to quantify the effectiveness of repellents are proposed herein and applied to the results of the above-mentioned experiments. Particular emphasis was placed on the importance of incorporating the interreplication variance in statistical models and estimating confidence intervals. Finally, the validity and limitations of evaluation using indices of repellents' effects, and the identification of important criteria that should be considered when assessing the effects of repellents also are discussed.

Average fecundity rates and survival are the main components of fitness estimates in studies comparing performance of insect populations. Reproduction is inherently age related in most insect species, and age-specific offspring production is very important in determining fitness components. However, comparison of age-specific reproduction rates are not straight forward and most studies limit analyses to comparisons of average fecundity rates and survival as the main components of the performance of insect populations. We develop a receiver operating characteristic (ROC) curve approach to compare lifetime oviposition distributions. We use empirical data of a study of Mediterranean fruit fly, Ceratitis capitata (Wiedemann) (Diptera: Tephritidae) populations, where each fly's lifetime oviposition distribution was recorded for samples studied in natural and artificial oviposition substrates. Currently, there exists no routinely used methodology for the comparison of oviposition distributions and assessment of their separation. ROC analysis is regularly used in two-sample problems in medical biostatistics when the main task is depiction and quantification of the separation of the empirical distributions from which the data arise. Adaptation of such an analysis to our data has shown that age-specific egg-laying distributions can differ, whereas average fecundity rates do not. Therefore, ROC analysis provides a method of gaining insight in the biological process of egg-laying patterns in relatively long-lived insects with many practical and theoretical implications in entomological experimentation.

A series of studies was conducted to determine the effects of temperature on toxicity of the insect growth regulator methoprene to eggs and larvae of Plodia interpunctella (Hübner), the Indianmeal moth. When methoprene was applied to Kraft paper at the rate of 0.0003 mg of active ingredient [(AI)]/cm², there was little direct toxicity against eggs of P. interpunctella, and temperature did not affect insecticide efficacy. Similarly, exposure of eggs on a paperboard surface treated with different rates of methoprene resulted in delayed adult emergence but not a reduction in adult emergence. However, wandering-phase larvae of P. interpuctella were susceptible to methoprene, and exposure of larvae for 0.5, 1, and 2 h on different packaging materials resulted in reduced adult emergence. There was variation in emergence depending on the specific surface, but temperature had no effect on resulting adult emergence from exposed larvae. A partial budget analysis described treatment costs and reduction of risks associated with control of eggs and larvae of P. interpunctella. Results indicate methoprene could be used in management programs to control larvae of P. interpunctella, but eggs may be able to compensate for exposure to methoprene residues on treated surfaces.

Industry concerns over insect resistance, regulatory action, and the needs of organic processors have renewed interest in nonchemical alternative postharvest treatments to fumigants used for California tree nuts. The development of inexpensive polyvinyl chloride containers capable of holding low pressures has increased the practicality of vacuum treatments for durable commodities such as tree nuts. To develop vacuum treatment protocols, we determined the relative tolerance to vacuum (50 mmHg) at 25 and 30°C of different life stages of three postharvest pests of tree nuts: codling moth, Cydia pomonella (L.), navel orangeworm, Amyelois transitelle (Walker), and Indianmeal moth, Plodia interpunctella (Hübner). At both temperatures, nondiapausing codling moth larvae were the least tolerant stage tested. LT95 values for diapausing Indianmeal moth larvae were similar to Indianmeal moth eggs at both temperatures. Indianmeal moth diapausing larvae and eggs were the most tolerant at 25°C, whereas navel orangeworm eggs were most tolerant at 30°C. Field tests using GrainPro Cocoons (GrainPro, Inc., Concord, MA) to treat shelled almonds, Prunus dulcis (Mill.) D.A. Webb, in bins at vacuum levels of 18–43 mmHg at average winter temperatures (6–10°C) showed that diapausing codling moth larvae were the most tolerant under these conditions and that exposures of 7–13 d provided incomplete control. Summer field tests treating in-shell almonds in bags at average temperatures of 25–30°C provided complete control with 48 h exposure to average vacuum levels of 50 mmHg, and navel orangeworm eggs were the most tolerant stage.