Rates of development of Melanoplus sanguinipes F. from Alaska were determined at eight constant temperatures between 21 and 42°C. Diurnally alternating temperatures were used to estimate rates of development at temperatures too low for nymphs to complete development under constant temperatures. Two previously published equations were fit to these data and used to predict developmental rates as a function of temperature. The first equation, nonlinear and only approaching zero rate of development asymptotically, was fit to the data from constant and alternating temperature treatments. The second equation, which included an intercept, was fit to the data from constant temperature treatments only. Estimated developmental times based on these equations were tested against observed developmental times in two fluctuating temperature regimes in growth chambers, and two seasons of field sampling. Elevation of body temperature of grasshoppers above ambient temperatures in the field was modeled as a linear function of solar irradiance, based on field measurements. The effect of behavioral thermoregulation on nymphal developmental times in the field was estimated using standard air temperatures and solar-adjusted temperatures. Rates of development under most of the constant temperature treatments were higher than any previously published for M. sanguinipes. Estimated rates of development in the field using air temperatures only were about one-half those using solar-adjusted temperatures. Observed developmental times in the field were 45 and 42 d in 2000 and 2002, respectively. Because of local adaptation and behavioral thermoregulation, duration of nymphal stages in M. sanguinipes is relatively independent of latitude.

The parasitoid wasp Aphidius ervi (Haliday) disrupts formation of wings by its host, the pea aphid, Acyrthosiphon pisum (Harris). Because apterous aphids are larger than alates, we hypothesized that blocking wing formation leads to larger parasitoids emerging from apterous hosts. In an initial experiment, we found that parasitoid larvae could not always prevent host wing formation when the parasitoid began development in fourth instar hosts, allowing us to experimentally test the hypothesis. Both male and female parasitoids emerging from hosts that did not develop wings were heavier than those emerging from alate hosts. Parasitoids emerging from apterous mummies also had significantly longer thoraxes. For insect parasitoids, increasing size has been positively correlated with several measures of fitness. Thus, A. ervi likely gains a fitness advantage by disrupting host wing development.

The postdiapause development, hatching characteristics, and survival of the overwintering eggs of the grasshopper species Oedaleus asiaticus Bei-Bienko, Angaracris barabensis (Pallas), and Chorthippus dubius (Zubowsky) from the Inner Mogolian steppe grasslands were studied at six constant temperatures (15, 20, 25, 30, 35, and 40°C). The results show that the three species had different postdiapause embryonic developmental rates, survival curves, and cumulative hatching probabilities. O. asiaticus had the highest developmental threshold at 13.1°C and the least effective accumulated thermal unit, 191.7 degree-days (DD). A. barabensis had the lowest developmental threshold at 11.1°C and the most effective accumulated thermal unit, 329.7 DD. C. dubius, a later hatching species, had a moderate developmental threshold of 11.4°C and an effective accumulated thermal unit of 230.3 DD. The effective thermal unit at which 50% of postdiapause eggs hatched was 202.7 DD for O. asiaticus, 340.8 DD for A. barabensis, and 251.6 DD for C. dubius. The greatest percentage hatch of O. asiaticus (71.06%), A. barabensis (75.28%), and C. dubius (87%) occurred at 27.3, 27.8, and 27.4°C, respectively. Thermal death points of the three grasshopper species were 41.0°C, 40.5, and 44.8°C, respectively. The optimal temperature ranges of each species were different, 21.9 to 32.7°C for O. asiaticus, 22.0 to 33.5°C for A. barabensis, and 17.8 to 37.1°C for C. dubius. These results suggest that postdiapause embryonic developmental rate and accumulated heat cannot help to explain the different hatching sequences of these species. Much variation in springtime emergence could be attributed to the species-specific overwintering egg stage. In addition, results also indicate that C. dubius has a wider adaptive temperature range than O. asiaticus and A. barabensis.

The rare maritime ringlet butterfly (Coenonympha tullia nipisiquit McDonnough), which inhabits salt marshes in maritime Canada, experiences tidal flooding throughout its development. Its low vagility and the imminence of sea level rise call for the immediate investigation on the effect of flooding on survival. The maritime ringlet’s tolerance to tidewater submergence for up to 24 h was compared with that of the inornate ringlet (C. tullia inornata Edwards), a subspecies occupying nearby upland meadows. The suitability of salt meadow cordgrass [Spartina patens (Aiton) Muhl.], a major host of the maritime ringlet, for neonate inornate ringlet larvae was tested as well. Maritime ringlet larvae showed higher tolerance to tidewater submergence than inornate ringlet larvae, which were more likely to die from submergence stress after a few days. Although tidal submergence is probably not lethal to the maritime ringlet, there is a possibility of negative impact caused by prolonged submergence during storm tides. The inornate ringlet larvae failed to adopt S. patens, and all larvae died within 1 wk when forced to feed on it. The results suggest that the maritime ringlet has evolved physiological adaptations to saline wetland conditions that have enabled it to exploit its current habitat.

The rice water weevil, Lissorhoptrus oryzophilus Kuschel, is the most destructive insect pest of rice in the United States. Degree-day (DD) models were developed to predict the emergence date of adult rice water weevils from overwintering in the spring and to describe larval and pupal development on two varieties of rice under field conditions. The model that best described emergence of weevils from overwintering was derived from 14 yr of light trap captures. The temperature threshold for the best-fit model was 15.6°C, the start date for the model (date at which degree-day accumulation begins) was 33 d after 1 January, and the end point for the model was a cumulative light trap capture of six weevils. By using these parameters, emergence of weevils occurred after accumulation of 139.2 DD (°C × day). The model predicted emergence of weevils in 2001, 2002, 2003, and 2004 with an error of 4, 7, 1, and 2 d, respectively. For the model describing larval development, the number of degree-days required for development from egg to 50% pupation was 359.1 ± 19.4 DD (°C × day) with a low temperature threshold of 10°C. The number of degree-days required for pupal development was 264.3 DD (°C × day), and the total degree-days required for development of one generation was ≈623.4 DD (°C × day). Larval development did not differ on cultivars ‘Jefferson’ and ‘Bengal’.

Life history characteristics of Lygus elisus Van Duzee were studied at 10, 15, 20, 25, 30, and 35°C in the laboratory. The egg incubation period, instar-specific nymphal development, survivorship, and longevity of L. elisus were influenced by temperature. Eggs did not hatch at 10°C. For the five remaining selected temperature treatments, the incubation period was longest at 15°C and decreased nonlinearly with an increase in temperature. Temperature influenced the developmental period differently for different instars, with the second stadium being the shortest at 10, 20, 25, and 30°C, whereas first and third stadia were the shortest at 15 and 35°C, respectively. The final stadium was longest across all six temperatures. The relationships between temperature and total durations were described by the same equation for both males and females. Total nymphal duration was not significant with sexes. Sex ratio (proportion of males) of emerging adults of L. elisus did not deviate from 1:1. Both instar-specific and total nymphal survivorship varied significantly with temperature. Total nymphal survivorship was highest at 15°C and lowest at 10°C. Adult longevity ranged from 16 (35°C) to 122 d (15°C), with a curvilinear response to temperature. Females survived ≈10 d longer than males at 20°C, but survivorship of males and females was similar at other temperatures. These life history data will be useful in developing a computer model simulating L. elisus population dynamics in the field.

Effective management of bark beetles (Coleoptera: Curculionidae, Scolytinae) relies on accurate assessments of pest and predator populations. Semiochemicals provide a powerful tool for attracting bark beetles and associated predators, but the extent to which trap catches reflect actual population densities are poorly understood. We conducted field experiments in California during 2 consecutive yr to determine how attraction of Ips pini (Say) and its major predators to synthetic pheromones vary from each other and from attraction to natural volatiles emitted from colonized hosts. Synthetic lures consisted of different ratios of the ( ) and (–) enantiomers of ipsdienol, the primary pheromone component of I. pini, with or without lanierone, an additional component that synergizes attraction in some populations. I. pini was consistently attracted to either 3( )/97(−) ipsdienol or infested host plant material. Lanierone had no effect on the attraction of I. pini. Coleopteran predators showed a range of responses, more of which coincided with I. pini. Temnochila chlorodia (Mannerheim) (Trogositidae) was attracted to infested host materials and all synthetic lures. Enoclerus lecontei (Wolcott) (Cleridae) preferentially responded to higher ratios of ( )-ipsdienol, and its attraction was strongly enhanced by lanierone. Enoclerus sphegeus F. was most attracted to infested hosts and exhibited a preference for (−)- over ( )-ipsdienol. Our results suggest that preferences of bark beetles and predators for bark beetle pheromones at the regional scale should be considered before deploying semiochemicals. These results are also consistent with a model of co-evolving responses to pheromones by predators and their prey. The roles of plant volatiles should be further investigated, both to improve monitoring programs and from an ecological perspective.

Evidence of repellent properties in catnip, Nepeta cataria L., to flies and cockroaches was observed in preliminary studies. This study compared catnip essential oil from steam distillation and elemol, a major constituent of osage orange essential oil, to current commercial repellents. These comparative studies found both the catnip steam distillate and elemol to be as good, and in some cases better, at repelling house flies, Musca domestica L., and American cockroaches, Periplaneta americana L., than N,N-diethyl-m-toluamide (DEET) or citronellal. Both short-term and long-term repellency bioassays were used to assess repellency. Catnip essential oil showed greater repellency than DEET and citronellal in the short term. Extended repellency bioassays showed elemol to be more repellent than catnip steam distillate, citronellal, and DEET. Nepetalactone, the major constituent of catnip essential oil, is present as two isomers, and previous studies have shown the E,Z-nepetalactone [2-(2-hydroxy-1-methylethenyl)-5-methyl-cyclopentanecarboxylic acid delta lactone] isomer to be even more repellent to cockroaches than the dominant isomer, Z,E-nepetalactone. This study examined the seasonal variation of the two isomers, Z,E- and E,Z-nepetalactone, in catnip. Samples of fresh catnip mature leaves, immature leaves, and stems were steam-distilled separately, and isomer composition was analyzed using high-performance liquid chromatography and gas chromatography (GC). An analysis of variance (ANOVA) showed significant differences by week. The mature leaf essential oil samples were tested in a repellency bioassay and exhibited significant repellency to German cockroaches, Blattella germanica L. The catnip floral volatiles were sampled using solid phase microextraction, and analysis with GC/mass spectrometry showed the presence of Z,E-nepetalactone, E,Z-nepetalactone, and β-caryophyllene as the major constituents. Phytophagous insects and potential pollinators present on sampling dates were recorded.

The development, body weight, survivorship, and reproduction of the cotton bollworm, Helicoverpa armigera (Hübner), were evaluated in the laboratory at 27°C and photoperiod L:D = 14:10 on six host plants: cotton (Gossypium hirsutum L.), corn (Zea mays L.), tomato (Lycopersicon esculentum Mill), hot pepper (Capsicun frutescens L.), tobacco (Nicotiana tobacum L.), and common bean (Phaseolus vulgaris L.). Cotton bollworm larvae successfully survived on all six host plants, although mortality was very high on hot pepper and tomato. The developmental time of immature stages ranged from 26.6 d on corn to 35.1 d on tomato. Body weight of young fourth instar larvae ranged from 22.8 mg on corn to 5.9 mg on tobacco, while body weight of young last instar larvae and pupae ranged from 176.7 mg on cotton to 132.5 mg on tomato, and 285.2 mg on corn to 167.1 mg on tomato, respectively. Immature survival from egg to pupa varied from 33.1% on cotton to 1.7% on hot pepper. The average number of eggs oviposited by adults reared on cotton, corn, common bean, tomato, hot pepper, and tobacco were 708.4, 784.8, 778.1, 559.1, 562.5, and 314.3, respectively. The net reproductive rate of this species, measured from egg to egg, varied from 117.6 on cotton to 5.1 on hot pepper. We conclude that H. armigera can complete their life cycle on all six host plants, although tomato and hot pepper were relatively unsuitable.

Spatial resource distribution patterns play an important role in mediating density-dependent phase change (gregarization) in locusts. The degree of contagion or aggregation of resources in a habitat can increase the probability of locust gregarization by increasing the frequency of contact among individual locusts. The spatial distribution patterns of two resources upon which gregarization can occur, the tussock grasses Aristida pungens and Panicum turgidum (Poaceae), were examined in two adjacent regions of the desert locust (Schistocerca gregaria Forskål) plague recession area in Mauritania that differ in their frequencies of locust gregarization. The hypothesis that the distribution of grass tufts should be more aggregated and thus more likely to promote locust phase change in the high frequency gregarization area was tested. Tufts were more abundant, and both species were larger in the high frequency gregarization area. The spatial distribution patterns of tufts in both areas were largely aggregated at the 200- to 2000-m² scale corresponding to the population-level scale of locust resources. As predicted, the degree of aggregation was more extreme across the high frequency gregarization area. This study provides support across a large area for the predicted association between local resource distribution and locust gregarization. The observed differences in grass abundance and size between the high and low frequency gregarization areas suggest that factors such as topography or hydrology may underlie differences in plant distribution and contribute to locust gregarization in the high frequency area.

The leafminer Cameraria ohridella Deschka & Dimič is an invasive pest of horse chestnut, Aesculus hippocastanum L., trees that has spread rapidly across Europe over the past 19 yr. It was recently reported in the United Kingdom, Denmark, and the Ukraine, and this spread is expected to continue through the Scandinavian countries until the northern limit of the host tree distribution is reached. The presence of the species is generally reported first in the cities, either as consequence of human-related transportation or because of the higher number of host trees in these areas. As a consequence, detailed studies of the spread of this pest through rural areas have not yet been carried out. We have monitored the spread of the moth at the fringe of its known distribution in eastern France during the period 2001–2003. The population was estimated by observing the damage caused by the pest and by establishing a network of pheromone traps. Pheromone traps were set up to measure two generations in 2001 and 2002, whereas the spatial pattern of the spread of the species measured by damage assessment was followed for each generation between 2001 and 2003 (nine generations). Spatial and temporal patterns in the population estimates made using these two methods were compared. We found that estimates made from damage assessment correlated with log-transformed estimates from pheromone trap catches, suggesting that both techniques can be used to monitor the spread of this pest. Over the period 2001–2003, the spread rate ranged from 17.0 to 37.9 km/yr, depending on the population threshold and method used.

Alfalfa is a source for viruses that may be acquired by aphids and transmitted to snap bean, Phaseolus vulgaris L. Snap bean fields in proximity to alfalfa could have an increased risk of virus infection. Knowledge of the abundance and temporal and spatial dispersal patterns of commonly encountered aphids in commercial snap bean fields, varying in distance from alfalfa, could provide insight into this risk. Alate aphids were monitored using water pan traps in snap bean and alfalfa fields that were adjacent to or >1 km away from each other. The pea aphid, Acyrthosiphon pisum (Harris), was the most common aphid species captured in early-planted snap bean fields in 2002 and 2003 (56 and 23% of total, respectively), whereas the corn leaf aphid, Rhopalosiphum maidis (Fitch), also was common in 2003 (15% of total). In contrast, the yellow clover aphid, Therioaphis trifolii (Monell), and soybean aphid, Aphis glycines Matsumura, were the most abundant species trapped in late-planted snap bean fields in 2002 (77% of total) and 2003 (64% of total), respectively. These species were prevalent in traps in alfalfa as well. The abundance and temporal dispersal patterns of these species in snap beans adjacent to and >1 km away from alfalfa were similar, suggesting that the risk for virus infection may not be affected by proximity to alfalfa. A similar number of alate aphids also were captured along snap bean field edges and field centers, regardless of their proximity to alfalfa. This suggests that the aphids dispersed into snap bean randomly rather than directionally from the field edge. The implication of these results is that separating snap bean fields from alfalfa or using crop borders/barriers are not likely to be successful virus management strategies.

Measurements of ant colony sizes and neighboring colony spatial structure figure importantly in a variety of socio-biological considerations. In this study, we used mass-marking and recapture techniques to quantify the foraging distribution and abundance of red imported fire ants, Solenopsis invicta Buren, on individual bait cards from neighboring polygyne (multiple queens) colonies. Ants in six to eight adjacent colonies, at each of 10 sites, were mass-marked a unique color. Ants were collected at olive-oil baits in a 10 by 10-m area consisting of 61 baits at each site. Stepwise nonlinear regression showed that the distance to baits, colony size, and average internidal (between nests) spacing were significant predictors of the foraging distribution of ants from colonies. Most marked ants were collected within ≈4 m of their colony. Foraging was more constrained at closer internidal distances. As internidal distances increased, colony foraging distances increased. There was a significant difference in the number of observed ants from colonies on individual baits compared with the expected number from the regression model. A χ² analysis showed that high numbers of ants on individual baits from a colony had a significant negative effect on the number of foragers from adjacent colonies. Results show ≈66% of the variation in foraging can be explained through colony size, location, and recruiting ability; however, foraging interference among ants from adjacent colonies occurs and may result in unequal sharing of resources (i.e., resource partitioning) among colonies.

Rising levels of atmospheric [CO₂] will directly affect the responses and community composition of plants. However, few studies have examined how these changes to plant communities will alter insect communities that rely on them. Here, we report on a study that examined the community-level responses of plants, herbivores, detritivores, predators, parasitoids, and omnivores to increased [CO₂] at a Free Air Carbon Enrichment (FACE) facility at Oak Ridge National Laboratory. We found that aboveground net primary productivity for the five dominant plant species in the understory community, C:N ratios of leaf tissue for four of the five dominant understory taxa, amounts of herbivory, and arthropod abundance and richness across all trophic groups did not differ between ambient and elevated CO₂ plots. Abundance and richness of particular trophic groups were higher in ambient than in elevated CO₂ plots. There were also strong temporal effects on community composition, but no distinct treatment effects. These results, although preliminary, suggest that community-level responses to future atmospheric [CO₂] are likely to be species- and trophic-group specific.

While weather can contribute significantly to grasshopper population dynamics in North American grasslands, local environmental conditions resulting from land use practices may be equally important. In this study, significant differences in grasshopper density were detected among adjacent watersheds from Kansas Flint Hills tallgrass prairie that differed in fire frequency and especially bison grazing treatments. Grasshopper densities were ≈2.5 times greater in grazed watersheds compared with ungrazed ones. Grasshopper densities also varied somewhat in response to fire frequency, mostly in species-specific ways. No treatment interactions on overall grasshopper density were detected. The effects of fire frequency and bison grazing were implemented in part through their combined effect on the structural heterogeneity of vegetation, and other habitat characteristics. Individual grasshopper species responded uniquely to combinations of fire frequency and bison grazing. Grazing resulted in significant increases in density for seven of the nine most abundant species; fire frequency affected two species; and one species did not respond to either fire or grazing. Understanding effects of habitat on grasshopper densities provides opportunities to manage these populations for economic or conservation needs.

Although the red imported fire ant, Solenopsis invicta Buren, has spread across the southern United States, its population varies widely from one area to another. Earlier research has demonstrated that queens that land in areas with a native ant population suffer high levels of predation, but it has been assumed that once the first workers are present, the colonies vulnerability rapidly decreases. Recent laboratory studies, reported elsewhere, demonstrated that several native ant colonies were able to raid and destroy small S. invicta colonies. One of these native species was Solenopsis (Diplorhoptrum) molesta. We report here that small colonies of S. invicta were unable to establish in plots with the thief ant, Solenopsis molesta (Say), but were able to establish in an identical plot with no S. molesta. These results suggest that high density of at least one species of native ant can eliminate or at least reduce the establishment of small colonies of S. invicta that may have started to develop after the escape of the founding queen.

Physical and biotic effects of straw mulch applied at two different times to potatoes and watermelons were assessed in field trials over 2 yr. Plots with straw mulch generally had lower soil temperatures and higher soil moisture than control (weedy, no straw) plots. When straw was applied at planting weeds were suppressed, whereas straw applied after cultivation 4 wk after planting had less effect on weeds. In 2000, potatoes with straw at planting had fewer potato leafhoppers, Empoasca fabae (Harris) (and less associated plant damage) and more colonizing Colorado potato beetle, Leptinotarsa decemlineata (Say), adults than the other treatments. Subsequent Colorado potato beetle egg mass and larval numbers, however, were not higher in this treatment, possibly because of the higher numbers of predators in these plots as assessed by pitfall trapping. In 2001, there were no differences in numbers of colonizing potato leafhopper or Colorado potato beetle adults, but by midsummer there were more Colorado potato beetle larvae in the control plots than in the straw plots, again possibly due to differential predation. The few pests observed in the watermelon plots were not affected by the straw treatments. Potato yields were similar in all treatments, but melon yields were higher in plots with straw at planting (in which weeds were suppressed) in 2000. In 2001, when melons were planted earlier in the spring, melon plant biomass at 4 wk was lower in plots with straw at planting than in the other treatments, probably due to reduced soil temperatures. Thus, for potatoes, straw may be useful to control weeds and enhance predator numbers, but insect pests may still require control. In melons, straw should be used only if the crop is planted after the soil is sufficiently warm.

A 3-yr study was conducted in California’s southern San Joaquin Valley to determine the overwintering survival of the corn leafhopper, Dalbulus maidis (DeLong and Wolcott), and the mollicute, Spiroplasma kunkelii, the causal agent of corn stunt disease. Corn leafhopper populations were sampled from November to March using yellow sticky cards, D-vac suction samples, and inspection of volunteer corn plants and spring planted corn. S. kunkelii presence was determined by sampling sentinel plants placed in the field during the winter, leafhoppers collected throughout the winter, and evaluation of volunteer plants over the winter and spring planted corn. Leafhoppers were collected on yellow sticky cards throughout the winter during all 3 yr. They were also regularly recovered from alfalfa, Medicago sativa L., winter forage (wheat, Triticum aestivum L., and triticale, Triticale hexaploide Lart. and riparian areas by D-vac suction sampling. Females constituted the majority of leafhoppers (>80%) recovered on both sticky cards and from D-vac samples. S. kunkelii was recovered from leafhoppers throughout the winter, from sentinel plants, and in spring planted corn. Volunteer plants were determined to be a critical key in leafhopper overwintering, and consequently, the survival of S. kunkelii. Volunteers extended the season by as much as 2 mo, thus shortening the period of time the leafhoppers were forced to go without a food source. The possible reasons for a shift in the leafhopper from cyclic pest to persistent pest in the region are also discussed.

The balsam twig aphid (Mindarus abietinus Koch) (Homoptera: Aphididae) is a major insect pest of balsam and Fraser firs grown for Christmas trees. Few control methods other than chemical insecticides have been evaluated. In this study, we identified insect predators associated with M. abietinus in three fir Christmas tree fields in Michigan. We also conducted laboratory and field studies to assess the effectiveness of augmentative releases of Chrysoperla rufilabris Burmeister (Neuroptera: Chrysopidae) for M. abietinus control. A diverse complex of predators, primarily generalists including syrphids, coccinellids, and lacewings, was observed on infested trees. Predator abundance was generally low early in spring when M. abietinus fundatrices were present, but predators became more common as sexuparae and later aphid stages appeared. In controlled laboratory tests, C. rufilabris were capable of consuming at least 35 M. abietinus per day, but were able to develop on 10 aphids per day. Average adult weight of C. rufilabris increased with the number of aphids consumed by larvae. In field studies, release of one C. rufilabris larva onto caged branches with moderate M. abietinus infestations significantly reduced the density of M. abietinus overwintering eggs. In open field releases, C. rufilabris larvae significantly reduced the density of M. abietinus sexuparae and overwintering M. abietinus eggs in two of three fields.

Habitat manipulation in the form of beetle banks and flowering insectary strips has been a successful method to increase natural enemy and alternative prey abundance. In this study, beetle banks and flowering insectary strips were combined to create conservation strips as refuge for a variety of natural enemies in golf course ecosystems. Conservation strips were installed in the roughs next to golf course fairways. Pitfall traps were used to monitor the abundance of predatory, parasitoid, alternative prey, and pest insects in the roughs and fairways near conservation strips and in roughs and fairways without conservation strips (controls). In addition, Agrotis ipsilon (Hufnagel) larvae were placed in the roughs and fairways to evaluate the effect of conservation strips on the predation of pests. Conservation strips were successful at increasing predator, parasitoid, and alternative prey abundance in golf course fairways and roughs overall. Increases were most evident within 4 m of conservation strips. Moreover, predation of A. ipsilon larvae was greater in fairways adjacent to conservation strips than fairways adjacent to roughs only. Differences in predation did not correspond to differences in predator abundance in the fairways, suggesting “predator abundance” may not be the most reliable estimate of the effect of habitat manipulations. These results suggest conservation strips could be an important new tool in conservation biological control on golf courses and may be applicable in other agro-ecosystems. Other methods of estimating and enhancing the effects of conservation strips are discussed.

The beetle Thamnurgus euphorbiae Küster, whose larvae feed in the inner stems of Euphorbia characias L., found in Italy, was selected as a candidate agent for the biological control of Euphorbia esula-virgata Waldstein and Kitaibel in the United States. Its adaptation to and survival on several E. esula-virgata ecotypes from North America justified host range studies conducted in Italy during 1993–2001. Of the 47 plant species or varieties in 13 families tested, the beetle fed and completed its development on the control plant E. characias L. and test plants E. esula L. and E. cyparissias L. from Italy and E. esula-virgata from Nebraska, Montana, Oregon, Colorado, and Idaho. The other plant species in the subgenera Agaloma, Euphorbium, Chamaesyce, and Poinsettia, and the economic test plants including Zea mays L. and Ficus spp., were unsuitable for the development of eggs, larvae, and adults. Plants in the Labiatae, Tamaricaceae, Ranunculaceae, and Tropaealaceae families (hosts of other Thamnurgus species) were tested, but no feeding or oviposition was observed. A laboratory cage test was carried out testing the most important ecotypes of leafy spurge to be controlled in the United States. T. euphorbiae attacked 60% of the exposed stems present on test plants and control plants. No significant difference was found between E. esula-virgata American ecotypes, the control plant E. characias, and the E. esula ecotype from Italy. T. euphorbiae adults attacked big stems measuring 3.1–4.1 mm in diameter. Smaller stems (1–2 mm in diameter) were not attacked. A petition for the introduction of the beetle into U.S. quarantine has been approved by the U.S. Department of Agriculture-Animal and Plant Health Inspection Service’s Technical Advisory Group for Biological Control Agents of Weeds in 1999. The release of the beetle in the field is dependent on additional host range studies with native and rare U.S. plant species requested by Technical Advisory Group for Biological Control Agents of Weeds. This paper reports results of host range testing conducted at the USDA-ARS-EBCL, Rome Substation, Italy, from 1993 to 2001.

Turfgrass ecosystems contain a variety of generalist predators that may contribute to the regulation of pest insect populations. The black cutworm, Agrotis ipsilon (Hufnagel) (Lepidoptera: Noctuidae), is frequently a pest of short-mown golf course greens and fairways and may be a candidate for management by conservation biological control tactics. However, little is known about the susceptibility of different instar A. ipsilon to the many species of carabids, staphylinids, and spiders that inhabit greens, fairways, and roughs. These ecosystems also contain nonpest arthropods that could serve as alternative prey for generalist predators and help bolster their populations. In these laboratory experiments, 12 species of predators, commonly found on golf courses, were evaluated for their ability to consume five different instars of A. ipsilon and for their feeding voracity. The palatability of five potential alternative prey items, to a subset of predators, was also tested. All predator species tested were able to consume at least one instar of A. ipsilon. Two of the most common predators found on golf courses, Amara impuncticollis (Say) (Coleoptera: Carabidae) and Philonthus sp. (Coleoptera: Staphylinidae), could consume all A. ipsilon instars and were also among the most voracious predators tested. In addition, all five alternative prey items were readily eaten by the predator species that were tested. These results suggest that these generalist predators play a role in the regulation of A. ipsilon larval populations on golf courses and that several nonpest arthropod taxa could contribute to attracting and maintaining predator populations.

Seasonal and daily flight patterns of Scaphoideus titanus Ball were investigated in northern Italy, throughout a 3-yr period, using yellow sticky traps placed in an experimental vineyard. Capture data were also analyzed in relation to temperature and relative humidity values. The leafhopper was found to be more active from 1800 to 0800 hours, whereas little movement occurred during high light intensity hours. Although the sex ratio was always male biased, no difference in flight periodicity was found between genders. The seasonal flight peak occurred each year in different periods, ranging from the end of June to the beginning of July, depending on mean temperature values. Daily capture increases were correlated with daily minimum and maximum temperatures and were negatively correlated with maximum values of relative humidity. As a result, this species could be crepuscular or nocturnal, and a bimodal flight periodicity is likely.

We studied relationships between adult apple maggot, Rhagoletis pomonella (Walsh), and apple genotypes in the field and laboratory by counting male and female flies trapped on unbaited sticky red spheres and by counting fruit punctures in choice tests. Six apple genotypes were chosen for both field and laboratory tests grouped into three categories of phenological development (early, mid, and late ripening). In the field, where comparisons were made over a 2-yr period in five commercial orchards, apple maggot trap captures tended to be aggregated on trees of certain genotypes rather than uniformly distributed. For early ripening genotypes, traps on Jersey Mac accumulated moderately high to high numbers of apple maggot during early and mid-season, whereas traps on Paula Red accumulated few flies during both periods. For mid-ripening genotypes, traps on Gala accumulated high numbers of apple maggot during early, mid-, and late season, whereas traps on McIntosh accumulated comparatively small numbers during all parts of the season. Fuji, a late-ripening genotype, was among the preferred genotypes during mid- and late season, whereas Red Delicious, another late-ripening genotype, received high numbers of apple maggot during early and mid-season. In the lab, during early season, fruit of all genotypes except Red Delicious were accepted for boring in high proportions by caged apple maggot. During mid- and late season, fruit of Fuji and Red Delicious were accepted for boring in lower proportions than fruit of other genotypes. The degree to which apple genotypes were accepted for oviposition in the laboratory did not correspond with tree visitation rates in the field. Sugar content and pulp pressure of fruits of different genotypes also did not correspond with tree visitation rates. Our results suggest that the distribution of apple maggot in orchards is influenced by the tendency of flies to preferentially visit trees of particular apple genotypes. Preferences for apple genotypes seem to be independent of the ripening phenology, sugar content, and pulp pressure of fruit. We discuss the nature of such preferences and implications for an attract-and-kill approach to apple maggot control in commercial orchards.

The host selection process of most phytophagous insects can be described as a sequence of behaviors leading from landscape-scale habitat location to host-plant scale, microsite selection. For the whitespotted sawyer, Monochamus scutellatus (Say), a fire-associated xylophagous cerambycid, host location and acceptance patterns have been relatively well described, whereas landscape-scale distribution patterns in recently disturbed areas have received virtually no attention. In a 5,097-ha recently burned black spruce forest of Quebec, Canada, we evaluated the variability of larval density of 569 trees in 114 plots, by using entry hole counts. This variability was then related to environmental variables ranging from tree- to landscape-scale. Both diameter at breast height (positive relationship) and fire severity (negative relationship) were significant at explaining larval density at tree scale. At larger scales, altitude had a negative effect on larval density, whereas plots having a higher percentage of unburned forest in a 500-m radius were more intensely colonized. The importance of the proximity of unburned stands could be linked to the feeding requirements of the adults, which should show preference for stands offering both egg-laying and feeding substrata, because several species of Monochamus have been shown to feed while being reproductively active. In our models, large-scale variables explained more variability in entry hole counts than did tree-scale variables. Thus, our results suggest that large-scale habitat location mechanisms may play an important role in the host selection process of the whitespotted sawyer.

RÉSUMÉ (FRENCH). La sélection d’hôte des insectes phytophages comporte plusieurs étapes allant de la localisation d’un habitat à l’échelle du paysage jusqu’à la sélection d’un microsite de ponte à l’échelle de la plante hôte. La localisation et l’acceptation d’hôte ont été relativement bien décrites pour le longicorne noir Monochamus scutellatus (Say); cependant, la localisation d’habitat à grande échelle a retenu peu d’attention. Dans un feu ayant eu lieu en pessière noire au Canada, nous avons évalué la densité de larves dans 569 arbres de 114 parcelles d’échantillonnage par décompte de trous d’entrée. Ces densités ont été confrontées à des variables environnementales à échelles multiples. À l’échelle de l’arbre, la densité de larves était liée au diamètre de l’arbre et à la sévérité du feu. À plus grande échelle, l’altitude a eu un effet négatif sur la densité de larves, alors que les peuplements ayant davantage de forêt verte dans un rayon de 500 mètres ont été plus intensément colonisés. L’importance de la proximité de massifs verts peut être liée aux éxigences nutritionelles des adultes, qui devraient préférenciellement coloniser des peuplements comportant à la fois des sites d’oviposition et d’alimentation, puisque plusieurs espèces de Monochamus continuent de s’alimenter lorsque sexuellement actifs. Les variables à grande échelle ont expliqué plus de variabilité dans nos modèles que les variables à l’échelle de l’arbre. Il semble donc que les mécanismes de localisation d’habitat à grande échelle jouent un rôle important dans le processus de sélection d’hôte chez le longicorne noir.

Codling moth, Cydia pomonella (L.), and redbanded leafroller, Argyrotaenia velutinana (Walker), are two key tortricid orchard pests in Minnesota. Field trials were conducted during 2001 and 2002 in Minnesota apple orchards to determine seasonal phenology of C. pomonella and A. velutinana and to evaluate two popular trap designs (Pherocon 1CP or 1C “Wing” trap versus Pherocon VI “delta” trap) for monitoring both species. Trap performance was determined by comparing the number of males captured, date of first moth capture, and the capture of nontarget beneficial insects. For C. pomonella, two distinct flight periods were recorded, suggesting two generations per year in Minnesota. Emergence and flight activity of first generation C. pomonella began at ≈110 degree-days (DD) base 10°F. This corresponded to apple bloom in southern Minnesota. The delta trap captured significantly more C. pomonella males than the wing trap (Pherocon 1CP version). For A. velutinana, three flight periods were recorded at all three locations in both years of the study. The first flight began at ≈55 DD base 10°F, around the tight cluster stage of apple in southern Minnesota. Both trap types captured approximately the same numbers of A. velutinana males in both years of this study. For both species, the dates of first moth capture were generally the same for both trap types, indicating that both types of traps are capable of detecting the first flights of C. pomonella and A. velutinana males. In general, the delta trap was less selective than the wing trap (Pherocon 1C), capturing significantly more nontarget beneficial insects, in particular bees.

Satellite imagery (0.65-m resolution, panchromatic) was tested as a detection tool for imported fire ant mounds in northeast Mississippi pasture. Photointerpretation of satellite imagery resulted in an average detection rate of 46.9 ± 1.2% of mounds. Mound size and mound height had a significant effect on mound visibility. Predicted detection rates, based on mound height and mound area, ranged from 24% for small mounds (15 cm high, 0.05 m²) to 66% for large mounds (30 cm high, 0.30 m²). Limitations and possible uses for satellite imagery in fire ant mound detection are discussed.

Bactrocera latifrons is a tephritid fruit fly that invaded the Hawaiian Islands in 1983 and has since spread throughout the island chain. Its invasion was facilitated by the invasion of two previous nonendemic species of solanaceous plants: Solanum torvum and Solanum linnaeanum. This study explored three aspects of B. latirfrons biology: (1) the short-term temporal patterns of wild flies were examined in invasive populations of S. torvum; (2) B. latifrons’ host preference for two principal wild hosts, S. torvum and S. linnaeanum; and (3) the movement of B. latifrons among host patches of established populations of S. torvum in Iao Valley, Maui, HI. For the third objective, we conducted a mark-release-recapture study using flies dyed with a phosphorescing marker and flies marked with a vertebrate protein. The laboratory studies suggest the flies prefer ovipositing in S. linnaeanum to S. torvum and that survival in S. linnaeanum is higher than in S. torvum. Trap catches in the dispersal study did not exceed 200 m during the 6-wk course of the study, suggesting that dispersal rates are similar to those seen in other tephritid fruit fly species.