Native and exotic siricid wasps (Hymenoptera: Siricidae) can be ecologically and/or economically important woodboring insects in forests worldwide. In particular, Sirex noctilio (F.), a Eurasian species that recently has been introduced to North America, has caused pine tree (Pinus spp.) mortality in its non-native range in the southern hemisphere. Native siricid wasps are known to have a rich complex of hymenopteran parasitoids that may provide some biological control pressure on S. noctilio as it continues to expand its range in North America. We reviewed ecological information about the hymenopteran parasitoids of siricids in North America north of Mexico, including their distribution, life cycle, seasonal phenology, and impacts on native siricid hosts with some potential efficacy as biological control agents for S. noctilio. Literature review indicated that in the hymenopteran families Stephanidae, Ibaliidae, and Ichneumonidae, there are five genera and 26 species and subspecies of native parasitoids documented from 16 native siricids reported from 110 tree host species. Among parasitoids that attack the siricid subfamily Siricinae, Ibalia leucospoides ensiger (Norton), Rhyssa persuasoria (L.), and Megarhyssa nortoni (Cresson) were associated with the greatest number of siricid and tree species. These three species, along with R. lineolata (Kirby), are the most widely distributed Siricinae parasitoid species in the eastern and western forests of North America. Depending upon certain abiotic and biotic factors, we hypothesize that these four parasitoid species may contribute to the biological control of S. noctilio. Major gaps exist regarding parasitoid ecology, including their taxonomy, distribution range, exact siricid and tree hosts, interactions with hosts, phenology, and chemoecology in forest stands. As S. noctilio continues to expand its distribution in North America, a better understanding of the biology of these parasitoids may be needed in coniferdominated landscapes.

We evaluated the hypothesis that the use of an autumn-seeded winter rye, Secale cereale L., cover crop in soybean, Glycine max (L.) Men., could lead to decreased insect pest pressure. We compared insect pest and natural enemy populations in an organic soybean production system with soybeans planted into an autumn-seeded rye cover crop (i.e., soybeans planted in spring into a rye cover crop that had been planted the previous autumn). Small-plot experiments were conducted at two locations in southwestern Minnesota to compare insect populations on soybean planted into fallow ground versus soybean planted into rye that was managed by mowing using three different techniques. Densities of potato leafhopper, Empoasca fabae (Harris), were significantly lower on soybean in all of the rye treatments compared with soybean without rye at both locations. Densities of soybean aphid, Aphis glycines Matsumura, were significantly lower on all of the treatments incorporating rye than the soybean-only treatment at one site, but the suppressive effect of rye depended on the specifics of rye planting at the other site. Densities of bean leaf beetle, Cerotoma trifurcata (Förster), were significantly lower in the rye plots than soybean-only plots at one of the two sites. Foliar-foraging insect predator densities did not differ significantly among treatments at either site. Soybean yields did not differ significantly among treatments at either location although there was a trend for lower yield in two of the rye treatments. A statewide survey also was conducted to compare A. glycines infestations in Minnesota soybean fields with and without a rye cover crop. The proportion of plants infested and infestation ratings were both significantly lower in soybean fields with rye than in those without.

To improve cereal leaf beetle scouting efficiency and encourage the use of thresholds, temperature-based degree-day models were developed and tested to determine their accuracy to predict the date of egg and larval peaks. Previously published cereal leaf beetle temperature development data were used to create the degree-day model. This model of 182 DD using a base development temperature of 8°C was validated using cereal leaf beetle sampling data from four locations in Virginia and North Carolina in 2010, and six locations in 2011. In both years, the degree-day model predicted the average egg peak within 3 d of the observed calendar date. There was also a consistent period between egg and larval peaks averaging 17.5 d. Given the accuracy of this model, historical high and low temperature data were used to create a predictive map of the calendar week that different areas of Virginia and North Carolina would exceed 182 DD, and was validated using survey data from 60 field sites in 2010 and 65 sites in 2011 throughout Virginia and North Carolina. Finally, correlation and linear regression analyses were performed using data from all cereal leaf beetle study populations in 2010 and 2011, as well as previously collected data to determine if the number of eggs at peak could be used to predict larval peak numbers. There was a significant positive linear relationship between egg peak density and larval peak density, explaining 94% of the variation seen in larval peaks, indicating that egg peaks could reliably predict larval infestation levels.

Beet leafhoppers (Circulifer tenellus Baker) have been identified as the vector for a plant-pathenogenic phytoplasma known as beet leafhopper-transmitted virescence agent. Beet leaf-hopper-transmitted virescence agent causes purple top disease in potatoes, which can reduce yields and tuber quality. A trapping network, composed of ≈100 sites, monitors leafhoppers in the Columbia Basin of Oregon and Washington through a collaborative effort of regional researchers and stakeholders. Yellow sticky cards were used to determine the timing and spatial distribution of beet leafhoppers in the Columbia Basin; insects were counted weekly from early April through late October in 2006, 2007, and 2008. Weather data collected from a network of weather stations in Oregon and Washington were used in a nonparametric multiplicative regression analysis to determine which abiotic environmental variables might influence beet leafhopper populations. Weather conditions (mean temperature, dew point, precipitation, and wind speed) for 2006–2008 were also characterized using CIs established based on weather data from 1998 to 2004 for each weather variable. Several abiotic environmental factors significantly correlated with beet leafhopper populations, including temperatures the preceding fall and winter, elevation, and precipitation. Beet leafhopper populations appear to be highly variable across the region, with low numbers at a majority of the sites and only a limited number of high populations in localized areas.

Ambrosia beetles are normally defined as a secondary insect pest; in recent decades however, some species of beetles have become pestiferous, invading living trees and causing enormous damage to both indigenous and exotic species. However, ecological studies of these beetles in agricultural and native forests are lacking. In the current study we address the species diversity and the seasonal flight pattern of Xyleborini ambrosia beetles found in fruit orchards. Beetles were collected with ethanol baited panel traps in 20 durian orchards in southern Thailand throughout 15 mo. In total, 15,444 xyleborine ambrosia beetles representing 64 species (21 genera) were captured. Of these 64 species, 12 had not been recorded previously in Thailand. In this relatively homogenous habitat, only a few species were frequently captured. The species diversity and mean abundance per trap were not significantly different among cropping systems and study zones. However, the mean abundance per trap was significantly different between the dry and rainy seasons (t = 9.497; df = 12; P = 0.001). The flight pattern of xyleborine ambrosia beetles in the perennial fruit community fluctuated seasonally with the highest abundance in the middle of the rainy season continuing into the early summer and low abundance occurring in the remaining months. A linear regression analysis indicated that temperature and relative humidity predicted the flight pattern and that the climatic variables in the two previous months have a higher predictive power of the number of beetles than the variables in the month being investigated.

Both spatial (bioclimatic stages) and temporal (seasons) analyses were contemplated to estimate the influence of Mediterranean bioclimate on dung beetle assemblage's distribution. Insects were pitfall trapped once per season from 2008 to 2009 at eight bioclimatic sites from north to south of Tunisia. In total, 3,278 specimens and 39 species (18 Aphodiinae and 21 Scarabaeinae) were collected and the completeness of sampling was of 76.81%. Along the bioclimatic gradient species richness of these two families were of the same order (Scarabaeinae/Aphodiinae ratio 1.16). The highest value of species richness occurs in subhumid site (27 species) and the lowest in the arid sites (5 species). More beetles were captured in spring and few beetles in autumn. However, more Scarabaeinae were captured in summer and more Aphodiinae in winter. Humid and subhumid sites were more diverse with high temporal turnover and, 80% of species occur in this area of the north-west of Tunisia. Conversely, the arid sites have the lowest values of α- and β-diversity. The highest spatial turnover occurs between semiarid middle and semiarid inferior. Several factors could explain these results such as the soil nature, the geographical position, and latitude. Multivariate analyses showed that: 1) latitude greatly influenced the assemblage organization than bioclimate; 2) spatial factors (soil, bioclimate, latitude, altitude, marine influence) have greater effect than temporal factors (season); and 3) the Tunisian Dorsale is a stronger determinant where it act as a barrier or a filter that limit the colonization of arid sites by dung beetles and species occurred in these sites were those locally abundant an largely distributed. Results indicate that there were no spatio-temporal patterns according to bioclimate, but the influence of local and regional factors predominates on the dung beetle assemblages distribution.

Agricultural drainage ditches are artificial structures used to optimize soil hydrology for crop production and secondarily have been co-opted as a tool to manage the quality of water draining from agricultural lands. We investigated the relationship between the aquatic macroinvertebrate community and environmental variables associated with physical and biogeochemical processes that affect water quality. Aquatic macroinvertebrates were sampled along with physical and chemical measures of the soil and water from 29 agricultural drainage ditches on the Eastern Shore of Maryland. Cluster analysis and multivariate ordination showed that ditches that had higher flow velocities supported communities of lotic invertebrates (i.e., Stenelmis, Prosimulium) versus those that had properties of linear wetlands, which supported communities of lentic invertebrates (i.e., Oligochaeta, Caecidotea). Taxon richness varied from four to 31 taxa per ditch, and was higher within ditches that had higher flow velocities. Small ditches had low diversity, but may have provided refugia from fish predators. Macroinvertebrate communities did not show a significant linear relationship with water quality or with nutrient concentrations within the soil or water. The addition of flow-control structures designed to improve the quality of water draining from agricultural lands may decrease the quality of ditches as habitat for certain aquatic macroinvertebrates. Management decisions for drainage ditches may consider tradeoffs between the benefits of ditches as a source of biodiversity and as a tool for improving water quality.

Few baseline data exist regarding the role of wild, primarily native, non-Apis bees in pollinating crops through the growing season in the mid-Atlantic United States. Apis mellifera L., honey bees, generally are assumed to provide the majority of crop pollination, with the value of pollination provided by non-Apis bees estimated at between one-half and one-sixth the value of honey bees, though many non-Apis bees are known to be more effective in pollinating some crops. In this study, the first documenting wild bees visiting crop flowers through the growing season, non-Apis bees accounted for the majority of crop visitation for several economically important entomophilous crops in Virginia, such as apple, blueberry, caneberry, and cucurbit) and likely provided most of the pollination. Wild bees made up between 68% (in caneberries) and 83% (in cucurbits) of bees visiting crop flowers. Between 43 and 59 non-Apis bee species visited flowers of each crop (105 species overall). Species turnover was very high between sites, ranging from only 13% shared species in pairwise comparisons for blueberries to 30% shared species for caneberries. Native bee taxa most abundant on crops were Andrena F., mining bees, Bombus Latreille, bumble bees, and Osmia Panzer, mason bees, on apples and blueberries; Losioglossum Curtis, sweat bees, on caneberries; and Peponapis pruinosa Say, squash bees, and Bombus on cucurbits. Overall, this study highlights the substantial role of native bees in agricultural pollination in this region.

The ambrosia beetle Xyhsandrus germanus (Blanford) (Coleoptera: Curculionidae) is among the most important exotic pests of orchards and nurseries in the United States. It attacks a wide range of hosts and is difficult to control using conventional insecticides. As part of our studies on the biology and control of X. germanus, we are trying to optimize conditions for rearing beetle progeny to adulthood in the laboratory. In this study we tested the brood production by X. germanus reared on artificial diet based on sawdust from American beech (Fagus americana L.), black walnut (Juglans nigra. L.), European buckthorn (Rhamnus cathartica L.), and red oak (Quercus rubra L.). We also tested the growth of different strains of the beetle fungal symbiont, Ambrosiella hartigii Batra, on these sawdust diets. Among the sawdust types tested, we found significantly higher average number of progeny produced on diet made with sawdust from European buckthorn (43.9 ± 1.6) compared with those made with American beech (29.2 ± 1.7), black walnut (25.5 ± 1.9), or red oak (26.3 ± 1.8). The percentage of females producing brood and the brood sex ratio (females:males) were not affected by sawdust type. Sex ratio, however, was correlated with progeny size, with fewer males produced as the number of progeny increased. In smaller broods the ratio observed was ≈4:1; in larger broods it approached 20:1. Growth of the fungal symbiont varied with strain and with sawdust. Comparison of progeny production on sawdust-based diet with symbiont growth in vitro suggests that variables other than speed of symbiont growth may be more critical in optimizing brood production.

The virulence of two species (three isolates) of pine wood nematodes in stressed adult Japanese red and black pines was tested using an inoculation experiment. Three thousand nematodes, Bursaphelenchus xylophilus isolate ‘Ka4’ (virulent), isolate ‘C14-5’ (less virulent) or B. mucronatus isolate ‘M’ (less virulent), were inoculated into 15-yr-old naturally shaded and stressed pine trees planted in two separated experimental stands, in which shelterwood cutting had not been carried out after planting. The inoculation was conducted at the beginning of August 2010, and the trees were then visually examined every month for disease symptoms until February 2011. Trees that died during the experimental period were cut and brought back to the laboratory for reisolation attempts of the pathogenic nematodes. The Ka4 isolate killed all inoculated trees within one to 2-mo, whereas C14-5 and M each killed about half. The inoculated nematodes were reisolated from all the dead trees and some of the surviving ones. These results corroborated those of previous research by using small saplings (i.e., that less virulent nematodes can kill shaded (stressed) trees). Further, a feeding preference experiment using their vector beetles, Monochamus alternatus Hope, showed that both healthy and stressed trees are at equal risk of being used by beetles and hence of getting infected by the nematodes. Therefore, pine wilt disease in shading-stressed trees is assumed to occur in susceptible pine trees in natural pine stands. The dead tree is used by insects as an oviposition resource.

Wolbachia and Cardinium are both maternally inherited intracellular bacteria that infect a wide range of arthropods and are associated with various reproductive abnormalities in their hosts. Cytoplasmic incompatibility (CI) is the most common effect associated with the infection of endosymbionts. The CI results in a failure of karyogamy when infected males mate with uninfected females. Although infection by both Wolbachia and Cardinium is fairly common, little is known about their interactions and each symbiont's contribution to the phenotype of doubly-infected hosts. In this study we measured the strength of CI induced by Wolbachia, Cardinium, or both in the Hainan population of Sogatella furcifera (Horváth) by performing all possible crossing combinations, and show that Cardinium induced strong CI, Cardinium and Wolbachia together caused partial CI, and Wolbachia did not induce CI. We found that doubly-infected females could slightly rescue CI induced by Cardinium-infected males, Cardinium-infected females could also weakly rescue CI induced by Cardinium-infected males. The investigation of the fitness costs, benefits, or both of infection by each bacterium in planthopper showed that the infection with Cardinium alone could shorten the developmental time of nymphs in the Hainan population. Based on these results, we estimated that Cardinium may be the leading factor of CI in S. furcifera.

A biological control program has been initiated against the European swallow-worts Vincetoxicum nigrum (L.) Moench and V. rossicum (Kleopow) Barbar. (Family Apocynaceae) that have become invasive in North America. The leaf-feeding moth, Hypena opulenta Christoph (Lepidoptera: Erebidae), originating from eastern Europe, has been under measurement as a potential biological control agent of swallow-worts since 2006. In this study we measured the host range of H. opulenta by screening 82 potential host plant species for larval development under no-choice conditions. In addition, we also monitored female fecundity, longevity, and oviposition preference among suitable larval hosts. Successful larval development occurs only on Vincetoxicum spp. Partial larval development by one larva was observed on Boehmeria cyclindrica (L.) Sw. (Urticaceae) to the final instar, but this individual failed to pupate. Exploratory feeding occurred on Gonolobus stephanotrichus Griseb. (Apocynaceae) and Urtica dioica L. (Urticaceae), but all larvae failed to develop past the first and second instar, respectively. Additional testing with mature larvae on a subset of the plant species demonstrates that no species outside the genus Vincetoxicum are suitable for complete larval development of H. opulenta. The longevity and fecundity of females raised on each target weed are similar and gravid females do not display an oviposition preference among Vincetoxicum spp. Hypena opulenta does not present a risk to any native plant species or species of economic importance in North America. Petitions have been submitted for experimental open-field releases of H. opulenta in the United States and Canada.

Grapholita molesta (Busck) is one of the main pests of apple trees, and lives on their shoots and fruits. In southern Brazil, the insect is also found on old branches and structures similar to aerial roots, so-called burrknots. This study evaluated the development and population growth potential of G. molesta fed on burrknots, compared with apple fruit cultivar. Fuji and a corn-based artificial diet. The study was carried out in the laboratory under controlled temperature (25 ± 1°C), relative humidity (70 ± 10%), and photophase (16 h). The biological parameters of the immature and adult stages were determined, and a fertility life table was constructed. Insects fed on burrknots showed a longer duration and a lower survival for the egg-to-adult period (29.3 d and 22.5%) compared with those that fed on apples (25.1 d and 30.0%) and artificial diet (23.9 d and 54.8%). Insects reared on aerial roots had a lower pupal weight (10.0 mg) compared with those reared on either artificial diet (13.7 mg) or apple cultivar. Fuji (12.4 mg). The fecundity and longevity of males and females did not significantly differ for the three foods. Based on the fertility life table, insects reared on burrknots had the lowest net reproductive rate (Ro), intrinsic rate of population growth (r_m) and finite rate of increase (λ), compared with insects reared on artificial diet and apple fruit. Burrknots support the development of the complete cycle of G. molesta, which allows populations of this pest to increase in orchards.

Greenhouse tomato (Lycopersicon esculentum Mill) production relies on pollination by commercially-produced bumble bee (Bombus impatiens Cresson) colonies. Inadequate pollination by bumble bees has been a problem for growers at certain times of year; however, its cause has yet to be determined. Bumble bees have been shown to exit tomato greenhouses to forage on flowers of other plants. This study investigates tomato's floral characteristics and their affect on bumble bee pollination by 1) observing foraging preferences for bumble bees on greenhouse tomato, 2) determining if the plant's floral advertisements could be used by the bees to estimate pollen availability, and 3) identifying temporal changes in floral display which correspond to peak bumble bee activity. Flower size (petal length, anther cone width, and anther cone length) and floral scent (release of β-phellandrene, 2-carene, α-pinene, and p-cymene) were evaluated to identify the pollinator-important characteristics of tomato flowers. Our results indicate that 1) bumble bees preferred to pollinate flowers which produce less β-phellandrene and 2-carene in comparison to flowers producing more of these volatiles, 2) flower size and floral scent are not likely used by the bees to estimate pollen availability, and 3) cultivars are inconsistent in their production of floral volatiles during peak bumble bee activity, β-phellandrene and 2-carene may be antiherbivory volatiles and reduced production during peak bee activity may help to facilitate pollination of tomato. Pollinator-repellent volatiles may help to protect flowers from damage caused by over-pollination.

Injury from stem-boring caterpillars has been observed on the perennial grass Miscanthus × giganteus Greef and Deuter ex Hodkinson and Renvoize in both its native and introduced ranges. Because some species causing stem injury in the United States have not been identified, potential biomass reductions to M. × giganteus were measured using southwestern corn borer, Diatraea grandiosella Dyar (Crambidae), an insect pest of several related crops within the Andropogoneae. Results indicate D. grandiosella is capable of survival on whorl and stem tissue from hatch to 21 d in the laboratory, and field infestations with third instars support adult development, as exuviae were found during dissection of injured tillers. Relative to uninfested controls, M. × giganteus tillers with stem injury yielded 12–30% less dry mass in four infestations over 2009–2010. As in some D. grandiosella hosts, data indicate decreased susceptibility to stem-boring as tillers increase in size or age. Regressions of residuals (observed — predicted mass) for injured M. × giganteus tillers onto the cumulative length of tunnels per tiller also showed significant negative slopes (i.e., decreasing tiller mass with increasing tunnel length). Although D. grandiosella survival appeared low in both laboratory and field trials, results indicate that M. × giganteus productivity could become limited by other stem-boring caterpillars known to attack Andropogoneae, including the following: Elasmopalpus lignosellus (Zeller) (Pyralidae), Diatraea saccharalis (F.) (Pyralidae), and Eoreuma loftini (Dyar) (Crambidae). For perennial grasses grown exclusively for biomass, certain management strategies for stem borers or other pests may be uneconomical or impractical, suggesting long-term investment in breeding for host plant resistance may be needed.

Habitat management is important for the regulation of arthropod community structures to reduce pest populations in orchard ecosystems, but there is limited information on how intercropping with aromatic plants regulates arthropod community structure at trophic levels. We selected four aromatic plants, Mentha canadensis L., Agerarum houstonianum Mill, Tagetes patula L., and Ocimum basilicum L., as intercrops in apple orchard to analyze the effects of intercropping on herbivore and predator abundance, species richness, and to measure the changes of trophic levels of the associated arthropod community. We found that intercropping with aromatic plants, compared with intercropping with natural herb vegetation, significantly reduced herbivore abundance and species richness by 25.62 and 11.6%, respectively. Intercropping significantly increased predator abundance and species richness by 18.78 and 15.6%, respectively, with predator abundance most notably affected during the flowering period of aromatic plants. Furthermore, herbivore abundance and species richness were strongly negatively correlated with predator species richness. Intercropping affected herbivore-predator dynamics, with an observed increase in the ratios of predator abundance and richness to herbivore abundance and richness. Our results indicate that intercropping with aromatic plants in apple orchards may play a role in the observed shift from a herbivore-dominated to a predator-dominated trophic structure, which is likely to have important flow-on effects on arthropod community structure.

The diamondback moth, Plutella xylostella (L.) (Lepidoptera: Plutellidae), a major pest of cruciferous crops throughout the world, has demonstrated an ability to develop resistance to many different classes of insecticides, including proteins from Bacillus thuringiensis that are expressed in plants (Bt plants). The ovipositional preferences and larval survival of strains (resistant strain, RR; heterozygous strain, RS; susceptible strain, SS) of P. xylostella to Cry1Ac-expressing broccoli or broccoli plants treated with lambda-cyhalothrin or spinosad were studied under greenhouse condition. Numbers of eggs per plant did not differ between Bt broccoli and non-Bt broccoli for Bt-RR, Bt-RS, and Bt-SS adults. Ovipositing adults (spinosad-RR, spinosad-RS, and spinosad-SS) also could not discriminate between spinosad-treated and untreated plants, and oviposition did not increase over the 13 d after spinosad treatment. For broccoli treated with lambda-cyhalothrin at the diagnostic dose of 20 ppm, all three insect strains (Ic-RR, Ic-RS, and Ic-SS) had constant oviposition over time based on linear regressions. At the field dose of 80 ppm, the Ic-RR strain had constant oviposition over time. The Ic-SS susceptible strain had increasing oviposition over time, but the oviposition pattern on the nonsprayed broccoli also increased over time. Susceptible females layed fewer eggs on plants sprayed with lambda-cyhalothrin than on unsprayed plants. A residue-persistence test showed that spinosad and lambda-cyhalothrin could effectively control SS P. xylostella larvae for 7–9 d after application. These results are discussed in relation to their potential impact on insecticide resistance management strategies.

The southern chinch bug, Blissus insuhris Barber, forms dense, multigenerational aggregations in St. Augustinegrass lawns leading to grass death from sap feeding. We conducted laboratory bioassays to better understand the signals responsible for the formation and maintenance of southern chinch bug aggregations. In small arena assays, chinch bugs demonstrated a stronger aggregation response over time and aggregated more often on or beneath St. Augustinegrass leaf blades than on or under artificial leaf-like shelters constructed from white or green paper. In Y-tube olfactometer assays, bugs of different age and sex were attracted to volatiles from mixed-sex chinch bug aggregations and showed particular attraction to groups of adult female chinch bugs. Adult males and nymphs were also attracted to adult males. Nymphs were attracted to nymphs and were also more attracted to aggregation volatiles when they could see bugs in the arm of the Y-tube. Adult males were more attracted to short-winged than long-winged adults, while females and nymphs demonstrated no preference. All bugs were attracted to St. Augustinegrass volatiles when presented alone, but only males preferred the odor of grass over odor released from a chinch bug mixed-sex aggregation. When presented with a choice of grass and grass aggregation volatiles, males preferred the combined treatment. The results of these assays suggest that a complex combination of life stage, sex, as well as plant and insect-derived signals influence chinch bug aggregation behavior.

Predation, egg production, and survivorship of Laricobius nigrinus Fender, L. rubidus LeConte, and L. osakensis Montgomery and Shiyaki, predators of hemlock woolly adelgid, Adelges tsugae Annand, were investigated in the laboratory and in the field. In individual assays in the laboratory, L. rubidus oviposited fewer eggs than either L. nigrinus or L. osakensis. In assays containing congeneric or conspecific groups of adult Laricobius, L. osakensis preyed upon the greatest number of ovisacs. The number of ovisacs preyed upon was not different between treatments with all three species and those with only L. osakensis or L. nigrinus. Adult predators fed on few predator eggs and when they did no species preference was observed. The numbers of A. tsugae ovisacs fed upon did not differ significantly by groups of congeneric or conspecific Laricobius larvae. Laricobius adults and larvae had high survival rates throughout all experiments. In the field, L. nigrinus and L. rubidus were enclosed in sleeve cages with both high (>120 ovisacs) and low (<90 ovisacs) A. tsugae densities for 1 wk. All branches with caged beetles had significantly greater numbers of ovisacs preyed upon than branches caged without beetles. No differences in predation or egg production were found among the conspecific and congeneric groupings. Predation was uniformly greater on high prey-density branches than on low prey-density branches. Survivorship among predators did not differ significantly at either prey density. Results from both laboratory and field experiments suggest that these species are able to coexist and can be released in the same location for biological control of A. tsugae.

Foraging behaviors of bumble bee workers have been examined in natural habitats, whereas agricultural landscapes, which can provide insights on flight distances to fragmented patches of bloom, have received limited attention. In particular, information on worker flight distances to crops blooming several months after nests have been established is invaluable. Here, we examined foraging patterns of Bombus vosnesenskii Radoszkowski in late-season blooming clover in the agriculturaldominated Willamette Valley in Oregon. Workers from 10 fields collected over 2 yr were assigned to full sibling families (colonies) by using eight microsatellite loci. With estimation of numbers of unseen species, we inferred the presence of 189 colonies from 433 bees genotyped in year 1, and 144 from 296 genotyped the next year. Worker foraging distance was estimated to be at least 11.6 km, half the distance between the most remote fields visited by the same colonies. Numbers of nests contributing workers to each field ranged from 15 to 163. Overall, 165 (50%) colonies foraged in two or more fields, and thus used common resources within the landscape. Estimates of average nest densities in the landscape each year ranged from 0.76/km² to 22.16/km², and highlighted the influences of various study parameters incorporated into the calculation including sample size, distances between sites, and analytical tools used to estimate unsampled individuals. Based on the results, bumble bees can fly long distances, and this could facilitate their survival in fragmented agricultural landscapes. This has important implications for the scale of habitat management in bumble bee conservation programs.

Groups of Folsomia Candida (Willem) were chilled to 0°C and warmed back to room temperature to measure their locomotor response to cooling and determine the chill coma temperature of the species. Results showed that the frequency of walking springtails, in groups being chilled down to 0°C, was initially similar to that of control groups held at room temperature before consistently declining to chill coma thresholds well above the freezing point. Body size had a significant effect on response to chilling but not to recovery. Jumping, in groups being chilled, was absent from tests conducted in humid arenas but an important part of the locomotor response in dry arenas. Chill coma thresholds were higher in dry than in humid arenas. In a 4–33°C thermal gradient, warm-acclimated and cold-acclimated springtails distributed themselves over the whole gradient, but with a preference for sections at 8–11 and 5–8°C, respectively. Together, test results did not support the hypothesis that, for F. Candida, locomotion is the main strategy to avoid cold temperatures. Results suggest that F. Candida remain in the upper soil layers as the season becomes colder and increase their cold tolerance to continue foraging in the food-rich upper soil layers. Survival of the species to freezing temperatures may depend more on development of cold tolerance and cold hardiness (supercooling) than on relocation to warmer deeper soil lavers.

Understanding interspecific competition among insect parasitoids is important in designing classical biological control programs that involve multiple species introductions. Spathius galinae Belokobylskij and Strazenac, a new idiobiont ectoparasitoid from the Russian Far East, currently is being considered for introduction to the United States for biological control of the emerald ash borer, Agrilus planipennis Fairmaire, whereas Tetrastichus planipennisi Yang, a koinobiont endoparasitoid native to China, is another natural enemy that already has been introduced in the same program. In a laboratory study, we examined the potential interactions between these two parasitoids when they compete for the same emerald ash borer host larvae. In multiple-choice assays where healthy emerald ash borer larvae were presented along with emerald ash borer larvae previously parasitized by T. planipennisi at different times, S. galinae attacked host larvae already parasitized by T. planipennisi for up to 4 d, but not 8 d. However, parasitism rates were significantly lower in previously parasitized hosts as compared with healthy host larvae. In no-choice tests where S. galinae females were presented either with healthy emerald ash borer larvae or emerald ash borer larvae parasitized by T. planipennisi at several earlier time points, S. galinae again parasitized significantly more healthy host larvae than T. planipennisi-parasitized larvae. These results suggest that the ectoparasitoid S. galinae can discriminate between healthy host larvae and T. planipennisi-parasitized larvae, and competitive interactions between the two parasitoids are likely to be minimal if coreleased by the emerald ash borer biological control program.

The primary insect pest of the developing chestnut industry in the central United States is the small chestnut weevil, Curculio sayi (Gyllenhal), which is a specialist on only Castanea trees. Recent research has shown this insect is attracted to and feeds upon the reproductive tissues of the chestnut tree, including the flowers, burs, and nuts. In this study, the major volatile components emanating from the chestnut's reproductive tissues were sampled using solid phase microextraction and static headspace analysis. In total, 59 compounds from these tissues were separated and identified using GC-MS and authenticated reference standards. The majority of compounds identified from the bur and nut tissues were esters (60.2 and 67.4%, respectively). The majority of compounds identified from catkins were alcohols and benzenoids (53.2 and 19.8%, respectively). A subset of those compounds identified from the chestnut plant tissues was used in electroantennogram testing to determine the insect's electrophysiological response to host-generated volatiles. This study identifies the major components of the volatile profile from several important chestnut plant tissues, and was the first to report the volatile compounds from bur tissue. The identification of the major volatiles emanating from chestnut tissue, as well as the associated insect response, are both critical to the successful utilization of these host-plant volatiles as attractants in the development of a semiochemical-based monitoring trap for C. sayi adults.

Recent studies to elucidate relationships between the western tarnished plant bug, Lygus hesperus Knight, and injury to cotton (Gossypium spp.) have identified important differences in feeding behaviors among adults of different gender and reproductive states. These findings suggest a need for improved knowledge of L. hesperus temperature-dependent reproductive development. We used nonlinear biophysical development rate models to describe the reproductive development of adult L. hesperus held under constant temperatures from 12.8 to 35.0°C. In addition, abdominal coloration was measured as a nondestructive indicator of reproductive maturity. The nonlinear models indicated most stages of ovary, seminal vesicle, and medial accessory gland development were subject to mild high-temperature inhibition, except for the stage of filled seminal vesicles. Development of filled seminal vesicles was subject to minor low-temperature inhibition and severe high-temperature inhibition. Estimated development times reflected extensive interindividual variation, especially at low temperatures. This variation suggests the opportunity to select for more rapid or more consistent reproductive development under the conditions of laboratory culture. Although presence of a dark aqua coloration of the ventral abdominal cuticle was statistically associated with reproductive maturity, especially in female L. hesperus, color-based predictions of reproductive maturity were often inaccurate for bugs reared at temperatures above or below 26.7°C. Therefore, use of abdominal coloration as an indicator of reproductive development in ecological studies seems inappropriate. The results provide mathematical descriptions of L. hesperus temperature-dependent reproductive development which should facilitate improved planning and interpretation of studies involving manipulation of adult reproductive status.

The nonbiting midge, Glyptotendipes tokunagai Sasa (Diptera: Chironomidae), is an organism that can be used as a water quality indicator. Development of this insect under different temperatures was evaluated. The highest egg hatching rate was 99.12 ± 1.47% at 30°C, and the lowest was 84.50 ± 11.09% at 10°C. No eggs hatched at temperatures of 8 and 42°C. Developmental rate (1/h) increased gradually as temperature increased from 10 to 35°C with a peak rate (0.045 ± 0.0079) at 35°C. The estimated lower thermal threshold for egg hatching was 9.3°C. Adult emergence rate was highest (80.6%) at 30°C and lowest (22.2%) at 15°C. The developmental times (egg to adult) for both males and females decreased from 2,102.6 to 457.2 h and from 2,337.1 to 619.8 h as temperatures increased from 10 to 30°C. The estimated lower thermal thresholds for males and females were 11.4 and 10.4°C, respectively. The body sizes of all G. tokunagai decreased as temperature increased from 15 to 35°C. From the results of this study, the approximate rearing temperature for G. tokunagai is suggested to be 25–30°C for egg hatching, larval development, and emergence. Our results demonstrate that G. tokunagai is a potential test insect species that can be reared in the laboratory by providing optimal temperature conditions.

It is usually assumed that a host's survival after pathogen exposure should correlate with the host's immune strength. In the laboratory and using two species of white grubs, Phyllophaga polyphylla (Bates) exhibited a higher survival than Anomala cincta (Say), when inoculated with Metarhizium anisopliae and Beauvieria bassiana (two fungus pathogens of the above white grub species). We tested whether such survival difference correlates with differential expression of immune ability. Thus, immune response (phenoloxidase [PO], and nitric oxide production [NOP]) and survival after experimental fungal infection were compared among and within (challenged versus control groups) white grub species. As expected, results showed that P. polyphylla had higher PO and survival values compared with A. cincta. However, only A. cincta produced NOP. Thus, our study provides support for the idea that survival correlates with host's basal immune strength that never-theless only applies to PO, but not to NOP. The interspecific difference in PO and NOP may be because of the distinct pathogenic pressures that each grub species faces according to their different feeding regimes. Paradoxically, no differences in survival and immune response were found within each white grub species. This suggests that the difference observed between species is better explained by their basal immune response but not to challenge. We discuss possible scenarios to explain why white grubs are attacked by fungus in the field but not in our laboratory conditions.

Laboratory studies were conducted to assess the effect of soil moisture and temperature on the development of the preimaginal stages of Ceratitis capitata (Wiedemann) (Diptera: Tephritidae). The number of days required for the immature flies to complete their development and reach the adult stage (development time) were studied at five temperatures (15, 20, 25, 30, and 35°C) and under five soil moisture regimes (-2.14 Mpa [mega Pascal] [1% (wt:wt)], -0.5 MPa [5.0% (wt:wt)], -0.47 MPa [9.0% (wt:wt)], -0.28 MPa [13.0% (wt:wt)], and -0.23 MPa [17.0% (wt:wt)]). A parametric survival model describing the effect of linear and quadratic combinations of temperature and soil moisture and their interaction on the probability of completing the development over the experimental period was used. The lognormal parametric survival model was significant for C. capitata preimaginal development, with DT50 (the development time for 50% of the preimaginal C. capitata to reach the adult stage) ranging from 12.8 to 32.4 d. The highest percentages of adult emergence at 30 d were obtained at 24.8°C and intermediate soil moistures of 5.0 to 13.0% wt:wt. The average development time of the medfly preimaginals reaching the adult stage was inversely related to temperature and ranged from 7.4 to 26.1 d. This model could allow the monitoring of medfly preimaginal natural mortality in the soil, the prediction of adult emergence under field conditions, and therefore, the identification of suitable application times in the medfly lifecycle to achieve the maximum degree of adult and preimaginal control.

Black soldier flies, Hermetia illucens (L.) (Diptera: Stratiomyidae) are of particular interest for their application in waste management such as reducing manure accumulations in confined feeding operations. Determining black soldier fly development time as a result of climatic variations will allow for optimizing their utilization as a waste management agent at landfill sites and confined animal feeding operations. To implement a black soldier fly waste management program in Canada, where seasonal variability does not support H. illucens development on a year round basis, determining maximum and minimum abiotic thresholds to sustain larval development is important. In Canadian winters, maintaining greenhouse temperatures necessary for black soldier fly development results in low relative humidity that could impact their development. The objective of this study was to determine relative humidity thresholds on egg eclosion and adult emergence. Egg eclosion success was measured at 25, 40, 50, 60, and 70% relative humidities and adult emergence success was measured at 25, 40, and 70% RH. Egg eclosion and adult emergence success increased with increasing relative humidities, while development time decreased with rising relative humidities.

The aim of the current study was to analyze the direction and range of changes in wing size and shape in both sexes of Drosophila subobscura (Collin, 1936) flies that originated from two natural populations with different evolutionary history (sampled from ecologically distinct habitats) maintained during seven generations in laboratory conditions on different lead (Pb) concentrations. The results showed significant wing size variability differences across seven generations of rearing on lead for both populations. Wing size is negatively correlated with lead level, in contrast with wing shape in which significant variation was observed in just one of the populations. According to our results, wing size seems to be more affected by lead pollution in both tested populations compared with wing shape. Our data suggest that presence of lead in higher concentration over extended period of time may reduce the stability of wing morphology and consequently reduce the fitness of exposed individuals. Therefore, specific stress that persists over multiple generations could increase the probabilities for extinction of populations composed of sensitive individuals.

Developmental and reproductive traits of two little studied anthocorid predators from southern Africa, Orius thripoborus (Hesse) and Orius naivashae (Poppius), were examined at several constant temperatures. Development was studied at 12, 15, 23, 25, 29, 33, and 35°C. Eggs of both species did not hatch at 12°C. Nymphal survival was poor at 15°C for O. naivashae, and at 33°C and 35°C for O. thripoborus. Total development time of males and females decreased with increasing temperature. Based on a linear degree-day (DD) model, lower threshold temperatures for egg and nymphal development were estimated to be 9.4 and 10.2°C for O. thripoborus, and 11.3 and 11.8°C for O. naivashae. Thermal requirements for these stages were 73.8 and 191.1 DD, and 65.2 and 168.2 DD, respectively. Adult reproduction was studied at 15, 19, 25, and 33°C. Highest lifetime fecundities for O. thripoborus and O. naivashae were found at 25°C. At 15°C, half of the O. thripoborus females oviposited, whereas O. naivashae females only produced infertile eggs. At 33°C, however, most of the O. naivashae females produced eggs, whereas O. thripoborus females did not oviposit. Our observations suggest that O. thripoborus is adapted to a slightly cooler temperature range as compared with O. naivashae. The complementarity of both predators in terms of their temperature adaptation opens possibilities for their use in biological control programs at different times of the season.

The western bean cutworm, Striacosta albicosta (Smith) (Leptidoptera: Noctuidae) is a pest of corn (Zea mays L.) and dry beans that underwent a dramatic range expansion in North America during the 1st decade of the 21st century. Research into the population genetics of this species has been hindered by a lack of genetic markers. The transcriptome of adult male S. albicosta was partially sequenced using Illumina sequencing-by-synthesis. Assembly of the sequence reads yielded 16,847 transcript sequences, of which 6,631 could be assigned a putative function. A search for single nucleotide polymorphisms (SNPs) identified 2,487 candidate SNPs distributed among 1,265 transcripts. A panel of 108 candidate SNPs was selected for empirical testing, of which 68 proved to be assayable polymorphisms that are suitable for population studies. This work provides significant genetic resources for studying S. albicosta and demonstrates the power of applying of second-generation sequencing to previously understudied species.

In 2002, a new invasive pest ant in the genus, Nylanderia (formerly Paratrechina), was found in Houston, TX. This invasive ant has been causing significant economic and ecological damage in infested areas. Because of the morphological and behavioral similarities to Nylanderia pubens Forel (Caribbean crazy ant) found in Florida, this ant was named Nylanderia sp. nr. pubens (Rasberry crazy ant). So far, morphometric and phylogenetic analyses have not determined if the two ants are the same or separate species. To determine the relationships between the two populations, a molecular approach was undertaken. Five novel genes with various functions from N. pubens and N. sp. nr. pubens were cloned, sequenced, and identified, including a chemosensory protein (NpCsp), the cyclophilinlike protein (NpClp), the fatty acid binding protein (NpFabp), the ferritin 2-like protein (NpFlp), and an odorant binding protein (NpObp). The cDNA sequences of NpCsp, NpFabp, NpFlp, and NpObp, shared 100% identity between N. sp. nr. pubens and N. pubens. The cDNA of NpClp shared 99% identity, with the only difference at the nucleotide position 358. Comparisons of four partial genomic DNA sequences from Caribbean and Rasberry crazy ants indicated 100% identity for a 710-bp partial genomic DNA sequence of cytochrome oxidase subunit I gene, 99% identity for a 774 bp, and a 452-bp partial genomic DNA sequence of NpFabp and NpObp containing noncoding regions, and 100% identity for a 289 bp partial genomic DNA sequence of NpCsp containing only coding region. This study showed that N. sp. nr. pubens in Texas is the same, or at most an intraspecific variant or ecotype of the species in Florida.

The potato psyllid, Bactericera cockerelli (Sulc) (Hemiptera: Triozidae), is a vector of the bacterium “Candidatus Liberibacter solanacearum,” the putative causal agent of potato zebra chip disease that has seriously affected the potato industry in the Central and Southwestern United States for the past decade. The 2011 potato growing season saw the first report of zebra chip disease in Washington, Oregon, and Idaho; however, B. cockerelli has been recorded in this region every season at least for the past 7 yr. Studies were conducted to determine the relationship between psyllids collected from the Pacific Northwest potatoes in 2011 and those from the Southwestern and Central United States. High resolution melting analysis of the B. cockerelli mitochondrial Cytochrome C Oxidase subunit I-like gene was conducted on over 450 psyllids collected from numerous locations across the Central and Western United States. Results suggest that at least three potato psyllid haplotypes exist in the United States, correlating to the Central, Western, and Northwestern United States geographical regions. The high resolution melting analysis results were subsequently supported by DNA sequencing data.

Widespread planting of crops genetically modified to express Bacillus thuringiensis (Bt) toxins for pest control may potentially affect nontarget pests and soil-borne disease. In this study, a field trial was conducted to explore the effects of habitat diversification, specifically an intraspecies mixture of genetically distinct cotton lines, on nontarget pests and soil-borne disease. It was hypothesized that the mixture would suppress disease severity and would alter pest and predator abundances. Results confirmed that a row-mixture of 75% insect-resistant cotton and 25% disease-resistant cotton suppressed Fusarium wilt and controlled cotton aphids. However, intercropping at the genotypic level increased mirid bug and sweetpotato whitefly densities in cotton. Moreover, the effect of the mixture on predator abundance ranged from neutral to positive and was highly variable among species and years. Species-specific pest responses to the crop mixture provide new insights for optimally sized and configured refuge construction in the future.

In fields of genetically engineered maize that produce insecticidal Bacillus thuringiensis (Bt) proteins, generalist predators are likely to be exposed to the toxin via prey consumption. For the assessment of risks of Bt proteins to nontarget species, information on Bt protein uptake, fate after feeding, and accumulation after long-term exposure is valuable. One objective of this study was to determine uptake and fate of Bt protein in an arthropod predator. Phylloneta impressa (L. Koch) spiders were fed with a single Diabrotica virgifera virgifera LeConte western corn rootworm beetle or Chrysoperla carnea (Stephens) lacewing that were reared on Cry3Bb1-expressing Bt maize material. The Bt protein concentration measured in spiders 1 d after feeding was 55% of the concentration in beetles and 37% of the concentration in lacewings. Five days after feeding, the Bt protein concentration in P. impressa decreased by ≈90%, indicating rapid excretion, digestion, or both. To investigate the potential accumulation of Cry3Bb1 in spiders, lacewings, and rootworm beetles, concentrations after a short period of feeding (1–8 d) on food containing Bt protein obtained in the present study were compared with published data on long-term continuous feeding (28–64 d). Concentrations of Cry3Bb1 after long-term feeding were similar or lower than those after short-term feeding, which indicates that the Bt protein does not accumulate in the tested arthropods over time.