A 3-yr field survey was carried out in France, from 2002 to 2005, to study honey bee (Apis mellifera L.) colony health in relation to pesticide residues found in the colonies. This study was motivated by recent massive losses of honey bee colonies, and our objective was to examine the possible relationship between low levels of pesticide residues in apicultural matrices (honey, pollen collected by honey bees, beeswax) and colony health as measured by colony mortality and adult and brood population abundance. When all apicultural matrices were pooled together, the number of pesticide residue detected per sampling period (four sampling periods per year) and per apiary ranged from 0 to 9, with the most frequent being two (29.6%). No pesticide residues were detected during 12.7% of the sampling periods. Residues of imidacloprid and 6- chloronicotinic acid were the most frequently detected in pollen loads, honey, and honey bee matrices. Several pairs of active ingredients were present concurrently within honey bees and in pollen loads but not in beeswax and honey samples. No statistical relationship was found between colony mortality and pesticide residues. When pesticide residues from all matrices were pooled together, a mixed model analysis did not show a significant relationship between the presence of pesticide residues and the abundance of brood and adults, and no statistical relationship was found between colony mortality and pesticide residues. Thus, although certain pesticide residues were detected in apicultural matrices and occasionally with another pesticide residual, more work is needed to determine the role these residues play in affecting colony health.

Southeastern Australia is situated in a temperate zone with generally mild winters. The diamondback moth, Plutella xylostella L., can be a serious pest of canola as well as of other Brassica crops in this region. However, the ability of P. xylostella to overwinter in southeastern Australia, as well as in other temperate regions of the world, remains controversial. Laboratory experiments indicated that after 60 d in a temperature regimen alternating between 0 and 5°C, 32% of third- and fourth-instar larvae pupated, 38% remained as larvae, and 57% of pupae survived, whereas only 15–20% of adult moths were still alive. Second-, third-, and fourth-instar larvae and pupae survived -5°C for up to 2, 4, 6, and 13 d, respectively, with some adults surviving >20 d. Furthermore, adults that survived 60 d of exposure to 0–5°C and 20 d at -5°C reproduced normally without supplemental food. An experiment simulating outdoor overwintering with caged populations and field survey for natural overwintering populations of P. xylostella on volunteer canola (Brassica napus L.) and wild turnip (Rapistrum rugosum L.) plants indicated that development and reproduction continued on these host plants through the winter months. These empirical results provide evidence that P. xylostella is capable of overwintering on suitable host plants in southeastern Australia, and the overwintering populations may contribute significantly to local population levels in spring and summer seasons.

The relative abundance and seasonal flight activity of dogwood borer, Synanthedon scitula Harris (Lepidoptera: Sesiidae), was measured using weekly records from traps baited with its sex pheromone and deployed in apple orchards, urban landscapes, and native woodland sites in New York, West Virginia, Virginia, North Carolina, and Tennessee in 2005 and 2006. The mean total number of moths captured per site in apple orchards was 3,146 ± 644 and 3095 ± 584 SE in 2005 and 2006, respectively, exceeding captures at urban sites by 16 and 13 times and at woodland sites by 210 and 206 times in 2005 and 2006, respectively. Mean total captures at urban sites exceeded those in woodland habitats by 13 and 16 times in 2005 and 2006, respectively. The mean duration (wk) of the flight period did not differ significantly between apple orchards (22.6 ± 0.6 SE) and urban sites (20.3 ± 1.2 SE). The onset of flight was somewhat later in New York (around early June) than further south (around early to mid-May), but moth captures continued into October in all states. Captures in apple orchards and at urban sites with higher populations were essentially continuous throughout the flight period, with substantial weekly fluctuations, and tended to show a bimodal pattern with peaks from late May through mid-July and from late August through mid-September. Captures at woodland sites tended to occur predominantly from mid-May through about mid-June and were very sporadic thereafter.

The population dynamics of a fire ant (Solenopsis invicta Buren) parasitoid (Pseudacteon tricuspis Borgmeier) was studied in Louisiana. The objectives of this study were to understand the daily and seasonal population dynamics of P. tricuspis in the context of environmental variables, determine whether P. tricuspis populations were synchronized over local and regional scales, determine the sex ratios and frequency distributions of P. tricuspis at disturbed S. invicta mounds, and determine the minimum sample size and sampling methodology that would provide an estimate of the true relative abundance of P. tricuspis at any location. Daily patterns of relative abundance of P. tricuspis followed a quadratic pattern, with peak fly activity during the afternoon. Seasonally, P. tricuspis relative abundance was variable but tended to positively fluctuate with soil moisture levels. Peak seasonal population abundance occurred during the late summer and fall, whereas population abundance was lowest during the late winter and early spring. Population dynamics of P. tricuspis were found to be synchronized at local and regional scales. Sampling protocols were derived for sampling P. tricuspis populations in Louisiana to account for local spatial heterogeneity in relative population abundance. To obtain an estimate of the true relative population abundance of P. tricuspis, at least 15 S. invicta mounds should be sampled, preferably allocated in groups to different areas at a location to account for spatial population heterogeneity. Phorid fly sampling should be conducted during the afternoons during the summer and fall, when fly abundance is highest.

Imported fire ant colonies were quantified in 1,000-m² circular subplots spaced ≈425 m apart on a sheep and goat farm in Oklahoma. Social form (percent polygyny), mound density, cumulative above-ground mound volume, and average mound volume were subjected to multiple regression analyses to examine trends related to landscape metrics and habitat characteristics. Monogyne populations were spatially autocorrelated, and polygyne mounds tended to be smaller and more numerous. A model incorporating the effects of percent polygyny, canopy cover, and 1-d cumulative incident solar radiation explained 34% of the variation in mound density. Percent polygyny was not significantly related to cumulative mound volume, which provides a better estimate of overall ant biomass. A model incorporating the effects of 1-d cumulative incident solar radiation on the summer solstice, elevation, canopy cover, distance from cisterns, distance from water, and distance from trees explained 42% of the variation in cumulative mound volume. Monogyne mounds in areas that were flat and close to water in low-lying areas were largest. Results indicate that remotely sensed data in combination with publicly available U.S. Geological Survey data may be useful in predicting areas of high and low fire ant abundance at a field scale.

Aethina tumida Murray is an African native that has become an important pest of honey bee colonies in North America and Australia. Adults and larvae feed on pollen, honey, and brood in bee hives. The beetle is also able to feed and reproduce on fresh or rotting fruit, but natural occurrence on this diet has rarely been observed. We compared the reproductive success—as measured by progeny production, weight of progeny, developmental rate, and survival of immature stages—of beetles reared on various diets of fruit and bee products. Reproduction on all of the diets was sufficient for population growth. Using baited flight traps to monitor the presence of A. tumida, we found persistent although tenuous populations in wooded habitats lacking managed bee colonies. On the basis of these findings and the habits of other nitidulid beetles, we propose that A. tumida is an ecological generalist able to maintain adequate levels of reproduction in marginal environments but able to reach high levels in favorable, resource rich environments, such as honey bee colonies. This hypothesis has significance for active dispersal and range expansion, because reproduction in the absence of bees would facilitate long range dispersal by flight through successive generations. Although our findings support the hypothesis, definitive proof would require association of beetles with hosts, trapping adults as they emerge from the soil, or other methods that would confirm feeding and reproduction at a given site, rather than immigration from bee colonies.

Red locusts, Nomadacris septemfasciata (Serville, 1838), frequently damage crops in Madagascar, and this problem has worsened in recent years, likely because of intensive deforestation. Little is known about this pest in Madagascar, contrary to southern Africa. We studied the reproductive maturation in relation to climate and vegetation in northwestern Madagascar. Our results show that adults overwinter, with females undergoing a 6- to 7-mo-long reproductive diapause, followed by a variable quiescent period of 2–4 wk, depending on ecological conditions, during which vitellogenesis is delayed,. Food availability in response to good rains at the end of spring seems to be the key factor for triggering the end of quiescence and the beginning of rapid vitellogenesis (= reproductive maturation). Hind wing color in adults changes throughout the year and was correlated with age and reproductive state in females and seasonal climate change.

The hemlock woolly adelgid (Adelges tsugae Annand) is a small, aphid-like insect native to East Asia and western North America. First documented in the eastern United States in Richmond, VA, in 1951, it has spread to at least 17 states, where it causes increased mortality among both eastern and Carolina hemlocks (Tsuga canadensis Carrière and T. caroliniana Engelmann., respectively). Previous work has suggested low temperatures may limit northward spread of the adelgid. Using recent surveys of A. tsugae mortality across the infested latitudinal gradient of the eastern United States, we show there is a significant positive relationship between minimum winter temperatures and winter survival at the landscape scale. The strength and nature of this relationship, however, varies through time, with absolute minimum winter temperatures explaining almost one half of the tree-level variance in survival in the spring of 2004 but only 9% in 2003. Post hoc analyses of the data suggest the explanatory power of temperature can be improved in ongoing studies by examining seasonal temperature profiles. Previous studies have also suggested adelgid survival may be density dependent, and although these data support this observation, contemporary density is a poor predictor of adelgid survival at the landscape scale. Using landscape estimates of minimum winter temperature, we show two simple methods of estimating landscape-scale adelgid survival rates. Both methods suggest much of the range of T. canadensis in the eastern United States, and the entire range of T. caroliniana falls in areas where winter temperatures will not impose critical limits on A. tsugae populations.

Rhagoletis pomonella (Diptera: Tephritidae) populations in North America have diverged by exploiting host plants with varying fruiting phenologies in environments that differ markedly in temperature and humidity. As a result, four genetically and ecologically distinct R. pomonella populations that display partial reproductive isolation have evolved. Host shifting by Rhagoletis and similar evolutionary histories could have had cascading effects across trophic levels, influencing the diversity and distribution of associated parasitoid guilds. To establish the basis for a future understanding of the possible effect of divergence in R. pomonella populations on the parasitoids attacking these flies, we surveyed parasitoids from five different species of hawthorns distributed over 15 states in México and 2 states in the midwestern United States. Emerging parasitoids were identified, parasitism rates were calculated, and regional fly and parasitoid emergence schedules were determined. Parasitism rate, emergence schedules, Shannon-Weiner diversity indexes, and species accumulation curves were compared across three main geographical regions. Parasitism levels varied greatly among regions from an overall high of 27.2% in the United States to 5.5% in the Sierra Madre Oriental (SMO) mountains of Mexico, to as low as 0.19% in the Eje Volcánico Trans Mexicano (EVTM). Shannon-Weiner diversity indexes showed that parasitoid species diversity was similar across the distribution range of R. pomonella in Mexico and the United States because of the fact that total parasitism was dominated by only two species, one of them recovered across the whole North American range of hawthorn infesting Rhagoletis. Nevertheless, eight parasitoids were found attacking R. pomonella in Mexico compared with only four collected in the United States. Only two diapausing parasitoid species were shared between the U.S. and Mexican R. pomonella populations: Utetes canaliculatus and Diachasmimorpha mellea. Interestingly, many subtropical parasitoid species, usually associated to flies in the subtropical genus Anastrepha, were recovered in the SMO in low numbers. The wide distribution of U. canaliculatus and D. mellea offers an ideal opportunity to test for a shared biogeography and co-evolution between fly and parasitoids. In this regard, one factor contributing to the success of U. canaliculatus seems to be the wasp's ability to modulate its eclosion time to track regional variation in hawthorn fruiting phenology and host (i.e., fly larvae) availability. Both R. pomonella and U. canaliculatus from southern sites emerged later than insects from northern populations, mirroring seasonal differences in hawthorn fruiting times across Mexico and the United States. These results suggest that molecular studies and crossing experiments could show, as they have for Rhagoletis, recent speciation events for parasitoid species of Nearctic origin that were found to be ecologically tracking environmentally driven divergence of their tephritid hosts.

Urbanization impacts biodiversity, yet few studies examine general impacts of urbanization on insects. Furthermore, few studies examine availability and limitation of potential cavity nesting sites for ants, an important regulating factor in ant communities that may vary in different urban habitats. We compared three urban habitat types (gardens, vacant lots, and forests) in Toledo, OH, to examine availability and ant preferences for different cavity nesting resources (small and large hollow twigs and cavities). We added 72 artificial large hollow twigs (83 by 6 mm), small hollow twigs (140 by 2 mm), and spherical hollow cavities (6.52–31.1 cm3 in volume, 1-mm opening) to six sites from May to August 2007 to determine whether nest-site limitation impacts ant communities. We collected natural nests to compare natural abundance and occupancy of cavity nests in different urban habitats. We opened artificial and natural nests to calculate the percentage occupied by cavity-nesting ants. Across all habitats, small twigs represented 81.1% of natural nests, spherical nests represented 10.1%, and large twigs 8.2%. Ants occupied 8.1% of natural large twigs, 14.6% of cavities, and 4.1% of small twigs. For artificial nests, 21.5% of large twigs, 1% of small twigs, and 1% of spheres were occupied. The high percentage of occupied artificial large twigs could imply this is a preferred and limiting resource in urban habitats. The results show that certain types of nesting resources may be an important factor mediating ant communities in urban green spaces.

Between 1997 and 2005, a study was made of the Chrysididae, Eumeninae, and Spheciformes wasps in the Arribes del Duero Natural Park (Provinces of Salamanca and Zamora, western Spain), a highly heterogeneous Mediterranean landscape. We collected, respectively, 127, 57, and 230 species of these groups, constituting ≈50% of the species known for the Iberian Peninsula. The inventory was fairly complete according to the final slope of the species accumulation curves. From a biogeographic point of view, the predominant elements of the Arribes del Duero fauna are Mediterranean in the broad sense, together with a high percentage of species of Euro-Atlantic distribution. The proportion of endemic species obtained is similar to those known for the whole of the Iberian Peninsula. The species endemic to the northern subplateau and to the southwestern quadrant predominate. The Arribes del Duero territory is the northern limit of the distribution of some Iberian-Maghrebine species, although it is also the southern limit of species widely distributed throughout central and northern Europe. The Atlantic influence in the territory has facilitated the persistence of some species, with an Atlantic or sub-Atlantic distribution, related in particular to riparian forests. This space constitutes a large eco-corridor that joins the north of the Peninsula to the south, linking communities corresponding to the Eurosiberian and Mediterranean biogeographic regions and to territories encompassed within the Temperate and Mediterranean macrobioclimates. Thus, because of its geographic situation and extensive latitudinal range, together with the fact that it has a good representation of European biodiversity, the Arribes del Duero Park is proposed as a priority area for insect diversity conservation in the Mediterranean region.

We tested the hypothesis that pupal predation by shrews underlies the altitudinal distribution pattern of the geometrid moth species Operophtera brumata L. (winter moth) and Epirrita autumnata Bkh (autumnal moth) in a sub-arctic birch forest in northern Fennoscandia. In particular, we predicted more intense pupal predation at low altitudes where the two moth species normally do not reach outbreak densities. Predation of pupae of both moth species was estimated along 10 parallel altitudinal transects, spanning from sea level to the altitudinal tree-limit in a coastal birch forest in northern Norway. Shrew abundance and the abundance and population growth rate of the two moth species were assessed in the same transects. Our study provided no support for the hypothesis that pupal predation by shrews can account for the altitudinal distribution of the two moth species. Despite high densities of common shrews (Sorex araneus L.) and an observed predation rate of ∼90%, there was no difference in the rate of pupal predation either between the two geometrid species or between the various altitudes. These results narrow down the range of possible explanations for the altitudinal distribution pattern of these insects in northern birch forests.

The seasonal pattern of adult fly production in both fresh and aged biosolid cake was established by the exposure of biosolid cake to natural conditions in the central coastal region of Perth, Western Australia, over the course of a year. Relationships between fly emergence and six factors (weeks exposed, pH, NH₄, rainfall, temperature, and moisture) suspected of facilitating the attraction of adult flies to biosolid cake were measured. The aim was to study the production of adult flies with regard to weeks exposed in different seasons to establish a “best practice” storage procedure for aged biosolid cake. Four fly species were collected during the study; Musca domestica L. (house fly), Stomoxys calcitrans L. (stable fly), Fannia canicularis L. (lesser house fly), and Muscina stabulans (Fallén) (false stable fly). Of the 5,303 flies identified, >97% of these were either M. domestica or S. calcitrans. Adult flies emerged from biosolid cake all year round with a sharp decline in winter. The number of emerged flies peaked in summer (3,163 flies) and declined during autumn (1,545 flies) and spring (532 flies). Significant positive relationships were observed between the number of adult flies emerging from biosolid cake and ambient temperature, NH₄ content, and weeks exposed. Higher ambient temperatures and a higher NH₄ content of the biosolid cake were associated with increased number of adult flies emerging from the biosolid cake. Similarly, the majority of flies emerged from biosolid cake in the first 10 wk of exposure to fly activity.

Interspecific interactions among tree-killing bark beetle species may have ecologically important consequences on beetle population dynamics. Using two tree-killing beetle species (Dendroctonus brevicomis and D. frontalis), we performed observational and experimental studies to verify cross-attraction and co-colonization under field conditions in northern Arizona and test the effects of gallery density and species ratio on response variables of average gallery length, offspring size (progeny fitness), and offspring production per centimeter gallery (fecundity). Our results show that both D. frontalis and D. brevicomis aggregate to pheromones synthesized de novo by D. brevicomis under field conditions and that galleries of both D. brevicomis and D. frontalis occurred together in the same region of a single host tree with significant frequency. In experimental manipulations of species ratios, the presence of conspecific beetles in the gallery environment strongly mediated fecundity, but D. frontalis was the only species that suffered negative impacts from the presence of heterospecific beetles in the gallery environment. Interactions did not result in any apparent fitness effects for progeny of either species, which suggests that multispecies aggregations and co-colonization may be a dominant ecological strategy in the region and result in niche sharing.

Partitioning of niches can play an important role in structuring faunal communities. We tested the hypothesis that differences between four species of orb-weaving spiders (Araneidae) in body size and the structure and position of their webs resulted in their partitioning the available prey. The study species are sympatric in a grassland habitat and included Argiope trifasciata (Forskål), Cyclosa turbinata (Walckenaer), Mangora gibberosa (Hentz), and Neoscona arabesca (Walckenaer). The spider species differed in body size, web diameter, height of web above the ground, spacing of mesh within webs, and the type of plant to which the web was attached. The spider species had a generalist diet and captured prey of multiple trophic levels. Nevertheless, the hypothesis was supported: the spider species differed in the types of prey that they captured. Partitioning of the available prey was influenced by body size, with larger spiders capturing larger prey, but not by the structure or position of their webs. Differences between spider species in niche may reduce competitive interactions and allow them to coexist in sympatry.

Intensive pine (Pinus spp.) management is a primary land use in the southeastern United States. In eastern North Carolina, intensively managed pine stands often occur on land previously ditched and drained. Because modification of natural vegetation and water sources are known to affect dipteran community structure, we studied effects of intensive pine management on abundance and diversity of dipteran families in the northern coastal plain of North Carolina during 2006 and 2007. We used malaise traps and emergence traps to sample different types of forest stands (n = 143 sample nights) and water sources (n = 147 sample nights) in a managed pine forest and a natural forested wetland. Cecidomyiids were more abundant in stands with canopy cover, chironomids were more abundant at edges between forested stands and open canopy stands, and chloropids were more abundant in open canopy stands. Families Ceratopogonidae, Dolichopodidae, Ephydridae, Muscidae, Psychodidae, and Tipulidae were more abundant in the natural forested wetland than in all types of modified water sources. Dipteran diversity and evenness were highest in stands with open canopy and at forest edges, and highest in the natural forested wetland. Unmanaged, natural stands on the intensively managed landscape did not support a higher abundance or diversity of dipteran families than intensively managed stands. Restoration of natural wetlands may increase dipteran diversity in unmanaged stands. Heliponds, a modified water source, supported a comparable dipteran abundance to that of the natural forested wetland. Increased numbers of heliponds may facilitate higher dipteran abundance in managed pine landscapes.

Competition theory suggests that a single resource should support one consumer species. However, competitive exclusion may be relaxed by periodic disturbances, temporal or spatial segregation of consumers, or fine-scale resource partitioning. This last mechanism may be especially common for competing phytophagous insects. Unlike many predators, herbivores rarely consume their entire prey item and often have specialized feeding modes on specific plant parts. Thus, different herbivore guilds may “avoid” each other, thereby facilitating their coexistence. I analyzed a simplified metabolic pool model that includes two herbivore types: a “leaf chewer” and a “phloem feeder.” Phytophagous insects with the same feeding mode never coexisted, but different guilds may coexist stably—depending on productivity of the carbohydrate pool, allocation to vegetative biomass, and defoliation rate. Differences in herbivore feeding mode are equivalent to fine scale resource partitioning, potentially within the individual plant. Thus, the addition of physiological detail changes the predictions of simple competition models and is relevant to weed biocontrol by informing decisions on which guilds of biocontrol agents to introduce.

The dispersal ability of Trichogramma ostriniae Pang and Chen, a biological control agent of Ostrinia nubilalis Hübner, was studied in commercial potato fields on the Eastern Shore of Virginia. The purpose was to quantify dispersal of T. ostriniae after an inundative release to aid in determining the number of release points needed per unit area for effective biological control of O. nubilalis in solanaceous crops. A single release of ≈0.5 million wasps was made in two spatially separate potato fields in summer 2005 and 2006. Each release area contained 25 monitoring points at distances from 5 to 45 m from the release point bearing a yellow sticky card and O. nubilalis egg sentinels to observe for adult parasitoids and parasitism, respectively. Results showed that movement of T. ostriniae adults from the release point was rapid with individuals captured at 45 m within 1 d of emergence. High rates of parasitization (20–50%) also were observed at this distance, but the levels decreased with increasing distance from the release point. The distances that encompassed 98% recaptured T. ostriniae adults (x₉₈) were 27.5 and 12.9 m from the release point in 2005 and 2006, respectively. The (x₉₈) distances for parasitization of O. nubilalis were 21–26 m in 2005 and 8–10 m in 2006. However, the highest levels of parasitization in both years occurred nearest the release point. T. ostriniae showed uniform dispersal within an area of ≈0.1 ha, indicating that multiple release points should be used for effective dispersal of T. ostriniae and control of O. nubilalis in solanaceous crops. Based on the assumption that a distance of 16 m represents the radius around a release point in which T. ostriniae activity was at its maximum, we estimate that ≈12 release points/ha would be required in potato fields.

Anoplophora glabripennis, the Asian longhorned beetle, is a wood-boring insect that can develop in a wide range of healthy deciduous hosts and requires gut microbes to aid in wood degradation and digestion. Here we show that larval A. glabripennis harbor a diverse gut bacterial community, and this community can be extremely variable when reared in different host trees. A. glabripennis reared in a preferred host (Acer saccharum) had the highest gut bacterial diversity compared with larvae reared either in a secondary host (Quercus palustris), a resistant host (Pyrus calleryana), or on artificial diet. The gut microbial community of larval A. glabripennis collected from field populations on Brooklyn, NY, showed the highest degree of complexity among all samples in this study. Overall, when larvae fed on a preferred host, they harbored a broad diversity of gut bacteria spanning the α-, β-, γ-Proteobacteria, Firmicutes, Actinobacteria, and Bacteroidetes. Cellulase activities (β-1,4-endoglucanase, β-1,4-exoglucanase, and β-1,4-glucosidase) in the guts of larvae fed in a preferred host (A. saccharum) or a secondary host (Q. palustris) were significantly higher than that of artificial diet fed larvae. Larvae that fed on wood from a resistant host (P. calleryana) showed suppressed total gut cellulase activity. Results show that the host tree can impact both gut microbial community complexity and cellulase activity in A. glabripennis.

Attack rates, progeny production, sex ratios, and host utilization efficiency of Muscidifurax raptorellus (Kogan and Legner) (Hymenoptera: Pteromalidae), Tachinaephagus zealandicus Ashmead (Hymenoptera: Encyrtidae), and Trichopria nigra (Nees) (Hymenoptera: Diapriidae) were evaluated in laboratory bioassays with five dipteran hosts: house fly (Musca domestica L.), stable fly (Stomoxys calcitrans L.), horn fly (Hematobia irritans L.), black dump fly [Hydrotaea aenescens (Weidemann)] (Diptera: Muscidae), and a flesh fly (Sarcophaga bullata Parker) (Diptera: Sarcophagidae). M. raptorellus killed and successfully parasitized all five host species and produced an average 2.6 parasitoid progeny from each host. Host attack rates were highest on stable fly and lowest on horn fly; there were no differences among hosts in the total number of progeny produced. T. Zealandicus killed larvae of all fly host species in similar numbers, but parasitism was most successful on H. aenescens and S. bullata and least successful on horn fly and house fly hosts. Significantly more parasitoid progeny emerged from S. bullata (10.2 parasitoids per host) than the other hosts; only 2.5 progeny were produced from parasitized horn fly hosts. Most of the killed puparia that produced neither adult flies nor parasitoids (“duds”) contained dead parasitoids; in house fly, stable fly, and horn fly hosts, >30% of these dudded pupae contained adult wasps that failed to eclose. T. nigra successfully parasitized pupae of all host species except house fly and was most successful on stable fly. Significantly more parasitoid progeny emerged from S. bullata (30.6 parasitoids per host) than the other hosts; only 5.7 progeny were produced from horn fly hosts.

Coccinella septempunctata L. and Harmonia axyridis Pallas are key natural enemies of soybean aphid, Aphis glycines Matsumura, in North America. Third instars, adult females, and adult males of both C. septempunctata and H. axyridis exhibited a type II functional response for predation toward adult soybean aphids at 26 ± 1°C. In C. septempunctata, the functional response curve of adult males differed from those of third instars and adult females, but there was no difference between third instars and adult females. In H. axyridis, the functional response curves of larvae, adult females, and adult males all differed significantly. Third instars and adult females consumed significantly more soybean aphids than did adult males at prey densities of 150 and 180 aphids per arena for C. septempunctata and at prey densities of 60, 90, 120, 150, and 180 aphids per arena for H. axyridis. The theoretical maximum daily predation rate of adult aphids by C. septempunctata was predicted to be 204 per third instar, 277 per adult female, and 166 per adult male, and 244, 156, and 73, respectively, for H. axyridis. Third instars and adult females of both species consumed significantly more aphids than did adult males on soybean plants with the recommended action threshold of 250 soybean aphids per plant. Both C. septempunctata and H. axyridis have high predation capacities and are important in suppressing soybean aphid populations.

Tetranychus kanzawai Kishida and Panonychus citri (McGregor) are two major acarine pests of the principal papaya variety in Taiwan, and they often co-occur in the same papaya screen-houses. This study measured prey acceptability, foraging schedule, short-term consumption rate, and handling time of larvae of a domesticated line of the green lacewing, Mallada basalis (Walker), in no-choice tests with different life stages of these two mite pests. After a period of prey deprivation, all three larval instars of M. basalis exhibited a high rate of acceptance of all life stages of both T. kanzawai and P. citri. In 2-h trials, second- and third-instar predators foraged actively most of the time, whereas first instars spent ≈40% of the time at rest. Consumption increased and prey handling time decreased as predator life stage advanced and prey stage decreased. Third-instar lacewings consumed an average of 311.4 T. kanzawai eggs (handling time: 6.7 s/egg) and 68.2 adults (handling time: 58.8 s/adult), whereas first instars consumed 19.6 eggs (handling time: 23.6 s/egg) and 4.0 adults (handling time: 633.4 s/adult). M. basalis generally consumed more P. citri than T. kanzawai. Except for prey eggs, handling times of T. kanzawai were generally longer than those of P. citri by all M. basalis instars. Handling times were shorter, and consumption were greater, at the higher P. citri density than at the lower one, whereas there were generally no significant differences in prey acceptability and foraging time between those two densities. This study suggests that M. basalis larvae may have high potential for augmentative biological control of mites on papayas.

The poppy stem gall wasp, Iraella luteipes (Thompson) (Hymenoptera: Cynipidae), is one of the main pests of the opium poppy, Papaver somniferum L., an economically important pharmaceutical crop cultivated worldwide. In a previous study, we obtained from I. luteipes larvae a strain of the entomopathogenic fungus Beauveria bassiana (Ascomycota: Hypocreales) that can become established endophytically in opium poppy plants. A field experiment was conducted to study the ability of this B. bassiana strain to provide systemic protection against damage by I. luteipes in opium poppy in southern Spain for three seasons. Conidial suspensions were applied as seed dressings, leaf sprays, or soil sprays. The effect of the treatment was studied by harvesting fully ripened plants and dissecting I. luteipes larvae from the stem. The effect of treatment on growth and yield was also evaluated. Emergence of I. luteipes adults was not uniform over the 3 yr, with important differences exhibited in the duration of the emergence period, although the flight peaks tended to occur in mid-late April. B. bassiana seed dressings, leaf sprays at the fourth true-leaf stage, and soil sprays were not significantly different in their ability to reduce the number of larvae per plant compared with the controls, with percentage reductions of 36.5–58.5, 64.4–73.4, and 51.9–57.2% in 2005, 2006, and 2007, respectively. Even though the population level of I. luteipes increased over the 3 yr, the efficacy of the fungal inoculation in reducing the larval population was maintained throughout the study period. No significant differences between inoculation methods were detected in the percentage of leaf pieces showing fungal growth when placed on B. bassiana selective medium, with mean values in the range of 10–15% for the three seasons. Leaf pieces from controls did not exhibit any sign of B. bassiana growth when placed on B. bassiana-selective medium. Neither adverse effects on growth and yield nor symptomatic tissues were observed in B. bassiana-treated plants compared with controls in any of the three seasons.

Postrelease studies can provide data with which to evaluate expectations based on prerelease tests of biological control insects. In 2004, we observed Trichosirocalus horridus Panzer (Coleoptera: Curculionidae), the rosette weevil introduced into North America against Eurasian thistles, feeding on native tall thistle, Cirsium altissimum L. Spreng., in tallgrass prairie. In this study, we examined the rosette weevil's use of tall thistle, compared with its use of the co-occurring exotic bull thistle, C. vulgare (Savi) Tenore. For both thistle species, we quantified weevil frequency, abundance, and seasonal variation in incidence, using both timed observations at two sites over two growing seasons (2004, 2005) and dissections of thistle flowering shoots from 13 sites (2005). Based on prerelease information, we expected the Eurasian thistle to be the quantitatively preferred host plant for this Eurasian weevil. Instead, we found that both the frequency of infestation and the mean number of adult rosette weevils per plant were at least as high, and sometimes higher, on the native thistle as on the exotic thistle. Furthermore, adult weevil phenology coincided on the two host species. This study provides new quantitative evidence of nontarget feeding by another weevil released for thistle biological control; and it raises important questions for further research. We conclude that continued new releases, as well as augmentation of existing populations, of T. horridus should wait until more research is done on the impact of the nontarget occurrence now reported for this biological control insect.

Interactions between pollinators and nectar-producing flowers are usually assumed to be mutualistic, but the exploitative basis of these relationships can lead to antagonistic interactions. Flowers of the African milkweed, Pachycarpus appendiculatus E. Mey, produce concentrated nectar that is consumed primarily by the large spider-hunting wasp Hemipepsis dedjas Guerin (Hymenoptera: Pompilidae). Pollinaria of this milkweed become attached to the palps of these wasps during nectar feeding. Broken wasp palps were found between guide rails, attached to corpuscula that were trapped behind the guide rails, and attached to pollinia that were inserted into the stigmatic chambers of the flowers. Approximately 85% of wasps captured on flowers of P. appendiculatus were missing one or more palps, whereas only 9% of wasps captured on flowers of another asclepiad species were missing any palps. It thus seems that wasps face a high risk of losing their palps when foraging on these flowers. The interaction may thus be antagonistic for the wasps if the cost of losing their sensory palps (not yet established) is greater than the benefits of the nectar reward. The plants, however, gain clear benefit from the interaction, as verified by the removal and insertion of pollinia in flowers exposed solely to visits by pompilid wasps.

Bees feed almost exclusively on nectar and pollen from flowers. However, little is known about how food availability limits bee populations, especially in high elevation areas. Foraging distances and relationships between forager densities and resource availability can provide insights into the potential for food limitation in mobile consumer populations. For example, if floral resources are limited, bee consumers should fly farther to forage, and they should be more abundant in areas with more flowers. I estimated subalpine bumble bee foraging distances by calculating forager recapture probabilities at increasing distances from eight marking locations. I measured forager and flower densities over the flowering season in six half-hectare plots. Because subalpine bumble bees have little time to build their colonies, they may forage over short distances and forager density may not be constrained by flower density. However, late in the season, when floral resources dwindle, foraging distances may increase, and there may be stronger relationships between forager and flower densities. Throughout the flowering season, marked bees were primarily found within 100 m (and never > 1,000 m) from their original marking location, suggesting that they typically did not fly far to forage. Although the density of early season foraging queens increased with early-season flower density, the density of mid- and late-season workers and males did not vary with flower density. Short foraging distances and no relationships between mid- and late-season forager and flower densities suggest that high elevation bumble bees may have ample floral resources for colony growth reproduction.

We studied the host selection behavior and feeding preference of the emerald ash borer, Agrilus planipennis Fairmaire (Coleoptera: Buprestidae). A. planipennis is an exotic forest insect pest native to Asia that was discovered in North America in 2002 and is causing widespread mortality of ash trees (Fraxinus spp.) in southeast Michigan and surrounding states. We compared host selection and feeding behavior on different species of ash including Manchurian ash (F. mandshurica Rupr.), green ash (F. pennsylvanica Marsh), white ash (F. americana L.), black ash (F. nigra Marsh), blue ash (F. quadrangulata Michx.), and European ash (F. excelsior L). Manchurian ash is native to Asia, whereas the other species (native to North America or Europe) represent novel hosts for A. planipennis. Beetles distributed themselves more frequently and fed to a greater extent on green, black, and white ash compared with blue, European, and Manchurian ash. Although beetles consumed every ash species offered to them, Manchurian ash and blue ash were least preferred in feeding bioassays. When we analyzed the volatile content of intact and girdled ash for quantitative variation in 11 compounds that elicited antennal activity, we found that the overall volatile profiles of the six ash species differed significantly in their relative amounts of antennally active compounds. Green ash has lower relative amounts of volatiles compared with Manchurian ash, which might render it more attractive and less resistant to A. planipennis. Lower tolerance and resistance of green ash might make it more susceptible to mortality compared with Manchurian ash, which coevolved with the beetle in its native range. Repellent odors, potential antifeedants, and genes for resistance in Manchurian ash could be explored for methods to manage A. planipennis populations.

The cotton fleahopper, Pseudatomoscelis seriatus (Reuter), is an early-season pest of developing cotton in Central Texas and other regions of the Cotton Belt. Cotton fleahopper populations develop on spring weed hosts and move to cotton as weed hosts senesce or if other weed hosts are not readily available. To identify weed hosts that were seasonably available for the cotton fleahopper in Central Texas, blooming weed species were sampled during early-season (17 March-31 May), mid-season (1 June-14 August), late-season (15 August-30 November), and overwintering (1 December-16 March) periods. The leading hosts for cotton fleahopper adults and nymphs were evening primrose (Oenothera speciosa T. Nuttall) and Mexican hat [Ratibida columnifera (T. Nuttall) E. Wooton and P. Standley], respectively, during the early season. During the mid-season, silver-leaf nightshade (Solanum elaeagnifolium A. Cavanilles) was consistently a host for fleahopper nymphs and adults. Woolly croton (Croton capitatus A. Michaux) was a leading host during the late season. Cotton fleahoppers were not collected during the overwintering period. Other suitable hosts were available before previously reported leading hosts became available. Eight previously unreported weed species were documented as temporary hosts. A compendium of reported hosts, which includes >160 plant species representing 35 families, for the cotton fleahopper is provided for future research addressing insect-host plant associations. Leading plant families were Asteraceae, Lamiaceae, and Onagraceae. Results presented here indicate a strong argument for assessing weed species diversity and abundance for the control of the cotton fleahopper in the Cotton Belt.

The objective of this study was to evaluate the role of host volatiles in the relationship between a blueberry plant Vaccinium corymbosum L. and the raspberry weevil Aegorhinus superciliosus (Guérin) (Coleoptera: Curculionidae), the principal pest of blueberry in the south of Chile. Volatiles from the aerial part of different phenological stages of the host were collected on Porapak Q and analyzed by coupled gas chromatography-mass spectrometry (GC-MS). Several chemical groups were identified including green leaf volatiles, aromatic compounds, and terpenes. The olfactometric responses of A. superciliosus toward different odor sources were studied in a four-arm olfactometer. Blueberry shoots at the phenological stages of fruit set, and blue-pink fruit color elicited the greatest behavioral responses from weevils. Five compounds (2-nonanone, eucalyptol, R- and S-limonene, and 4-ethyl benzaldehyde) elicited an attractant behavioral response from A. superciliosus. The results suggest the host location behavior of A. superciliosus could be mediated by volatiles derived from V. corymbosum. This work has identified a number of compounds with which it is possible to develop a lure for the principal pest of blueberry in southern Chile.

Much literature is dedicated to the study of density dependence in host-parasitoid systems. The theoretical literature identifies two potential stabilization mechanisms relating the response of the parasitoid to host density. One is a behavioral response that occurs at a local level, and the other is a demographic response that occurs at a larger spatial scale with heterogeneous patches of host concentrations. In a series of field trials at the small spatial scale (tens of meters) and a 10-mo census at the large spatial scale (hundreds of meters), we examined the attack rates of Pseudacteon sp. phorid flies on Azteca instabilis F. Smith ant hosts. At the local scale, we examined phorid attack rates on ants placed at increasing distances from ant nests (0–12 m) and on different densities of ants (1–50 workers) placed near the nests. At the large scale, we placed whole body extracts of A. instabilis in areas with several A. instabilis nests and in areas >100 m from the nearest nest. For all observations, we recorded the time of the first phorid attack and the number of phorid attacks in a defined time period. We found clear density-dependent responses at both scales. Phorid attack rates were highest within 2 m of A. instabilis nests and at ant densities >25. At the larger scale, phorid attack rate was greater in areas with A. instabilis nests, although this result was obscured during the dry season when the population of parasitoids is dramatically reduced. We propose several behavioral and population-level responses that may contribute to the observed results and propose several testable hypotheses. We conclude that, in this system, density dependence does happen through a behavioral mechanism of the phorid actively seeking concentrations of ants, but also, a population level response is likely caused by the significant difference in phorid attack rates in areas far from ant nests compared with areas nearby to nests.

We examined landing patterns of phloeophagous and xylophagous Coleoptera among trees and snags of different physiological and decay states in a pure open-canopy black spruce stand in boreal Canada to study prelanding host selection mechanisms in the absence of nonhost volatiles. Sticky traps were used to capture insects landing on high- and low-density natural snags (i.e., wood density), girdled trees, living trees, and stovepipe controls. Patterns were generally weak, with high within-group variability in species composition and landing rates. Within-group variability differed between groups, with highest variations in living trees and recent snags. Despite this evidence of frequent landing on suboptimal or inappropriate hosts, affinities were detected in most common taxa. Cerambycidae showed preferences for girdled trees. Common species of Scolytinae showed divergent preferences, because Crypturgus borealis Swaine and Dryocoetes autographus (Ratzeburg) were captured more often on high-density natural snags, Polygraphus rufipennis (Kirby) on girdled trees, and Orthotomicus latidens (LeConte) on living trees. These observed landing patterns are broadly consistent with current knowledge on the ecology of these species. Although preferences, and thus prelanding assessment of hosts based on volatiles, were detected in several species, the numerous landings observed on inappropriate hosts suggest that random landing at close range may be as common in pure stands as what was previously observed in mixed stands.

In this study, we explore how an invasive social wasp, Vespula germanica (F.), deals with contextual changes while searching for a food source that is no longer available. Four experiments were conducted to evaluate the effect of different degrees of context modification on wasp behavior. Learning sessions consisted of a variable number of feeding trials during which an individual wasp fed from a landmark array made up of a feeder surrounded by four cylinders of the same color. The food and cylinders were subsequently removed from the training site, and this learned landmark array was modified in such a way that information relating to color and/or location of the resulting feeding arrays varied from that previously learned. The results indicate that the color most recently associated with food is prioritized over a formerly learned color, and this pattern is also maintained when wasps have learned the alternative color during a higher number of feeding experiences. This highlights the high plasticity with which V. germanica responds to unpredictable contextual changes while foraging.

Aggregation behavior of adult western spotted cucumber beetles (Diabrotica undecimpunctata undecimpunctata Mannerheim) (Coleoptera: Chrysomelidae) was examined in six snap bean (Phaseolus vulgaris) fields adjacent to corn fields in western Oregon in 2004–2006. In the 2004 and 2005 studies, sweep net sampling was used to estimate beetle numbers along transect lines running perpendicular to the edges of the bean fields next to sweet corn fields. Beetles were collected from the fields and dissected to determine sex and egg development. Beetles were highly aggregated along the edge of the snap bean field next to the sweet corn, with the highest number of beetles occurring within the first meter next to the edge. Beetles in the aggregation areas were mostly females (average female to male ratio of 8.4 to 1), whereas beetles in the field section away from the edges were mostly male (female to male ratio of 0.6 to 1). Of the females collected in the aggregation areas, an average of 53% contained developing or fully developed eggs. In the 2006 study, beetle densities in the field edges were compared with densities within the fields in 40 bean fields with adjacent corn fields. Linear regression analysis showed that, across fields, nearly two times as many beetles were found in the field borders as in the rest of the field. These data suggest modifying traditional field scouting protocol to include field margins when a bean field is adjacent to or near a sweet corn field. A pest management strategy of only spraying the edges of bean fields containing beetle aggregations shows potential for significant pesticide reduction, as well as reducing risk of economic loss from crops harvested from the highly aggregated areas.

The pear psylla, Cacopsylla pyricola (Förster), is a major economic pest of pears in North America and Europe. Laboratory studies have shown that males of both the summerform and winterform morphotypes in this species are attracted to volatiles given off by females. This study tested whether attraction by males to females can be shown in the field. We showed that males had a clear preference for sticky traps that had been baited with live females compared with traps baited with live males or traps that were left unbaited. Female C. pyricola did not exhibit a preference among the three types of trap treatments. These results were obtained for both morphotypes. Trap catch was also monitored at 2-h intervals to assess whether capture of males on female-baited traps varied with time of day. Summerform male C. pyricola were caught in highest numbers between 1445 and 1645 hours, whereas winterform males were most often captured between 1300 and 1700 hours on traps baited with females. In both trials, there was again a significant preference by males for the female-baited traps compared with unbaited traps. Long-term practical benefits of the methods developed here provide a platform for the development of more effective monitoring tools, use in mating disruption, or development of lure and kill technologies.

Habitat structure and resources availability may differentially influence movement between habitat patches. We examined fly movement decisions (stay or leave) at the scale of individual trees by measuring the response of marked Rhagoletis indifferens (Diptera: Tephritidae) to sweet cherry trees (Prunus avium) that were manipulated by changing the shape of the tree (structure treatment = normal or reduced) and the fruit load (fruit treatment = augmented, normal, or reduced). More than 600 observations were made at two field sites that differed in the average inter-tree distance: Senger site, 10.1 ± 4.5 m; Tuemp site, 29.0 ± 19.3 m. At the Senger site, flies were resighted most often in the normal structure-augmented fruit trees. At the Tuemp site, however, there were fewer transfers between trees, unusual tree preferences, and significant treatment interaction terms. Using a first principles diffusion model of attraction and by varying fly perceptual range to limit tree choice, we generated unusual tree preferences based on differential attraction to individual trees. Our results suggest that manipulating tree attractiveness may be a viable pest management strategy for closely spaced trees but not for dispersed trees. Further study into the relationship between the spatial arrangement of trees and the flies' ability to detect specific tree characteristics is warranted.

In choice bioassays, Rhopalosiphum padi L. nonviruliferous apterae preferentially locate near volatile organic compounds (VOCs) emitted from Barley yellow dwarf virus (BYDV)infected wheat plants compared with VOCs from noninfected plants. However, the specific VOCs responsible for R. padi responses are unknown. It is unclear also if R. padi responses to BYDV-infected wheat are caused by arrestment or attraction. Additionally, the responses of viruliferous apterae and nonviruliferous alate to BYDV-infected wheat have not been examined. R. padi responses were studied through emigration, immigration, and settling laboratory bioassays using BYDV-infected and noninfected wheat plants. Two wheat genotypes, virus-susceptible Lambert and virus-resistant Lambertderived transgenic 103.1J expressing the BYDV-PAV coat protein gene, were evaluated. In a settling bioassay, alates preferentially settled on noninfected 103.1J. Responses of viruliferous and nonviruliferous R. padi to virus-infected, noninfected, and sham-inoculated (exposed to nonviruliferous aphids) Lambert and 103.1J were examined in separate bioassays. A paper leaf model served as a control. Immigration by viruliferous apterae was significantly lower toward the paper leaf model, but no significant differences were observed among plant treatments. Nonviruliferous apterae exhibited no significant differences in emigration among treatments, suggesting no arrestment occurred. Nonviruliferous apterae significantly preferred to immigrate toward BYDV-infected Lambert. Immigration toward the paper leaf model was significantly lower compared with plant treatments. Responses of R. padi to VOCs were tested by applying compounds to paper leaf models at concentrations designed to mimic those present in headspace of wheat plants. Nonviruliferous apterae immigrated in significantly greater numbers toward paper leaf models individually treated with nonanal, (Z)-3-hexenyl acetate, decanal, caryophyllene, and undecane than toward paper leaf models that served as controls and toward leaf models treated with synthetic blends made to mimic headspace of BYDV-infected compared with blends made to mimic headspace of noninfected wheat plants. Results suggest responses of R. padi to BYDV-infected plants are caused by attraction rather than arrestment.

Interactions between lady beetles and the European fire ant (Myrmica rubra L.) tending potato aphids [Macrosiphum euphorbiae (Thomas)] were compared in the laboratory. Lady beetle species native to North America (Coccinella trifasciata perplexa Mulsant, Coleomegilla maculata lengi Timberlake, Hippodamia convergent Guérin-Méneville) and non-native species of Palearctic origin [Coccinella septempunctata L., Harmonia axyridis (Pallas), Hippodamia variegata (Goeze), Propylea quatuordecimpunctata L.)] were evaluated. Harmonia axyridis consumed a significantly greater number of aphids compared with all other species but C. septempunctata. Ant stings affected H. variegata and C. septempunctata to a greater extent than other species. Ants showed a significantly greater amount of aggression toward H. convergent and H. variegata compared with P. quatuordecimpunctata. P. quatuordecimpunctata, C. trifasciata, and H. axyridis reacted significantly less to ants compared with H. variegata, H. convergens, C. maculata, and C. septempunctata. Differences in interactions with natural enemies may explain, in part, the successful establishment of some non-native coccinellids in new habitats.

A number of fragmentary reports suggest that the endangered diving beetle Cybister japonicus larvae feed on tadpoles, fish, and aquatic insects. However, no quantitative study on the feeding habits of C. japonicus larvae has been reported. In this study, field observations and rearing experiments were carried out to show the feeding ecology of C. japonicus larvae. Unlike previous commentaries, the first- and second-instar larvae of C. japonicus preyed on insects, mainly Odonata nymphs and Notonecta triguttata, irrespective of prey availability, but did not eat vertebrates such as tadpoles and fish in the field. On the contrary, the third-instar larvae fed on both insects and vertebrates. Rearing experiments showed that the number of Odonata nymphs consumed was significantly more than the number of tadpoles consumed by the first and second instars but third-instar larvae ate both the Odonata nymphs and tadpoles in the tadpole-Odonata nymph mixture experiment. The total body lengths of C. japonicus new adults in the Odonata nymph and tadpole-Odonata nymph mixture treatments were statistically equal. These results suggested that the first- and second-instar larvae of C. japonicus prey mainly on insects and do not eat vertebrate animals (insectivore), whereas the third-instar larvae fed on both insects and vertebrates (generalist).

The oligophagous cranberry weevil, Anthonomus musculus Say, causes economic losses to blueberry growers in New Jersey because females deposit eggs into developing flower buds and subsequent larval feeding damages buds, which fail to produce fruit. A cost-effective and reliable method is needed for monitoring this pest to correctly time insecticide applications. We studied the behavioral and antennal responses of adult A. musculus to its host plant volatiles to determine their potential for monitoring this pest. We evaluated A. musculus response to intact and damaged host plant parts, such as buds and flowers in Y-tube bioassays. We also collected and identified host plant volatiles from blueberry buds and open flowers and performed electroantennograms with identified compounds to determine the specific chemicals eliciting antennal responses. Male weevils were more attracted to blueberry flower buds and were repelled by conspecific-damaged buds compared with clean air. In contrast, females were more attracted to open flowers compared with flower buds. Nineteen volatiles were identified from blueberry buds; 10 of these were also emitted from blueberry flowers. Four of the volatiles emitted from both blueberry buds and flowers [hexanol, (Z)-S-hexenyl acetate, hexyl acetate, and (Z)-3-hexenyl butyrate] elicited strong antennal responses from A. musculus. Future laboratory and field testing of the identified compounds in combination with various trap designs is planned to develop a reliable monitoring trap for A. musculus.

Reliable electroantennogram (EAG) responses were obtained from the plum curculio, Conotrachelus nenuphar (Herbst), by using a whole body mount with glass electrodes filled with KCl-saturated AgCl solution that penetrated the antennal club (recording electrode) and the membrane attached to the cervical sclerite between the thorax and the head (indifferent electrode). Known attractive odor sources including extracts of headspace collections of ‘Stanley’ plum and ‘Empire’ apple tissues and a synthetic source of racemic grandisoic acid were used to verify the sensitivity of the technique. The amplitude of responses was significantly greater for females than males among all candidate stimuli evaluated. The recorded amplitudes for all odor stimuli evaluated were significantly greater than the methylene chloride solvent control. The development of this EAG technique will facilitate use of a coupled gas chromatographic-electroantennographic detection system to aid in detection of novel, biologically and behaviorally active volatile sources that can be subsequently evaluated in behavioral trials and ultimately lead to more powerful attractants for use in monitoring and management programs for plum curculios in commercial fruit orchards.

Solenopsis geminata (F.) was introduced into southern Taiwan decades ago and has continued to threaten the residents. Although the venom compositions of various fire ant species have been studied, the effects of environmental cues on the secretion pattern have received relatively little attention in an area with subtropical climate and high humidity, such as Taiwan. This study characterizes the effects of temperature and season on the venom compositions of S. geminata in Taiwan. Pure venom was sampled by using a microcapillary pipette and immersing the whole ant in hexane and subjected to gas chromatography-mass spectrometry analysis. The results showed that the ratio of cis C₁₁ to trans C₁₁ alkaloids in major workers was significantly higher than that in minor workers. No significant differences could be found in either the relative alkaloids content or the ratio of cis C₁₁ to trans C₁₁ alkaloids in venom of minor workers while rearing at four temperature conditions. Nevertheless, the ratio of cis C₁₁ to trans C₁₁ alkaloids in the venom of minor workers was the highest in spring and the lowest in winter. The results also showed that the body length, abdomen length, head length, head width, and venom volume differed significantly between major workers and minor workers of S. geminata. The venom volumes of these two castes were positively correlated with their body sizes.

Developmental rate models and biological parameters estimated from them, especially lower and upper temperature thresholds and optimal temperature, can help to forecast phenological events of codling moth, Cydia pomonella L. (Lepidoptera: Tortricidae), in apple orchards. We studied the developmental time of immature stages of codling moth at eight constant temperatures ranging from 10 to 35°C and modeled their developmental rate as a function of temperature using 13 published nonlinear and 2 linear models. Data were fitted to developmental rate models and temperature thresholds and the optimal temperatures were estimated. The models were evaluated based on adjusted coefficient of determination (R²_adj) and Akaike information criterion (AIC), in addition to coefficient of determination (R²) and residual sum of squares (RSS). The thermal constants were 79.80, 312.60, 232.03, and 615.32 DD for egg, larva, pupa, and overall immature stages of codling moth, respectively, using the Ikemoto and Takai linear model. The Ikemoto and Takai linear model estimated lower temperature thresholds as 9.97, 8.94, 10.04, and 9.63°C for egg, larva, pupa, and overall immature stages, respectively. Among the nonlinear models, the third-order polynomial fit the data well. This model estimates optimal temperature accurately. Brière-1 and Brière-2 accurately estimated the lower and upper temperature thresholds considering model evaluation criteria and accuracy of estimations.

Climatic conditions and the physiological state of aparasitoid may alter its host selection behavior and thus its efficiency as a biological control agent. We studied the influence of these parameters on the behavior of Fopius arisanus (Sonan), an egg-pupal parasitoid of many Tephritidae. In the first experiment, we assessed in field cage assays the influence of temperature, humidity, light intensity, barometric pressure, and wind speed. Both flight and parasitism were mainly affected by temperature and humidity. However, because these two factors were strongly correlated in our experiments, the direct influence of each one cannot be specified. Flight activity was affected by variations in barometric pressure. In a second set of experiments, we conducted release and recapture assays with dyed insects to determine the influence of sex, mating status, egg load, age, and starvation on attraction toward infested fruit. Males were not attracted, suggesting that fruit are not a mating site. The egg load seemed to be a major parameter of foraging motivation. Finally, we showed that flight activity strongly decreased after 48 h of starvation. We observed a possible switch to food in the foraging motivation of starved females, but this result was impaired by poor recoveries: <10% of released females were recaptured after 96 h of starvation. We finally discuss the importance of these observations on the efficiency of F. arisanus as a biological control agent in tropical humid areas.

Scelionid egg parasitoids of Telenomus spp. have been shown to significantly affect noctuid stemborer populations and yields of maize in western Africa. One of them, T. isis, has never been reported from eastern Africa and was introduced into the laboratories of the International Centre of Insect Physiology and Ecology, Kenya. This study evaluates the biotic potential of T. isis using East African stemborers as hosts. Host acceptance was tested using 15 lepidopteran borer species. Only noctuid stemborers were accepted for oviposition by T. isis. Sesamia calamistis Hampson, Sesamia nonagrioides (Lefebvre), and Busseola fusca (Fuller) were further used to study the effect of host species, host age, duration of host deprivation, temperature, and humidity on the performance of the parasitoid. In contrast to sex ratio, developmental time, parasitism, and parasitoid emergence varied significantly with host species, and the former two decreased with the age of host eggs. Female longevity increased with duration of host deprivation, whereas average lifetime fecundity decreased, probably because of oocyte resorption. T. isis successfully developed between 18 and 32°C at both low (40–50%) and high (70–80%) relative humidity regimens, but temperature played a more critical role. Using the modified Logan model, the lower and upper temperature thresholds for development were estimated at 11.5 and 37.5°C, respectively, with an optimum at 30.5°C for both humidity regimens. Depending on temperature and relative humidity regimen, the intrinsic rate of increase (rm) varied from 0.077 to 0.300, net reproductive rate (Ro) from 7.70 to 83.96, and generation time (G) from 11 to 38 d. The results of this study indicate that T. isis is likely to establish in eastern Africa.

The herbivorous spider mite Tetranychus urticae usually remains on the lower leaf surfaces of its host plants. Although terrestrial animals are generally thought to be well protected from damage because of UV radiation, insect herbivory frequently increases when solar UV-B (280–315 nm) radiation is attenuated. As UV transmission through leaves is generally low because of the accumulation of compounds that act as selective sunscreens (e.g., phenolics), we hypothesized that T. urticae avoids solar UV-B radiation by staying on lower leaf surfaces. We examined whether artificial UV irradiation and solar UV affected the survival and reproduction of T. urticae and whether staying on lower leaf surfaces was beneficial to their performance under ambient UV radiation. We found that T. urticae was not well protected from UV-B radiation, because artificial UV-B irradiation strongly decreased survivorship and egg production. More importantly; compulsory solar UV irradiation treatments also had lethal effects on T. urticae, whereas the mites could avoid them if they remained on the lower leaf surfaces of their host plants. These results showed that access to habitats protected from sunlight, such as lower leaf surfaces, is likely essential for T. urticae survival under ambient UV-B radiation. The lethal effects of solar UV radiation may also affect the population dynamics of spider mites, and habitat (resource) limitation may increase the probability of interspecific interactions, such as competition and predation. In turn, the occurrence of these interactions in sheltered areas may be associated with observed increases in herbivory under conditions of solar UV-B-attenuation.

The black soldier fly, Hermetia illucens L., was reared on a grain-based diet at 27, 30, and 36°C. Survival of 4- to 6-d-old larvae to adults averaged 74–97% at 27 and 30°C but was only 0.1% at 36°C. Flies required a mean of ≈4 d (11%) longer to complete larval and pupal development at 27°C than at 30°C. At 27 and 30°C, females weighed an average of 17–19% more than males but required an average of 0.6–0.8 d (3.0–4.3%) longer to complete larval development. At both temperatures, adult females lived an average of ≈3.5 d less than adult males. The duration of larval development was a significant predictor of adult longevity. Temperature differences of even 3°C produce significant fitness tradeoffs for males and females, influencing life history attributes and having practical applications for forensic entomology.

Insecticidal Bt crops and seed treatments represent additional pest management tools for growers, prompting ecological studies comparing their impact on farm system inputs and effects to nontarget organisms compared with conventional practices. Using high taxonomic and temporal resolution, we contrast the dominance structure of carabids and dynamics of the most abundant species in maize (both sweet and field corn) agroecosystems using pest management tactics determined by the purchase of seed and application of pyrethroid insecticides. In the seed-based treatments, sweet corn contained Cry1Ab/c proteins, whereas field corn contained the coupled technology of Cry3Bb1 proteins for control of corn rootworm and neonicotinoid seed treatments aimed at secondary soil-borne pests. The insecticide treatments involved foliar pyrethroids in sweet corn and at-planting pyrethroids in field corn. The carabid community, comprised of 49 species, was dominated by four species, Scarites quadriceps Chaudoir, Poecilus chalcites Say, Pterostichus melanarius Illiger, and Harpalus pensylvanicus DeGeer, that each occupied a distinct temporal niche during the growing season. Two species, Pt. melanarius and H. pensylvanicus, exhibited differences between treatments over time. Only H. pensylvanicus had consistent results in both years, in which activity densities in field corn were significantly higher in the control in July and/or August. These results, along with laboratory bioassays, led us to hypothesize that lower adult captures resulted from decrease in prey availability or exposure of H. pensylvanicus larvae to soil-directed insecticides—either the neonicotinoid seed treatment in the transgenic field corn or an at-planting soil insecticide in the conventional field corn.

Alteration of weed flora as consequence of the deployment of genetically modified herbicide-tolerant crops may affect higher trophic levels in agrosystems. A 4-yr study is being conducted in Spain to investigate interrelations between weeds and associated arthropods in corn fields. In a first step, the work aimed to detect the most responsive arthropods to weed management changes. To identify the most responsive arthropods, arthropod composition and abundance in herbicide-tolerant corn plots treated twice with glyphosate and untreated plots were compared for 2 yr. Plots were sampled seven times during the season by visual inspection and pitfall and yellow sticky traps to estimate abundance and activity of the main arthropod herbivores, predators, and parasitoids. As intended, the abundance and composition of weed flora was strongly altered by the differential herbicide treatments. Several groups of arthropods responded to the weed changes but in variable directions. Whereas leafhoppers and aphids were more abundant on herbicide-treated plots, the contrary was found for phytophagous thrips. Among predators, Orius sp., spiders, and trombidids were more abundant on treated plots, whereas nabids and carabids were more abundant in untreated plots; the same case was found for carabids and spiders caught in pitfall traps. Among parasitoids, ichneumonids were more abundant in untreated plots and mymarids in treated plots. These results cannot be interpreted in terms of nontarget effects of postemergence treatments with broad-spectrum herbicides; for this, a comparison with conventional weed management practices should be done and this is the current step in the study.