Potted cowpea, Vigna unguiculata (L.) Walp., plants were used to determine the effects of defoliation and pod position relative to the leaf canopy on infestation and damage by the coreid pod-bugs Clavigralla tomentosicollis Stål and Anoplocnemis curvipes (F.). Temperature measurements were taken within and outside the canopy to determine whether there was a correlation to seed damage. Seed damage decreased significantly with increasing defoliation in plants infested with C. tomentosicollis; an inverse trend was observed with A. curvipes. Temperatures within the canopy increased as the number of leaves decreased. As observed in the defoliation experiment, C. tomentosicollis and A. curvipes reacted differently in a free-choice situation between pods located outside or within the canopy. Significantly higher numbers of C. tomentosicollis concealed themselves within the canopy, where they caused more severe damage to seeds, in comparison with numbers and damage outside the canopy. These trends were reversed for A. curvipes. There was a significant negative correlation between percentage of seed damage and temperature with C. tomentosicollis, and a significant positive correlation with A. curvipes, both in defoliated plants and those with pods distributed outside and within the canopy. Overall, plants with less dense canopy, and long peduncles holding pods outside the canopy showed some resistance to C. tomentosicollis, which is the most damaging pod bug on cowpea. Because such cowpea plants harbor fewer C. tomentosicollis, they are likely to suffer less overall damage from infestation by the complex of pod bugs that occur concurrently in cowpea fields.

The potato tuberworm, Phthorimaea operculella Zeller, is a serious pest of the potato, Solanum tuberosum L., in subtropical and tropical production systems around the world. Knowledge of the temperature-dependent population growth potential is crucial for understanding population dynamics and implementing pest control strategies in different agro-ecological zones. The development, mortality of immature life stages, and reproduction of P. operculella were studied at constant temperatures ranging from 10 to 32°C. The theoretical developmental thresholds were 11, 13.5, and 11.8°C, and required incubation times were 65.3, 165.1, and 107.6 degree-days (DD) for the egg, larval, and pupal stages, respectively. The nonlinear shape of the temperature–development curve at low temperatures was well described by the modified four-parameter Sharpe & DeMichele model. The log-normal function was fitted to the normalized cumulative frequency distributions of developmental times for each life stage. Temperature effects on immature mortality were described by polynomial regressions. The optimal temperature for survival was within the range of 20–30°C. Temperature effects on adult senescence were described by the modified Sharpe & DeMichele model. A polynomial function was fitted to total fecundity and temperature. Fecundity was highest around 21°C. Age-related cumulative proportions of fecundity were well described by a Gamma function. Most eggs were laid within the first quarter of the female life span. The established functions were used to build a P. operculella population model, and life table parameters were simulated over a range of temperatures. Calculations gave good predictions when compared with published data. Populations increase within a temperature range of 10–35°C, with an optimum at 28–30°C.

Southwestern corn borers, Diatraea grandiosella Dyar, were reared on a control meridic diet and diets that incorporated rubidium chloride (RbCl) or cesium chloride (CsCl) at the rate of 1000 μg/g (1 g/liter of wet diet) to evaluate the effects on biology of D. grandiosella and to determine whether the resulting adults are marked with the rubidium (Rb) and cesium (Cs) physiological markers. The effects of RbCl and CsCl on survival, diet consumption, larval and pupal weight, developmental time, adult deformity, adult longevity, fecundity, and adult dry weight were generally minor and seldom reached statistically significant proportions. Males and females mated successfully when paired in different combinations across treatments. Graphite furnace atomic absorption spectrophotometer and neutron activation analysis were both effective in detecting Rb and Cs in male and female adults reared on RbCl and CsCl diets. Rb and Cs concentrations of males and females reared on RbCl and CsCl diets were above the background levels found in adults reared on the control diet. Rb and Cs can be used as physiological markers to mark D. grandiosella in dispersal experiments.

Life table parameters and other biological characteristics were estimated for the predator Macrolophus pygmaeus Rambur (Hemiptera: Miridae) when fed on pepper plant/leaves with or without prey Myzus persicae (Sulzer) (Homoptera: Aphididae). The experiments were conducted at 15, 20, 25, and 30°C, under a photoperiod of 16:8 (L:D) h and at 65 ± 5% RH. Egg incubation was shortest at 30°C (10.5 d), egg hatch percentage reached 90% at 20°C, sex ratio was 78% at 25°C, and preoviposition period was shortest at 25°C (6.1 d). Only females with access to prey were able to reproduce. Fecundity was highest at 20°C (203.9 eggs). Females and males survived longer at 15°C (120.7 and 132.9 d, respectively). When provided with prey, M. pygmaeus can increase its numbers at all temperatures tested. Its intrinsic rate of increase and doubling time were highest at 25°C (0.0958 d⁻¹ and 7.2 d, respectively). The lowest temperature threshold for population increase was 9.06°C. In the absence of prey, the predator did not oviposit, but females and males survived for a relatively long time at 15°C (26.5 and 28.7 d, respectively) and for a shorter time as temperature increased. The results indicate that M. pygmaeus performs very well when it feeds on the aphid M. persicae on pepper plants. Although the pepper plant can support adults, it does not permit population increase when prey is not available. However, these results are discussed with other findings in the context of a better and more effective use of this predator for biological control of M. persicae on pepper plant.

The development of the lesser appleworm, Grapholita prunivora (Walsh), was studied using immature apples as the food source. Degree-hour developmental rates for all life stages were calculated. Developmental rates in degree-hours at 25°C for the eggs, four instars, pupae, and adults were 1,503 (4 d), first larval ecdysis 1,109 (3 d posthatch), second larval ecdysis 1,941 (5 d posthatch), third larval ecdysis 3,186 (8 d posthatch), pupation 5,196 (13 d posthatch), and adult 8,925 (22 d posthatch), respectively. It was determined that 8.5°C was the lower thermal threshold for development of lesser appleworm eggs. Comparisons of growth, survival, and reproduction were made between two different laboratory populations, the wild type and a golden color sport (strain).

The course of diapause development under field conditions for diapausing larvae of Adoxophyes orana (F.v.R.) (Lepidoptera: Tortricidae) was investigated. Larvae of A. orana were collected during the winter and early spring from 1996 to1999 from peach and cherry trees in the area of Naousa in northern Greece. Each larva was placed individually in a plastic cylindrical cell with a piece of artificial diet at 20°C under long-day (16:8 L:D) or short-day photoperiods (8:16 L:D). Photoperiod had a significant influence on diapause development. Duration in days, from transfer from the orchard to the laboratory until first molt and pupation of larvae, was also significantly affected by sampling date. Photoperiodic sensitivity was no longer detected after late January. Short-day photoperiod maintained diapause for larvae sampled until late January. Thus, A. orana may complete diapause development in late January, but it will not break diapause until spring, when temperatures are sufficiently high to induce diapause break.

We investigated the biology of Tiphia pygidialis Allen, a previously unstudied native parasitoid of masked chafer, Cyclocephala spp. grubs, in central Kentucky and the seasonal dynamics of Tiphia vernalis Rohwer, an introduced parasitoid of Japanese beetle, Popillia japonica Newman. T. pygidialis was active from mid-August to early October, parasitizing third-instar masked chafers, whereas T. vernalis attacked overwintered third-instar P. japonica from mid-April to early June. Adult T. vernalis were attracted to modified Japanese beetle traps and yellow pan traps and to 10% sugar water sprayed on tree foliage. Spraying sugar water directly on turf most effectively monitored T. pygidialis wasps. Parasitism rates as high as 33 and 58% were observed for T. pygidialis and T. vernalis, respectively. In the laboratory, T. pygidialis larvae progressed through five instars to cocoon formation in ≈22 d. They overwinter as prepupae. Field-collected female wasps lived 32 ± 4 d, parasitizing 22 ± 6 grubs. In no-choice tests with eight species of native and exotic white grubs, T. pygidialis readily parasitized only Cyclocephala spp., including C. lurida Bland and C. borealis Arrow, which it normally encounters in Kentucky, but also C. pasadenae Casey, a western species not know to occur within the wasp’s geographic range. Wasps did not discriminate between nematode-infected and healthy grubs, indicating potential for interference between these biological control agents.

Despite being model taxa for theoretical research into sex ratio manipulation, there is a paucity of field studies that assess sex ratios of hymenopteran parasitoids. Here, the field variation in the sex ratio, brood size, and larval mortality of the parasitoid A. fuscicollis is quantified and related to variation among host species and brood types. There was a significant relationship between brood size and host volume. Brood size was significantly higher in the larger host species (Yponomeuta cagnagellus and Y. rorellus) than the smaller host species (Y. evonymellus and Y. padellus), but after controlling for host volume, brood size was significantly higher in Y. padellus and significantly lower in Y. evonymellus than the other host species. Brood size was also significantly higher in mixed broods than female or male broods. Larval mortality differed significantly among hosts and was lowest in Y. padellus. The proportion of mixed broods varied from 4 to 44% per host population. Within mixed broods, the sex ratio was highly variable (>90% females to >90% males). The median sex ratio within mixed broods differed significantly among host species and was least female biased in Y. padellus. There was no significant relationship between the percentage of females, female mortality, or male mortality, and host volume in mixed broods. Although highly variable among populations, the global sex ratio was slightly male biased in the smaller host species and female biased in the larger host species.

The effectiveness of yellow sticky cards for coccinellid sampling was compared with sweep and visual techniques in laboratory and field tests. Total catch, catch per minute of exposure, and catch per minute effort were compared across methods. Differences in escape rates from sticky cards, which might bias density comparisons, were assessed for the most commonly collected species, Harmonia axyridis (Pallas), Coleomegilla maculata (De Geer), and Coccinella septempunctata (L.). In terms of total catch, sticky cards caught significantly more coccinellids than sweep and visual searching. If sticky cards are up for <10 d, then visual search exceeds sweep and sticky cards in catch per minute effort. However, if sticky cards remain in the field for 10 d or longer, they surpass visual and sweep in terms of number of coccinellids caught per minute effort. In field cages less C. septempunctata were caught than C. maculata or H. axyridis on sticky cards. H. axyridis escaped significantly more frequently than C. septempunctata or C. maculata, and propoxur proved ineffective at reducing escapes of any species. The three sampling methods lead to different predictions regarding population densities. Further research is needed to compare all methods to an absolute sampling method over a range of conditions.

Anoplophora glabripennis (Motschulsky) (Asian longhorned beetle) was found attacking street trees in New York City and Chicago in the 1990s, after its accidental introduction from East Asia, and is currently the subject of a major eradication campaign by the U.S. Department of Agriculture. The borer has been a destructive outbreak pest in poplar plantations in China for over 20 yr, but it has been collected only rarely in nearby South Korea. To learn more about the species in natural forest stands, we surveyed nine montane locations across South Korea in 2000 and 2001. The primary hosts of Korean A. glabripennis are Acer mono and A. truncatum, which grow in riparian habitats and rocky ravines. We surveyed two locations in Mt. Sorak National Park intensively, mapping all host trees. Less than 10% of the trees at each site exhibited evidence of beetle damage, and few adult beetles were observed. We hypothesize that the varying dynamics of A. glabripennis populations across its geographical range may be explained by considering it as an “edge specialist,” which evolved in riparian habitats.

Sipha flava is a serious pest in sugarcane in southern Florida, so efforts in better understanding its biology were initiated. Development, longevity, and fecundity of alate and apterous S. flava (Forbes) feeding on Sorghum bicolor [L.] Moench., cultivar ‘Kow Chow,’ were examined under near-ambient temperature and lighting conditions within a glasshouse. After examining several body dimensions during apterous aphid development (antennal length, head width, body length, and abdominal width), antennal length was found to be the best indicator of an instar. Apterous aphids completed development from nymph to adult in ≈8 d and passed through four instars. A comparison between the sizes of apterous and alate morphs indicated that apterous females were larger and weighed more than the alates. Both morphs survived equally as long during reproduction (21 d) but produced slightly different numbers of nymphs over their life (apterous = 54.3, alate = 48.2). During the first 8 d of reproduction, apterous adults produced 3.3 nymphs/d and alates produced 2.3 nymphs/d. However, during the following 8 d, nymphal production by apterous females dropped to 2.7 nymphs/d but increased to 2.9 nymphs/d by alates. The estimated intrinsic rate of natural increase (r_m) for apterous aphids was 0.314. The net reproductive rates (R_o) for alate and apterous adults based on 0% nymphal mortality were 45.80 and 53.09 and for 21% nymphal mortality were 36.3 and 41.9, respectively.

Ground beetles often prey on crop pests, and their relative abundance and assemblages vary among cropping systems and pest management practices. We used pitfall traps arranged in transects to study ground beetle assemblages in a large field-scale Bt corn–soybean cropping system for 3 yr. The transgenic corn expressed the Cry1Ab protein targeting lepidopteran pests. Three of the 57 ground beetle species collected accounted for 81% of all individuals captured. Six other species accounted for an additional 14% of all beetles captured. Ground beetles were captured equally in cornfields and soybean fields. They also were captured most frequently at field edges, but many were captured within field centers. Canonical correspondence analysis was used to arrange ground beetles along environmental gradients. Years 2001 and 2002 were the primary variables separating assemblages of ground beetles along the first canonical axis. The second canonical axis further separated the 2000 assemblage of ground beetles. With the effects of year and field removed, ground beetles were classified with respect to crop association and distance into the fields along axes 1 and 2 of a partial canonical correspondence analysis. Based on this analysis, ground beetles occupying the Bt cornfields were separated from those occupying soybean fields along the first canonical axis. The second canonical axis separated beetles occupying the field borders from field interiors. Ground beetles ordinating near the center of the axes may represent habitat generalists, and because of their high relative abundances, continuous seasonal activity, predatory nature, and ability to occupy field centers, they could assist in the biological control of agricultural pests.

Garlic mustard, Alliaria petiolata (Bieb.) Cavara and Grande, is a widespread invader that has aggressively colonized woodland edges and forest interiors across North America, yet its ecological impacts remain scantily documented. We evaluated the effects of garlic mustard on ground beetle (Coleoptera: Carabidae) assemblages and their invertebrate prey by comparing carabid captures and species richness and invertebrate abundance in invaded and noninvaded areas of two forests in central New York. Geostatistical techniques were used to model ground beetle distribution and to determine spatial correlation between carabids, garlic mustard, ground beetle prey availability, understory plant species richness, and litter depth. Data were collected from April to September 2002, using a grid of 64 by 64 m, with 89 sampling points arranged in nested grids to capture the spatial correlation within and between each variable. Garlic mustard invasion had no effect on carabid captures and species richness or on invertebrate abundance. Ground beetle abundance and biomass were spatially correlated, but their distribution was independent of garlic mustard and all other environmental factors we recorded. Our data on carabid assemblages and their invertebrate prey clearly show that absence or presence of garlic mustard did not influence these organisms at our study sites. It is possible that garlic mustard invasion has negative ecosystem impacts; however, the biennial nature of the plant and its pattern of spread may produce subtle ecological effects that are difficult to quantify or are easily confounded by other dominating factors.

Herbicide treatments were used in glyphosate-resistant field corn, Zea mays L., to produce treatments with weeds growing for varying periods of time in a replicated field trial conducted in three different fields over 3 yr. Increased weediness increased the activity-density of Harpalus pensylvanicus (DeGeer) (Coleoptera: Carabidae), the most common carabid species collected in pitfall traps. Field crickets, Gryllus spp. (Orthoptera: Gryllidae), showed a similar response, with generally higher numbers caught in weedier plots. Other ground-dwelling arthropod species showed variable responses to weediness. Wolf spiders (Lycosidae) showed an apparent response to fresh organic matter and dead weed thatch after herbicide treatments in 2002. Although several arthropods common in the field plots ate second instar western corn rootworms, Diabrotica virgifera virgifera LeConte (Coleoptera: Chrysomelidae), when the rootworms were presented to them on filter paper in the laboratory, rootworms were not consumed when presented to potential predators under a thin layer of soil. Predation on exposed larvae placed in the field for 24 h did not differ by treatment, possibly because the major species that differed by treatment were primarily herbivorous or omnivorous. Corn yields were lower in the weedy check plots all 3 yr, but no significant reduction in yield occurred in treatments with weeds present for 21, 31, or 41 d after planting, or in plots treated with preemergence herbicide only.

The ant Solenopsis invicta Buren has spread across the United States and is reported to have significantly reduced the diversity of the native ants. Much of this spread is occurring on land that has been repeatedly disturbed by continually changing land use practices. S. invicta seems to outcompete and eliminate other resident ant species. However, this inference may not be true because several resident native ant species are known to persist in S. invicta-infested areas. Thus, in this study, we analyze the aggressive interaction between selected resident ants and S. invicta by evaluating whether some of these ants are capable of attacking small worker-defended S. invicta colonies or are instead attacked by the S. invicta colonies. Our results suggest that the native ant species Monomorium minimum (Buckley), Pheidole dentata Mayr, and Solenopsis molesta (Say) and exotic tramp ants Tetramorium bicarinatum (Nylander) and Monomorium pharonis (L.) do interact with the S. invicta and will attack and eliminate worker-defended S. invicta colonies of varying sizes ranging from 30 to 480 workers. M. minimum, P. dentata, S. molesta, T. bicarinatum, and M. pharonis also were observed to prey upon S. invicta brood once most of the defending workers were eliminated. The native species Forelius sp. was not observed to invade the S. invicta colonies; instead, it prevented S. invicta workers from leaving their nest to forage, which may have contributed to the decline of S. invicta colonies of up to 60 workers over time.

The distribution of soil nutrients in deserts is heterogeneous, with high concentrations of organic and inorganic nutrients occurring under shrubs and near animal dwellings. Attention has focused on shrubs in creating “fertile islands.” In this study, we compare the effects of the harvester ant Pogonomyrmex rugosus Emery (Hymenoptera: Formicidae) and shrubs on soil composition in the Mojave Desert. Soil organic matter, total N, mineral N, and available P were significantly more concentrated in the nests of P. rugosus than under the dominant vegetation and in sparsely vegetated interspaces between shrubs and ant nests. Ant nests also contained high concentrations of total C, organic C, and soluble organic C and N relative to other microhabitat types. On an areal basis, ant nests stored 3% of mineral N and 0.7–1.6% of organic matter, total N, and available P on the landscape while covering 0.5% of the surface. At field moisture, microbial biomass C and N were significantly more concentrated in ant nests at one of two study sites. When moistened, ant nest soils had a higher capacity for microbial growth than soils from other microhabitats. As a result of ant activities, ant nests accumulated surface materials at an average rate 3.5 mm/yr faster than the surrounding soil. We conclude that P. rugosus nests impact arid ecosystems by creating highly concentrated patches of soil nutrients and microflora on the landscape that could affect biogeochemical cycling rates and plant community dynamics.

The soybean aphid, Aphis glycines Matsumura, is an invasive pest of soybean, first discovered in North America in 2000. We studied the ability of the existing predator community in soybean to suppress A. glycines population growth during June–August 2002, in field studies using predator exclusion and sham cages or no-cage controls. Cages were infested with uniform initial densities of A. glycines adults, and subsequent populations of aphids and predators were monitored. After 2 wk, exclusion and sham cages were switched, with aphid and predator density followed for additional 2 wk. The experiment was repeated a second time, allowing observation of predator community response to both low and high density aphid populations over several time periods and stages of soybean development. Cages had minimal effects on temperature, relative humidity, or soybean growth. In contrast, predator communities and aphid populations were strongly affected by cage treatments. In the first trial, the activity of foliar-foraging predators effectively prevented A. glycines population growth maintaining populations below 10 aphids per plant (adult nymphs) in sham cages, while populations exceeded 200 aphids per plant in exclusion cages. After cage switch, these high A. glycines populations in the former exclusion cages were rapidly colonized and reduced by nearly an order of magnitude within 2 wk by a combination of generalist and specialist predators. The second trial produced qualitatively similar results, but at much lower aphid densities. The most abundant predators in both trials included: Harmonia axyridis Pallas, Orius insidiosus (Say), and Leucopis spp. These studies demonstrate that existing predator communities comprised of a mixture of indigenous and naturalized species can suppress A. glycines population density in soybean. The impact of existing predator communities should be further investigated as a component of A. glycines management in United States soybean production systems.

We examined the effects of supplemental food sources on parasitism of turf-infesting white grubs (Coleoptera: Scarabaeidae) by tiphiid wasps (Hymenoptera: Tiphiidae). Survival of spring active Tiphia vernalis Rohwer and late summer active Tiphia pygidialis Allen, parasitoids of Japanese beetle, Popillia japonica Newman, and masked chafer, Cyclocephala spp., grubs, respectively, was significantly increased when wasps were provided with 10% sugar water in the laboratory. Presence of a grub for host feeding did not affect wasp longevity. Sugar sprays applied directly to turf were examined as a method for increasing grub parasitism rates. Large numbers of T. pygidialis visited turf sprayed with sugar water to feed. Parasitism of Cyclocephala spp. grubs by T. pygidialis was reduced in sugar-sprayed turf, but higher in turf plots located near sugar-sprayed turf. T. vernalis, which feeds on homopteran honeydew secretions, was never observed feeding on sugar-sprayed turf, nor did such treatments affect its parasitism of P. japonica in or near sugar-sprayed turf. Gardens of spring- or fall-blooming flowering plants were established and monitored to determine whether particular species might attract Tiphia spp. No T. pygidialis were observed feeding on flowers in fall-blooming gardens. Large numbers of T. vernalis were observed feeding on nectar from peony, Peonia lactiflora Pallas, in the spring-blooming garden. When replicated plantings of P. lactiflora were established in a stand of turf, parasitism of P. japonica was significantly higher near the peonies. Incorporating such nectar-producing flowers into a landscape may increase parasitism of P. japonica by T. vernalis.

After 15 failures to establish Cotesia flavipes (Cameron) as a parasitoid of the sugarcane borer, Diatraea saccharalis (F.), in Louisiana sugarcane fields (Saccharum spp.), four release refuges were established as sites for an intensive study of the crop, host, and parasitoid interaction for a full crop cycle. These refuges were maintained with minimal disturbance from June 2001 to June 2002 to encourage the establishment of C. flavipes. Refuges were managed in a manner such that (1) sugarcane borer larvae were abundant, (2) predation of parasitoids by the red imported fire ant, Solenopsis invicta (Buren), was minimized, (3) host and parasitoid were not exposed to insecticide applications used to control economically damaging sugarcane borer infestations, (4) presence of parasitoids was insured through repeated releases during the growing season, and (5) the sugarcane was not harvested to enhance overwintering opportunities for C. flavipes. C. flavipes was successfully recovered in all established refuges and overwintered in three of the four refuges. However, parasitoids were not collected during May of the following spring. The inability of the parasitoid to use first-generation sugarcane borer larvae seems to be a major limiting factor preventing establishment of C. flavipes in Louisiana sugarcane. In May, the sugarcane stalks have not formed internodes, which may preclude important host finding and host acceptance cues such as frass and silk in the tunnel entrance. Although efforts were made to suppress the red imported fire ant at the study sites, ant predation on C. flavipes was also a major factor limiting establishment.

In field crops in the southeastern United States, larvae of Heliothis virescens (F.) are often infected with ascoviruses, especially toward the end of the growing season. Ascoviruses are unusual in that they are difficult to transmit per os, and several studies have provided data indicating that these viruses are vectored mechanically by parasitic wasps during oviposition. In Georgia, three parasitoids commonly parasitize H. virescens larvae: Cardiochiles nigriceps Viereck, Campoletis sonorensis (Cameron), and Microplitis croceipes (Cresson). In the current study, we investigated the transmission of ascovirus by these parasitoids by using females that were collected in the field or reared in the laboratory. After a single oviposition by C. nigriceps in an H. virescens larva with a 4-d-old ascovirus infection, all subsequent healthy larvae parasitized by this female developed ascovirus infection. After oviposition in an infected larva, examination of C. nigriceps by using transmission electron microscopy showed that ascovirus virions and ascovirus vesicles adhered to the inner surface of the ovipositor. The ovipositor of M. croceipes was shorter than those of C. nigriceps or C. sonorensis, and this was correlated with a lower rate of ascovirus transmission by the former species. Observation of C. nigriceps populations in the field indicates this species survives even when ascovirus prevalence in H. virescens is high. Laboratory studies of this host–parasite–virus system showed C. nigriceps larvae survived infection of their host if parasitoid larvae were at least second instars at the time of infection. If an ascovirus infection in the first H. virescens host was no older 48 h, a C. nigriceps female sometimes did not transmit ascovirus to subsequent hosts. Exposure to environmental conditions of the field decreased the capacity of C. nigriceps to transmit ascovirus, and transmission also decreased over the longevity of female parasitoids.

Movements of 55 Anoplophora glabripennis (Motschulsky) adults were monitored on 200 willow trees, Salix babylonica L., at a site ≈80 km southeast of Beijing, China, for 9–14 d in an individual mark–recapture study using harmonic radar. The average movement distance was ≈14 m, with many beetles not moving at all and others moving >90 m. The rate of movement averaged almost 3 m per day. Movement patterns differed strikingly between the sexes: males averaged >6 times the total movement distance of females at ≈2 times their rate. The overall recapture rate in this short-term experiment was 78%, but the radar tags attached to individual beetles often broke or otherwise were rendered undetectable after several days in the field. Currently, the harmonic radar system is useful for tracking beetles and obtaining estimates of their movement rates over short time periods. It will become useful for longer-term studies as more durable tags are developed.

A variant of the western corn rootworm, Diabrotica virgifera virgifera LeConte (Coleoptera: Chrysomelidae), that circumvents crop rotation by flying out of cornfields to lay eggs in fields planted to other crops is presenting new management challenges to producers in the eastern Corn Belt. The rotation-resistant variant was first noted in east central Illinois and quickly dispersed to northern Indiana, southern Michigan, and northwestern Ohio. The spread of this variant throughout this region seems to be a result of high-altitude daytime flight. In this study, measurements of beetle flight activity at 10 m above ground level and meteorological factors are analyzed to evaluate the influence of atmospheric conditions on high-elevation flight of western corn rootworm. Collections of beetles from 72 d in July and August 2000–2002 reveal two pronounced peaks in high-elevation western corn rootworm flight, the first between 0645 and 1100 hours and the second between 1700 and 2030 hours. Low temperatures, high wind speeds, and darkness were found to limit beetle flight activity; however, within the range of weather conditions conducive to aerial movement, the level of flight activity was not strictly related to the values of individual environmental factors. Instead, peaks in western corn rootworm flight activity at 10-m elevation corresponded to predictable transitions in atmospheric conditions above the fields.

Nadezhdiella cantori (Hope) is an important longhorn pest of citrus trees in Asia. The sex ratio was male-biased (≈1 female:1.5 males) on the mating and oviposition site. Males were significantly smaller than females but had significantly longer antennae and greater slope for the linear antennal-body relationship than females, suggesting that males are subject to higher sexual selection pressures than females, and their antennal length is the highly selected phenotypic character. Males aggressively competed for mates and guarded females through prolonged pair-bonding. During pair-bonding, males performed a full-mounting when mating and a half-mounting when resting or during female oviposition. Larger males with longer antennae had an advantage over smaller ones with shorter antennae in both fighting and mating success, but the slopes for linear antennal-body relationships remained similar for all males. It is suggested that the male antennal and body lengths may have evolved symmetrically for both mating and fighting advantages. Larger females did not have greater probability of being mated, but females with greater slope for the antennal-body length relationship were more likely to be chosen by males for mating. The allometry in the female antennal length may be a phenotypic indicator of female reproductive fitness, with greater slope for antennal-body length relationship representing higher quality. After the initial fight, the male loser seemed to be able to remember the winner and retreated immediately without the occurrence of another fight after encountering (contacting) the previous victor. Such memory lasted for at least one night.

We compared predation of Orius insidiosus (Say) on adult and second instars of Frankliniella occidentalis (Pergande) and on adults of F. occidentalis and F. tritici (Fitch) in arenas with pepper flowers. Also, we compared the dispersal of these thrips in the presence and absence of the predator. For each experiment, two densities of thrips (10 and 20 total thrips) and two time exposures (10 and 34 h) were tested. Second instars were more likely to move from the flower where they were released than were F. occidentalis adults. F. tritici dispersed more than F. occidentalis. The presence of the predator enhanced movement by thrips from flowers in which they were released. Despite differences in prey movement, O. insidiosus successfully preyed on all types of prey that were offered. However, O. insidiosus appeared to deal differently with each type of prey. Predation of both larvae and adults was most likely to occur inside flowers. In trials with adults and second instars of F. occidentalis, larvae were significantly more vulnerable to predation than were adults. F. tritici, the more active species, may have been vulnerable to predation because of higher rates of encounter with the predator; however, O. insidiosus may have had greater attack success against the less active F. occidentalis. The ability of O. insidiosus to prey successfully on different life stages and species of thrips in complex environments indicates that it is an efficient predator of thrips and an important biological control agent.

Protein-rich pea flour is toxic and repellent to three major stored-grain pests: the rice weevil, Sitophilus oryzae L.; the red flour beetle, Tribolium castaneum (Herbst); and the rusty grain beetle, Cryptolestes ferrugineus (Stephens). This study found that protein-rich pea flour was not toxic to, and did not reduce the offspring of, Anisopteromalus calandrae (Howard), a parasitoid of S. oryzae, nor did it reduce offspring of Cephalonomia waterstoni (Gahan), a parasitoid of C. ferrugineus. Protein-rich pea flour was also not repellent to A. calandrae. Small-scale and large-scale tests of a combination of protein-rich pea flour and parasitoids were conducted in 2-liter jars and in barrels containing 330 kg wheat. A larger population of A. calandrae was found at a high host infestation rate (24 adults/kg for 25 d), but the parasitoid did not become established at middle and low host infestation rates (2.4; 0.24 adults/kg for 25 d). The combinations of protein-rich pea flour and parasitoids reduced populations of S. oryzae in both tests. Additional effects of protein-rich pea flour and parasitoids were found in the large-scale test. Releasing parasitoids alone reduced the populations of S. oryzae by 46% and C. ferrugineus by 49%. Treating wheat with 0.04 or 0.1% protein-rich pea flour reduced the population of S. oryzae by 26 and 79% and C. ferrugineus by 27 and 43%, respectively. Combining parasitoids with 0.04 or 0.1% protein-rich pea flour reduced S. oryzae populations by 76 and 98% and C. ferrugineus populations by 42 and 75%, respectively. At the end of the large-scale experiment, grain treated with protein-rich pea flour alone or in combination with parasitoids had better grain quality than the untreated controls.

With the recent commercialization of transgenic rootworm-resistant maize with high levels of antibiosis to larval feeding, the biology of western corn rootworm, Diabrotica virgifera virgifera LeConte, on hosts beyond maize, Zea mays L., has become an important topic for which data are limited. Larval survivorship and growth parameters were monitored on the roots of 29 plant species comprised of maize, maize-field weeds, native prairie grasses, forage grasses, and small grain crops. Data on larval recovery and growth (measured as increases in head capsule width and accumulation of dry weight) were recorded at five samplings (6, 10, 14, 20, and 24 d) after initial infestation of the 29 species. Recovery and growth parameters were analyzed for inter- and intraspecific differences within and among sampling dates. Larvae survived at least 6 d after infestation on 27 species and 24 d on 23 plant species. Larval recovery and growth were impacted by both species and time after infestation. Growth and development of larvae were significantly slower on most plant species beyond maize; however, 18 of the species had larvae develop to the second instar, whereas larvae on 14 species developed to the third instar. Adults were recovered from five plant species in addition to maize. Because rootworm-resistant transgenic maize with high levels of antibiosis has become a part of the agroecosystem, weeds in grassy maize fields as well as adjacent forage grass species may become more important in the western corn rootworm life cycle, particularly because genes conferring resistance to postemergent herbicides such as glyphosate are stacked with transgenic rootworm-resistant maize hybrids.

A 4-yr study (1997–2000) was conducted in the northern Texas Rolling Plains to determine whether the pyrethroid insecticide λ-cyhalothrin was associated with changes in nutritional quality (nonstructural carbohydrates, percentage leaf nitrogen and moisture, and total amino acids) of cotton leaves. Another objective was to determine the relationship between nonstructural carbohydrates (glucose, fructose, sucrose, and starch) in cotton leaves and change in cotton aphid, Aphis gossypii Glover, numbers during late summer and on formation of dark-colored morphs. Carbohydrate concentrations, percentage leaf moisture and nitrogen, and total amino acids were not significantly altered in cotton leaves by λ-cyhalothrin. Glucose, fructose, sucrose, sugar ratio [(glucose fructose)/sucrose concentrations], leaf nitrogen, and moisture were significantly influenced by year and irrigation treatment. Regression analysis indicated that change in aphid numbers was influenced by numbers of aphids per leaf, temperature, leaf moisture and nitrogen, and sugar ratio. A negative linear relationship was observed between change in aphid numbers and sugar ratio; population growth was limited by high levels of glucose and fructose in cotton leaves, especially when temperatures were high and leaf moisture low. Percentage of dark-colored aphids was negatively correlated with temperature and daylength and positively correlated with leaf moisture and nitrogen and the sucrose/glucose ratio. Some of the nutritional and abiotic environmental variables that interact to regulate the occurrence of dark morphs are also interacting with other variables to influence the extent to which the reproductive potential will be expressed.

Oviposition preference was examined in relation to offspring performance in a bud gall-forming sawfly, Euura sp., which attacks the Scouler or fire willow, Salix scouleriana (Barratt). The only known locality for this sawfly in Arizona is in the inner basin of the San Francisco Peaks, at 3,100–3,450 m above sea level. A random sample of shoots was taken in October of 1995, 1996, 1997, and 1998 to record shoot length, number of buds per shoot, number of galls per shoot, percent mortality, and overall percent survival for each generation. Oviposition preference was quantified for the first 3 yr, and larval performance was measured over all 4 yr. We found a strong oviposition preference for longer shoots. The longest shoot-length classes contained the smallest proportion of buds, and yet they were attacked more frequently than the short shoot-length classes. Therefore, the rarest shoot-length classes were the most preferred. Larval establishment and survival in galls were used to evaluate offspring performance. No significant correlation existed between larval establishment and shoot length, thus negating the prediction of a preference-performance linkage. Overall survivorship was high in 1995 (77%), 1997 (80%), and 1998 (82%), but drastically dropped in 1996 (16%), possibly because of a severe drought during that year. We discuss two alternative hypotheses to possibly explain these results: (1) all modules (long and short shoots) could provide sufficient nutrients for larvae to survive; and (2) selective pressures acting on female oviposition behavior are independent of larval performance.

“Bottom-up” factors strongly influenced the spatial and temporal pattern of survival of Asphondylia atriplicis Townsend (Diptera: Cecidomyiidae) on Atriplex canescens (Pursh) Nutall (Chenopodiaceae) at three locations in Phoenix, AZ. In contrast, “top-down” effects of natural enemies did not influence the pattern of A. atriplicis mortality. A. atriplicis induces a fleshy, multilocular, rounded stem-gall near the apical meristems of A. canescens. A. atriplicis survival increased as gall size increased, and as the depth of larva in the gall increased. Larval mortality from unknown factors on A. atriplicis decreased with gall size, but the overall interval parasitism rate did not change significantly with gall size. The interval parasitism rate for the eurytomid parasitoid group with the shortest ovipositor was negatively correlated with gall size, but interval parasitism by all other parasitoids was not influenced by gall size. Gall size was strongly influenced by the bottom-up forces of environmental and plant heterogeneity. Gall size varied among seasons, sites, and plants. Larval survival and gall-size covaried in each season and site and among plants.

Both the rice water weevil, Lissorhoptrus oryzophilus Kuschel, and rice stink bug, Oebalus pugnax (F.), are important pests of rice, Oryza sativa L., in the United States. The host ranges of both insects primarily consist of monocotyledonous plants. Previous research has shown that the rice water weevil prefers barnyardgrass, Echinochloa crus-galli Beauv., over rice for feeding and oviposition. Barnyardgrass is also a preferred host for rice stink bug. Thus, presence of barnyardgrass in rice fields may alter populations of one or both insects. Field experiments were conducted to determine how the presence of a preferred host influences rice water weevil and rice stink bug populations on rice. Mixed plots of barnyardgrass and rice were cultivated such that either rice was surrounded by barnyardgrass or barnyardgrass was surrounded by rice. Insects were collected from rice portions of mixed plots and compared with numbers collected from whole plots of rice in the same location. Presence of barnyardgrass had little impact on rice water weevil densities on rice. In contrast, presence of barnyardgrass influenced rice stink bug populations on rice. Rice stink bugs were found on barnyardgrass in mixed plots before panicle emergence of rice. After panicle emergence of rice, results varied from 2001 and 2002. In 2001 and 2003, rice stink bugs were up to 9 times more abundant on rice in mixed plots of barnyardgrass and rice compared with whole plots of rice. Rice stink bugs were up to 4 times greater on rice in whole plots of rice than in mixed plots in 2002. Differences are likely a result of the developmental stage of barnyardgrass relative to rice. Data suggest the presence and developmental stage of barnyardgrass can influence the severity and timing of rice stink bug infestations.

The collection of pollen by honey bees (Apis mellifera L.) provides valuable pollination services for many plants and the protein necessary for brood and young worker development. We collected and identified pollen gathered by feral honey bee colonies living in tree cavities in a coastal prairie landscape over the duration of 1 yr. Specific objectives included evaluating overlap in pollen use between colonies throughout the year, examining the influence of the spatial locations of the colonies on overlap in pollen use, and describing general pollen collection patterns. The feral colonies collected a wide variety of pollen types. Anemophilous (wind pollinated) pollen types were important in the fall, but entomophilous (insect pollinated) pollen types were important for the remainder of the year. Herbaceous plants and shrubs provided pollen during the spring and early summer, trees in mid- to late summer, and herbaceous plants in the fall. The pollen sources used by the feral colonies also tended to be good nectar sources. Overlap in pollen use between colonies varied throughout the year. Pollen overlap was correlated with distance for some sampling periods and not others, probably because of the way colonies select resources and the flowering phenology in the study area.

We evaluated 21 prairie grass species thought to be among those dominant 200 yr ago in the western Great Plains as larval hosts of the western corn rootworm, Diabrotica virgifera virgifera LeConte. Maize, Zea mays L., and sorghum, Sorghum bicolor L., were included as positive and negative controls. Twenty pots of each test species were planted, and each pot was infested 5 wk later with 20 neonate western corn rootworm larvae. Four pots within each of four replications were randomly assigned a sample date for larval extraction. The remaining pot from each replication was used to monitor adult emergence. At 5, 10, 15, and 20 d after infestation, pot contents from assigned pots were placed in Tullgren funnels equipped with 60 W-lights for extraction of larvae. The percentage of larvae recovered, larval head capsule width, and adult emergence varied significantly among the grass species. The percentage of larvae recovered from western wheatgrass, Pascopyrum smithii (Rydb.); pubescent wheatgrass, Elytrigia intermedia (Host); and side-oats grama, Bouteloua curtipendula Michx., was not significantly different than that from maize when sample dates were combined. The number of adults produced from pubescent wheatgrass was not significantly different than the number produced from maize. The average dry weight and head capsule width of adults produced from grass species were not significantly different than the head capsule widths and dry weights of those adults from maize. Overall, adults were produced from 14 of the 23 species evaluated. The results from this study are discussed in relation to the potential ancestral hosts of western corn rootworm larvae and in relation to resistance management of transgenic maize.

Intraspecific variation in herbivore fitness can generate populations locally adapted to different host species, or even individual plants. To test for occurrence of deme formation, local host species adaptation, and interspecific variation in host quality, we quantified survival and fecundity of pine needle scale, Chionaspis pinifoliae (Fitch), on red (Pinus resinosa Ait.) and Scots pine (P. sylvestris L.) in unmanipulated populations, as well as intra- and interspecific reciprocal host transfer experiments. Intraspecific transplants generated no evidence for deme formation on red or Scots pine as scale performance on natal and conspecific hosts did not differ, possibly because host uniformity and proximity may not have generated requisite environmental heterogeneity and genetic isolation. We did observe evidence for local adaptation to Scots, but not red pine. Survival of scales originating on Scots was 6 times higher on conspecific hosts relative to scales transferred from red to Scots pine; their fecundity was also higher, but the effect was not as strong. However, parental effects also contributed to this pattern, at least partially. In all experiments, Scots pine was a much better host than red pine, which is consistent with previous hypotheses that the long coevolutionary history between pine needle scale and red pine has selected for host defenses. These results add to previous studies that question the importance of deme selection in interactions between scales and trees, but do suggest that bottom-up effects contribute substantially to the variation in pine needle scale population dynamics frequently observed on different host species.

Survival, development, and oviposition of the polyphagous insect Mamestra configurata Walker (Lepidoptera: Noctuidae) were compared on different host plant species of the families Brassicaceae [Brassica rapa L., Brassica napus L., Brassica juncea (L.) Cosson, Sinapis alba L., and Thlaspi arvense L.], Compositae [Cirsium arvense (L.) Scop.], Leguminosae (Pisum sativum L. and Medicago sativa L.), Linaceae (Linum usitatissimum L.), and Chenopodiaceae (Chenopodium album L.). Larvae developed faster on intact host plant tissue of all species than they did on excised leaf tissue. First instars of M. configurata did not survive on leaves of T. arvense. Although 97% of larvae survived to the sixth instar on M. sativa, complete mortality was observed on this host plant before pupation. On the other host plants studied, survival rates to sixth instar and pupation were similar. C. album was significantly more preferred than all other species in larval feeding choice experiments, whereas B. juncea and M. sativa were significantly less preferred than the other species. Pupal weights were highest on C. album and S. alba and were lowest on P. sativum and B. juncea. Larval development was most rapid on C. album and was slowest on B. juncea. C. album was significantly more preferred for oviposition than B. napus, B. rapa, C. arvense, and B. juncea. The ovipositional and feeding preferences for C. album suggest that species of Chenopodiaceae were important hosts of M. configurata before vast monocultures of B. napus and B. rapa were introduced to western North America.

Many species of parasitic Hymenoptera inbreed regularly and do not suffer inbreeding depression. However, these inbreeding species could experience outbreeding depression due to the breakup of coadapted gene complexes. We measured the effects of outbreeding on three fitness components of the ectoparasitoid Nasonia vitripennis Walker, a chronic inbreeder. Experimental treatments varied the mating structure within and among populations: inbred (sib-matings within families), outbred within strains (nonsib-matings among families within strains), and outbred among strains, for 15 generations. Life span, fecundity, and sex ratio were measured in the parental generation and in four selected filial generations. We found no evidence of outbreeding depression for any of the fitness parameters tested. However, modest inbreeding depression was suggested as increased life span and fecundity when females were paired with nonsibling males from the same geographic strain, and by increased fecundity for interstrain crosses. Sex ratio did not respond to any of the levels of outbreeding. Consequently, we reject our hypothesis that N. vitripennis suffers outbreeding depression. However, heterosis within and among strains suggests that at least some local populations of N. vitripennis may suffer from modest inbreeding depression.

Lysiphlebus testaceipes (Cresson) is a solitary endoparasitoid of aphids and is the primary parasitoid attacking cereal aphids in the Great Plains, especially Schizaphis graminum (Rondani). In a previous study, it was found that a Lincoln, NE, isolate of L. testaceipes had a much higher survivorship at cold temperatures than isolates from Stillwater, OK, and Corpus Christi, TX. This suggested that the Nebraska isolate was locally adapted to the northern environment and perhaps genetically divergent from southern populations. We tested for genetic differentiation of the above isolates by sequencing portions of the COI and 16S mtDNA genes. We also examined a Florida isolate reared from Toxoptera citricida (Kirkaldy) and L. fabarum Marshall as an outgroup. The Great Plains isolates (Nebraska, Oklahoma, and Texas) were homogeneous with 0% and 0–0.2% sequence divergence in the COI and 16S gene fragments, respectively. The Florida isolate differed from the Great Plains isolates in nucleotide sequence by 1.4% (COI) and 0.5–0.7% (16S). Phylogenetic analysis placed the Florida isolate of L. testaceipes basal to the Great Plains isolates with L. fabarum, suggesting a possible species complex within L. testaceipes.

Studies on conflict and cooperation in insect mating behavior usually assay the relative costs and benefits of mating in unreplicated experimental designs. We assayed multiple populations for such potential costs and benefits in Musca domestica L. under different nutritional environments. We used four populations, each derived from the same field site, ranging from six to 46 generations in the laboratory. Under benign environmental conditions (i.e., ad libitum food and water), mated females lived up to 13% longer than virgins, but this difference was not significant. Under extreme nutritional stress (i.e., no food or water), mated females lived significantly longer, but in only one of the populations tested. Under more moderate stress (i.e., water alone), mated females of one population died significantly earlier. Thus, aspects of both cooperation and conflict were found, but the effects were not repeatable across populations or nutritional environments. Overall, older females were more susceptible to stress. Moreover, the populations were significantly different in longevity (1.5-fold difference) and starvation resistance (2.2-fold difference). The youngest population lived longer, was more resistant to nutritional stress, and was the only line to exhibit significant costs of mating. Thus, the reduced selection pressures of the laboratory could have allowed the erosion of ejaculate toxicity, longevity, and starvation resistance. However, the simplest explanation is that replicate samples from a single geographic source population show appreciable among-line variation in fitness parameters and the consequences of mating. In conclusion, sexual selection studies on the costs and benefits of mating should consider environmental conditions, evolutionary history, and, perhaps most importantly repeatability.