Bioassays were conducted to examine the response of Coptotermes formosanus Shiraki and Reticulitermes flavipes (Kollar) to whole body extracts of termites. Bioassays were also conducted to determine if trail-following behavior could be elicited in glass tubes after different lengths of exposure to termites and if termites showed any species-specific response to exposed tubes. Trail-following behavior was elicited in both species in response to whole body extracts of their nestmates. Although C. formosanus responded to the R. flavipes extract, R. flavipes did not show a difference in response to the C. formosanus extract versus solvent-treated controls. Trail-following behavior was elicited in both C. formosanus and R. flavipes by glass tubes exposed to termites for 5 min. Although neither species showed a preference for glass tubes exposed to their nestmates over tubes exposed to termites of the other species, there were differences in the persistency of trail-following substances deposited in tubes by the two species. When tubes were exposed to termites for 5 min, trail-following behavior was elicited by tubes exposed to C. formosanus for at least 1 h after exposure, whereas termites no longer responded to tubes that were exposed to R. flavipes 10–15 min after exposure. When tubes were exposed to termites for 14 d, termites deposited chemical markers which lasted for at least 8 d. There was no difference in the response of C. formosanus to tubes exposed to their nestmates versus tubes exposed to R. flavipes. However, R. flavipes showed a significant preference for tubes exposed to their nestmates over tubes exposed to C. formosanus. Because there was no evidence of a species-specific response by R. flavipes to tubes exposed to termites for only 5 min, it is possible that chemicals in the feces or in salivary secretions deposited in tubes influenced the behavior of R. flavipes in tests using tubes exposed to termites for 14 d.

The relationship between soil moisture and oviposition in an edaphic insect pest, the southern mole cricket, Scapteriscus borellii Giglio-Tos, was studied in a series of greenhouse experiments. Adults were captured in acoustic calling traps and associated pitfall traps during spring flights in southeastern North Carolina in 1996, 1997, and 1998. Female mole crickets were individually confined in chambers containing 2, 4, 7, 10, and 12% soil moisture. Oviposition and mortality were monitored daily. A significant linear relationship between oviposition and soil moisture was indicated by an increase in the number of crickets ovipositing in response to higher soil moisture levels. Additionally, a delay in oviposition was observed as a response to low soil moisture. There were no significant differences in the number of eggs per ovipositing female, indicating that when oviposition does take place, the individual response of the female is to lay a similar number of eggs regardless of moisture levels. The ovipositional response to a rapid increase in soil moisture was also examined. The rapid increase in moisture resulted in a significantly greater percentage of females ovipositing, as seen in the previous experiments.

The effect of habitat transformation on dung beetle assemblages in the north-western Free State was investigated by comparing the fauna of a nature reserve with that on neighboring farms. Dung beetle sampling was done in four different localities within two different habitat types, a grassveld area and a bushveld (savanna) area. In these two habitat types, dung beetle assemblages in Sandveld Nature Reserve (27° 37′ S, 25° 46′ E) and on farms were compared. Eighty-three species belonging to 26 genera were captured in the study area. Doube’s classification was used to divide the dung beetles into functional groups according to the manner in which they use and disturb dung. The grassveld habitats were dominated by larger dung beetles belonging to functional groups I and II, whereas in the bushveld habitats smaller dung beetles belonging to functional groups IV and V were dominant. There were definite habitat preferences, with the larger dung beetles belonging to functional group I and II preferring the grassveld habitats and having higher abundance in the natural rather than the disturbed habitats. The smaller dung beetles, belonging to functional group V, preferred the bushveld habitats. The better competitors (the larger dung beetles) occurred more abundantly in the grassveld habitats and also more abundantly in the natural grassveld habitat than in the disturbed habitat. None of the indices measuring species richness nor dominance showed significant differences between the four habitats. The dung beetle assemblages in all four habitats showed a log series pattern, with high abundance of a few dominant, highly effective competitors and a large number of ‘rare’ species, which were assumed to be less effective competitors. This does not, however, imply that the dung beetles were similarly affected by the different habitats, because the biomass of dung beetles was higher in the grassveld than the bushveld habitats and also higher in the natural habitats. A change in vegetational ground cover caused by overgrazing and trampling has a greater effect on the larger, more effective competitors in the assemblage, whereas the smaller less effective competitors do not seem to be affected by this change.

We evaluated the family-level richness, diversity, evenness, and abundance of ground- and litter-dwelling beetles in two forested areas of southeastern Kentucky for 2 yr, and related beetle diversity to habitat characteristics in these deciduous forests. Using pitfall traps and leaf litter samples, we collected over 13,420 beetle specimens in 42 families during this 2-yr study. Carabidae, Scolytidae, and Staphylinidae were the most abundant families in pitfall traps, and Nitidulidae, Staphylinidae, and Pselaphidae were most common in litter samples. Pitfall traps captured the widest array, with 41 beetle families, whereas litter samples produced 25 families. Plots from Robinson Forest had a higher family richness but lower evenness than Kentucky Ridge Forest plots in both 1997 and 1998. The greater evenness of the families at Kentucky Ridge contributed to a higher Shannon index at Kentucky Ridge than at Robinson Forest, though these differences were significant only in 1998. Kentucky Ridge plots tended to be less rocky, with greater amounts of coarse woody debris, less dense herbaceous cover, a smaller mid-canopy component, and less deciduous cover than Robinson Forest. Family richness, diversity, evenness and abundance varied with site, plot, and sample interval, but the site variables we measured were inconsistent in their ability to predict our response variables, as was the multivariate cluster analysis. The effects of site characteristics and habitat complexity on beetle family diversity are discussed.

The oviposition behavior of adult insects can have a major impact on the level of exposure of their offspring to natural and artificial toxins. Pollen from Bt-corn hybrids represents a novel toxin and very little is known regarding its detection and possible avoidance by ovipositing females. The effect of corn plant proximity and corn pollen presence on the oviposition behavior of the monarch butterfly, Danaus plexippus (L.), was assessed in cage and flight chamber studies. The proportions of monarch eggs oviposited on milkweed plants dusted pollen from with a Bt-corn hybrid, an untransformed hybrid, gravel dust, and undusted control plants were recorded from a cage study. None of the treatments differed significantly in the relative proportion of eggs found. The effect of Bt and untransformed corn plant proximity and corn pollen presence was also assessed in a flight chamber. A significantly higher proportion of eggs (96%) were recovered from patches of milkweed plants not surrounded by corn plants, and a significantly higher proportion of eggs (nearly 70%) were recovered from patches of milkweed plants not dusted with corn pollen. There were no significant differences in the effects of Bt corn plants or corn pollen compared with untransformed plants or pollen. These results may have important implications for the level of exposure of monarch larvae to Bt-corn pollen.

Field experiments were conducted from 1996 to 1998 to assess the effects of nitrogen fertilization rates and planting dates on the population dynamics of the cotton aphid, Aphis gossypii Glover, during the midgrowing season of California cotton. Cotton aphids reached higher densities in high nitrogen fertilized plants (227 kg N/ha, rate currently used by cotton growers) than in low nitrogen fertilized plants (57 kg N/ha). In addition, late-planted cotton (May–June), which had more nitrogen content, also harbored higher aphid populations than early plantings (April). Overall, aphid abundance was positively correlated with plant nitrogen content. In a moderate aphid pressure year (1996), planting the cotton early (April) was effective in keeping the aphid population below the midseason economic threshold. However, in a high aphid pressure year (1997), it was necessary to drastically reduce the nitrogen fertilization to 57 kg N/ha to maintain the aphid density under this threshold. Recent cultural practices in California cotton include higher rates of nitrogen fertilization, which increases nitrogen content of plants. The current data suggest that this practice (i.e., high fertilization) is an important factor contributing to the increased severity of the cotton aphid as a pest of California cotton during the midseason.

The beet armyworm, Spodoptera exigua (Hübner), is a sporadic but devastating secondary pest of cotton. Scouting cotton for egg masses is commonly recommended for identifying potential outbreaks and for proper timing of insecticide applications. However, there is disagreement regarding where to look on the plant for beet armyworm eggs. We investigated and quantified placement of egg masses by laboratory colony females within cotton and pigweed (a preferred wild host plant) canopies of different heights. In cotton, almost all egg masses were deposited on the undersides of leaves, and ≈80% of the egg masses were consistently located in the upper 50% of the cotton canopy, and horizontally within the inner 50% of the canopy around the central axis. Although this trend was consistent among all categories of plant height tested, variation about the means decreased with increasing height. A smaller sample of wild females indicated similar vertical placement, but horizontal placement extending further distally in the canopy. Our results indicate that scouting for egg masses on the underside of leaves in the upper half of the canopy will recover ≈80% of the egg masses present on the plants. In pigweed, egg masses were commonly laid within the inner 50% of the canopy, but along the upper 80% of the vertical axis. As in cotton, variation about the means was less in taller plants. The number of eggs per egg mass was 29% less in cotton than in pigweed. This positional information will aid in further efforts to investigate, predict, and manage beet armyworm populations in cotton and noncotton hosts.

We studied movement patterns of nymphs of a highly polyphagous herbivore, Lygus rugulipennis Poppius (Heteroptera: Miridae) on two host plants, wheat (Triticum aestivum) and scentless mayweed (Tripleurospermum inodorum Schultz). We used the observed movement patterns to model redistribution of nymphs with an individual based movement model and with a diffusion approximation of random walk, and we tested the predictions of the models by following redistribution of nymphs on small arenas in the laboratory. The nymphs were clearly more mobile on wheat than on T. inodorum, and on the arenas most of nymphs were found on T. inodorum after the period of redistribution. Both the simulation model and the diffusion approximation of random walk predicted the distribution well. The ability of the models to predict equilibrium distribution of L. rugulipennis nymphs in heterogeneous space, even though they were parameterized with data collected in homogenous vegetation, suggests that the observed distribution of individuals may have been caused by the host plant induced differences in movement patterns. The high speed of redistribution predicted by the models suggests that no tactic behavior, e.g., orientation toward T. inodorum, is needed for locating preferred hosts in a heterogeneous vegetation composed of small patches.

Improving the use of bioctechnological and classical plant resistance for herbivore pest control with less reliance on chemicals critically depends on predictable interactions with secondary pests. Performance of the potato aphid Macrosiphum euphorbiae (Thomas), a secondary pest of potato in eastern North America, was studied on potato, Solanum tuberosum L., lines with traits of potential resistance to primary pests. The lines tested were ‘Newleaf’, a transgenic ‘Superior’ cultivar expressing the Bacillus thuringiensis Berliner CryIIIA toxin, which is highly resistant to the Colorado potato beetle, Leptinotarsa decemlineata (Say); a transgenic ‘Kennebec’ cultivar expressing rice cystatin I, a protease inhibitor previously shown to inhibit cathepsin like digestive enzymes in the Colorado potato beetle; NYL 235–4, a potato derived by selective breeding following hybridization with S. berthaulthii, with a moderate density of glandular trichomes providing resistance to small insects by contact; and the commercial cultivars Superior and Kennebec used as controls. Transgenic Superior potatoes negatively affected M. euphorbiae’s growth and fecundity, in contrast with the OCI potato, which improved aphid performance. The flight incidence of young alatae of M. euphorbiae that completed development on transgenic Superior was significantly higher than in aphids from other potato lines. Aphid resistance in the ‘NYL 235–4’ line was complex and depended on aphid access being limited to leaves, which reduced survival and fecundity. However, when aphids had access to whole NYL 235–4 plants, aphid performance was restored, as they preferentially fed and reproduced on NYL 235–4 stems and apical buds of unfolding leaflets. The results illustrate that the performance of a secondary pest of potato can vary unpredictably, depending on the nature of the resistance factors involved in developing specific resistance to a primary pest.

Feeding injury and performance of the potato leafhopper, Empoasca fabae (Harris), was measured on two red maple clones (Acer rubrum L.), a Freeman maple cultivar (A. × freemanii E. Murray), two elm cultivars (Ulmus spp.), and an American elm clonal selection (U. americana L.), and was related to the leaf content of important nutritional elements. Significantly more eggs were laid and more nymphs became adults on American and Patriot elms than on the other clones. Although the mean number of eggs laid was not significantly different among the maple clones, nymphal survivorship was significantly higher on red maple 56026 than on the other maple clones. Although the number of eggs laid was linearly related to foliar nitrogen and phosphorus, survival of nymphs to adulthood was linearly related to foliar nitrogen. Significantly more leafhoppers from the wild population were collected from American elm, followed by Patriot elm and red maple 56026. Although none of the elms showed any evidence of feeding injury, the maple trees varied from tolerant (i.e., ‘Indian Summer’) to susceptible (i.e., red maple 56026). Leafhoppers may need to increase feeding on red maple 56026 as a compensatory response to the limited nutritional quality of this clone. Because the sex ratio of the wild population was close to 1:1, and consistent across clones, it appears that differences in the behavior of the potato leafhopper among clones were not a function of gender bias associated with each species. Resistance against the potato leafhopper among maples and elms is influenced, in part, by the nutritional content of the leaves. Yet, feeding injury is not a good indicator of host resistance against the potato leafhopper.

Photoperiod influences diapause induction in the grape berry moth, Endopiza viteana (=Polychrosis viteana), and eggs and neonates (<12 h) were the most sensitive to decreasing photoperiod. When held at photoperiods of 7–14 h, eggs produced mostly diapausing pupae, whereas at 15 h, development proceeded without diapause. Neonate larvae also showed sensitivity to short photoperiods, but responsiveness of larvae decreased rapidly with age, so that instars greater than 12 h old exposed to a short photoperiod of 8 h developed into adults without diapause. Eggs held at a high temperature (30°C) and 8-h photoperiod also produced diapausing pupae, suggesting that diapause induction in E. viteana is independent of temperature. Field studies showed considerable population variation in diapause induction, and an exponential saturation model predicted that 50 and 90% of individuals entered diapause at photoperiods of 14 h, 45.5 min and 14 h, 21.1 min, respectively.

We used fractal geometry to analyze the morphology of the tunneling system of two subterranean termite species, Reticulitermes flavipes (Kollar) and Coptotermes formosanus Shiraki, and to evaluate the effect of termite species, and the presence of wood on the degree of intricacy of the tunnels represented by the fractal dimension (D), and on the abundance of tunnels (log K). The differences in D and log K, before and after termites reaching a testing chamber, were also examined. Results indicated that termite tunneling systems have a fractal structure because –2 < D < −1. The tunnel fractal dimension (D) was not significantly different between C. formosanus and R. flavipes, before or after reaching a testing chamber, suggesting that C. formosanus and R. flavipes created tunnels with the same degree of intricacy at all time periods. The abundance of tunnels, log K, was higher before reaching a testing chamber, while termites were searching for food, than after regardless of the presence of wood or the species of termite introduced in the arenas. The utility of tunnel fractal dimension deserves further study, because it may provide new ways for understanding the functional implications of the branching patterns of termite tunnels in relation to optimum soil exploration by termites.

Boll weevil, Anthonomus grandis grandis Boheman, overwintering survivorship was quantified monthly throughout the overwintering period (October to May) in Texas High Plains and Rolling Plains for 12 yr. A negative exponential model was developed to dynamically predict survivorship throughout the overwintering months. Survivorship was modeled as a function of the number of days that weevils were in the habitat, negative degree-days (<0.0°C), positive degree-days (>6.1°C), rainfall, and mortality during the first month of overwintering. First month mortality was modeled as a function of overwintering survival potential of weevils determined by dissection examination of their body lipid content and gonad atrophy. A nonlinear iterative multiple regression analysis showed that the model explained 94% of the variability in parameterization-verification data; a goodness-of-fit test showed that 97% of the estimated survival values did not significantly depart from their corresponding observed values. With independent validation data, 94% of the variability was explained by the survival model; a goodness-of-fit test for validation data showed that 96% of the predicted survival values did not significantly depart from their corresponding observed values. This model offers a greater understanding of boll weevil overwintering biology as it demonstrates a link between biological and climatic parameters. The model can be used to forecast weevil survivorship throughout the overwintering period in the Texas Plains.

The lesser mealworm, Alphitobius diaperinus (Panzer), is an important economic pest in poultry production systems. Spatial analysis of the beetle population and environmental parameters can aid the integrated management of this pest species. A mealworm population was monitored weekly using tube traps in a broiler facility for five consecutive flock grow-outs ranging from 5 to 8 wk each. Litter temperature, pH, and relative humidity were measured concurrently at six of the same locations as tube trap placement. A geographic information system was used to display weekly spatial relationships of adult and larval beetles during each flock grow-out. Spatial maps of beetle populations showed that low numbers of the beetles were found in the half of the facility used to initiate each flock grow-out during weeks 1–3. Beetle numbers increased continuously in all areas of the facility in latter weeks of each grow-out. Using ranges of environmental conditions considered favorable to the beetles, we developed a model to predict locations of high beetle densities. A comparison of the predictive model to actual counts of adult and larval beetles showed percentages of agreement ranging from 20.0 to 86.7%. The accuracy of the predictive model had limits imposed by house environmental conditions and by beetle movement restrictions. Spatial maps of beetle occurrence based on trap counts display areas in the facility where control efforts would have the greatest impact on beetle numbers, whereas modeling is a less costly alternative than conventional sampling methods for finding areas of high beetle occurrence.

Linear regression and multiple regression stepwise selection procedure analyses were used to relate population fluctuations of bean leaf beetle, Cerotoma trifurcata (Förster), in soybean, Glycine max (L.) Merrill, to climatic factors. The study was conducted at Iowa State University Johnson farm near Ames, Iowa for 10 consecutive years (1989 through 1998, inclusively). Bean leaf beetle adults were sampled twice weekly from emergence to mature stages of soybean. Linear regression showed a strong relationship between first- and second-generation adult densities during the growing season, whereas multiple regression analyses indicated a high correlation between second-generation adult densities and environmental factors, including temperature and precipitation. The analyses demonstrated that field history of beetle density is important for pest management. The major factors that affected the population dynamics of bean leaf beetle and regression models for the beetle density prediction are discussed.

The prevalence of host-seeking ticks along animal trails has been taken for granted. In 1996 and 1997, we evaluated the effects of active animal trails on the spatial distribution of Ixodes scapularis Say and Amblyomma americanum (L.) under field conditions by comparing numbers of all postembryonic stages of both species collected along the center of and adjacent to known white-tailed deer, Odocoileus virginianus (Zimmermann), trails with numbers collected along randomly placed transects. Because of the difficulty in quantifying animal activity and replicating a consistent clustering response along deer trails, animal activity was artificially increased by establishing and maintaining ‘4-poster’ bait stations with corresponding control plots during 1998–2000. Sampling was performed three times during the peak activity period of each active stage of both species in forested habitats of central New Jersey, USA. Tick distribution varied significantly among habitats, both between years and for each active stage. Sampling along deer trails and around 4-posters failed to demonstrate a consistent association between increased host activity and higher tick densities, suggesting that tick distribution patterns may be influenced by factors other than or in addition to host activity.

Aphelinus albipodus Hayat & Fatima, A. asychis Walker (Hymenoptera: Aphelinidae), Diaeretiella rapae (M’Intosh), Aphidius matricariae Haliday, Aphidius colemani (Viereck), Aphidius picipes (Nees), Aphidius rhopalosiphi DeStefani-Perez, Ephedrus plagiator (Ness), and Praon gallicum Stary (Hymenoptera: Braconidae) were released in southeastern Wyoming for biological control of Diuraphis noxia (Mordvilko), Russian wheat aphid (Homoptera: Aphididae). A total of 407,028 parasitoids in the form of mummified aphids was released from 1989 to 1996. Three species, A. albipodus, A. asychis, and D. rapae, were first detected in winter wheat fields 3 yr after first release and spread throughout the wheat production region within 5 yr of release. Other primary aphid parasitoids were recovered sporadically and in very small quantities, and hyperparasitoids consisted of up to 20% of the specimens recovered. There were significant differences in abundance of A. albipodus, A. asychis, and D. rapae. In 1992, D. rapae was more abundant than the two aphelinids. By 1995, A. albipodus was becoming more prevalent than D. rapae, and A. albipodus was the most abundant species in 1997 and 1998. During these 2 yr, A. albipodus and D. rapae were detected in small grain fields and adjacent grasslands in similar abundance in both habitats. Of the parasitoids released in the D. noxia biological control program, A. albipodus and D. rapae commonly occurred in wheat and barley of southeastern Wyoming, with occurrence of the exotic A. albipodus directly attributable to the release effort. A. albipodus is likely becoming the predominant species in small grain production in the region. And A. albipodus and D. rapae range expansion and occurrence in grassland sites adjacent to wheat and barley may aid in their ability to control D. noxia.

In biological control projects, establishment of released natural enemies is a key step and must be efficiently detected. We studied the relative efficacy of larval versus adult sampling to detect establishment on spotted knapweed, Centaurea maculosa Lamarck, of the two root feeding insects Agapeta zoegana L. and Cyphocleonus achates (Fahraeus). Larval sampling was based on excavation and dissection of plant roots. Adult sampling consisted of either sighting adults along transects at release sites or collection of adults by sweep netting. Recovery rates for A. zoegana were higher through adult visual sampling (54.8%) than through larval sampling via root dissection (43.0%). Adult visual sampling required less time (30 min/site) than did root dissection (130 min/site). Sweep net sampling, although having the lowest detection rate (38.1%), required even less time (10 min/site) and was the most effective method per unit time. In contrast, for C. achates, larval sampling was the most effective method, with a recovery rate of 35.6%, compared with 8.9% for adult visual sampling. Sweep netting was more effective than visual sampling, with a detection rate of 18.1%. Adult visual sampling required less time (44 min/site) than did root dissection (130 min/site). Sweep net sampling, although having the lowest detection rate (18.1%), required even less time (10 min/site) and was the most effective method per unit time. However, other factors such as weather, travel time, and training levels needed for sampling make root sampling a more effective method, in a larger sense, for both of these insects.

We examined the role of extrafloral nectar in the ecology of a larval common green lacewing, Chrysoperla plorabunda (Fitch). Larval lacewings were observed foraging freely in cotton fields and almond orchards to quantify their consumption of extrafloral nectar. Extrafloral nectar was a major component of the diet of neonate lacewing larvae foraging on cotton. Extrafloral nectar consumption increased strongly as the local availability of aphid prey declined. Lacewing larvae also fed frequently on extrafloral nectar when foraging in almond orchards. A manipulative diet experiment in the field demonstrated that in the absence of arthropod prey, extrafloral nectar contributed only slightly to neonate lacewing growth and did not support lacewing development. Nevertheless, extrafloral nectar did promote substantial longevity of first-instar lacewing larvae, which were able to maintain a high level of searching activity. Both the field experiment and a laboratory experiment showed that extrafloral nectar provides nutritional benefits that extend beyond those provided by a simple water source. Lacewing larvae are highly omnivorous: they feed on plant-based resources (extrafloral nectar), on herbivorous arthropod prey (e.g., aphids), and on other predatory or omnivorous arthropods.

Aphantorhaphopsis samarensis (Villeneuve), a European tachinid, has been released in North America for classical biological control of the gypsy moth, Lymantria dispar (L.). This study examined the host range of A. samarensis. We used three approaches: (1) field collection and rearing of potential alternate or alternative hosts at European sites where A. samarensis was known to occur, (2) choice tests offering females of A. samarensis both gypsy moth and native North American species of Lepidoptera, and (3) host suitability tests in which we artificially inoculated European nontarget species with mature eggs of A. samarensis dissected from gravid females. In the field studies, we collected a total of 851 caterpillars, belonging to at least 54 species other than gypsy moth in 11 families, over several years, but none yielded A. samarensis, with the possible exception of a single larva of Lymantria monacha (L.) and the rusty tussock moth, Orgyia antiqua (L.), which yielded puparia resembling those of A. samarensis. In laboratory tests, we offered females of A. samarensis 11 native species of North American Lepidoptera in five families, but only the lymantriid Orgyia leucostigma (J. E. Smith), was successfully parasitized. In host suitability studies, we inoculated 10 species of Lepidoptera in eight families with mature eggs of A. samarensis, but parasitism was successful only in L. dispar. We conclude that A. samarensis has a high degree of host specificity.

The effect of the red imported fire ant, Solenopsis invicta Buren, on Rhinocyllus conicus Froelich in a musk thistle, Carduus nutans L., biological control program was evaluated in laboratory and field trials in pastures in middle Georgia in 1999 and 2000. In the laboratory, 30 thistle heads containing eggs and larvae were kept as controls and 30 heads were exposed to fire ant colonies. Foraging by fire ants for 72 h did not reduce the number of R. conicus eggs or larvae on musk thistle heads. Foraging by fire ant workers on musk thistle in pasture plots was nearly eliminated following treatment with Amdro bait (hydramethylnon). However, there were no noticeable differences in R. conicus egg, larva, or adult counts for thistle heads in treated and untreated plots. Results suggest R. conicus is largely unaffected by red imported fire ant activity on musk thistle.

Xylocoris flavipes (Reuter), the warehouse pirate bug, is a predator of many stored-products pests. This study compared the functional response of X. flavipes with different densities of the prey species Tribolium castaneum (Herbst), Oryzaephilus surinamensis (L.), Plodia interpunctella (Hübner), and Rhyzopertha dominica (F.) in two different habitats: empty glass jars and glass jars filled with wheat kernels that were designed to simulate more natural conditions in stored grain. Differences in the functional response of X. flavipes to all combinations of prey densities and grain conditions were compared with the predicted functional response curves from Holling’s type I and type II models, and to Hassell’s type III model. The functional response of X. flavipes was best described by Holling’s type II model, but a type III response occurred with prey that were more difficult to subdue, such as T. castaneum larvae. Numbers of prey attacked by females were greater than those attacked by males (P < 0.05) in both habitats for some of the prey life stages and species. The maximum attack rates for the different prey species in empty glass jars over 24 h were as follows: T. castaneum, 27.3 small larvae, 1.6 large larvae; O. surinamensis, 24.3 small larvae, 17.4 large larvae; P. interpunctella, 27.2 eggs, 23.7 small larvae; R. dominica, 26.4 eggs and 16.6 internally feeding larvae. The maximum number killed for the different prey species in glass jars containing wheat over 48 h were as follows: O. surinamensis 13.7 small larvae, 12.8 large larvae; P. interpunctella 41.4 eggs, 14.7 small larvae; R. dominica 22.0 eggs and 12.1 internally feeding larvae. Experiments with wheat-filled jars showed that single X. flavipes could locate and kill 27.1 out of 50 P. interpunctella eggs and 8.1 out of 10 R. dominica larvae inside kernels mixed into ≈18,000 kernels of wheat in 48 h.

Laboratory feeding studies were conducted to determine the effects on Orius insidiosus nymphs of feeding on 1-d-old European corn borer, Ostrina nubilalis (Hübner), larvae that had ingested a diet containing Bt toxins. A commercial formulation of Bacillus thuringiensis subsp kurstaki (Dipel ES) was incorporated into a meridic diet used to feed European corn borer larvae; they then were offered as food to O. insidiosus nymphs. Immediately after adult eclosion, O. insidiosus sex was determined, body weight and length were measured, and developmental time was calculated. Another feeding study was conducted to determine the effect of Bt corn silk on mortality of immature O. insidiosus. Fresh silks of Bt and non-Bt corn plants were offered to O. insidiosus nymphs until they reached adulthood. Mortality counts were made daily. Finally, visual counts of O. insidiosus were made on Bt and non-Bt corn in fields at three locations in Kansas. The numbers of O. insidiosus nymphs and adults were recorded on 40 plants per location on two sampling dates. No significant differences occurred in developmental time, body weight, or body length of mature O. insidiosus or mortality of immature O. insidiosus when reared on European corn borer larvae that had fed on a diet containing Dipel ES. The nymphs feeding only on Bt or non-Bt corn silk suffered 100% mortality. No significant difference occurred in mortality of immature O. insidiosus when they were fed on Bt or non-Bt silk one day and on corn earworm eggs the next day. Numbers of O. insidiosus adults and nymphs in fields of Bt corn and non-Bt corn did not differ significantly in most cases. Our results suggest that Bt corn does not have a significant effect on the predator O. insidiosus.