The seasonal abundance and temporal pattern of Frankliniella fusca Hinds dispersal were monitored from 1996 to 2000 at 12 locations in central and eastern North Carolina. The predominant vector species of tomato spotted wilt virus (TSWV) captured across all locations was F. fusca (98%). The temporal patterns of F. fusca dispersal observed during spring seasons varied among locations in all years except 2000. Regression analysis estimated that times of first flight in the spring seasons varied among locations, whereas flight duration intervals were similar. Temporal patterns of F. fusca captured varied significantly between aerial traps placed 0.1 and 1.0 m above the soil surface. Fewer total thrips were captured at 0.1 m, although thrips dispersal occurred earlier and over a greater time interval compared with 1.0-m traps. Temporal patterns of TSWV occurrence differed among locations in the spring seasons of 1999 and 2000, whereas patterns of virus occurrence were similar during the fall seasons. Patterns of F. fusca dispersal and subsequent TSWV occurrence were synchronous at locations in 1999 and 2000 where the greatest number of TSWV lesions was recorded. Knowledge of the temporal patterns of F. fusca dispersal and TSWV occurrence may be a useful indicator for describing the time when susceptible crops are at highest risk of TSWV infection.

A study was undertaken to elucidate the impact of an undescribed Nosema sp. on the southwestern corn borer (SWCB; Diatraea grandiosella Dyar). The Nosema sp. (isolate 506) included in the study was isolated from an overwintering SWCB larva in Mississippi. It was highly infectious per os, with a median infective dose of 2.0 × 10³ spores per larva. Even at the highest dosage tested (10⁷ spores per larva), minimal mortality (≤3%) was observed in infected larvae, pupae, and adults reared in the laboratory on an artificial diet. However, infected pupae (0- and 7-d-old) were smaller, and the time to adult eclosion from pupation was slightly increased. Furthermore, the number of eggs produced by infected SWCB female moths substantially decreased (32%), and this effect was most pronounced on day 2, when the greatest number of eggs were oviposited by infected and noninfected moths. For eggs produced by infected females mated with infected males, hatch was slightly decreased by 16 and 15% for eggs laid on days 2 and 3, respectively. In addition, egg hatch was reduced in eggs oviposited by noninfected females mated with infected males on day 3. A low prevalence of infection (<6%) was observed in the F₁ generation originating from infected females mating with noninfected males, from noninfected females mating with infected males, and from infected females mating with infected males. Nosema 506 spores were observed in the proximity of reproductive tissues of infected female and male moths. Spores also were detected on the chorion surface and within eggs laid by infected females. Furthermore, 1–11% of larvae hatching from surface-sterilized eggs were infected by Nosema 506 indicating a transovarial mechanism of transmission.

A field population of Scymnus louisianae Chapin (Coccinellidae) was found attacking soybean aphids, Aphis glycines Matsumura (Aphidae), a pest recently introduced into Kentucky. This coccinellid had not previously been found in Kentucky. A greenhouse population of S. louisianae was established and its predation on A. glycines studied under laboratory conditions. Total time to develop from egg to adult was about 20 d. About 70% of immatures survived to adulthood and they consumed ≈100 aphid nymphs per beetle larva during the beetle’s four larval instars. Adults lived for an average of 47 d (mated males) and 63 d (mated females) and, during their total adult lifetime, mated males consumed an average of 665 nymphs and mated females consumed 1261 nymphs. All developmental times and predation rates were comparable to those reported for other aphidophagous Scymnus spp. which, in conjunction with reports that Scymnus spp. are effective predators of cotton aphids, Aphis gossypii Glover, suggests that S. louisianae is a potentially important predator of A. glycines in the southern United States.

Both azadirachtin and Paecilomyces fumosoroseus (Wize) Brown & Smith have been used to control the whitefly Bemisia argentifolii Bellows & Perring, but with only moderate effectiveness. Azadirachtin is a botanical insecticide derived from the neem tree, and P. fumosoroseus is an entomopathogenic fungus. To test whether these two agents might be more effective for whitefly control if used together, different rates of each were combined in laboratory bioassays in factorial treatment. Both tank mixes and separate sprays were tested. Up to 90% nymphal mortality was obtained when both the fungus and azadirachtin were combined, a significant increase over the 70%, or less, mortality obtained when only one agent was used; however, the combined effects were less than additive. Azadirachtin had moderately inhibitory effects on growth and germination of P. fumosoroseus, which may explain this antagonism.

Field tests of 3-methyl-2-cyclohexen-1-one (MCH), the antiaggregation pheromone of the spruce beetle, Dendroctonus rufipennis Kirby, were conducted in south-central Alaska in stands of Lutz spruce, Picea x lutzii Little, and Sitka spruce, P. sitchensis (Bong.) Carr. The deployment of MCH in a novel releaser significantly reduced trap catches and spruce beetle attacks on standing live spruce by 96 and 87%, respectively. The results of this study demonstrate the first successful field test of MCH in Alaska for the prevention of spruce beetle attacks on standing, live spruce.

Lethal and sublethal effects of Neemix 4.5 EC, a commercial neem preparation, on balsam fir sawfly, Neodiprion abietis (Harris), were determined in the laboratory. Larval mortality of N. abietis increased in a concentration-dependent manner, and lethal time decreased with increasing Neemix 4.5 EC concentration. Fifty percent of the larvae died after 4.6 d at a concentration of 90 ppm azadirachtin (AZA) and 12.3 d at a concentration of 0.08 ppm. Neemix 4.5 EC showed some deterrent effects to feeding site selection on N. abietis larvae at high concentrations, but not at low concentrations. Strong reduction of food intake by N. abietis larvae after exposure to Neemix 4.5 EC was demonstrated by significant reduction of frass production. Larvae fed on Neemix 4.5 EC-treated foliage at 90 ppm AZA produced only 16% as much frass as that produced by larvae fed on control foliage (0 ppm). Neemix 4.5 EC at a concentration of 0.08 ppm AZA retarded larval and pupal development. Sublethal doses significantly reduced pupal weight and adult emergence, although the sex ratio of N. abietis adults was not affected. Results indicate that sublethal effects of Neemix 4.5 EC on N. abietis may contribute greatly to the overall field efficacy.

Lymantria monacha (L.) (Lepidoptera: Lymantriidae), the nun moth, is a Eurasian pest of conifers that has potential for accidental introduction into North America. To project the potential host range of this insect if introduced into North America, survival and development of L. monacha on 26 North American and eight introduced Eurasian tree species were examined. Seven conifer species (Abies concolor, Picea abies, P. glauca, P. pungens, Pinus sylvestris with male cones, P. menziesii variety glauca, and Tsuga canadensis) and six broadleaf species (Betula populifolia, Malus x domestica, Prunus serotina, Quercus lobata, Q. rubra, and Q. velutina) were suitable for L. monacha survival and development. Eleven of the host species tested were rated as intermediate in suitability, four conifer species (Larix occidentalis, P. nigra, P. ponderosa, P. strobus, and Pseudotsuga menziesii variety menziesii) and six broadleaf species (Carpinus caroliniana, Carya ovata, Fagus grandifolia, Populus grandidentata, Q. alba, and Tilia cordata) and the remaining 10 species tested were rated as poor (Acer rubrum, A. platanoidies, A. saccharum, F. americana, Juniperus virginiana, Larix kaempferi, Liriodendron tulipfera, Morus alba, P. taeda, and P. deltoides). The phenological state of the trees had a major impact on establishment, survival, and development of L. monacha on many of the tree species tested. Several of the deciduous tree species that are suitable for L. monacha also are suitable for L. dispar (L.) and L. mathura Moore. Establishment of L. monacha in North America would be catastrophic because of the large number of economically important tree species on which it can survive and develop, and the ability of mated females to fly and colonize new areas.

Locust leafminer, Odontota dorsalis (Thunberg), activity was observed for 2 yr on 70 black locust, Robinia pseudoacacia L., trees grown from seed collected from its native range. Four black locust seedlings from Tennessee had low numbers of eggs, larvae, pupae, and mines, and were selected for clonal propagation. These clonal propagules were resistant to locust leafminers collected from three different counties in Maryland. This resistance was also observed in controlled choice and no-choice tests in outdoor screen houses. Adults showed different ovipositional preferences for black locust trees from different seed sources, which were reflected in lower numbers of larvae, pupae, and mines in resistant clones. It was concluded that antixenosis and antibiosis were involved in the mechanisms of resistance to the locust leafminer in black locust.

The density of microcapsules was compared on ‘Golden Delicious’ mature and immature foliage, fruit, and 1-yr-old limbs after dip treatments with Phase III oriental fruit moth, Grapholita molesta (Busck), microencapsulated pheromone. Microcapsules were counted with a dissecting microscope at 50× magnification after apple tissues were treated with a two-step dye staining process to increase the visibility of the microcapsules. The number of Phase III microcapsules on 1-yr limbs treated with a field concentration was two- to threefold greater than the number of microcapsules on similarly treated fruit or foliage. Phase I, III, and V OFM MEC and Checkmate OFM-F formulations of microencapsulated pheromone also were compared to determine their abundance on mature apple foliage. The Phase V OFM MEC formulation had the highest density of microcapsules when mature foliage was treated at the field rate. The Phase I treatment had the greatest difference between upper and lower leaf surfaces with 18-fold greater microcapsule density on the upper surface. On mature apple leaves treated with Phase III MEC, the number of microcapsules/cm² was two- to threefold greater on fields of view without the mid-vein than those that included the mid-vein. The cuticle structure and abundance of trichomes are two factors that may have contributed to differences in microcapsule density among plant tissue types, top and bottom leaf surfaces, and fields of view with and without the mid-vein.

Adult squash bugs, Anasa tristis (De Geer) (Heteroptera: Coreidae), were confined on watermelon plants at differing phenological stages and at densities of zero to four per plant in one trial and zero to 32 per plant in three additional trials. Squash bugs were allowed to feed on the plants until plants died or fruit matured. Plant foliage, roots, and fruit were harvested and weighed to determine effects on growth and productivity. Growth and fruit production was regressed on number of squash bugs and results indicated that an increasing density of squash bugs feeding on vining and flowering stage plants resulted in significant reductions in plant growth and fruit yield. When plants were infested at the fruit set stage of growth, there was either less effect or no effect on plant growth and fruit production. Plant mortality increased as the density of squash bugs increased regardless of the stage of growth when plants were infested with squash bugs.

Sweet corn, Zea mays L., is attacked by a variety of insect pests that can cause severe losses to the producer. Current control practices are largely limited to the application of broad-spectrum insecticides that can have a substantial and deleterious impact on the natural enemy complex. Predators have been shown to provide partial control of sweet corn pests when not killed by broad-spectrum insecticides. New products that specifically target the pest species, while being relatively benign to other insects, could provide more integrated control. In field trials we found that transgenic Bt sweet corn, and the foliar insecticides indoxacarb and spinosad are all less toxic to the most abundant predators in sweet corn (Coleomegilla maculata [DeGeer], Harmonia axyridis [Pallas], and Orius insidiosus [Say]) than the pyrethroid lambda cyhalothrin. Indoxacarb, however, was moderately toxic to coccinellids and spinosad and indoxacarb were somewhat toxic to O. insidiosus nymphs at field rates. Bt sweet corn and spinosad were able to provide control of the lepidopteran pests better than or equal to lambda cyhalothrin. The choice of insecticide material made a significant impact on survival of the pests and predators, while the frequency of application mainly affected the pests and the rate applied had little effect on either pests or predators. These results demonstrate that some of the new products available in sweet corn allow a truly integrated biological and chemical pest control program in sweet corn, making future advances in conservation, augmentation and classical biological control more feasible.

Effectiveness of companion planting, and use of nonhost masking odors were evaluated under field conditions for protecting roses against the Japanese beetle, Popillia japonica Newman. Three reputedly effective companion species, rue (Ruta graveolens L.), zonal geranium (Pelargonium × hortorum Bailey), and garlic chives (Allium scheonparum L.) were interplanted with roses in replicated garden plots. Numbers of beetles on these roses were compared with rose-only control plots on 6 d during beetle flight. The masking odor hypothesis was tested by hanging mesh bags of aromatic herbs or other sources of reputedly repellent nonhost volatiles around potted roses in the field. Treatments included crushed red pepper (Capsicum frutescens L.), fennel seeds (Foeniculm vulgare Miller), crushed spearmint (Mentha picata L.), cedar shavings (Juniperus sp.), osage orange fruits (Maclura pomifera (Raif) Schneid.), and fleshy gingko seeds (Gingko biloba L.). No treatment significantly reduced numbers of beetles relative to the controls. Interplanting with geraniums significantly increased numbers of Japanese beetles on roses. Similarly, roses surrounded by sachets with fennel seeds, cedar shavings, crushed red pepper, or osage orange fruits had significantly more beetles than the control plants on two or more sample dates. Our results suggest that the use of companion or reputedly repellent plants or plant odors probably will be ineffective for protecting roses or other highly-susceptible ornamentals from P. japonica. Use of such tactics in an effort to discourage other garden pests might even increase Japanese beetle damage in those plantings.

Tunnel formation by Coptotermes formosanus and Reticulitermes flavipes was studied in a two-dimensional foraging arena with a moisture gradient. Moisture did not appear to affect tunneling when termite first emerged from the central release chamber. But as termites of both species moved further away from the chamber and into a moisture gradient, they tunneled significantly (P < 0.05) more in sand with a higher moisture content than in sand with a lower moisture content. Over the 10 d test period, both termite species tunneled more in sand with a higher moisture content. Fractal analysis indicated that regardless of the sand moisture content, termite tunnel geometry had a fractal dimension and termites generally tunneled more in higher moisture sand.

Three commonly used fire ant baits, Amdro (0.73% hydramethylnon [AI]), Ascend (0.011% abamectins [AI]), and Maxforce (1.0% hydramethylnon [AI]), were exposed to potential, volatile contaminants. The contaminants included the insecticides Orthene Fire Ant Killer (75.0% acephate [AI]), Cyren (44.6% chlorpyrifos [AI]), and Tempo 2 (24.3% cyfluthrin [AI]); cigarette smoke; gasoline (unleaded, 89 octane); and fertilizer (10-10-10). Fire ant baits previously exposed for 48 h to these contaminants were analyzed using gas chromatography analysis. Orthene Fire Ant Killer, Cyren, Tempo 2, cigarette smoke, and gasoline had volatile components transferred to the baits. Baits exposed to these products were used in a field evaluation of bait acceptance by Solenopsis invicta Buren, the red imported fire ant. Uncontaminated Amdro was significantly preferred by S. invicta over Amdro contaminated by smoke, Cyren, Tempo 2, and gasoline. Uncontaminated Maxforce was significantly preferred over Maxforce contaminated by Tempo 2, Cyren, and gasoline, and uncontaminated Ascend was preferred over Tempo 2- and Cyren-contaminated Ascend. Orthene-exposed Amdro, Maxforce, and Ascend baits, and smoke-exposed Maxforce and Ascend baits were not significantly different from the control. These results indicate that volatile insecticides and products can contaminate fire ant baits. Some insecticides and products, such as gasoline, can significantly affect bait palatability and may adversely impact control.

Exclusion of ants, particularly red imported fire ant, Solenopsis invicta (Buren), from homes, nursing facilities, hospitals, and electrical housings is an important strategy in urban and rural pest control. We conducted a laboratory bioassay to determine the repellency of granular bifenthrin (Talstar: rate 2.087 kg of formulated product/92.88 m² or 4.6 lb formulated product/1000 feet² or 4.2 g active ingredient/92.88 m²) to S. invicta foragers. In the field, we compared the efficacy of three widths (0.3, 2.0, and 3.0 m) of granular bifenthrin-treated zones at the rate 2.087 kg of formulated product/92.88 m² and investigated the survival of individual ants successfully crossing the respective zones. Granular bifenthrin was nonrepellent to fire ant foragers in the laboratory. The 2.0- and 3.0-m treatment zones provided 100% protection for 7 wk after treatment and provided a reduction in the number of ants breaching the treated zone compared with the control for the remaining 9 wk of the study. This level of control may be tolerable for homeowners and is, therefore, considered an effective treatment for 15 wk after treatment. Hospitals, nursing homes, and electrical boxes would have to be treated on a monthly or bimonthly to remain ant free.

The wood of 11 plant species was evaluated as a food source significantly impacting the growth and survival of incipient colonies of the Formosan subterranean termite, Coptotermes formosanus Shiraki (Isoptera: Rhinotermitidae). Colonies of C. formosanus feeding on pecan, Carya illinoensis (Wangenh.), and red gum, Liquidambar styraciflua L., produced significantly more progeny than colonies feeding on other wood species tested. Progeny of colonies feeding on pecan and American ash, Fraxinus americana L., had significantly greater survival than progeny of colonies feeding on other wood species. Colonies feeding on a nutritionally supplemented cellulose based matrix showed similar fitness characteristics as colonies feeding on the best wood treatments. These results indicate that differences observed in colony fitness can be partially explained by nutritional value of the food treatment, raising the possibility that wood from different tree species have different nutritional values to the Formosan subterranean termites. Colonies feeding on loblolly pine, Pinus taeda L., and ponderosa pine, Pinus ponderosa Laws., had significantly lower survival and produced significantly fewer workers and soldiers than colonies feeding on other wood species. Colony survival from 90 to 180 d of age and from 90 to 360 d of age was significantly correlated with the number of workers present at 90 d of colony age, indicating that colony survival depends on the presence of workers. Wood consumption in a multiple-choice study was significantly correlated with colony fitness value. This suggests that feeding preference of C. formosanus is at least partially influenced by the nutritional value of the food source.

Periodic sampling of 87 independent monitors, initially active with the Formosan subterranean termite, Coptotermes formosanus Shiraki, was conducted. Monitors, located in eight sectors adjacent to seven buildings, were various distances (1–46 m) from 57 trees treated with 0.1% imidacloprid foam. Termites collected from six of the eight sectors showed latent mortality attributed to imidacloprid intoxication at all monitor-tree distances. Approximately 6 mo after treatment, termite populations had recovered in these sectors. Another sector showed termite population suppression for ≈15 mo, followed by recovery. Imidacloprid tree treatments did not control C. formosanus populations in independent monitors adjacent to the treatments.

Trials were conducted during one year under field conditions to control the lesser mealworm, Alphitobius diaperinus (Panzer), in broiler and turkey houses. The tested combined treatment included an adulticidal compound (pyrethroid: cyfluthrin) and a larvicidal compound (insect growth regulator [IGR]: triflumuron). The combined insecticide treatment greatly reduced the adult and larval stocks throughout the different broiler growing periods, and control of A. diaperinus populations was achieved by the end of the second treatment. Control of the insect population in a turkey house was not similar. A reestablishment of the insect population was observed during the second turkey growing period in summer. Building characteristics and management practices of the breeding system (duration of the breeding period, management of the litter) interact with the the combined insecticide treatment and lead to a different efficiency.

Field populations of western corn rootworm, Diabrotica virgifera virgifera LeConte, were collected from three different sites (York Co., Phelps Co., and Saunders Co.) in Nebraska during 1996. Adult bioassays of these three populations were conducted with different concentrations of methyl-parathion and at a diagnostic concentration (1.0 μg/ml) to determine resistance levels among these populations. Self and reciprocal crosses were made between the two resistant and one susceptible laboratory-reared populations. Dose-responses and dominance ratios calculated for the four reciprocal crosses indicated that resistance was incompletely dominant in both strains, although in one of the strains there was an indication of sex linkage. However, evaluation of native polyacrylamide gels stained for nonspecific esterases and nonspecific esterase activity of parents and F₁ progeny of the crosses suggested that esterase inheritance was completely dominant and autosomal. The results of this study were inconclusive with regard to the precise nature of inheritance, because the bioassays and esterase assays could not discriminate between heterozygotes and homozygotes. However, they do provide insight into the potential for developing simple diagnostic assays to assess resistance frequencies. Based on the inheritance studies described in this investigation, we can begin to generate information on specific genetic factors that dictate the evolutionary divergence of discrete resistant populations and facilitate modeling efforts designed to approximate the movement of genes for resistance among populations.

In summer 2000, adult female bollworm moths, Helicoverpa zea (Boddie), were collected from light-traps at four locations near the Tidewater Research Station, Plymouth, NC. Female moths were allowed to lay eggs, and at hatch, 72 larvae from each female were screened for growth rate on normal artificial diet and on diets containing 5.0 μg of either Cry1Ac or Cry2Aa Bt toxin per milliliter of diet. The growth rate bioassays were performed to isolate nonrecessive Bt resistance genes present in field populations of bollworm. We found one individual out of 583 screened that appeared to carry a major gene for resistance to Cry1Ac. Assuming four alleles per individual, the gene frequency is 1/2332 or 0.00043. Other females appeared to have minor genes for Cry1Ac resistance or major genes with lower levels of dominance. We also found one individual out of 646 screened that appeared to carry a major gene for resistance to Cry2Aa. The gene frequency for Cry2Aa resistance was estimated at 1/2584 or 0.00039. Again, other females seemed to carry additional minor resistance genes. Along with other results that indicate partially dominant inheritance of Cry1Ac resistance in bollworm, these allele frequency estimates are important for determining the rate of resistance evolution in H. zea to specific Bt toxins.

Kale (Brassica oleracea L. acephala) is common in northwestern Spain where it is severely damaged by different insect pests. Damage could be reduced by using resistant varieties. The objectives of this work were to evaluate the resistance of kale populations to leaf damage by lepidopterous pests, to determine which traits are the best indicators of resistance, and finally to study the relationship between the glossy phenotype and resistance. Fifteen kale populations, sowed early and late, were evaluated at two locations in northwestern Spain. Significant differences among genotypes were found for all damage traits. Damage was not related to planting dates. Highest levels of damage were observed from July to November. Some populations with different performance under natural infestation in 1999 were again evaluated in 2000 under artificial infestation with Mamestra brassicae (L.) eggs. Two accessions, MBG-BRS0142 and MBG-BRS0170, showed resistance to attack by lepidopterous pests. Correlation coefficients among damage traits show that general appearance rating may be an useful indicator of resistance. Phenotype of kale with glossy leaves seems to be related to resistance although further research is needed.

Fiji disease (FD) of sugar cane caused by Fiji disease virus (FDV) is transmitted by the planthopper Perkinsiella saccharicida Kirkaldy (Hemiptera: Delphacidae). FD is effectively managed by using resistant cultivars, but whether the resistance is for the vector or for the virus is unknown. This knowledge would help develop a rapid and reliable glasshouse-based screening method for disease resistance. Sugar cane cultivars resistant, intermediate, and susceptible to FD were screened in a glasshouse, and the relationship between vector preferences and FD incidence was studied. Cultivar preference by nymphs increased with an increase in cultivar susceptibility to FD, but the relationship between adult preference and FD resistance was not significant. There was a positive correlation between the vector population and FD incidence, and the latent period for symptom expression declined with the increase in the vector populations. FD incidence in the glasshouse trial reflected the field-resistance status of sugar cane cultivars with known FD-resistance scores. The results suggest that resistance to FD in sugar cane is mediated by cultivar preference of the planthopper vector.

A simulation model is developed to examine the role of spatial processes in the evolution of resistance in Helicoverpa zea populations to Bt corn and Bt cotton. The model is developed from the stochastic spatially explicit Heliothis virescens model described by Peck et al. (1999), to accommodate a spatial mix of two host crops (corn and cotton), and to reflect the agronomic practices, as well as the spatial and temporal population dynamics of H. zea, in eastern North Carolina. The model suggests that selection for resistance is more intense in Bt cotton fields than in Bt corn fields. It further suggests that local gene frequencies are highly dependent on local deployment levels of Bt crops despite the high mobility of the adult insects. Region-wide average gene frequencies depend on the region-wide level of Bt deployment, so incomplete technology adoption slows the rate of resistance evolution. However, on a local scale, H. zea populations in clusters of fields in which Bt use is high undergo far more rapid evolution than populations in neighboring clusters of fields in which Bt use is low. The model suggests that farm-level refuge requirements are important for managing the risk of resistance. The model can be used as an aid in designing plans for monitoring for resistance by suggesting the appropriate distribution of monitoring locations, which should focus on areas of highest Bt crop deployment. The findings need to be placed in the context of the input parameters, many of which are uncertain or highly variable in nature, and therefore, a thorough sensitivity analysis is warranted.

The sensitivities of a model simulating the evolution of resistance in Helicoverpa zea to Bt toxins in transgenic crops were investigated by examining effects of each of the model parameters on the frequency of resistance alleles after 8 yr. The functional dominance of resistance alleles and the initial frequency of those alleles had a major impact on resistance evolution. The survival of susceptible insects on the transgenic crops and the population dynamics of the insect, driven by winter survival and reproductive rates, were also important. In addition, agricultural practices including the proportion of the acreage planted to corn, and the larval threshold for spraying cotton fields affected the R-allele frequency. Many of these important parameters are inherently variable or cannot be measured with accuracy, so model output cannot be interpreted as being a forecast. However, this analysis is useful in focusing empirical research on those aspects of the insects’ life system that have the largest effects on resistance development, and indicates ways in which to improve products and agricultural practices to increase the expected time to resistance. The model can thus be used as a scientific basis for devising a robust resistance management strategy for Bt crops.

The soybean aphid, Aphis glycines Matsumara, was discovered in the United States in the summer of 2000. Since that initial discovery, the aphid has spread across northern soybean production regions. In 2001, we examined the physiological responses of soybeans to low aphids densities (fewer than 50 aphids/leaf). In this study, we determined photosynthetic rates, leaf fluorescence responses, and photosynthetic responses to variable carbon dioxide and light levels. In addition, analyses for chlorophyll content and stable carbon isotope ratios were used to differentiate potential differences in stomatal versus mesophyll limitations to photosynthesis. We observed rate reductions of up to 50% on infested leaflets, including lealets with no apparent symptoms of aphid injury (such as chlorosis). Differences in fluorescence data indicated that photoelectron transport was not impaired. These results indicate that substantial physiological impact on soybean is possible even at low aphid densities. Also, the conventional view of aphid injury acting through reductions in chlorophyll content and light-harvesting reactions of photosynthesis is not supported by our findings in this system.

The impact of light and its role in Russian wheat aphid, Diuraphis noxia (Mordvilko), damage symptom formation, and photosynthetic capacity in ‘Arapahoe’ wheat (Triticum aestivum L.) were examined. After 72 h under continuous dark or continuous light regimes, the number of aphids (nymphs), leaf rolling and chlorosis ratings, fresh leaf weight, and chlorophyll contents were recorded. Photosynthetic rates, chlorophyll a, kinetics and chlorophyll extractions also were determined. Aphid infestation caused significant reductions in plant height, fresh weight, gas exchange, and chlorophyll fluorescence only under continuous light. Under the 72 h continuous dark regime, aphid infestation did not cause either damage symptom formation or reduction in plant growth or metabolism (photosynthesis). Furthermore, significantly more D. noxia nymphs were produced under continuous light condition than continuous dark. Our results demonstrate that the development of D. noxia feeding damage symptoms (i.e., leaf rolling and chlorotic streaks) on susceptible wheat seedlings is a light-activated process, even though the elicitor of the plant damage symptoms is aphid feeding.

Fifty-eight synthetic hexaploid wheats, developed by crossing Triticum dicoccum Schrank. and Aegilops tauschii (Coss.) Schmal., were evaluated at the seedling stage, together with their parents, for resistance to greenbug (Schizaphis graminum Rondani) under greenhouse conditions. Seedlings of different synthetic hexaploids showed large phenotypic differences for resistance. All the T. dicoccum parents were susceptible, while high levels of resistance were observed in some of the Ae. tauschii parents. Of the synthetic hexaploids derived from resistant Ae. tauschii parents, a high proportion (76%) showed levels of resistance to the greenbug biotype used that were comparable to those of the resistant parent. While there were clear indications of the presence of suppressor genes for greenbug resistance in the A and/or B genomes of T. dicoccum in some synthetics, positive epistatic interaction was also found in synthetic hexaploids with higher levels of resistance than that of either parent. Resistance from different Ae. tauschii accessions was expressed differently when crossed with the same T. dicoccum, indicating diversity among the resistance genes present in the test synthetic hexaploid wheats. Based on resistance reactions, the genes conferring greenbug resistance in these synthetic hexaploids are probably different from resistance genes previously transferred to wheat from Ae. tauschii.

Resistance of wild and cultivated rice bean (Vigna umbellata [Thunberg] Ohwi and Ohashi) to three bruchid species, Callosobruchus chinensis L., Callosobruchus maculatus F., and Callosobruchus analis F., was evaluated. All but three accessions of cultivated, and all wild rice bean accessions tested, exhibited complete resistance to all three bruchid species. Rice bean seeds with seed coat removed also showed complete resistance to the three bruchid species. Results indicate that physical attributes and/or chemical(s) present in the seed coat of rice bean are not the main factors responsible for resistance. Feeding tests were performed by using artificial beans prepared with varying proportions of rice bean (resistant) and azuki bean (susceptible) flour. Number of bruchid adults that emerged decreased, and larval developmental period (days) was extended, when artificial beans with an increasing proportion of rice bean flour were used. These tests revealed that a chemical compound(s) contained in the cotyledon of rice bean has an inhibitory effect on the growth of these bruchid species. The results also indicate that the chemical(s) in rice bean cotyledon is most effective against C. maculatus.

This study was designed to categorize the resistance to the Russian wheat aphid, Diuraphis noxia (Mordvilko), resistant hard red winter wheat, Halt, as compared with susceptible wheat, TAM 107, at four different growth stages. Antixenosis was expressed in Halt at growth stage Zadoks 30. Antibiosis in Halt affected fecundity, number of aphids produced per reproductive day, maximum number of nymphs produced in one day, and intrinsic rate of increase. Fecundity was lower on Halt than TAM 107, and more nymphs were produced on both varieties at growth stage 20 than 10 and 40. Fewer nymphs were produced per reproductive day and on maximum production days by aphids reared on Halt than by those reared on TAM 107. The intrinsic rate of increase of Russian wheat aphids reared on Halt was lower than aphids reared on TAM 107. Differences in plant height and plant dry weight did not occur. Chlorosis ratings showed greater damage at the earlier stages in Halt and TAM 107 and significantly more damage in TAM 107 than Halt at growth stages 10, 20, and 30. Leaf rolling occurred on infested plants of TAM 107 at growth stages 10, 20, and 30, but not growth stage 40. Halt plants did not exhibit leaf rolling. The presence of a significant level of tolerance could make Halt compatible with other integrated pest management programs. However, care should be taken with cultivars containing evidence of antixenosis or antibiosis that could cause selective pressure on the Russian wheat aphid, potentially causing biotypes to be produced.

Wheat (Triticum aestivum L.) varietal resistance to the lesser grain borer, Rhyzopertha dominica (F), was evaluated in hard spring and winter wheat produced 1997, 1998 (Bozeman, Montana). We tested the hypothesis that six Montana-grown spring wheat varieties, ‘Ernest’, ‘Scholar’, ‘Hi-Line’, ‘McNeal’, ‘Newana’, and ‘Amidon’, were equally and strongly resistant to R. dominica at low moisture contents (9–10%). Mortality/Feeding damage occurred in all varieties. In most assays, Ernest had significantly greater feeding damage from R. dominica than other varieties, usually not significantly different from the susceptible control. Mean adult mortality was significantly greater in McNeal (93%) and Hi-Line (92%) than in Ernest (34%) and Montana-grown, soft white spring wheat (Penawawa), the susceptible control (36%). In 9 wk, twice as many adult progeny were produced on Ernest than on McNeal, Hi-Line, or Scholar. We also compared three Montana-grown winter wheat varieties for resistance to R. dominica attack at low moisture contents (9–10%). Significantly more mortality after 6 wk was associated with all winter wheat varieties than the susceptible control. In ‘Nuwest’, ‘Rocky’, and ‘Vanguard’, significantly fewer progeny were produced than in the susceptible control; these varieties appeared more resistant. ‘Tiber’ and ‘Neeley’, in contrast, appeared more susceptible than other winter wheat varieties evaluated. Susceptibility decreased significantly with a 1.2% decrease in moisture content. Percentage of total protein was positively correlated with percentage of sound kernels and negatively with total progeny (r² = −0.69). Kernel hardness was positively correlated with percentage of sound kernels, but negatively correlated with total progeny (r² = −0.87) and dry weight loss.

The relative attractiveness of six commercially available protein hydrolysates and the influence of their concentration were evaluated in field cages by a release-capture method of lab-reared melon fly adults, Bactrocera cucurbitae (Coquillett). Buminal, Corn Steepwater, Hym-Lure, Pinnacle, Nulure, and SolBait were tested for both sexes of the melon fly. The tested products exhibited clear differences in attractiveness. SolBait was the most effective protein hydrolysate. Pinnacle and Corn Steepwater also gave promising results. A general tendency for an increase in effectiveness with increasing concentration within the range 0.5 to 10% was shown. This study will allow pest control practitioners to choose more effective attractants for use in bait sprays to control the melon fly thus reducing the intensive use of insecticides currently practiced in Reunion island and enabling the development of Integrated pest management (IPM) methods for cucurbit crops.

A 2-yr study was conducted to investigate the potential of using yellow sticky traps to survey lady beetles in cotton and to quantify seasonal activity patterns. The performance of sticky traps was compared with that of a 2-cycle vacuum sampler. The most common lady beetle species captured by sticky traps and vacuum sampler in cotton were Hippodamia convergens Guerin-Meneville and Scymnus loewii Mulsant. Sticky traps captured significantly more of both species of lady beetles, had greater capture efficiency, and more effectively detected lady beetles compared with the vacuum sampler. These data indicate that the sticky trap can be a valuable tool in monitoring lady beetle populations in cotton. In the second part of this study, a year-round survey of lady beetle populations in the periphery of a cotton farm using sticky traps showed that lady beetles remained active throughout the year in the Texas Rolling Plains, but the activity was influenced by winter severity. Over a 2-yr period, H. convergens, S. loewii, Coccinella septempunctata (L.), and Olla v-nigrum (Mulsant) comprised 89.6, 8.2, 1.9, and 0.3% of the specimens, respectively. Sticky trap captures were affected by year, trap height, and cropping season. Traps placed at 0.75 m above ground captured significantly more (80%) lady beetles than traps placed at 1.50 m (20%) above ground; traps at 0.75 m above ground also detected the rarer species while the traps at 1.50 m above ground detected only the abundant species. Trap captures were higher during the noncotton season (November to April) compared with the cotton season (May to October). A significant positive correlation between cotton aphid abundance during the growing season and H. convergens abundance during the following noncotton season was also detected, indicating a significant movement of H. convergens from cotton to the periphery of the farm to seek refuge after cotton termination.

Silwet L-77, an organosilicone surfactant, was applied to several arthropod pests of California table grapes. Eggs of grape mealybug, Pseudococcus maritimus (Ehrhorn), and omnivorous leafroller, Platynota stultana Walsingham, were tolerant to 0.1, 0.25, and 0.5% treatment solutions; however, eggs of Pacific spider mite, Tetranychus pacificus McGregor, were highly susceptible with mortality >99.4% (0.1% Silwet L-77). Mortality of immature and adult stages of cotton aphid (Aphis gossypii Glover), Western flower thrips (Frankliniella occidentalis Pergande), and Pacific spider mite (Tetranychus pacificus McGregor) was ≥93.8, ≥98.5, and ≥99.4% for 0.1, 0.25, and 0.5% Silwet L-77, respectively. Grape mealybug crawlers had 100% mortality when treated with 0.5 and 1.0% Silwet L-77 solutions; however, mortality was only 6.7% when 0.1% Silwet L-77 was applied. ‘Thompson Seedless’ table grapes were not damaged when treated with up to 1% Silwet L-77; however, grapes treated with the 0.5 and 1.0% solutions appeared wet after removal from cold storage because of the effect of the surfactant spreading the water condensation. Grapes dried with the normal bloom on the berries when they reached room temperature.