Reintroductions of the boll weevil, Anthonomus grandis grandis Boheman, into areas of the United States where it has been eradicated or suppressed are very expensive to mitigate. There is concern that a cotton gin in an eradication zone may serve as a site of boll weevil reintroductions when processing cotton harvested in a neighboring infested zone. Similarly, there is a question whether weevil-free areas can safely import gin products, such as cottonseed and baled lint, from infested areas without risking an introduction. Many countries require fumigation of imported U.S. cotton bales to protect against boll weevil introductions, costing the U.S. cotton industry millions of dollars annually. In previously reported experiments, we quantified the potential for boll weevils to survive passage through precleaning machinery in the gin. In this study, we quantified survival potential of boll weevils passing through the gin stand and segregating into the cottonseed, mote, or lint fractions. We also examined boll weevil survival when passed with ginned lint through a lint cleaner. We present a flow chart of experimentally determined survival potentials of boll weevils passing through the various subprocesses of the gin, from which one can calculate the risk of a live boll weevil reaching any point in the process. Our data show that there is virtually no chance of a boll weevil being segregated alive into the cottonseed or of one surviving in the lint to approach the bale press. Therefore, quarantine or fumigation of cottonseed and cotton bales to guard against boll weevil introductions is unnecessary.

Food, water, and worker protection regulations have driven availability, and loss, of pesticides for use in pest management programs. In response, public-supported research and extension projects have targeted investigation and demonstration of reduced-risk integrated pest management (IPM) techniques. But these new techniques often result in higher financial burden to the grower, which is counter to the IPM principle that economic competitiveness is critical to have IPM adopted. As authorized by the 2002 Farm Bill and administered by the U.S. Department of Agriculture (USDA) Natural Resources Conservation Service (NRCS), conservation programs exist for delivering public-supported financial incentives to growers to increase environmental stewardship on lands in production. NRCS conservation programs are described, and the case for providing financial incentives to growers for implementing IPM is presented. We also explored the opportunity and challenge to use one key program, the Environmental Quality Incentives Program (EQIP), to aid grower adoption of IPM. The EQIP fund distribution to growers from 1997 to 2002 during the last Farm Bill cycle totaled ≈$ 1.05 billion with a portion of funds supporting an NRCS-designed pest management practice. The average percentage of allocation of EQIP funds to this pest management practice among states was 0.77 ± 0.009% (mean ± SD). Using Michigan as an example, vegetable and fruit grower recognition of the program’s use to implement IPM was modest (25% of growers surveyed), and their recognition of its use in aiding implementation of IPM was improved after educational efforts (74%). Proposals designed to enhance program usefulness in implementing IPM were delivered through the NRCS advisory process in Michigan. Modifications for using the NRCS pest management practice to address resource concerns were adopted, incentive rates for pest management were adjusted, and an expanded incentive structure for IPM technique adoption was tabled for future consideration. The case is strong for using public-supported financial incentives offered by the EQIP to aid grower adoption of IPM as a means to address resource concerns, but current use of the EQIP for this purpose is modest to meager. With appropriate program adjustments and increased grower awareness, USDA NRCS conservation programs, and the EQIP in particular, may provide an important opportunity for growers to increase their use of IPM as a resource conservation and farm management tool.

The effects of different acquisition access periods (AAPs) and inoculation access periods (IAPs) on the transmission efficiency of barley yellow dwarf luteovirus (BYDV) by Rhopalosiphum padi (L.) (Homoptera: Aphididae) after feeding on transgenic or nontransformed wheat, Triticum aestivum L., genotypes were studied. Three wheat genotypes were tested as virus sources: virus-susceptible ‘Lambert’ and ‘Lambert’-derived transgenic lines 103.1J and 126.02, which express the BYDV-PAV coat protein gene. Lower virus titers were measured in BYDV-infected transgenic plants compared with Lambert. No significant differences in transmission efficiency were detected for R. padi after varying IAPs, regardless of genotype. Transmission efficiency increased with an increase in AAP in all genotypes tested. However, AAPs ranging from 6 to 48 h on Lambert resulted in significantly greater transmission efficiency than similar periods on transgenic 103.1J. Maximum transmission efficiency (70%) was observed after a 48-h AAP on Lambert, whereas the same AAP on 103.1J and 126.02 resulted in a significantly lower transmission efficiency (57%). Contrasts were used to compare the rates of transmission and the theoretical maximum transmission percentage among the different wheat genotypes serving as virus sources. Both parameters were significantly different among genotypes, indicating that viral acquisition from each genotype resulted in a unique pattern of virus transmission by R. padi. The lowest rate of virus transmission after an AAP was observed on 103.1J compared with 126.02 or Lambert. This is likely associated with a lower virus titer in 103.1J. This is the first report of transgenic virus resistance in wheat affecting the transmission efficiency of a virus vector.

Several hundred strains of Bacillus thuringiensis (Bt), isolated in New Zealand from samples of soil and sheep fleece, were tested for toxicity to larvae of the blowfly Lucilia cuprina Wiedemann. Characterization of the Bt strains revealed that three of the more active strains produced Cry1Ba (an insecticidal protein present in Bt mother cell crystal inclusion) that was toxic to blowflies. These strains were evaluated for the ability to prevent experimentally induced fly strike in a bioassay by using first instars. Results with undiluted spore/crystal preparations were variable, but they generally prevented fly strike on sheep maintained on pasture for 3–6 wk. Spore viability was satisfactory throughout the trials and environmental factors (e.g., precipitation and UV radiation) seemed to have minimal effect on persistence. The loss of fly strike protection in these experiments correlated with the movement of spore/crystal toxicity away from the skin as a result of wool growth. Solubilized protein preparations were not as potent as spore/crystal preparations and fly strike protection lasted only from 1 to 3 wk. Vegetative forms of the Cry1Ba-producing strains of Bt did not establish on the fleece of sheep, did not produce significant sporulation, and no protection against fly strike was achieved. Escherichia coli expressing recombinant Cry1Ba protein was toxic to larvae in vitro but did not effectively protect sheep from fly strike because blowfly larvae were able to establish readily 8 d posttreatment. In a single field experiment involving 80 sheep per group, a spore/crystal preparation from a Bt strain expressing Cry1Ba provided less protection from naturally acquired fly strike than afforded by a commercially available dip.

Bacillus thuringiensis that produce Cry1Ba are toxic to Lucilia cuprina Wiedemann blow fly maggots in vivo, and when applied in quantity to sheep fleece, provide up to 6 wk protection against flystrike in the field. These strains also are toxic to Epiphyas postvittana (Walker) light brown apple moth caterpillars. B. thuringiensis expressing Cry1Db are toxic only to E. postvittana. When Cry1Ba and Cry1Db proteins are expressed within Escherichia coli, the recombinant bacteria have the same toxicity profile as the wild-type B. thuringiensis strain. In an effort to develop a Cry protein with improved blow fly toxicity, three different internal regions of Cry1Ba coding DNA, encoding all or part of domains I, II and III respectively were systematically exchanged with the corresponding region from a pool of other Cry protein coding DNAs. The chimeric products were then expressed in recombinant E. coli, and the resulting bacteria assayed for toxicity on L. cuprina and E. postvittana. Clones having insecticide bioactivity were characterized to identify the source of the replacement Cry domain. Despite successfully expressing a large number and variety of chimeric proteins within E. coli, many with measurable insecticidal activity, none of the chimeras had greater potency against L. cuprina than the wild-type Cry1Ba. Chimeric replacements involving domains I and II were rarely active, whereas a much higher proportion of domain III chimeras had some bioactivity. We conclude that shuffling of Cry coding regions through joining at the major conserved sequence motifs is an effective means for the production of a diverse number of chimeric Cry proteins but that such toxins with enhanced bioactive properties will be rare or nonexistent.

Maximizing the contribution of endemic natural enemies to integrated pest management (IPM) programs requires a detailed knowledge of their interactions with the target pest. This experimental field study evaluated the impact of the endemic natural enemy complex of Plutella xylostella (L.) (Lepidoptera: Yponomeutidae) on pest populations in commercial cabbage crops in southeastern Queensland, Australia. Management data were used to score pest management practices at experimental sites on independent Brassica farms practicing a range of pest management strategies, and mechanical methods of natural enemy exclusion were used to assess the impact of natural enemies on introduced cohorts of P. xylostella at each site. Natural enemy impact was greatest at sites adopting IPM and least at sites practicing conventional pest management strategies. At IPM sites, the contribution of natural enemies to P. xylostella mortality permitted the cultivation of marketable crops with no yield loss but with a substantial reduction in insecticide inputs. Three species of larval parasitoids (Diadegma semiclausum Hellén [Hymenoptera: Ichneumonidae], Apanteles ippeus Nixon [Hymenoptera: Braconidae], and Oomyzus sokolowskii Kurdjumov [Hymenoptera: Eulophidae]) and one species of pupal parasitoid Diadromus collaris Gravenhorst (Hymenoptera: Ichneumonidae) attacked immature P. xylostella. The most abundant groups of predatory arthropods caught in pitfall traps were Araneae (Lycosidae) > Coleoptera (Carabidae, Coccinelidae, Staphylinidae) > Neuroptera (Chrysopidae) > Formicidae, whereas on crop foliage Araneae (Clubionidae, Oxyopidae) > Coleoptera (Coccinelidae) > Neuroptera (Chrysopidae) were most common. The abundance and diversity of natural enemies was greatest at sites that adopted IPM, correlating greater P. xylostella mortality at these sites. The efficacy of the natural enemy complex to pest mortality under different pest management regimes and appropriate strategies to optimize this important natural resource are discussed.

These studies compared three genetically distinct mosquito densoviruses Aedes aegypti (AeDNV), Hemagogus equinus (HeDNV), and Aedes Peruvian (APeDNV) densoviruses in a laboratory investigation to begin to evaluate their potential as mosquito control agents. A real-time polymerase chain reaction (PCR) assay for quantification of viral genomes and a standardized mosquito infection protocol were developed. Mortality associated with exposure to AeDNV increased in a dose-dependent manner, with the maximum mortality of 75.1% occurring in those organisms exposed to the highest dose of virus. The majority of death occurred as larvae. Similar results were observed with AeDNV produced from ground larvae and AeDNV produced from cell culture. Exposure of mosquitoes to HeDNV and APeDNV resulted in lower mortality, with values peaking at 33.5% for HeDNV and 27.8% for APeDNV. AeDNV-exposed larvae develop at a slower rate than nonexposed and HeDNV- and APeDNV-exposed larvae. Decreased virulence does not reflect a decrease in virus replication. PCR analysis of infectivity rates and titers in adults revealed reproduction of all three viruses, with an average viral titer of ≈10 logs/mosquito after exposure to the highest dose of each virus. Accumulation of virus in the larval-rearing water was also observed with values approaching 10–11 logs/ml for each virus. These data indicate that there are dramatic differences in the pathogenicity among mosquito densoviruses.

We investigated the effects of Bacillus thuringiensis variety kurstaki × aizawai (Bt) on infestation levels of two lepidopteran insects as well as on seed quality in Norway spruce, Picea abies L. (Karst.) in central Sweden. Spruce flowers (female strobili) were sprayed with a 0.2% suspension (wt:wt) of the Bt preparation Turex 50 WP, 25,000 IU/mg in water. To expose even those lepidopteran larvae that feed exclusively embedded within the cone tissue, the Bt treatment was applied to open flowers, before they closed and developed into cones. The experimental design included three main factors: treatment (untreated control, water, or Bt), spruce genotype (three clones), and spraying time (spraying before, during, and after the phase of highest pollen receptivity). The Bt treatment reduced the proportion of cones infested by the cone worm Dioryctria abietella Den. et Schiff. (Lepidoptera: Pyralidae) from ≈30 to 15%. There was no statistically significant treatment effect on the infestation rate of Cydia strobilella (L.) (Lepidoptera: Tortricidae). The Bt variety kurstaki × aizawai treatment caused no reduction in seed quality as measured by seed weight or percentage of nonfilled seeds. There was no difference in number of seeds per cone between the Bt-treated and untreated control cones. There was a significant effect of genotype on insect infestation rates, as well as on number of seeds per cone and seed weight. Neither level of insect damage nor any seed quality parameters were affected by time of application of the treatments.

The pathogenicity of the entomopathogenic nematodes Heterorhabditis bacteriophora Poinar and Steinernema scarabaei Stock & Koppenhöfer against different developmental stages of the Japanese beetle, Popillia japonica Newman, and the oriental beetle, Anomala (=Exomala) orientalis Waterhouse, were studied under laboratory conditions. The efficacy of S. scarabaei did not differ between second and third instars in P. japonica or A. orientalis or between small (young) and large (older) third instars in A. orientalis. However, H. bacteriophora efficacy decreased from first over second to third instar and also from small third instars to large third instars in A. orientalis but did not differ significantly between P. japonica larval stages. Once A. orientalis third instars had purged their intestines in preparation for pupation, no significant mortality by S. scarabaei and H. bacteriophora was observed. In contrast, P. japonica susceptibility to both nematode species gradually decreased from stage to stage from actively feeding third instars to pupae. In two additional experiments, we found no difference in Steinernema glaseri (Steiner) susceptibility between second and third instars of A. orientalis but an increase in S. scarabaei susceptibility from the second to third instar of Asiatic garden beetle, Maladera castanea (Arrow). Our observations combined with those of previous studies with other nematode and white grub species show that nematode efficacy against white grub developmental stages varies with white grub and nematodes species, and no generalization can be made.

We needed a technique to compare the consumption of baits by individual Carribbean fruit fly, Anastrepha suspensa (Loew). By improving consumption and determining individual dose, we could lower pesticide concentration while retaining bait/pesticide efficacy and potentially reduce the environmental impact of fruit fly bait/pesticide eradication methods. We report here a precise dye-based technique for the quantification of consumption by individual adult A. suspensa fruit flies. Fluorescein, measured at 491 nm, and cresol red, measured at 573 nm, were efficiently extracted with 0.1 M NaOH and quantified with a spectrophotometer. The lower limit for this method with 0.1% dye concentration is 300 nl consumed by an individual fly. Dye movement to the hindgut and possible defecation occurred in ≈4 h; maximum ingestion occurred in ≈1 h. Maximum experimental time is limited to 4 h. Flies preferred feeding upside down compared with right side up when given a choice; consumption was equal when flies were given no choice of feeding position. Thus, maximum bait/pesticide efficacy might be achieved with an upside-down presentation. Regurgitation led to a 100% overestimation of actual consumption with the J-tube presentation of food. Our individual fly consumption technique will be useful in comparing consumption in phagostimulant studies, estimating dose in oral toxicity tests, differentiating behavioral and physiological resistance in toxicant studies, ultimately leading to improved bait/pesticide methods and reduced environmental impact of area wide fruit fly eradication programs. This technique could be applied to studies of tephritid consumption, to the consumption of other insects, and to regurgitation studies.

A process for removing or killing California red scale, Aonidiella aurantii (Maskell), from citrus fruit as a postharvest treatment was evaluated. The process subjects the fruit to vacuum, steam, and vacuum that physically removes red scale from the fruit and kills those scales that are not removed from the fruit. Different numbers of cycles and steam temperatures were compared for efficacy in removing scale from lemons or killing those that remained. Multiple (two to three) cycles removed up to 96% of first molt scales on the fruit, but they were much less effective in removing other stages, especially those that had advanced beyond the second instar. However, it was extremely effective in killing the scales remaining on the fruit. Although this process does not eliminate cosmetic damage caused by scale presence, it might be used in combination with high-pressure washers currently used in packing houses to allow importers and exporters to meet the most stringent quarantine requirements. Because of its killing power, this technique should be tried on other insects and commodities to see whether it can be substituted for certain uses of methyl bromide.

While developing radio frequency heat treatments for dried fruits and nuts, we used a heating block system developed by Washington State University to identify the most heat-tolerant life stage of red flour beetle, Tribolium castaneum (Herbst), and to determine its thermal death kinetics. Using a heating rate of 15°C/min to approximate the rapid heating of radio frequency treatments, the relative heat tolerance of red flour beetle stages was found to be older larvae > pupae and adults > eggs and younger larvae. Lethal exposure times for temperatures of 48, 50, and 52°C for the most heat-tolerant larval stage were estimated using a 0.5th order kinetic model. Exposures needed for 95% mortality at 48°C were too long to be practical (67 min), but increasing treatment temperatures to 50 and 52°C resulted in more useful exposure times of 8 and 1.3 min, respectively. Red flour beetle was more sensitive to changes in treatment temperature than previously studied moth species, resulting in red flour beetle being the most heat-tolerant species at 48°C, but navel orangeworm, Amyelois transitella (Walker), being most heat tolerant at 50 and 52°C. Consequently, efficacious treatments for navel orangeworm at 50–52°C also would control red flour beetle.

The northward migration of Helicoverpa armigera (Hübner) and other moths in early summer was observed with radar in 2001 and 2002 at Langfang, Hebei province, China. Migratory flights typically occurred at heights up to 1.2 km above ground level (AGL), and high density layer concentrations frequently formed at 200–300 m AGL. Adult moths of local populations took off at dusk and ceased flight ≈0.5 h before sunrise with area density peaking ≈35 min after dusk. A strong dumb-bell pattern of echoes on the plan position indicator screen, indicating collective orientation of the targets, was evident in 2001, when targets were typically moving toward the northeast and when layering was associated with a temperature inversion and maximum wind speed. By contrast, there was no notable dumb-bell pattern in 2002, when targets were moving toward the northwest. However, orientations calculated from target and wind velocities showed that downwind common orientation also was occurring in 2002 and that the direction varied with the wind direction. The probable sources of the H. armigera observed at Langfang were deduced to be Henan province in 2001 and Shandong province in 2002, and the destination regions were Liaoning and Inner Mongolia.

Glyptotendipes paripes Edwards midge larval growth, development, survival, emerging adult size, and food digestibility when provided with six species of algae as food were studied in the laboratory. For the study, eggs from G. paripes adults maintained in the laboratory were reared to the adult stage at 30°C for 60 d on pure culture of each algal species at densities of 0.4, 0.1, and 0.02 mg of algae (fresh weight) per milliliter, as a sole food source. All larvae reared on Microcystis sp., Botryoccocus braunii, and Scenedesmus quadricauda died before completing development. The only larvae to complete development to adult were those reared on 0.4 mg/ml Lyngbia cf. aeruginosa (44.0 d), Anabaena flos-aquae (29.7 d), and Chlorella keslerii (44.8 d). No significant differences in body size of the adults achieving complete development on the three algal species were found. Algal digestion, measured by comparing amounts of live and dead algal cells in remains of cultures used for feeding and in larval excrement, revealed that >95% of all L. cf. aeruginosa, A. flos-aquae, and Microcystis sp. cells were digested; for C. keslerii, 13% of cells were digested, whereas little or no digestion of B. braunii and S. quadricauda was observed. To evaluate the effects of algal species on larval growth, laboratory-reared (on artificial food) late third/early fourth instars of G. paripes were fed individual algal species, and 10 d later, body mass changes were recorded and compared with nonfed larvae. Body mass of larvae reared on L. cf. aeruginosa and A. flos-aquae significantly increased, whereas those provided Microcystis sp. and the nonfed larvae showed significant body mass reductions. Overall, B. braunii and S. quadricauda were not suitable as larval food, probably due to their low digestibility, and Microcystis sp. because of its toxicity. This study identifies some algae that do and others that do not support G. paripes larval growth. The information is useful in understanding the feeding habits of G. paripes larvae as some of these algae occur in the larval environments of this pestiferous midge.

We compared the field competitiveness of sterile codling moth, Cydia pomonella (L.), males mass-reared through diapause or standard production protocols and treated with either 150 or 250 Gy of gamma radiation. Evaluations were performed during spring and summer 2003 by using field release–recapture tests. Released males were recaptured using traps baited with synthetic pheromone or with virgin females. In addition, mating tables baited with virgin females were used in the summer to assess the mating competitiveness of the released moths. Field performance of released males was significantly improved by rearing through diapause and by lowering the dose of radiation used to treat the insects. These effects were observed during spring when evening temperatures were relatively cool and in summer when evening temperatures were high. These effects were observed regardless of the sampling method (i.e., capture in pheromone-baited traps, virgin female-baited traps, or in mating tables). There were significant interactions between larval rearing strategy and radiation dose with respect to day of recapture. The effect of rearing strategy on male performance was observed immediately after release, whereas the effect of dose of radiation was usually delayed by 2–3 d. In general, the best treatment for improving codling moth male field performance was a combination of rearing through diapause and using a low dose of radiation (150 Gy). The difference in performance when insects were treated with 150 or 250 Gy was greater when males had been reared using standard (nondiapause) rearing protocols, suggesting that diapause rearing may attenuate some of the negative effects of the higher doses of radiation.

The plum curculio, Conotrachelus nenuphar (Herbst), is a well known pest in apple and peach orchards, but it also is capable of having an economic impact in highbush blueberries. Host phenology and plum curculio oviposition patterns were determined on four highbush blueberry cultivars differing in fruit maturation period. Numbers of oviposition scars were higher on early- (‘Weymouth’) and mid-season (‘Duke’ and ‘Bluecrop’) blueberries than on late-season ‘Elliott’ in 2001, 2002, and 2003. In 2002, eggs were first present on the three earliest cultivars 21 d before those on ‘Elliott’, whereas eggs were found on ‘Elliott’ >40 d after the last sample with eggs for the other three cultivars. The pattern of host phenology and infestation levels suggested that plum curculio oviposition synchronizes well with the availability of suitable fruit for oviposition on early and mid-season cultivars compared with a late-season cultivar of highbush blueberries. The implications of a transition to use of reduced-risk insecticides are discussed in relation to plum curculio management.

The toxicity of two biorational insecticides, spinosad (Tracer) and methoxyfenozide (RH-2485), was tested against eggs, larvae, and pupae of the noctuid Spodoptera littoralis (Boisduval). In the first experiment, filter paper circles containing egg masses of two different age classes, young (<24 h old) and old (24–48 h old), were dipped in different concentrations of each insecticide diluted in either water or acetone. No ovicidal activity was recorded when insecticides were diluted in water. In contrast, when insecticides were diluted in acetone, both egg age classes generally showed a concentration-dependent response for both compounds. Mortality of larvae that hatched from both egg age classes was significantly increased, compared with control larvae, at all concentrations of both insecticides when diluted in water or acetone alike. The prevalence of mortality was similar with each insecticide. In the second experiment, third instars of S. littoralis were fed semisynthetic diet containing different concentrations of both insecticides. According to LC₅₀ values, no significant differences were observed between spinosad (2.11 mg [AI]/kg diet) and methoxyfenozide (3.98 mg [AI]/kg diet) after 48 h of treatment, based on the overlap of 95% CL. Toxic effects on the mortality of pupae, adult emergence, and the prevalence of deformed adults after topical application on young pupae also were examined. Only methoxyfenozide caused pupal mortality and deformed adults. Our results suggest that spinosad and methoxyfenozide are potentially potent compounds for control of S. littoralis.

Extracts of a perennial and poisonous weed, Stellera chamaejasme L. (Thymelaeaceae) were bioassayed to determine their acaricidal activities against Tetranychus viennensis Zacher (Acari: Tetranychidae) in the laboratory. Extracts had both contact and systemic toxicity to the mite. After liquid chromatography and thin layer chromatography, the extract was further concentrated, separated, and bioassayed. This study is the first to report the acaricidal property of S. chamaejasme and its potential as a botanical pest control agent.

The effect of Nilaparvata lugens (Stål) (Homoptera: Delphacidae), infestation on the content of zeatin ribosides (ZR) in rice plants was investigated with enzyme-linked immunosorbent assay. Hydroponics experiments were conducted on ‘Zhendao 2’ rice, in which plants were subjected to N. lugens infestation at three nonhopperburn-causing densities (15, 30, and 60 nymphs per hill) for 2, 4, 6, and 8 d and at one hopperburn-causing density (240 nymphs per hill) for 2, 4, and 6 d, respectively. When rice plants were infested at the nonhopperburn-causing densities, ZR content in leaves varied significantly with the infestation density. Compared with the control plants, ZR content in rice leaves decreased significantly after infestation by 60 nymphs per hill for 2 d, but it tended to increase due to prolonged infestation at all the nonhopperburn-causing densities. In contrast, ZR content in rice roots significantly reduced after the plants being infested at the density of 15 nymphs for 2 d and at all densities for prolonged duration, except for the plants infested by 60 nymphs for 6 and 8 d, in which the ZR content increased or did not change significantly. However, infestation at the hopperburn-causing density caused significant reduction in ZR content in rice roots, regardless of infestation duration, and in rice leaves from the plants subjected to 2-d infestation. These results are discussed in relation to the possible physiological reaction of rice plants to N. lugens infestation and the resultant severe damage or hopperburn.

The effect of Leptocorisa oratorius (F.) on the yield, grain quality, and seed viability of four rice, Oryza sativa L., lines was studied. Three of the lines, C2, IR64, and PSBRc20, are grown in the Philippines. The fourth, IR72164-201-1 is an unreleased experimental line of an O. sativa japonica × O. sativa indica cross. Each line was exposed to four infestation densities for 21 d. L. oratorius feeding produced unfilled and partially filled grains, resulting in a negative correlation of yield to rice bug density. When filled grains were sown, germination rates were negatively correlated with rice bug densities. The percentage of discolored grains was positively correlated with L. oratorius density on all rice lines. At the same infestation rates, PSBRc20 and IR64 had higher yields, less damaged grain, and higher germination rates than IR72164-201-1 and C2, suggesting host plant tolerance to rice bug feeding. The economic injury levels (EILs) currently used for rice bug management are based solely on yield loss estimates. The results of this study suggest that EIL for rice bugs should be revised to take into account reductions in grain quality and seed germination rates in addition to yield loss.

Brown stink bug, Euschistus servus (Say), was infested on cotton, Gossypium hirsutum L., plants during reproductive stages to determine the effects on boll injury and seedcotton yield. During each week in 2002 and 2003, significantly more bolls with ≥1 injured locule, bolls with ≥2 injured locules, and bolls with discolored lint were recorded on stink bug-infested plants compared with that on noninfested plants. Significantly fewer bolls displayed external injury on the boll exocarp compared with bolls with only internal locule injury. Boll injury was significantly underestimated by the presence of external symptomology. The boll population increased 6.6- and 5.1-fold from weeks 1–5 in 2002 and 2003, respectively. There was a corresponding 6.2- and 4.6-fold increase in 2002 and 2003, respectively, for total bolls injured from weeks 1–5. Percentage of boll injury ranged from 10.7 (week 4) to 27.4 (week 2) in 2002 and from 9.2 (week 3) to 16.0 (week 2) in 2003. Percentage of injury was greatest during weeks 1 and 2 in both years and also in week 5 in 2002. Brown stink bug significantly reduced seedcotton yield of bolls present on cotton plants during weeks 1, 2, and 5 in 2002 and in weeks 4 and 5 in 2003. However, total seedcotton yield, as a function of bolls exposed to brown stink bug and subsequent bolls produced on plant in the absence of stink bugs, was not significantly different for plots infested during weeks 1–4 in 2002 and weeks 1–3 in 2003. Flowering period and boll population influence the severity of stink bug injury on seedcotton yield. Infestation timing and number of bolls should be considered, in addition to insect densities, when initiating treatments against brown stink bug.

The impact of a herbicide-tolerant rice, Oryza sativa L., variety was assessed for its resistance to rice water weevil, Lissorhoptrus oryzophilus Kuschel (Coleoptera: Curculionidae), and its place in current integrated pest management (IPM) programs. Greenhouse experiments were conducted to evaluate the resistance of a glufosinate-tolerant rice variety and its glufosinate-susceptible parent line Bengal to the rice water weevil in the presence and absence of glufosinate applications. The LC₅₀ dose–response and behavioral effects of glufosinate on adult rice water weevils also were studied. Field studies investigated the impacts of glufosinate-tolerant rice on rice water weevil management in the presence and absence of glufosinate under early and delayed flood conditions. Greenhouse studies demonstrated that in the absence of glufosinate, oviposition was 30% higher on the glufosinate-tolerant rice line than on Bengal rice or on glufosinate-tolerant line treated with recommended rates of commercially formulated glufosinate. Applications of glufosinate to glufosinate-tolerant rice resulted in a 20% reduction in rice water weevil larval densities compared with nontreated glufosinate-tolerant rice. The LC₅₀ of glufosinate against adult rice water weevil was nearly 2 times the concentration recommended for application to glufosinate-tolerant rice. There was no difference in the amount of leaf area consumed by adult rice water weevils on glufosinate-treated and nontreated foliage. The absence of direct toxicity of glufosinate to rice water weevil at recommended glufosinate use rates and lack of behavioral effects suggest that the reduction in rice water weevil densities observed after glufosinate applications resulted from herbicide-induced plant resistance. Field experiments showed that neither rice variety nor herbicide use affected larval densities; however, delaying flood and applying insecticide effectively reduced numbers of rice water weevil larvae.

The northern corn rootworm, Diabrotica barberi Smith & Lawrence (Coleoptera: Chrysomelidae), creates economic and environmental concerns in the Corn Belt. To supplement the population control tactics of the Areawide Pest Management Program in Brookings, SD, geographic information systems were used from 1997 to 2001 to examine the spatial relationships between D. barberi population dynamics and habitat structure, soil texture, and elevation. Using the inverse distance weighted interpolation technique, D. barberi population density maps were created from georeferenced emergence and postemergence traps placed in maize, Zea mays L., fields. For each year, these maps were overlaid with vegetation, soil, and elevation maps to search for quantitative relationships between pest numbers and landscape structure. Through visual interpretation and correlation analysis, shifts in landscape structure, such as size, number, and arrangement of patches were shown to associate with D. barberi population abundance and distribution in varying degrees. D. barberi were found in greater proportions than expected on loam and silty clay loam soils and on elevations between 500 and 509 m. An understanding of the interactions between D. barberi population dynamics and landscape variables provides information to pest managers, which can be used to identify patterns in the landscape that promote high insect population density patches to improve pest management strategies.

The biology of the weevil Hylobitelus xiaoi Zhang was studied in both field and laboratory in Shangyou, Jiangxi Province, China. This species required 2 yr to complete one generation with overwintering by adults in pupal chambers and larvae in galleries in the bark of host trees. Adults emerged from early March to early April and fed on the inner bark of branches of the trees. Adults fly little. Adults exhibited a diel periodicity, climbing up the trees around sunset and returning to the tree base the next morning. The mean preovipostion period was 46 d. Oviposition commenced in early May and ended in late August. The average fecundity per female was 36 eggs. Overwintered adult females and males lived 208 and 227 d, respectively. At 25°C, the mean egg incubation period was 13 d. In the field, egg hatch occurred in 12–15 d with 83% survival. There were five to seven instars. At 25°C, duration of the larval stage averaged 129 d. Pupation commenced in late August. At 25°C, pupation averaged 20 d. In the field, pupation required 20–26 d. Transformation to adults occurred from late September to October. New adults remained in the pupal chambers until the next year. Infection by Beauveria bassiana Vuill. occurred in 0.8% of the pupae and 8.8% of the overwintered adults.

After its recent introduction to Chile, the aphid Chaitophorus leucomelas Koch is becoming a serious pest affecting commercial poplar, Populus spp., plantations. The pattern of natural infestation of C. leucomelas among poplar hybrids with different pedigrees and the aphid intrinsic rate of increase (r_m), of C. leucomelas were assessed in the field. In most of the hybrids, aphid abundance peaked in March (late summer). Among 12 types of poplar crosses, [(P. trichocarpa Torr. & Gray × P. deltoides Bartram ex Marshall) × (P. trichocarpa × P. deltoides)] and [(P. trichocarpa × P. maximowiczii Henry) × P. maximowiczii] showed the highest and lowest aphid densities, respectively. A trend to find more aphids in branch bases was apparent. The intrinsic rate of C. leucomelas increase was higher in [(P. trichocarpa × P. deltoides) × P. deltoides] hybrids, and lower in [(P. trichocarpa × P. maximowiczii) × P. trichocarpa] hybrids. Aphid density and performance were higher in hybrids with P. deltoides parentage, whereas hybrids with P. maximowiczii parentage showed lower aphid densities and performance. Hybrids with P. nigra L. parentage, namely, [P. trichocarpa × P. nigra], also had high aphid density, but aphid performance was lower compared with hybrids with P. deltoides parentage. These results suggest that among poplar hybrids studied, susceptibility to C. leucomelas is inherited through P. deltoides, whereas resistance seems to be inherited through P. maximowiczii. Thus, P. maximowiczii hybrids are recommended for commercial or ornamental planting programs in zones where there is a high risk of aphid infestation.

The southwestern pine tip moth, Rhyacionia neomexicana (Dyar) (Lepidoptera: Tortricidae), is a native forest pest that attacks seedlings and saplings of ponderosa pine, Pinus ponderosa Dougl. ex Laws, in the southwestern United States. Repeated attacks can cause severe deformation of host trees and significant long-term growth loss. Alternatively, effective control of R. neomexicana, vegetative competition, or both in young pine plantations may increase survival and growth of trees for many years after treatments are applied. We test the null hypothesis that 4 yr of R. neomexicana and weed control with insecticide, weeding, and insecticide plus weeding would not have any residual effect on survival and growth of trees in ponderosa pine plantation in northern Arizona 14 yr post-treatment, when the trees were 18 yr old. Both insecticide and weeding treatment increased tree growth and reduced the incidence of southwestern pine tip moth damage compared with the control. However, weeding alone also significantly increased tree survival, whereas insecticide alone did not. The insecticide plus weeding treatment had the greatest tree growth and survival, and the lowest rate of tip moth damage. Based on these results, we rejected our null hypothesis and concluded that there were detectable increases in the survival and growth of ponderosa pines 14 yr after treatments applied to control R. neomexicana and weeds.

The feeding and attraction of Agelastica coerulea (Baly) to nine species of Betulaceae in four genera (Alnus, Betula, Carpinus, and Corylus) were examined in the laboratory by using choice and no-choice as well as olfactometer bioassays. In no-choice feeding bioassays with A. coerulea larvae, Alnus hirsuta (Spach) Ruprecht, Alnus japonica Steudel, Corylus sieboldiana variety mandshurica (Max.) c. k. Schneider, and Corylus heterophylla variety thunbergii Blume were the most preferred, whereas Betula davurica Pallas, Betula schmidtii Regel, and Carpinus cordata Blume were the least preferred. The larvae showed moderate preference for Alnus maximowiczii Callier and Carpinus tschonoskii variety brevicalycina Nakai. In choice feeding bioassays, no differences in preference between A. hirsuta and A. japonica were observed. However, there were significant differences in preference between A. hirsuta and each of the other seven plant species. In olfactometer bioassays with adult female A. coerulea, fresh leaf odor from A. hirsuta attracted significantly more adults than that from A. japonica and C. sieboldiana variety mandshurica. These results indicate that A. coerulea differed in its ability to discriminate among the Betulaceae plants at the feeding preference and attraction of host selection.

Eight ratios of l-valine:l-isoleucine methyl esters were tested in Robbins traps for capture of Phyllophaga anxia (LeConte) adult males. The 90:10, 80:20, and 60:40 ratios of valine:isoleucine were the most effective blends for capture of beetles in Rhode Island. Females were captured in small numbers in some traps but not consistently to any particular blend. Other male Phyllophaga species captured included Phyllophaga fusca (Frölich), Phyllophaga forsteri (Burmeister), P. hirsuta (Knoch), and P. marginalis (LeConte). The number of these species collected was low, and it was not possible to determine whether they were attracted to any particular pheromone blend. Peak captures of P. anxia males occurred 31 May in 1999 and 2002 in Kingston, RI. The standard Japanese beetle trap manufactured by Trécé (Adair, OK) captured significantly more beetles than the Robbins trap. Because the Trécé trap is already marketed for Japanese beetles, a lure and trapping system can be adopted for P. anxia.

The rainfastness of a microencapsulated sex pheromone formulation for codling moth, Cydia pomonella (L.), was evaluated in a series of laboratory experiments with detached apple, pear, and walnut leaves. Increasing the intensity and duration of simulated rainfall significantly increased the removal of microcapsules from both the top and bottom of apple leaves. The removal of microcapsules was significantly higher from the top versus the bottom of leaves at all rates tested. Leaf angle was a significant factor affecting the removal of microcapsules from the top surface of apple leaves with fewer microcapsules removed, because leaves were oriented with a steeper downward angle. Both leaf surfaces of apple and pear retained a higher proportion of microcapsules than walnut leaves, and the bottom surface of apple leaves retained significantly more than pear leaves. Three spray adjuvants were evaluated as stickers for microcapsules. No difference was found in the number of microcapsules deposited on apple leaves among three stickers tested at rates from 0.06 to 0.25%. However, in a second test a latex sticker significantly increased the deposition of microcapsules on apple leaves compared with a polyvinyl polymer and a pine resin sticker at a rate of 0.06%. Significantly more microcapsules were retained on the bottom versus the top of apple leaves with all stickers. The latex and polyvinyl stickers significantly increased the retention of microcapsules versus the pine resin sticker and the control on apple leaves. In another test, the addition of 0.06% latex sticker did not increase the deposition of microcapsules on any of the three leaf types. However, the addition of the latex sticker significantly increased the retention of microcapsules on the top of apple and pear leaves and the bottom of apple leaves. The addition of a latex sticker did not affect the retention of microcapsules on walnut leaves.

Interactions between host plant resistance and biological control may benefit or hinder pest management efforts. Turfgrass cultivars have rarely been tested for extrinsic resistance characteristics such as occurrence and performance of beneficial arthropods on plant genotypes with resistance to known turf pests. Parasitism of fall armyworm, Spodoptera frugiperda (J.E. Smith), among six turfgrass genotypes was evaluated. The six grasses tested [Sea Isle-1 and 561-79 seashore paspalum, Paspalum vaginatum Swartz; TifSport and TifEagle hybrid Bermuda grass, Cynodon dactylon (L.) × C. transvaalensis (Burtt-Davy); and Cavalier and Palisades zoysiagrass, Zoysia japonica von Steudel and Z. matrella (L.) Merrill, respectively] represented a range in resistance to S. frugiperda. Differential recovery of larvae released as first instars reflected this gradient in resistance of Cavalier ≥ Palisades ≥ TifSport = TifEagle ≥ 561- = Sea Isle-1 Larval recovery (percentage of initial number released) was greatest in May, less in July and August, and least in October, probably reflecting the increase in activity of on-site predators and disease pressure. Parasitism of the fall armyworm by the braconid Aleiodes laphygmae Viereck varied among turfgrass genotypes. Parasitism was greatest during July. In total, 20,400 first instars were placed in the field; 2,368 were recovered; 468 parasitoids were subsequently reared; 92.2% were A. laphygmae. In the field, the greatest percentage of reduction in S. frugiperda larvae by A. laphygmae occurred on the armyworm-susceptible seashore paspalums (51.9% on Sea Isle-1 in July). Cotesia marginiventris Cresson and Meteorus sp. also were reared from collected larvae. No parasitoids were reared from larvae collected from resistant Cavalier zoysiagrass. A. laphygmae and C. marginiventris were reared from larvae collected from the other five grass cultivars. No parasitoids of older larvae or pupae were observed.

Two watermelon pest management practices, a squash trap crop and a standard recommendation using soil-applied carbofuran, were compared using large-scale field plots to assess trap crop suitability as a replacement for the standard in 2000, 2001, and 2002. In both systems, foliar insecticide applications were used to control squash bugs when populations exceeded threshold levels. During 2001 and 2002, a treatment of untreated watermelon was used. Early season adult insects, from seedling to fruit set, are most critical for watermelon. Significantly fewer early adult bugs were found on watermelon in the trap crop than in the standard recommended practice in 1 of 3 yr. In both years, significantly fewer adult squash bugs were found in watermelon in the trap crop than in untreated fields. The standard recommended practice significantly reduced adult squash bugs in watermelon compared with the untreated in 1 of 2 yr. There was no significant correlation of watermelon yield and squash bug density, indicating that squash bug densities were too low to impact yield. Although squash bugs were reduced significantly by the trap crop, marketable watermelon yields were lower in the squash trap crop than in untreated watermelon, suggesting that pest management treatments may interfere with crop productivity factors other than squash bug colonization. Results suggest that mid-season production squash bug should be managed by monitoring populations and using insecticides as needed rather than using at-plant treatment. Further research is needed to compare treatments during early-season production.

A series of laboratory and field assays were performed to evaluate new methods for an attract-and-kill approach to control blueberry maggot, Rhagoletis mendax Curran. In laboratory assays, fly mortality was similar among insecticide-treated matted paper, plastic, and biodegradable sphere traps. Plastic and biodegradable traps baited with ammonium acetate captured significantly more flies than baited matted paper traps in field assays, whereas fly captures were similar in baited matted paper traps and unbaited plastic sphere traps. Treatments containing imidacloprid resulted in the highest amount of fly knockdown, and spheres coated with this insecticide still had significant knockdown after 6 wk of field exposure. Fly mortality was comparable on sphere traps coated with fipronil and imidacloprid, with both resulting in significantly more fly mortality than the control when flies were exposed to traps that had been weathered for 4 wk in the field. Spheres coated with acetamiprid resulted in fly mortality, but further evaluation is necessary to determine the potential of this compound. Deltamethrin was ineffective in causing fly knockdown at the rate tested. Our results indicate that fipronil and imidacloprid have potential as insecticidal coatings on either plastic or biodegradable spheres in an attract-and-kill system for control of R. mendax.

Effects of the chitin synthesis inhibitors (CSIs) diflubenzuron, hexaflumuron, and lufenuron on the Formosan subterranean termite, Coptotermes formosanus Shiraki, primary reproductives were studied in the laboratory. Incipient colonies were established by collecting and pairing C. formosanus alates and placing them in dishes containing an artificial diet. Three groups of 56 colonies each were fed with a diet containing 10 ppm of one of each of the CSIs and were compared with a control group fed with an untreated diet. All eggs oviposited by treated young queens failed to hatch at the end of 6 mo. Estimated queen fecundity was significantly lower in the lufenuron treatment compared with the control group. Fecundity of hexaflumuron-treated queens did not differ significantly from that of queens from the control group and the other treatments. Adult mortality was significantly higher in the diflubenzuron and lufenuron treatments than in the control group at the end of 6 mo., but not in the hexaflumuron treatment. All the pairs died within 8 mo. in the diflubenzuron and lufenuron treatments, even after treatment was suspended at the end of 6 mo. Mortality in the hexaflumuron treatment was significantly higher than in the control group by the end of 9 mo. The three CSIs tested eliminated reproduction in C. formosanus by preventing egg hatching and induced adult mortality. Possible mechanisms by which CSIs induce termite adult death are discussed.

Brief exposures of Argentine ants to four different insecticide treatments, bifenthrin, β-cyfluthrin, bifenthrin β-cyfluthrin, and fipronil, were conducted to determine Kaplan–Meier product limit survivorship percentiles (SPs) at 21–23 and 27–29°C. Bifenthrin, β-cyfluthrin, and bifenthrin β-cyfluthrin provided rapid kill at 21–23°C with SP₁₀ values ranging from 11.2 to 33.7 min. Fipronil provided delayed toxicity at 21–23°C with SP₁₀ values ranging from 270 to 960 min. At 27–29°C, all of the SP₁₀ values significantly decreased. Field tests in which Argentine ants were induced to forage across insecticide-treated surfaces were used to determine the effect that speed of action has on foraging and recruitment ability, and whether these insecticides are repellent. The slower-acting fipronil allowed a greater amount of foraging and consequently a greater fraction of the colony to be exposed, whereas fast-acting bifenthrin, β-cyfluthrin, and bifenthrin β-cyfluthrin inhibited recruitment, resulting in fewer ants being exposed and killed. Implications for controlling ants by using perimeter barrier treatments are discussed.

The effects of bait applications on the overall activity of the Formosan subterranean termite, Coptotermes formosanus Shiraki, in a town of 1.2 km² were assessed between 2001 and 2003 by using a bait impact index. The index incorporated the amount of baits applied and the distance between bait application loci and the monitoring stations from which termite activity was measured. Even with the collaboration of only 35% of the residents and incomplete treatment records, the bait impact index demonstrated that more baits applied in proximity to monitoring loci significantly caused the decline of C. formosanus activity.

The effects of contamination of insecticidal bait formulations, by using mint oil and silica aerogel, were evaluated in a series of laboratory experiments against the German cockroach, Blattella germanica (L.). Bait consumption at 3 d for uncontaminated baits ranged from 0.01 g for Avert dust to 0.399 g for Combat dry bait with hydramethylnon presented in a station. LT₅₀ values for uncontaminated gel bait deposits ranged from 0.4 d for PreEmpt containing imidacloprid to 4.1 d for Maxforce containing hydramethylnon. As a group, significantly more gel bait was consumed than solid formulations even when both formulations had similar concentrations of the same active ingredient. As a result, gel baits were significantly more toxic than solid formulations. Application of mint oil directly to bait deposits significantly decreased bait consumption and increased overall LT₅₀ values. When bait formulation types were examined individually, there was no difference in consumption or toxicity between contaminated and uncontaminated gel formulations. Contaminated solid baits, however, had significantly greater LT₅₀ values and less consumption than uncontaminated solid baits. Gel formulations probably absorbed the contaminants and removed them from the surface of the bait deposits resulting in normal bait consumption and toxicity. Gel and solid bait deposits, inside plastic exposure stations or alone with no station and placed onto mint oil-contaminated substrates, had significantly lower bait consumption and greater LT₅₀ values than baits placed on uncontaminated substrates. Contamination of a baited area is more likely than contamination of just the bait deposit and therefore a more realistic test of the effects of contamination on bait performance. The importance of contamination to the performance of cockroach baits is discussed.

Bioassays (at generation 1, G₁) using fipronil, spinosad, indoxacarb, and Bacillus thuringiensis toxins Cry1Ac and Cry1Ca with a newly collected field population of Plutella xylostella (L.) from farmers fields in the Cameron Highlands, Malaysia, indicated a resistance ratio of ≈400-, 1,170-, 330-, 2,840-, and 1,410-fold, respectively, compared with a laboratory-susceptible population of P. xylostella (ROTH). At G₃, the field-derived population was divided into two subpopulations, one was selected (G₃ to G₇) with fipronil (fip-SEL), whereas the second was left unselected (UNSEL). Bioassays at G₈ found that selection with fipronil gave a resistance ratio of ≈490 compared with UNSEL and ≈770 compared with ROTH. The resistance ratio for fipronil, spinosad, indoxacarb, Cry1Ac, and Cry1Ca in the UNSEL population declined significantly by G₈. Logit regression analysis of F₁ reciprocal crosses between fip-SEL (at G₈) and UNSEL indicated that resistance to fipronil in the fip-SEL population was inherited as an autosomal, incompletely recessive (D_LC = 0.37) trait. At the highest dose of fipronil tested, resistance was completely recessive, whereas at the lowest dose it was incompletely recessive. A direct test of monogenic inheritance based on a backcross of F₁ progeny with fip-SEL suggested that resistance to fipronil was controlled by a single locus. The fip-SEL population at G₈ showed little change in its response to spinosad and indoxacarb compared with G₁, whereas its susceptibility to Cry1Ac and Cry1Ca increased markedly over the selection period. This suggests that there may be some low level of cross-resistance between fipronil, spinosad, and indoxacarb.

The dynamics of resistance in the sweetpotato whitefly, Bemisia tabaci (Gennadius), to the neonicotinoids acetamiprid and thiamethoxam was studied extensively in cotton fields in Israel during the cotton-growing seasons 1999–2003. Whitefly strains were collected in early and late seasons mainly in three locations in northern, central, and southern Israel. The whiteflies were assayed under laboratory conditions for susceptibility to neonicotinoids, as part of the Israeli cotton insecticide resistance management strategy. Selections to both acetamiprid and thiamethoxam and cross-resistance between them also were conducted in the laboratory. Although no appreciable resistance to acetamiprid was observed up to 2001, a slight increase of approximately five-fold resistance was detected during 2002 and 2003. However, from 2001 to 2003 thiamethoxam resistance increased >100-fold in the Ayalon Valley and Carmel Coast cotton fields. In cross-resistance assays with both neonicotinoids, the strain that had been selected with thiamethoxam for 12 generations demonstrated almost no cross-resistance to acetamiprid, whereas the acetamiprid-selected strain exhibited high cross-resistance of >500-fold to thiamethoxam.

The resistance to and the effects of synergists on the toxicity of six insecticides in Diaeretiella rapae (M’Intosh) (Hymenoptera: Aphidiidae), a parasitoid of vegetable aphid collected in Jianxin at Fuzhou-City, Fujian, China, were studied. In comparison with susceptible F₂₁ progeny, the resistance ratios in resistant F₀ parents were 27.6 for methamidophos, 20.8 for fipronil, 47.5 for avermectin, 3.3 for fenvalerate, 4.5 for cypermethrin, and 74.7 for imidacloprid. Piperonyl butoxide (PB), triphenyl phosphate (TPP), and diethyl maleate (DEM) were chosen to be applied in susceptible F₂₁ progeny, as well as in resistant F₁₁ progeny and F₀ parents. Significant synergistic effects on the toxicity of the six insecticides were found by using PB, TPP, and DEM in F₀ parents; on methamidophos, avermectin, and imidacloprid by PB, TPP, and DEM in F₁₁ progeny; on fipronil by PB and DEM in F₁₁ progeny; and on fenvalerate and cypermethrin by PB in F₁₁ progeny. PB also showed significant synergism on the six insecticides in susceptible F₂₁ progeny, although the synergism was far less in F₂₁ progeny than those in resistant F₀ parents. TPP and DEM showed little or no synergistic effects on the toxicity of the six insecticides in F₂₁ progeny. Compared with TPP and DEM, the highest synergistic ratios of PB for methamidophos, fipronil, avermectin, fenvalerate, cypermethrin, and imidacloprid were observed in F₀ parents, and F₁₁ and F₂₁ progeny. The resistance levels to methamidophos, fipronil, avermectin, fenvalerate, and cypermethrin could be inhibited strongly by applying PB in F₀ parents. From the results, oxidative degradation is believed to play a critical role in resistance to methamidophos, fipronil, avermectin, fenvalerate, and cypermethrin in D. rapae. To a lesser extent, hydrolytic reactions also were partially involved in the resistance to these five insecticides by using the synergists PB, TPP, and DEM. However, although high synergism of PB, TPP, and DEM on imidacloprid was found, the resistance levels to imidacloprid remained high in the presence of PB, TPP, and DEM. The mediated detoxification of oxidative degradation and hydrolytic reactions was thought to be involved in the resistance to imidacloprid in F₀ parents.

A gel bait-resistant German cockroach, Blattella germanica (L.), strain Cincy was collected in Cincinnati, OH. This strain exhibited a high level of behavioral resistance to Avert (0.05% abamectin) and Maxforce FC (0.01% fipronil) gel baits. Topical application assays indicated moderate levels of physiological resistance of the Cincy strain to abamectin and fipronil. Resistance ratios (based on LD₅₀ values from topical applications) to abamectin and fipronil were 2.5 and 8.7, respectively. The Cincy strain of had a significantly lower LD₅₀ value to abamectin than a nonaverse field strain (Dorie) and similar LD₅₀ values to fipronil as the Dorie strain. The aversion behavior (avoidance of gel baits) was therefore caused by food ingredients in the gel baits. The Cincy strain showed avoidance of agar containing fructose, glucose, maltose, and sucrose, which are phagostimulants to the laboratory strain. Modifications of the inert ingredients in the Maxforce FC gel bait significantly improved the efficacy against the Cincy strain. The Cincy strain produced significantly smaller oothecae and lower numbers of eggs in each egg capsule than the nonaverse Jwax and Dorie strains of cockroaches, suggesting fitness costs are associated with resistance.

A population of cabbage looper, Trichoplusia ni (Hübner), collected from commercial greenhouses in the lower mainland of British Columbia, Canada, in 2001 showed a resistance level of 24-fold to Dipel, a product of Bacillus thuringiensis (Bt) subspecies kurstaki. This population was selected with Cry1Ac, the major Bt Cry toxin in Dipel, to obtain a homogenous population resistant to Cry1Ac. The resulting strain of T. ni, named GLEN-Cry1Ac, was highly resistant to Cry1Ac with a resistance ratio of ≈1000-fold. The larvae from the GLEN-Cry1Ac strain could survive on Cry1Ac-expressing transgenic broccoli plants that were highly insecticidal to T. ni and diamondback moth, Plutella xylostella (L.). The inheritance of Cry1Ac resistance in this T. ni strain was autosomal and incompletely recessive. The degree of dominance of the resistance was −0.402 and −0.395, respectively, for the neonates in reciprocal crosses between the GLEN-Cry1Ac and a laboratory strain of T. ni. Using χ² goodness-of-fit test, we demonstrated that the inhibition of larval growth resulting from testing 12 toxin doses in the progeny of the backcross fit the predicted larval responses based on a monogenic inheritance model. Therefore, we conclude that the inheritance of the resistance to Cry1Ac in the T. ni larvae is monogenic.

With the objective to develop a potato, Solanum tuberosum L., resistance program against aphids, we propose a rapid screening method with Myzus persicae (Sulzer) in the laboratory. We aimed to optimize the duration of the whole procedure and to decrease the frequency of measurements. In a first experiment, intrinsic rate of natural increase (r_m) values were compared between adult aphids reared throughout their entire life and adults reared only during a period equivalent to their prereproductive period. No significant differences were observed. In a second experiment, four groups of aphids were distinguished according to the sampling frequency, i.e., those whose biological parameters were evaluated every single, second, third, and fourth day. Except for the fourth-day experiment, the r_m values estimated on aphids reared on the three potato lines were not significantly different whatever sampling frequency of single, second, or third day used to check aphids. Thus, screening efforts in laboratory can be largely optimized by evaluating adult aphids only during a period equivalent to their prereproductive period and assessing M. persicae populations every third day. Our method is reliable and adapted to screen a large number of potato plants against M. persicae because it allows an average 70% reduction in the time required for the whole experimental process.

Fruit yield and quality of zucchini, Cucurbita pepo L., plants infested with Bemisia argentifolii Bellows & Perring were evaluated in a screenhouse under spring and fall growing conditions by using closely related sister lines that were either susceptible (ZUC61) or tolerant (ZUC76-SLR) to squash silverleaf disorder. Our objective was to test separately the effects of level of whitefly infestation and expression of silverleaf symptoms on zucchini yield and quality. In a second experiment, yield and quality of fruit produced by silverleaf-tolerant zucchini genotypes incorporating two different sources of tolerance (ZUC76-SLR and ZUC33-SLR/PMR) were compared with that of ‘Zucchini Elite’, a silverleaf-susceptible commercial hybrid. Zucchini fruit yield was reduced in plants exposed to repeated infestations of whiteflies in spring and fall of both experiments. In addition, fruit grew to harvestable size more slowly under the highest whitefly infestations. Fruit quality was reduced at high infestations because of uneven and reduced pigmentation. The fruit yield and quality of ZUC61 and ZUC76-SLR were similarly affected by whitefly infestation despite differences in their susceptibility to squash silverleaf disorder. Fruit from infested plants showed decreased levels of chlorophyll and carotenoids causing the “blanching” of the fruit that is associated with loss of quality and reduced marketability. Leaves of infested plants of all genotypes had reduced levels of photosynthetic and photoprotectant pigments, possibly leading to reduced photosynthesis and consequently reduced yield. We conclude that feeding by high whitefly populations rather than expression of squash silverleaf disorder is responsible for yield and quality reduction in zucchini.

Genetic engineering may be used to introduce multiple insect resistance genes with different modes of action into crop plants. We explored the possible interactions of two differing gene products fed in the diet of cowpea weevil, Callosobruchus maculates (F.), a stored grain pest. The soybean cysteine protease inhibitor soyacystatin N (scN) and α-amylase inhibitor (αAI) from wheat have defensive function against this coleopteran. When artificial seeds containing both scN and α(AI) were infested with eggs of C. maculatus, the delays in larval development were longer than was predicted by summing the developmental delays seen when larvae were fed a diet containing the individual proteins, indicating that the effects of scN and α(AI) are synergistic. α(AI) was readily hydrolyzed when incubated with insect gut extract. This proteolytic degradation was inhibited by scN, but not by Kunitz inhibitor (a serine protease inhibitor). Thus, degradation of α(AI) was due to proteolysis by insect digestive cysteine proteases. These data suggest that C. maculatus uses digestive enzymes not only to function in food protein digestion but also to defend the insects themselves by helping reduce the concentration of a toxic dietary protein.

Plant germplasm collections may offer genetic variability useful in identifying insect resistance. The goal of this project was to evaluate buffalograss genotypes [Buchloë dactyloides (Nutt.) Engelm.] for resistance to the chinch bug, Blissus occiduus Barber (Hemiptera: Lygaeidae), and to relate resistance to ploidy level, chinch bug number, and pubescence. Forty-eight buffalograss genotypes from diverse geographic locations were evaluated in replicated studies under greenhouse conditions. Of the genotypes studied, four were highly resistant, 22 were moderately resistant, 19 were moderately susceptible, and three were highly susceptible to chinch bug damage. The mean number of chinch bugs was significantly different among the 48 genotypes. There was no significant correlation between chinch bug resistance and ploidy level or chinch bug resistance and pubescence. These results indicate the genetic source of resistance to chinch bugs exists in buffalograss germplasm. Highly resistant genotypes can be used in breeding programs to further improve buffalograss cultivars.

The efficacy of transgenic corn hybrids expressing an insecticidal Bacillus thuringiensis (Bt) δ-endotoxin from different transformation events was evaluated in field corn, Zea mays L., against the southwestern corn borer, Diatraea grandiosella Dyar, and sugarcane borer, Diatraea saccharalis (F.). Susceptibilities of neonates and third instars were determined on Bt and non-Bt corn plants (V6 and R1 stages) in field plots and corn leaf tissue feeding exposure in laboratory bioassays. Bt corn hybrids associated with MON810 and CBH351 transformation events sustained significantly less injury by southwestern corn borer and sugarcane borer during mid-whorl stage infestations compared with their respective non-Bt hybrid equivalents. Southwestern corn borer and sugarcane borer feeding injury to ear leaf-sheath and husk tissues during the silking stage of corn was significantly reduced in MON810 and CBH351 Bt corn compared with their respective non-Bt hybrids. However, resistance levels to feeding injury in Bt hybrids associated with the MON810 event were significantly higher than that in the hybrid associated with the CBH351 event. Southwestern corn borer and sugarcane borer caused more feeding injury to husk tissue than to ear leaf-sheath tissue in both Bt and non-Bt hybrids infested during the silking stage. Laboratory performance of the MON810 event against southwestern corn borer and sugarcane borer varied among hybrids associated with the same event. Third instars of southwestern corn borer were highly susceptible to MON810 Bt corn hybrids in leaf tissue experiments. However, sugarcane borer larvae were susceptible to the MON810 event only in one of the Bt hybrids evaluated. Sugarcane borer mortality was significantly lower after 96 h of feeding exposure on CBH351 Bt corn leaf tissue than on MON810 Bt corn leaf tissue. Plant resistance to southwestern corn borer and sugarcane borer increased as plants matured, independent of the presence of a Bt construct. These results are essential to estimate the importance of Bt transgenic corn in areas of southern United States and other areas where mixed populations of southwestern corn borer and sugarcane borer are predominant and cause severe damage to corn production.

RESUMEN La eficacia de híbridos de maíz transgénico que expresan δ-endotoxinas de Bacillus thuringiensis (Bt) a través de diferentes eventos de transformación fue evaluada en maíz duro (Zea mays L.) contra el barrenador del maíz del suroeste, Diatraea grandiosella Dyar, y el barrenador de la caña de azúcar, Diatraea saccharalis (F.). Se determinaron las susceptibilidades de larvas neonatales y de tercer instar en plantas de maíz Bt y maíz no-Bt convencional (en las etapas de desarrollo V6 y R1) tanto en lotes de campo como en bio-ensayos de laboratorio a través del consumo de tejido de hojas frescas. Los híbridos de maíz Bt asociados con los eventos de transformación MON810 y CBH351 recibieron significativamente menos daño por el barrenador del maíz del suroeste y el barrenador de la caña de azúcar durante infestaciones en la etapa de cogollo comparado con el daño observado en sus respectivos híbridos no-Bt convencionales. El daño causado por el barrenador del maíz del suroeste y el barrenador de la caña de azúcar a la vaina de la hoja de la mazorca y tusas se redujeron significativamente con los eventos MON810 y CBH351 comparados con el daño observado en sus respectivos híbridos no-Bt convencionales durante infestaciones en la etapa reproductiva del maíz. Sin embargo, el nivel de resistencia al consumo de tejido por barrenadores que se observó en el evento MON810 fue significativamente mayor que el observado con el evento CBH351. El barrenador del maíz del suroeste y el barrenador de la caña de azúcar consumieron mas tejido de la tusa que de la vaina de la hoja de la mazorca tanto en híbridos Bt como en híbridos n

In the United States, insecticide is used extensively in the production of sweet corn due to consumer demand for zero damage to ears and to a sweet corn genetic base with little or no resistance to ear-feeding insects. Growers in the southern United States depend on scheduled pesticide applications to control ear-feeding insects. In a study of quantitative genetic control over silk maysin, AM-maysin (apimaysin and methoxymaysin), and chlorogenic acid contents in an F₂ population derived from GE37 (dent corn, P1A1) and 565 (sh2 sweet corn, p1a1), we demonstrate that the P1 allele from field corn, which was selected against in the development of sweet corn, has a strong epistatic interaction with the a1 allele in sh2 sweet corn. We detected that the p1 gene has significant effects (P < 0.0001) not only on silk maysin concentrations but also on AM-maysin, and chlorogenic acid concentrations. The a1 gene also has significant (P < 0.0005) effects on these silk antibiotic chemicals. Successful selection from the fourth and fifth selfed backcrosses for high-maysin individuals of sweet corn homozygous for the recessive a1 allele (tightly linked to sh2) and the dominant P1 allele has been demonstrated. These selected lines have much higher (2 to 3 times) concentrations of silk maysin and other chemicals (AM-maysin and chlorogenic acid) than the donor parent GE37 and could enhance sweet corn resistance to corn earworm and reduce the number of applications of insecticide required to produce sweet corn.

Since the discovery of the soybean aphid, Aphis glycines Matsumura, in midwestern U.S. soybean, Glycine max L., in 2000, the aphid has become a significant economic pest. Basic information about estimating population density within fields is unknown. Therefore, we developed two sampling plans to efficiently characterize A. glycines densities. Enumerative and binomial sequential plans were developed using 89 data sets collected from 10 commercial fields sampled during 2001–2003. Resampling software was used to validate the enumerative plan on whole plant counts, based on Taylor’s power law parameters (a = 9.157 and b = 1.543). For research applications, the enumerative plan was modified to provide an actual precision level of 0.10 (SE/x̄), which resulted in an average sample number of 310 individual plants. For integrated pest management (IPM) purposes, we developed an enumerative plan with an actual precision of 0.25, which resulted in an average sample number of 38 individual plants. For IPM applications, the binomial plan will likely be more practical. Binomial plans were developed using two tally thresholds at five action thresholds. Final analysis of the operating characteristic curve for each plan indicated that the tally threshold of ≥40 aphids per plant, and an action threshold of 0.837 (84% of the plants infested) provided the most correct treat (4%) and no-treat (95%) decisions, with very low incorrect treat (0.5%) and no-treat (0.5%) decisions. A tally threshold of ≥40 aphids per plant and action thresholds of 84% of plants infested is equivalent to a mean density of 250 aphids per plant, a recently recommended economic threshold. Using this threshold, the minimum required sample number for the binomial plan was 11 plants.

Captures of the Mediterranean fruit fly, Ceratitis capitata (Wiedemann), in Jackson traps baited with trimedlure were compared with captures in cylindrical open-bottom dry traps baited with a food-based synthetic attractant (ammonium acetate, putrescine, and trimethylamine). Tests were conducted in Guatemala during a sterile male release program in an area where wild flies were present in low numbers. More wild and sterile females were captured in food-based traps, and more wild and sterile males were captured in trimedlure traps. The food-based traps captured almost twice as many total (male plus female) wild flies as the trimedlure traps, but the difference was not significant. Females made up ≈60% of the wild flies caught in the food-based attractant traps; the trimedlure traps caught no females. The ratio of capture of males in trimedlure traps to food-based traps was 6.5:1 for sterile and 1.7:1 for wild flies. Because fewer sterile males are captured in the food-based traps, there is a reduction in the labor-intensive process of examining flies for sterility. The results indicate that traps baited with food-based attractants could be used in place of the Jackson/trimedlure traps for C. capitata sterile release programs because they can monitor distributions of sterile releases and detect wild fly populations effectively; both critical components of fruit fly eradication programs by using the sterile insect technique.

Toxigenic and allergen-producing fungi represent a serious hazard to human food and animal feed safety. Ninety-four fungal species were isolated from mite-infested samples of seeds taken from Czech seed stores. Fungi were isolated from the surface of four kinds of seeds (wheat, poppy, lettuce, and mustard) and from the gut and external surface of five species of mites (i.e., Acarus siro L., 1758, Caloglyphus rhizoglyphoides (Zachvatkin, 1973), Lepidoglyphus destructor (Schrank, 1781), Tyrophagus putrescentnae (Schrank, 1781) and Cheyletus malaccensis Oudemans 1903) separately. Multivariate analysis of fungi complex composition showed that the frequency of fungal was species significantly influenced by the kind of seed. Fungal frequencies differed between mites gut and exoskeleton surface and between the surfaces of mites and seeds. Three groups of fungal species were recognized: 1) mite surface-associated fungi: Penicillium brevicompactum, Alternaria alternata, and Aspergillus versicolor; 2) mite surface- and seed-associated fungi: Aspergillus niger, Penicillium crustosum, Penicillium aurantiogriseum, Penicillium chrysogenum, and Aspergillus flavus; and 3) seed-associated fungi: Cladosporium herbarum, Mucor dimorphosporus f. dimorphosporus, Botrytis cinerea, Penicillium griseofulvum, and Eurotium repens. Mite-carried species of microfungi are known to produce serious mycotoxins (e.g., aflatoxin B₁, cyclopiazonic acid, sterigmatocystin, ochratoxin A, and nephrotoxic glycopeptides) as well as allergen producers (e.g., A. alternata and P. brevicompactum). Storage mites may play an important role in the spread of some medically hazardous micromycetes. In addition, these mite–fungi associations may heighten the risk of occurrence of mycotoxins in food and feed stuffs and cause mixed contamination by fungal and mite allergens.

Two field strains of the Indianmeal moth, Plodia interpunctella (Hübner); red flour beetle, Tribolium castaneum (Herbst); and lesser grain borer, Rhyzopertha dominica (F.), and one field strain of the rusty grain beetle, Cryptolestes ferrugineus (Stephens), were collected from hard red winter wheat stored on farms in northeastern Kansas. Fifty eggs of P. interpunctella and 25 beetle adults of each species were exposed to 100 g of untreated wheat or wheat treated with various rates of spinosad, to determine susceptibility of the field and corresponding insecticide-susceptible laboratory strains. Mortality of beetle adults and P. interpunctella larvae was assessed after 7 and 21 d postinfestation, respectively. Field strains of P. interpunctella, C. ferrugineus, and T. castaneum were less susceptible to spinosad than the corresponding laboratory strains. The LD₅₀ and LD₉₅ values for P. interpunctella and C. ferrugineus field strains were 1.7–2.5 times greater than values for corresponding laboratory strains. Adults of both laboratory and field strains of T. castaneum were tolerant to spinosad, resulting in <88% mortality at 8 mg/kg. The LD₅₀ and LD₉₅ values for the field strains of T. castaneum were 2.0–7.5 times greater compared with similar values for the laboratory strain. The field and laboratory strains of R. dominica were highly susceptible to spinosad, and one of the field strains was relatively less susceptible to spinosad than the laboratory strain. Our results confirm a range of biological variability in field populations, which is consistent with findings for other compounds, and underscores the need to adopt resistance management programs with stored grain insect pests. The baseline data generated on the susceptibility of the four insect species to spinosad will be useful for monitoring resistance development and for setting field rates.

Bioassays were conducted in the laboratory to assess the effect of the diatomaceous earth (DE) formulations Insecto, SilicoSec, and PyriSec, on stored oat, rye, and triticale, against adults of the rice weevil, Sitophilus oryzae (L.), and the confused flour beetle, Tribolium confusum Jacquelin du Val. The DEs were tested at three dose rates, 0.75, 1, and 1.5 g of DE/kg of grain. Adults of the two aforementioned species were exposed to all combinations of grain-formulation-dose rate, at 26°C and 60% RH. Mortality in DE-treated commodities was recorded after 24 h, 48 h, 7 d, and 14 d of exposure for S. oryzae and T. confusum and after 21 d for T. confusum. In S. oryzae, adult mortality was almost 100% after 7 d of exposure in all three grains examined. The mortality of T. confusum adults in DE-treated grains did not reach 100%, even after 21 d of exposure. Generally, the application of DE in rye caused higher adult mortality of T. confusum than in the other two products. All three dose rates tested provided the same mortality level of S. oryzae adults after 7 d of exposure. In contrast, 1.5 g of DE resulted in significant higher adult mortality of T. confusum, in comparison with the other dose rates, even after 21 d of exposure. All formulations were equally effective after 7 d of exposure against S. oryzae, but at 48 h of exposure, PyriSec caused significantly higher mortality than the other two formulations. For both species, progeny production in the treated grains was significantly reduced in comparison with the untreated grains, whereas significant differences were noted among commodities, formulations, and dose rates. No progeny were recorded in the treated rye for either species or in the treated triticale for S. oryzae.

Methyl bromide, a space fumigant used in food-processing facilities, may be phased out in the United States by 2005. The use of elevated temperatures or heat treatment is gaining popularity as a methyl bromide alternative. During heat treatment, the temperature of the whole food-processing facility, or a portion of it, is raised and held between 50 and 60°C for 24–36 h to kill stored-product insects. We determined time–mortality responses of the confused flour beetle, Tribolium confusum (Jacquelin du Val), eggs, young larvae, old larvae, pupae, and adults exposed to six constant temperatures between 46 and 60°C. Responses of all five insect stages also were measured using exposure times of 160, 40, and 12 min at 46, 50, and 60°C, respectively. Time–mortality responses of all T. confusum life stages increased with an increase in exposure time and temperature. Both time–mortality and fixed time responses showed eggs and young larvae to be most susceptible at elevated temperatures and old larvae to be least susceptible. Our results suggest that old larvae should be used as test insects to gauge heat treatment effectiveness, because heat treatment aimed at controlling old larvae should be able to control all other T. confusum life stages. Besides providing baseline data for successful use of heat treatments, time–mortality data collected at the six temperatures can be used for developing thermal death kinetic models for this species to predict mortality during actual facility heat treatments.