In most developing countries, crop production is by small scale farmers, who mainly produce for their own consumption and the extra for market. Pollination in such systems is unmanaged and is usually incidental, supported by nearby ecosystems. One of the reasons of not managing pollination is the lack of understanding of its economic value. The “public-good” nature of pollination in these systems also discourages individual initiatives intended to conserve pollinators. We evaluate the economic returns from bee pollination in small-holder farming systems. To do this we apply the factor of production method, a form of revealed preferences methods available for valuing ecosystem services. Our analyses show that bee pollination enhances the yield of most crops grown in the farmland and improves immensely the quality of produce. Almost 40% of the annual value of crops under consideration represented the net returns derived from bee pollination. More than 99% of this benefit is attributed to pollination by feral bees. We provide in-depth valuation of pollination service and discuss applicability and limitations of the factor of production method in developing countries.

The varroa mite, Varroa destructor Anderson & Trueman, is a devastating pest of honey bees, Apis mellifera L., that has been primarily controlled over the last 15 yr with two in-hive miticides: the organophosphate coumaphos (Checkmite ), and the pyrethroid tau-fluvalinate (Apistan). Both coumaphos and tau-fluvalinate are lipophilic compounds that are absorbed by the wax component of the hive, where they are stable and have the potential to build up over repeated treatments such that bees could be exposed to both compounds simultaneously. Although these compounds were chosen as in-hive miticides due to their low toxicity to honey bees, that low toxicity depends, at least in part, on rapid detoxification mediated by cytochrome P450 monooxygenase enzymes (P450s). In this laboratory study, we observed a large increase in the toxicity of tau-fluvalinate to 3-d-old bees that had been treated previously with coumaphos, and a moderate increase in the toxicity of coumpahos in bees treated previously with tau-fluvalinate. The observed synergism may result from competition between miticides for access to detoxicative P450s. These results suggest that honey bee mortality may occur with the application of otherwise sublethal doses of miticide when tau-fluvalinate and coumaphos are simultaneously present in the hive.

Establishment of a closed population honey bee, Apis mellifera L. (Hymenoptera: Apidae), breeding program based on ‘black’ strains has been proposed for eastern Australia. Long-term success of such a program requires a high level of genetic variance. To determine the likely extent of genetic variation available, 50 colonies from 11 different commercial apiaries were sequenced in the mitochondrial cytochrome oxidase I and II intergenic region. Five distinct and novel mitotypes were identified. No colonies were found with the A. mellifera mellifera mitotype, which is often associated with undesirable feral strains. One group of mitotypes was consistent with a caucasica origin, two with carnica, and two with ligustica. The results suggest that there is sufficient genetic diversity to support a breeding program provided all these five sources were pooled.

We evaluated the performance of six named types of package honey bees, Apis mellifera L (Hymenoptera: Apidae), from four commercial producers. We examined the effects of levels of the parasitic mite Varroa destructor Anderson & Trueman, the endoparasitic mite Acarapis woodi (Rennie), the gut parasite Nosema (species not determined) in samples from bees in 48 packages, and levels of adult drones in the same packages on corresponding levels of those same traits in the fall in colonies that developed from those 48 packages. After package installation, we measured the rate of queen failure, the removal of freeze-killed brood (an assay to assess hygienic behavior), varroa-sensitive hygiene, and short-term weight gain in all colonies. We examined the correlations among these traits and the effect of initial package conditions and package-type on the expression of these traits. In general, differences among sources were not significant, except that we did observe significant differences in the proportion of mite infected worker brood in the fall. There was no significant difference in weight gain in colonies established from nosema-infected packages versus those established from noninfected packages. Freeze-killed hygienic behavior and varroa-sensitive hygienic behavior were positively correlated, suggesting that both traits could be selected simultaneously. Neither trait was correlated with colony weight gain, suggesting that both traits could be selected without compromising honey production.

Field and laboratory studies were conducted to determine the impact of using a herbicide as a bananacide on aphid transmission of Banana bunchy top virus (family Nanoviridae, genus Babuvirus, BBTV) to healthy banana (Musa spp.) plants. BBTV-infected banana plants in a commercial orchard were treated with Roundup Weathermax herbicide. Using polymerase chain reaction, the time after herbicide treatment that BBTV could no longer be detected in the infected plants was determined. The impact of the herbicide treatment on Pentalonia nigronervosa Coquerel (Hemiptera: Aphididae) virus acquisition and ability to inoculate healthy banana plants with BBTV also were determined. Generally, banana plants were dead beyond 42 d after herbicide injection (DAI), and BBTV was detected in a similar high percentage of treated plants from 0 up to 21 DAI. During two field trials, 0 and 32% of P. nigronervosa acquired the virus from treated plants at 42 DAI, respectively, but none successfully inoculated a healthy banana plant beyond 35 DAI. Finally, 22% of P. nigronervosa colonies collected directly from the pseudostem of injected plants at the final sample date (42 DAI) tested positive for BBTV and infected 9.5% of the healthy banana plants. The findings indicate that banana plants may remain a potential source of virus inoculum 6 wk after injection with a bananacide. The implications of these findings with respect to BBTV management are discussed.

Commercial shipments of Orius spp. (Hemiptera: Anthocoridae) commonly include water and protein, the latter typically supplied by eggs from a moth such as Ephestia kuehniella (Zeller). To determine whether modified dietary conditions might improve predation, newly eclosed adult female Orius pumilio (Champion) were fed on E. kuehniella eggs plus encapsulated water, encapsulated 5% sucrose solution only, or encapsulated water only for periods of 24, 48, or 72 h. Feeding activity was assessed by measuring the area of a crop in digital images of dissected digestive tracts. Adult females fed continuously on eggs had larger crops than did females fed on encapsulated sucrose solution. When females were prefed encapsulated water or sucrose and then fed 3 h on eggs, their crops became highly engorged and were larger than those in females fed continuously on eggs for the same periods. In behavioral choice tests, adult females prefed on encapsulated water or 5% sucrose solution spent a larger portion of time in contact with eggs, presumably feeding, whereas females prefed on eggs showed no preference between eggs or encapsulated water. After overnight shipping, females prefed on water or sucrose and held for 48 h total consumed 3.6- and 4.3-fold, respectively, more western flower thrips, Frankliniella occidentalis (Pergande), in 3 h than those prefed on eggs. Survival rates when prefed on sugar or water were comparable with prefeeding on eggs. Thus, inundative releases of Orius can be enhanced by starvation, because females initially feed much more voraciously after shipment with no apparent reduction in fitness.

Aerial applications of granular insecticides are preferable because they can effectively penetrate vegetation, there is less drift, and no loss of product due to evaporation. We aimed to 1) assess the field efficacy of VectoBac G to control Aedes vigilax (Skuse) in saltmarsh pools, 2) develop a stochastic-modeling procedure to monitor application quality, and 3) assess the distribution of VectoBac G after an aerial application. Because ground-based studies with Ae. vigilax immatures found that VectoBac G provided effective control below the recommended label rate of 7 kg/ha, we trialed a nominated aerial rate of 5 kg/ha as a case study. Our distribution pattern modeling method indicated that the variability in the number of VectoBac G particles captured in catch-trays was greater than expected for 5 kg/ha and that the widely accepted contour mapping approach to visualize the deposition pattern provided spurious results and therefore was not statistically appropriate. Based on the results of distribution pattern modeling, we calculated the catch tray size required to analyze the distribution of aerially applied granular formulations. The minimum catch tray size for products with large granules was 4 m² for Altosid pellets and 2 m² for VectoBac G. In contrast, the minimum catch-tray size for Altosid XRG, Aquabac G, and Altosand, with smaller granule sizes, was 1 m². Little gain in precision would be made by increasing the catch-tray size further, when the increased workload and infrastructure is considered. Our improved methods for monitoring the distribution pattern of aerially applied granular insecticides can be adapted for use by both public health and agricultural contractors.

Effectiveness of GF-120 (Dow Chemical) Fruit Fly Bait containing the insecticide spinosad in controlling mango-infesting fruit flies (Diptera: Tephritidae) was assessed by comparing treated orchards with untreated orchards. Twelve mango, Mangifera indica L., plantations located in six villages (two similar orchards per village: one orchard treated and orchard untreated) scattered in the Borgou department (northern Benin) were monitored weekly with fly traps, and the fruit was sampled twice for larval infestation at the beginning and in the middle of May in both 2006 and 2007. The two main mango fruit fly pests are Ceratitis cosyra (Walker) and Bactrocera invadens Drew, Tsuruta & White, an invasive species that recently spread throughout West Africa. In both the 2006 and 2007 seasons, C. cosyra had the earliest peak of abundance, and the difference between treated and untreated orchards, in terms of mean number of flies trapped per week and per trap, was significant only in 2007. B. invadens populations quickly increased with the onset of the rains, from mid-May onward, with no significant difference between treated and untreated orchards. In 2006 and 2007, the larval infestation by B. invadens was significantly lower in plots treated with GF-120 than in untreated control plots. GF-120 provided an 81% reduction in the number of pupae per kilogram of fruit after weekly applications for 7 wk in 2006 and an 89% reduction after 10 wk of weekly applications in 2007. The possibility of integrating GF120 bait sprays in an integrated pest management package is discussed in relation to market requirements.

The late-aged egg and third-instar life stages of laboratory-reared Malaysian fruit fly, Bactrocera latifrons (Hendel); Mediterranean fruit fly, Ceratitis capitata (Wiedemann); melon fly, B. cucurbitae Coquillett; and oriental fruit fly, B. dorsalis (Hendel), (Diptera: Tephritidae); and the third instars of wild Mediterranean fruit fly were exposed to thermal treatments. A heating block system was used to determine the thermal death kinetics of the four fruit fly species. Treatments consisted of heating the fruit fly life stages to 44, 46, 48, and 50°C and holding for different times ranging from 0 to 120 min depending on the thermal mortality response and time required to obtain 100% mortality for each species and life stage. The 0.5-order kinetic model had the best fit to the survival ratio for all the treatment temperatures and was used to predict lethal times. The thermal death time (TDT) curves showed a tolerance order of Mediterranean fruit fly eggs ≤ third instars at 44, 46, and 50°C, third instars ≤ eggs at 48°C, and wild third instars < the laboratory-reared third instars. Comparison between Mediterranean fruit fly third instar thermotolerance from Hawaii and Israel showed that Israel Mediterranean fruit fly was more thermotolerant. A comparison of minimum treatment times at a given temperature required to obtain 100% mortality of laboratory-reared Malaysian, Mediterranean (Hawaii and Israel strains), melon, Mexican, and oriental fruit fly eggs or third instars and wild Mediterranean fruit fly (Hawaii strain) eggs or third instars showed that oriental fruit fly was the most thermotolerant among the third instars, and the difference in heat tolerance between third instars and eggs was negligible at 50°C.

The Russian wheat aphid, Diuraphis noxia (Kurdjumov), is a pest of small grain crops that has caused hundreds of millions of dollars of damage since it was first reported in the United States in 1986. Much is known about D. noxia population dynamics during the spring and early summer when most of the crop damage occurs, whereas little is known about the system during the overwintering period. Using a spatially explicit model developed from field observations in a wheat/fallow agroecosystem, we sought for predictable variation in overwintering success of D. noxia based on environmental factors such as topography and soil type. Successful modeling of densities of D. noxia would facilitate early control efforts targeting locations where D. noxia successfully overwintered. D. noxia density data were collected over 3 yr at two sites in eastern Colorado. The model incorporates georeferenced data from soil surveys, topography, and satellite imagery as predictor variables. Our approach links an information theoretic approach for model inference and model selection to landscape ecology, allowing for the examination of multiple candidate models and variables within each of the candidate models. Results were used to create trend surface models for D. noxia density in winter wheat agroecosystems. The model has the potential for use in site specific pesticide applications. Using site specific pesticide applications, pesticide inputs could be reduced by an estimated 30%, reducing input costs to the producer, increasing natural enemy refuges, reducing environmental contamination, augmenting pesticide resistance management practices, and reducing exposure of agricultural workers.

The demographic changes in Anastrepha obliqua (Macquart) (Diptera: Tephritidae) throughout laboratory colonization were characterized over the course of 11 generations. Four significant changes were determined. The first change was a reduction in the preoviposition period from the G_p to G₁. The second was that wild female flies had difficulty ovipositing in an artificial substrate, yielding the lowest fecundity rates observed throughout the experiment. The third significant change was a decrease in longevity and life expectancy from G_p to G₁, which then continued to decrease with successive generations. This resulted in a lab strain with high fecundity limited to a short period of oviposition. The last significant change was a reduction in larval and pupal weight. In addition, larval recovery decreased from G_p to G₁ but displayed rapid recovery over the course of generations. There was no change in adult emergences for all generations, and flight ability increased with successive generations. These changes were correlated with demographic parameters, indicating that the increased investment in early age reproduction incurs costs such as a reduction in life expectancy or fecundity later in life. This trend was also correlated with an increase in early fecundity and reduction in the oviposition period.

Methyl eugenol (ME) and cue-lure (C-L) traps to detect tephritid flies on the U.S. mainland were tested with and without insecticides under Hawaiian weather conditions against small populations of oriental fruit fly, Bactrocera dorsalis (Hendel) and melon fly, Bactrocera cucurbitae (Coquillett), respectively. In comparative tests, standard Jackson traps with naled and the Hawaii fruit fly areawide pest management (AWPM) trap with 2,2-dichorovinyl dimethyl phosphate (DDVP) insecticidal strips outperformed traps without an insecticide. Addition of the reduced risk insecticide spinosad did not increase trap capture significantly compared with Jackson traps without an insecticide. Captures in AWPM traps with DDVP compared favorably with those for the Jackson trap with liquid naled (the Florida standard). In subsequent tests, captures with solid Farma Tech wafer dispensers with ME or C-L and DDVP placed inside Jackson and AWPM traps were equal to those for a Jackson trap with naled, currently used for detection of ME and C-L responding fruit flies in Florida. Farma Tech ME and C-L wafers with DDVP would be more convenient and safer to handle than current liquid insecticide formulations (e.g., naled) used for detection programs in Florida.

Cues that elicit a characteristic localized search behavior by neonate larvae of the western corn rootworm, Diabrotica virgifera virgifera LeConte (Coleoptera: Chrysomelidae), were extracted from living corn, Zea mays L., roots with acetone. Larvae were exposed to corn roots or to an acetone extract of corn roots and then transferred into a bioassay arena where their movements were tracked and recorded. After a 5-min exposure to live corn roots, larvae produced highly convoluted tracks that were indicative of a localized search behavior, and these distinctive tracks were also produced by larvae exposed to an acetone extract of corn roots. Larvae exposed to a filter paper control moved in relatively straight paths that were indicative of ranging behavior. Larval tracks were recorded by means of a videocamera and tracking software, and four parameters of movement were used to quantify the tracks: mean turn angle, mean meander, total distance, and maximum distance from origin. For every parameter measured, tracks resulting from exposure to the control were significantly different from tracks resulting from exposure to live corn roots and to all doses of the corn root extract. In a separate experiment, larvae exposed to corn root pieces or corn root juice exhibited the localized search behavior, but larvae exposed to oat root pieces and oat root juice (nonhost) exhibited ranging behavior.

Recent declines in managed and feral honey bee populations have greatly increased interest in the current and potential role of wild pollinators in agricultural pollination. Pumpkin (Cucurbita pepo L.) has great potential to be served by wild pollinators because of a reliable and widespread group of bee species that are commonly associated with their flowers, including bumble bees (Bombus spp.), and, in the Americas, two genera of specialist ground nesting bees (Peponapis and Xenoglossa). We examined the effects of several key farm management practices and landscape variables on bee abundance in pumpkin on 20 farms in Virginia and Maryland during summer 2006. We evaluated bee abundance with respect to tillage, irrigation practices, soil properties, natural habitat (forest and grassland), flowering crop, and disturbed areas. Additionally, we examined nest site preference (within or outside of crop areas) of Peponapis pruinosa (Say) at one farm and in a large screenhouse. We found P. pruinosa nesting preferentially within crop areas and near the vines and leaves of their host plant. Although these bees typically place some of their brood cells within tillage depth, we did not find a tillage effect on their abundance at flowers. We found a negative effect of soil clay content (R² = 0.24, P = 0.03) and a positive effect of irrigation (F_1,15 = 12.2; P < 0.001) on P. pruinosa abundance. Using published data on pollinator visitation requirements, we found wild bee densities were sufficient to fully pollinate all pumpkin flowers on 13–17 of the 20 farms studied.

Marmara gulosa Guillén & Davis (Lepidoptera: Gracillariidae) is a sporadic pest of citrus and a number of other crops in southern and central California. Coupled gas chromatographic-electroantennogram detection analyses of headspace volatiles collected by solid phase microextraction from virgin female moths revealed at least four related compounds in the extracts that elicited significant antennal responses from antennae of male moths. These compounds were identified as (8E,10E)-tetradecadien-1-ol, and the corresponding aldehyde, acetate, and formate ester, representing the first report of a formate as a lepidopteran pheromone component. The four compounds were consistently found in headspace volatiles collected from virgin female moths from different regions of the state and from M. gulosa collected from different host plants (citrus and squash). Repeated field trials determined that the formate ester alone was as attractive or more attractive than any blend of the formate with one or more of the remaining compounds. Although large numbers of moths were caught in some field trials, trap catches were not consistent. Thus, the pheromone may be useful for detection of the moth and setting an initial biofix, but it remains unclear whether the pheromone can be used as a reliable and accurate tool for monitoring densities of M. gulosa populations.

We investigated the behavioral and electrophysiological responses of male and female Mexican fruit fly, Anastrepha ludens (Loew) (Diptera: Tephritidae), to volatiles of bitter orange fruit, Citrus aurantium L. In field cage tests, the number of A. ludens caught in Multilure traps baited with mature green bitter orange fruit was significantly higher than the number captured in traps baited with ripe yellow bitter orange fruit and control (unbaited traps). Both sexes were more attracted to mature green bitter orange fruit extracts than to controls in both flight tunnel and field cage assays. Gas chromatography-mass spectrometry analysis of the mature green bitter orange fruit volatiles identified 10 different compounds. Limonene was the most abundant volatile compound, followed by an unknown compound, tentatively identified as trans-ocimene. Linalool, β-pinene, and methyl salicylate were found in lower proportions. Both sexes of A. ludens evoked higher antennal response to linalool, methyl salicylate, and to a blend of these four components in comparison with limonene, and β-pinene. In flight tunnel, both sexes were more attracted and landed more often on spheres baited with the four-component blend compared with control spheres. In field cage tests, Multilure traps baited with the four-component blend captured significantly more A. ludens flies than traps baited with hydrolyzed protein or control traps.

Life tables of twospotted spider mite, Tetranychus urticae Koch (Acari: Tetranychidae), were studied on leaf discs and whole leaves of the common bean plant, Phaseolus vulgaris L. Data were analyzed based on the age-stage, two-sex life table theory. Durations of deutonymph stage, total preadult stage, and preoviposition period of mites reared on whole leaves (1.22, 7.6, and 0.29 d, respectively) were significantly shorter than those reared on leaf discs (1.73, 8.2, and 0.89 d, respectively). The lifetime fecundities were 22.81 and 12.05 offspring on whole leaves and leaf discs, respectively. Although hooked trichomes on the lower surface of the bean leaf contribute to adult mortality, spider mites successfully survive and reproduce on bean plants. The intrinsic rate of increase on whole leaves (0.235 d^-1) was higher than that on leaf discs (0.159 d^-1). Higher intrinsic rate and fecundity found in mites reared on whole leaves may be due to the higher nutritional quality of whole leaves over leaf discs. We suggest that whole leaves should be used in future studies to better simulate realistic life history characteristics. The advantages of using age-stage, two-sex life tables over female age-specific life tables are discussed.

Greenhouse experiments were conducted in 2004–2006 to examine the reciprocal effects of aboveground herbivory by European corn borer, Ostrinia nubilalis (Hübner) (Lepidoptera: Crambidae), and belowground herbivory by root-knot nematode, Meloidogyne incognita Chitwood (Tylenchida: Heteroderidae), on one another at three corn, Zea mays L., growth stages. Two experiments were conducted to study the effect of aboveground herbivory by O. nubilalis on the number of M. incognita juvenile penetration/root system and eggs/root system. In the first experiment, the O. nubilalis infestation level by plant growth stage main effect interaction was not significant for either M. incognita juvenile penetration or eggs. The overall effect of stalk tunneling by O. nubilalis resulted in 48.9% fewer juvenile penetration and 40.0% fewer eggs than in the respective controls. In the second experiment, the main effects interaction was significant for juvenile penetration (P = 0.0422) and eggs (P = 0.0134). At the eight- and 10-leaf growth stages, the combined effect of one and three O. nubilalis larvae per plant resulted in 41.2 and 44.7% significantly fewer juvenile penetration than in the respective controls. Similarly, the combined effect of stalk tunneling (with the exception of one larvae per plant at the 10-leaf growth stage) at the six-, eight-, and 10-leaf growth stages resulted in 46.3, 53.3, and 55.2% fewer eggs than in the respective controls. In all instances, M. incognita juvenile penetration and eggs were significantly negatively correlated with O. nubilalis tunnel length. In a reciprocal experiment conducted two times, no significant (P > 0.05) effect of M. incognita inoculation level on stalk tunneling was found in either experiment.

Plodia interpunctella (Hübner) (Lepidoptera: Pyralidae) is a cosmopolitan insect infesting a broad range of commodities, including raw or processed cereal. It has a high fecundity and short generation time, making it a useful tool in testing host-parasitoid hypotheses. The current study examined the interactions between trophic levels during parasitism and host location by Habrobracon hebetor Say (Hymenoptera: Braconidae) within a closed environment by carrying out multiple tests to evaluate the role of refuge and host instar, on the mortality of P. interpunctella and on the emergence of H. hebetor. Results showed that H. hebetor was able to parasitize all instars (first through fourth) of P. interpunctella, but significantly fewer early instars (first through fourth) were parasitized. Parasitized third and fourth instars were more profitable to H, hebetor, irrespective of refuge or choice factors, as significantly more adult parasitoids emerged from third and fourth instars. H. hebetor females consistently showed a preference for fourth instars of P. interpunctella when they were offered a choice between early and late host instars in arenas both with and without a refuge. Generally, parasitization of early instars was higher in no-choice than in choice tests. The behavior of H. hebetor in relation to host choice and its influence on the pest mortality are discussed.

Beekeepers suspected maize, Zea mays L., treated with imidacloprid to result in substantial loss of honey bee (Hymenoptera: Apidae) colonies in Belgium. The objective of this study was to investigate the potential impact of maize grown from imidacloprid-treated seeds on honey bee mortality. A survey of 16 apiaries was carried out, and all maize fields treated or not with imidacloprid were located within a radius of 3,000 m around the observed apiaries. Samples of honey, beeswax, and bees were collected in three colonies per apiary and analyzed for pesticide contain by liquid chromatography-tandem mass spectrometry and gas chromatography-tandem mass spectrometry. We first found a significant correlation between the number of colonies per apiary and the mortality rates in an apiary. In addition, this mortality rate was inversely correlated with the surface of maize fields treated and not with imidacloprid, suggesting that this pesticide do not interact with bees' fitness. Moreover, a very large number of our samples contained acaricides either prohibited or ineffective against Varroa destructor (Anderson & Trueman) (Acari: Varroidae), suggesting that the treatment methods used by the beekeepers to be inadequate for mite control. Our results support the hypothesis that imidacloprid seed-treated maize has no negative impact on honey bees.

Ostrinia nubilalis (Hübner) (Lepidoptera: Crambidae) is one of the most damaging insect pests of corn. Studies were conducted to determine whether live larval counts obtained from corn whorls were predictive of the amount of larval tunneling that would result in the stalk of the plant 40 d later at the end of larval development. Whorls from plants treated with Dipel 10G (6,400 IU per whorl) and untreated controls, both infested with O. nubilalis neonates, were evaluated for the number of live larvae in 50 whorls 5, 7, 9, and 12 d after Bacillus thuringiensis (Berliner) (Bacillales: Bacillaceae) application. Forty days after larval infestation, 25 plants from each plot were split from tassel to base, and the length of larval tunneling was recorded. There was a strong relationship between numbers of live larvae in the plant whorl and the length of larval tunneling that resulted. While linear at each location, there was significant variation in the relationship among locations, indicating that comparisons could not be made between years or locations within a year. Blocks within a location on a given year did not vary significantly and reproducible results were obtained each year within a given location as well as on any of the whorl pulling dates evaluated. Because of its ease of use, predictability, and rapid return of results, we propose this technique as an additional method to shot-hole feeding and stalk splitting to evaluate the effectiveness of O. nubilalis management strategies.

One important mortality factor of Semanotus japonicus Lacordaire (Coleoptera: Cerambycidae) larvae in the trunks of Cryptomeria japonica (L.f.) D. Don (Taxodiaceae) is the presence of oleoresin secreted from traumatic resin canals (TRCs) in the phloem. The present 2-yr investigation examined whether the extent of feeding in the phloem and/or the survival of S. japonicus larvae were negatively influenced by TRCs occurred by Epinotia granitalis (Butler) (Lepidoptera: Tortricidae) larval feeding when these larvae fed simultaneously in the same trunk. The survival of S. japonicus larvae until they reach the xylem, the damage to the xylem, and emergence were investigated. The occurrence of TRCs at the E. granitalis feeding sites was significantly higher at the 1-3-yr-old annual layer compared with nonfeeding sites, suggesting that E. granitalis feeding induces the occurrence. The extent of feeding in the phloem by S. japonicus larvae that were dead there tended to be shorter with number of E. granitalis feeding sites, but the extent of some larvae was long in spite of the existence of E. granitalis feeding, suggesting that larvae feeding opposite to E. granitalis feeding sites could not be influenced by TRCs occurred by E. granitalis. The survival of S. japonicus larvae until they reached xylem did not decrease with the number of E. granitalis feeding sites because preformed TRCs considerably influenced the survival, whereas the survival until damaging the xylem and until emerging decreased. These results indicate that E. granitalis feeding induces the occurrence of TRCs in C. japonica and negatively influences the feeding behavior and survival of S. japonicus, although the survival varies with the feeding direction in respect to E. granitalis feeding sites or the existence of preformed TRCs.

Larvae of the whitemarked tussock moth, Orgyia leucostigma (J.E. Smith) (Lepidoptera: Lymantriidae), defoliate and contaminate blueberries, Vaccinium corymbosum L., in eastern North America, but infestations are often not detected until economic damage has been caused. To improve monitoring techniques and understand the phenology of the whitemarked tussock moth in blueberry, we compared four trap types and determined temperature-based phenology of this pest over two growing seasons. Large delta traps captured the greatest number of male moths, and similar moth captures were found with or without monthly lure changing. Traps placed at field perimeters adjacent to woods trapped significantly more moths than those inside fields, whereas position in the canopy (high versus low) did not affect captures. Under laboratory conditions, the lower developmental threshold for larvae was 12.3°C, in close agreement with field studies indicating a 12.8°C threshold. Using the 12.8°C threshold, monitoring of O. leucostigma cohorts on caged blueberry plants revealed a spring generation with egg hatch starting at 206 ± 3 growing degree-days (GDD) and a late-summer generation with egg hatch starting at 1,157 ± 52 GDD. Combined use of optimized monitoring methods and the phenology model for O. leucostigma is expected to improve integrated management of this pest in blueberry.

New pesticides are required to maintain effective resistance management strategies for control of western flower thrips, Frankliniella occidentalis (Pergande) (Thysanoptera: Thripidae). We tested the efficacy of acetamiprid, and thiamethoxam, two neonicotinoids that represent a newer class of insecticides for the control of thrips. We also tested chlorfenapyr, a pyrrol compound, and a lower than registered rate of the biopesticide spinosad. Laboratory bioassays were used to predict the relative efficacy of insecticides against F. occidentalis and to forecast likely field rates. Two doses within the calculated LC_99.99 range were used to predict field rates and trial rates of 0.5 g and 1.0 active ingredient (AI)/liter acetamiprid, 0.025 and 0.05g (AI)/liter chlorfenapyr, 0.3 and 0.6g (AI)/literthiamethoxam, and 0.01 g (AI)/liter spinosad were tested in the greenhouse against pepper, lettuce, and tomato. With the exception of acetamiprid, field trial doses predicted from laboratory bioassay translated to effective field efficacy. All products controlled F. occidentalis at the rates trialed and so have potential to augment current chemical controls. Increasing mortality correlated with increasing acetamiprid concentration in a greenhouse lettuce trial, suggesting that the higher trial rate (1.0 g [AI]/liter) may be required in some lettuce crops. The lower than registered (0.01 g [AI]/liter) rate of spinosad also significantly reduced F. occidentalis numbers and is a viable control option that may be useful in specific integrated pest management programs. The implications of introducing neonicotinoids into existing insecticide resistance management strategies for F. occidentalis are discussed.

Two species of invasive crane flies are damaging pests of turfgrass in the Great Lakes region after their inadvertent introduction and establishment. In New York, where Tipula paludosa Meigen and Tipula oleracea L. (Diptera: Tipulidae) were first detected in 2004, baseline data on the extent of establishment is needed to monitor range expansion, make predictions about pest status, and guide management efforts. The incidence of both species was therefore addressed at two spatial scales to ascertain how widespread they were across the state and across sites of recent local establishment. Based on divergent natural history, T. oleracea was predicted to be more widespread both geographically and locally than T. paludosa. To delimit the current area of occurrence, surveys were conducted from 2004 to 2006. T. paludosa was detected in four counties and T. oleracea in 12 counties. In western New York, T. oleracea was established in more than a six-fold greater area than T. paludosa. T. oleracea was additionally detected on Long Island, shown to be a geographically disjunct area of establishment. To measure local incidence, putting greens and tee boxes were scouted on golf courses. Contrary to predictions, 56–97 and 22–56% of those surfaces were already infested by T. paludosa and T. oleracea, respectively, within one or two seasons after initial detection. Because damage thresholds are relatively high, scouting for the insect, rather than its injury, will promote earlier detection. Given the impact of invasive Tipula across diverse turf habitats, continued range expansion will have serious repercussions for regional turfgrass management.

Cost is a potential limiting factor in the adoption of mating disruption to control oriental beetle, Anomala orientalis (Waterhouse) (Coleoptera: Scarabaeidae). A 3-yr study was conducted in 1-ha blueberry, Vaccinium corymbosum L, plots to test the possibility of lowering cost by reducing the number of point-source dispensers and pheromone [(Z)-7-tetradecen-2-one] concentrations, while maintaining mating disruption. Trap shutdown, as measured by the disruption index (DI), caged females, and sentinel potted-plants with tethered females were used to assess the success of mating disruption. Disrupted plots had DI values of ≥93% in all years, and a lower percentage of mated females, compared with control plots. However, DI values were ≥95% at ≥50 dispensers per ha. When 25 dispensers containing 0.05 g of active ingredient (AI) were used per hectare, the numbers of males in female cages and larvae in sentinel pots were similar to controls. Thus, dispenser density was critical for successful mating disruption of oriental beetles. Male oriental beetles approach the dispensers at all times of the day according to field observations, indicative of competitive attraction as a potential mechanism for mating disruption. However, at peak activity, greater male attraction was observed to dispensers containing 0.1 g of pheromone than 0.05 or 0.025 g, demonstrating the importance of pheromone rate. Although dispensers continued to emit pheromone for at least 7 wk in the field, emission rates dropped to levels close to 0 after 3 wk. We conclude that deployment of ≥50 dispensers/ha at ≥0.1 g (AI) per dispenser is the most effective rate for mating disruption of oriental beetle in blueberries.

After the 2004 discovery of the Bemisia tabaci (Gennadius) (Hemiptera: Aleyrodidae) Q biotype in the United States, there was an urgent need to determine its distribution. As part of a coordinated country-wide effort, an extensive survey of B. tabaci biotypes was conducted in Florida, with the cooperation of growers and state and federal agencies, to monitor the introduction and distribution of both the B and Q biotypes. The biotype status of submitted B. tabaci samples was determined by polymerase chain reaction (PCR) amplification and sequencing of a 700–800-bp mitochondrial cytochrome oxidase I small subunit (mtCOI) gene fragment, PCR amplification, and size determination of two unique microsatellite markers and esterase zymogram analysis. One hundred and eighty collections were sampled from 23 counties. Of these samples, 58% were from vegetables, 37% were from ornamentals, and 5% were from peanuts, alfalfa, and weeds. Eighteen percent of all collections were found to be the Q biotype that came from greenhouse grown ornamental and herbs located in six counties. Sequence comparison of the mtCOI gene identified three separate haplotypes within Florida that were defined as Q1, Q2, and Q3. Haplotypes could be used to associate populations known to be related by grower and plant type. For example, collections from five counties were made on hibiscus linked to the same grower and all samples contained only the Q1 haplotype. Other populations contained a mix of the Q2 and Q3 haplotypes, supporting the conclusion that the Q biotype must have entered Florida through at least two separate introductions. Our data also show that two microsatellite markers are a cost-effective diagnostic alternative for biotype identification with 100% concurrence with mtCOI sequence data.

Late-season plantings of sweet corn in Minnesota result in an abundant supply of silking corn, Zea mays L., throughout August to early September that is highly attractive to the corn earworm, Helicoverpa zea (Boddie) (Lepidoptera: Noctuidae). During a 10-yr period, 1997–2006, insecticide efficacy trials were conducted in late-planted sweet corn in Minnesota for management of H. zea. These data were used to develop a logistic regression model to identify the variables and interactions that most influenced efficacy (proportion control) of late-instar H. zea. The pyrethroid lambda-cyhalothrin (0.028kg [AI]/ha) is a commonly used insecticide in sweet corn and was therefore chosen for use in parameter evaluation. Three variables were found to be significant (α = 0.05), the percentage of plants silking at the time of the first insecticide application, the interval between the first and second insecticide applications, and the interval between the last insecticide application and harvest. Odds ratio estimates indicated that as the percentage of plants silking at the time of first application increased, control of H. zea increased. As the interval between the first and second insecticide application increased, control of H. zea decreased. Finally, as the interval between the last insecticide application and harvest increased, control of H. zea increased. An additional timing trial was conducted in 2007 by using lambda-cyhalothrin, to evaluate the impact of the percentage of plants silking at the first application. The results indicated no significant differences in efficacy against late-instar H. zea at 0, 50, 90, and 100% of plants silking at the first application (regimes of five or more sprays). The implications of these effects are discussed within the context of current integrated pest management programs for late-planted sweet corn in the upper midwestern United States.

The psyllid Diaphorina citri Kuwayama (Hemiptera: Psyllidae) is one of the most important pests of citrus worldwide because it efficiently vectors three bacteria in the genus Candidatus Liberibacter that cause the devastating citrus greening disease (huanglongbing). Current management practices for this insect pest rely on multiple sprays of foliar insecticides and one or two applications of soil systemic insecticides per season. Effective psyllid and disease management in Florida requires insecticide applications throughout the entire season over wide ranging temperature and environmental conditions. Using a petri dish bioassay technique, the effect of posttreatment temperature (range, 17–37°C) on the toxicity of selected organophosphate (chlorpyrifos and dimethoate), carbamate (carbaryl), avermectin (abamectin), pyrethroid (bifenthrin, zeta-cypermethrin, fenpropathrin, and lambda-cyhalothrin), and neonicotinoid (acetamiprid, imidacloprid, and thiamethoxam) insecticides was evaluated against adult D. citri. The toxicity of both organophosphates showed a positive temperature correlation within the 17–37°C range. Similarly, carbaryl (carbamate) and abamectin (avermectin) exhibited increased toxicity with increasing temperature from 17 to 37°C, with abamectin showing higher overall temperature-dependent toxicity against D. citri adults than carbaryl. With the exception of bifenthrin, which showed a positive temperature-dependent toxicity correlation between 27 and 37°C, all other pyrethroids tested exhibited a negative correlation over the temperature range examined. The toxicity of fenpropathrin and lambda-cyhalothrin dramatically decreased with increasing temperature from 17 to 37°C. The neonicotinoids imidacloprid and thiamethoxam exhibited a mixed response to increasing temperature, whereas acetamiprid showed a positive temperature correlation. However, all three neonicotinoids showed positive temperature-dependent toxicity correlations against D. citri adults over the temperature range tested. These data will enable citrus growers to choose the most effective insecticides for D. citri control from the various classes currently available depending on the prevailing temperature conditions.

We monitored the phenology of oviposition by grape berry moth, Paralobesia viteana (Clemens) (Lepidoptera: Tortricidae), in grape (Vitis spp.) vineyards, to determine the optimal timing for control of this pest. Egg deposition was monitored throughout the growing season by visually inspecting grape clusters twice weekly and counting the number of eggs. Male moths were captured on pheromone-baited traps during the same period. Two main periods of egg deposition were detected in all farms and years: the first period in June-July and the second period during August. These episodes of concentrated oviposition were separated by a brief period of low intensity but continuous oviposition. The proportion of eggs laid during the first peak ranged from 9 to 35% of all eggs laid throughout the monitoring period at each site, whereas eggs laid during the second peak ranged from 43 to 78% of all eggs laid. From 49 to 99% of male moths were captured before or during the first peak in oviposition. In field trials with varying application timing of methoxyfenozide targeting the postbloom oviposition, a single application of this selective insecticide at ≈700 degree-days, or ≈12% of cumulative season-long oviposition, provided significant control of grape berry moth comparable with two applications of methoxyfenozide or a three-spray program with broad-spectrum insecticides. Use of predicted oviposition phenology and selective insecticides with long residual activity can improve protection of grapes against infestation by P. viteana.

A monitoring program that used a glass-vial bioassay to detect acephate resistance in populations of the tarnished plant bug, Lygus lineolans (Palisot de Beauvois) (Heteroptera: Miridae), was carried out with weed-collected populations from 20 sites in the delta of Arkansas, Louisiana, and Mississippi. Additional results from field tests using recommended rates of formulated acephate in cotton showed that plant bug populations with resistance ratio (RR₅₀) values >3.0 for acephate (from the glass-vial bioassay) would be difficult to control in the field. Over a 4-yr-period from 2001 through 2004, only one population tested with the glass-vial bioassay was found with an RR₅₀ value >3.0 for acephate, but six populations having RR₅₀ values >3.0 were found in the delta in 2005. In fall 2005, an additional 10 populations from the hill region (the cotton growing areas outside the delta) were tested and four of these populations had RR₅₀ values >3.0. The number of populations with RR₅₀ values >3.0 increased to five of 10 and 18 of 20 in the hills and delta, respectively, in fall 2006. Laboratory tests using resistant populations found that resistance to acephate was not sex-linked and the alleles controlling the resistance were semidominant in nature. Because of the large increase in resistant populations and the nature of the resistance found in this study, along with control problems experienced by growers in 2006, entomologists in the mid-South strongly recommended that alternation of insecticide classes in field treatments for plant bug control be used by growers in 2007. This control strategy probably helped control plant bugs in the hills of MS where plant bug pressure was low in 2007, and only one population was found in the fall with an RR₅₀ value >3.0. Plant bug pressure was very high in many parts of the delta in 2007, and 15 of the 20 populations tested in the fall had RR₅₀ values >3.0. In one field test in cotton, a population with multiple resistance was tested and not effectively controlled in treatments using recommended rates of carbamate, organophosphate, and pyrethroid insecticides. Alternation of insecticide classes may not work very well when populations are present that are resistant to three of the four main classes of cotton insecticides. New insecticides in different classes are badly needed for control of tarnished plant bugs in cotton in the mid-South.

Bollgard II cotton (which expresses two Bt insecticidal genes cry1Ac/cry2Ab) and conventional cotton, grown in the laboratory or field and sampled at different stages, was exposed to Helicoverpa armigera (Hübner) larvae of three genotypes: homozygous for resistance to Cry2Ab; homozygous for susceptibility to Cry2Ab, and heterozygous for resistance. Survival of all genotypes was limited on Bollgard II but increased as plants aged. This was particularly the case for homozygous resistant individuals, with 8.5% of this genotype surviving to pupation on mature cotton. The increasing survival is assumed to be caused by the decline in the titer of Cry1Ac toxin after flowering in Bollgard II because Cry2Ab homozygous resistant larvae can tolerate high levels of Cry2Ab toxin. Larvae heterozygous for resistance performed no better on Bollgard II than homozygous susceptible larvae. Survivors on Bollgard II grew more slowly and produced smaller pupae that yielded adults with reduced longevity and fecundity. When reared on conventional cotton, all genotypes generally performed equally, indicating an absence of fitness costs associated with Cry2Ab resistance under the conditions examined.

Transgenic crops producing insecticidal toxins are widely used to control insect pests. Their benefits would be lost if resistance to the toxins became widespread in pest populations. The most widely used resistance management method is the high-dose/refuge strategy. This requires toxin-free host plants as refuges near insecticidal crops, and toxin doses intended to be sufficiently high to kill insects heterozygous for a resistant allele, thereby rendering resistance functionally recessive. We have previously shown by mathematical modeling that mass-release of harmless susceptible (toxin-sensitive) insects engineered with repressible female-specific lethality using release of insects carrying a dominant lethal ([RIDL] Oxitec Limited, United Kingdom) technology could substantially delay or reverse the spread of resistance and reduce refuge sizes. Here, we explore this proposal in depth, studying a wide range of scenarios, considering impacts on population dynamics as well as evolution of allele frequencies, comparing with releases of natural fertile susceptible insects, and examining the effect of seasonality. We investigate the outcome for pest control for which the plant-incorporated toxins are not necessarily at a high dose (i.e., they might not kill all homozygous susceptible and all heterozygous insects). We demonstrate that a RIDL-based approach could form an effective component of a resistance management strategy in a wide range of genetic and ecological circumstances. Because there are significant threshold effects for several variables, we expect that a margin of error would be advisable in setting release ratios and refuge sizes, especially as the frequency and properties of resistant alleles may be difficult to measure accurately in the field.

Helicoverpa punctigera and Helicoverpa armigera (Hübner) (Lepidoptera: Noctuidae) are important pests of field and horticultural crops in Australia. The former is endemic to the continent, whereas the latter is also distributed in Africa and Asia. Although H. armigera rapidly developed resistance to virtually every group of insecticide used against it, there is only one report of resistance to an insecticide in H. punctigera. In 1996 the Australian cotton industry adopted Ingard, which expresses the Bacillus thuringiensis (Bt) toxin gene cry1Ac. In 2004/2005, Bollgard II (which expresses Cry1Ac and Cry2Ab) replaced Ingard and has subsequently been grown on 80% of the area planted to cotton, Gossypium hirsutum L. From 2002/2003 to 2006/2007, F₂ screens were used to detect resistance to Cry1Ac or Cry2Ab. We detected no alleles conferring resistance to Cry1Ac; the frequency was <0.0005 (n = 2,180 alleles), with a 95% credibility interval between 0 and 0.0014. However, during the same period, we detected alleles that confer resistance to Cry2Ab at a frequency of 0.0018 (n = 2,192 alleles), with a 95% credibility interval between 0.0005 and 0.0040. For both toxins, the experiment-wise detection probability was 94%, i.e., if there actually was a resistance allele in any tested lines, we would have detected it 94% of the time. The first isolation of Cry2Ab resistance in H. punctigera was before the widespread deployment of Bollgard II. This finding supports our published notion for H. armigera that alleles conferring resistance to Cry2Ab may be present at detectable frequencies in populations before selection by transgenic crops.

Wireworms are a common soil-dwelling pest of maize, Zea mays L., in the midwestern United States. Wireworms are a problematic group to control and study due to the difficulty involved in identification. The objectives of this study are to identify this species complex of wireworms by using molecular diagnostic techniques and to reconstruct a phylogeny of economically important wireworm species. The cytochrome oxidase I gene of mitochondrial DNA was sequenced from >300 individuals. The species analyzed include all economically important members of the genus Melanotus Eschscholtz as well as Conoderus lividus (De Geer). The species that are indistinguishable in the larval stage were successfully separated using nucleotide p-distances, and sequence data were then used in phylogenetic analyses. The data presented here represent an initial phylogenetic hypothesis concerning economically important wireworms. Our results indicate that the molecular phylogeny of the mitochondrial cytochrome oxidase subunit I gene provides a fast and accurate method of separating wireworm species. By increasing the ease and accuracy of identification, we hope to facilitate further investigations into their biology and control.

Whiteflies, heteropterans in the family Aleyrodidae, are globally distributed and severe agricultural pests. The mitochondrial cytochrome c oxidase I (mtCOI) sequence has been used extensively in whitefly phylogenetic comparisons and in biotype identification of the agriculturally important Bemisia tabaci (Gennadius) whitefly. Because of the economic importance of several whitefly genera, and the invasive nature of the B and the Q biotypes of Bemisia tabaci, mtCOI sequence data are continually generated from sampled populations worldwide. Routine phylogenetic comparisons and biotype identification is done through amplification and sequencing of an ≈800-bp mtCOI DNA fragment. Despite its routine use, published primers for amplification of this region are often inefficient for some B. tabaci biotypes and especially across whitefly species. Through new sequence generation and comparison to available whitefly mtCOI sequence data, a set of polymerase chain reaction (PCR) amplification primers (Btab-Uni primers) were identified that are more efficient at amplifying ≈748 bp of the ≈800-bp fragment currently used. These universal primers amplify an mtCOI fragment from numerous B. tabaci biotypes and whitefly genera by using a single amplification profile. Furthermore, mtCOI PCR primers specific for the B, Q, and New World biotypes of B. tabaci were designed that allow rapid discrimination among these biotypes. These primers produce a 478-, 405-, and 303-bp mtCOI fragment for the B, New World, and Q biotypes, respectively. By combining these primers and using rapid PCR and electrophoretic techniques, biotype determination can be made within 3 h for up to 96 samples at a time.

The boll weevil, Anthonomus grandis grandis Boheman (Coleoptera: Curculionidae), is a serious pest of cultivated cotton, Gossypium hirsutum L., in the Americas, and reinfestation of zones from which they have been eradicated is of perpetual concern. Extensive arrays of pheromone traps monitor for reintroductions, but occasionally the traps collect nontarget weevils that can be misidentified by scouts. For example, the congeneric pepper weevil, Anthonomus eugenii Cano, and other superficially similar weevils are attracted to components of the boll weevil lure or trap color. Although morphologically distinguishable by trained personnel, the potential for misidentification is compounded when captured weevils are dismembered or partially consumed by ants or ground beetles that sometimes feed on them in the traps. Because misidentification can have expensive consequences, a molecular diagnostic tool would be of great value to eradication managers. We demonstrate that a cocktail of three primer pairs in a single polymerase chain reaction (PCR) amplify species-specific microsatellites that unambiguously distinguish the boll weevil from three other weevil species tested, including pepper weevil; cranberry weevil, Anthonomus eugenii musculus Say; and pecan weevil, Curculio caryae Horn. However, it does not distinguish the boll weevil from the subspecific “thurberia” weevil. A universal internal transcribed spacer primer pair included in the cocktail cross-amplifies DNA from all species, serving as a positive control. Furthermore, the diagnostic primers amplified the target microsatellites from various boll weevil adult body parts, indicating that the PCR technology using the primer cocktail is sensitive enough to positively identify a boll weevil even when the body is partly degraded.

Kale (Brassica oleracea L. acephala group) crops are common in northwestern Spain, where they are severely damaged by different insect pests. The damage notably affects the value of this crop because it is freshly consumed and fresh processed. The objective of this work was to determine the abundance and relative importance of the main Lepidoptera pests of Brassica crops for 6 yr at five localities in northwestern Spain and to relate the seasonal changes of larval populations and environmental conditions. Pheromone traps were used as a method of monitoring adults. Larval populations were monitored on kales by counting the larvae for several years and locations at different sample dates. Five species were found: Mamestra brassicae (L.); imported cabbageworm, Pleris rapae (L.); Pieris brassicae (L.); diamondback moth, Plutella xyllostella (L.); and Autographa gamma L. Proportions of each insect fluctuated over the years and in the different locations. M. brassicae was the most abundant (48.5% of the total of Lepidoptera species) followed by P. xyllostella (25%) and P. rapae (15%). The use of pheromone traps combined with plant sampling permitted the detection of two generations of M. brassicae. However, adult counts were not correlated to the number of larvae on plants.

In recent years, the number of wheat, Triticum aestivum L., fields heavily infested by Hessian fly, Mayetiola destructor (Say), has increased in the Great Plains of the United States. Historically, resistance genes in wheat have been the most efficient means of controlling this insect pest. To determine which resistance genes are still effective in this area, virulence of six Hessian fly populations from Texas, Oklahoma, and Kansas was determined, using the resistance genes H3, H4, H5, H6, H7H8, H9, H10, H11, H12, H13, H16, H17, H18, H21, H22, H23, H24, H25, H26, H31, and Hdic. Five of the tested genes, H13, H21, H25, H26, and Hdic, conferred high levels of resistance (>80% of plants scored resistant) to all tested populations. Resistance levels for other genes varied depending on which Hessian fly population they were tested against. Biotype composition analysis of insects collected directly from wheat fields in Grayson County, TX, revealed that the proportion of individuals within this population virulent to the major resistance genes was highly variable (89% for H6, 58% for H9, 28% for H5, 22% for H26, 15% for H3, 9% for H18, 4% for H21, and 0% for H13). Results also revealed that the percentages of biotypes virulent to specific resistance genes in a given population are highly correlated (r² = 0.97) with the percentages of susceptible plants in a virulence test. This suggests that virulence assays, which require less time and effort, can be used to approximate biotype composition.

The behavior of pests targeted by Bacillus thuringiensis (Bt) crops has been recognized as an important factor to define resistance management plans. However, most data do not include the possible impact resistance may have on the behavior of pests. To examine whether resistance influences behavior of European corn borer, Ostrinia nubilalis (Hübner) (Lepidoptera: Crambidae), neonates after exposure to dietary Bt, the responses of Cry1Ab-resistant, -susceptible, and hybrid (F1) lines from two populations were compared in laboratory tests by using artificial diet mixed with 10–50% Cry1Ab or non-Bt isoline corn, Zea mays L., tissue. In no-choice tests, resistant (and usually hybrid) lines were less likely to be irritated (i.e., to move away after physical contact with diet containing Cry1Ab) than susceptible larvae after exposure to diets containing 10–50% Cry1Ab leaf tissue. Early in the no-choice tests (8 h), neonate O. nubilalis also were more likely to move off of diets that contained 10% non-Bt tissue compared with diets with 25 or 50% non-Bt tissue. In agreement with results from no-choice tests, choice tests with 10 or 25% tissue indicated that resistant (and sometimes hybrid) larvae were more likely than susceptible neonates to be found on diet with Cry1Ab. For choice tests, differences among lines seemed dependent on the amount of Cry1Ab tissue incorporated into diets. Results suggest differences in behavior are a result of reduced physiological susceptibility to Cry1Ab and are not an independent behavioral component to resistance.

Stable fly (Diptera: Muscidae) populations in south central Ontario, Canada, first occur on dairy farms in late spring, grow exponentially throughout the summer, and are frozen back each autumn. We examined the extent of overwinter persistence on 22 dairy farms in a 55- by 60-km region north of Lake Ontario that spans four climatic zones. Our overwintering sampling of larval habitat identified three farms located in the southern section of the study region as potential overwintering refugia. Using sticky trap catches to identify the timing of first spring appearance at each farm, we then tested two models of how local farm populations are reestablished annually:1) stable flies disperse from local climatic refuges and colonize neighboring farms (the local source model); and 2) stable flies are carried into the study region by frontal weather systems (the distant source model). The timing of when stable flies first occurred at these farms supported a local source of dispersing colonists from a small proportion of local refuge farms. We discuss our results in terms of how yearly fluctuation in climate would affect refuge farm density in the region and how this, in turn, would shift the recolonization dynamic. Implications for controlling stable flies also are discussed.

The effects of dietary pH and viscosity on larval development of the New World screwworm, Cochliomyia hominivorax (Coquerel) (Diptera: Calliphoridae), were studied in the laboratory using a gel-based and a cellulose fiber-based media. The mean initial pH of the standard gelled diet was lower (6.5 ± 0.3) than that of the standard cellulose fiber-based diet (6.8 ± 0.6). As larval development progressed, these values decreased to below 6.0 possibly due to the accumulation of acidic metabolic waste. Diets formulated with higher initial pH (7.5) produced a slightly larger and greater number of pupae compared with those for untreated standard diets. The diets with lower than normal initial pH (4.0) produced significantly smaller and lower numbers of pupae compared with those produced by the untreated standard diets. The effects of viscosity were studied using the cellulose fiber-based diet at six different initial viscosity levels ranging from 2,000 to 7,000 cP. The viscosity level of the diet increased as the larval development progressed due to gradual loss of moisture from the diet. The diet viscosity levels of 4,000 and 5,000 cP proved superior for larval development showing significantly higher yield and larger pupae compared with those obtained from diets with initial viscosities of 2,000–3,000 or 6,000–7,000 cP. The cellulose fiber-based diet used for mass rearing should be formulated to an initial viscosity reading of 4,000–5,000 cP for optimal larval growth and development. Adoption of a diet formulated to provide a higher initial pH such as 7.5 may produce better quality insects.

A gel formulation formed by incorporating technical doramectin into a 10% hydroxypropyl methylcellulose aqueous solution was used to subcutaneously inject steers at varying dosages. Doramectin serum concentration of steers receiving 600 µg (AI)/kg body weight declined from 21.9 ppb at 0.5 wk to below detectable at 8 wk postinjection. The 1,200 µg (AI)/kg injection resulted in serum concentrations of 29.1 ppb at 0.5 wk and declined to 0.5 ppb at 8 wk postinjection. Both the 600 and 1,200 µg (AI)/kg injections provided 100% inhibition of index of fecundity (IF) in adult lone star ticks, Amblyomma americanum L. (Acari: Ixodidae) through week 8, after which inhibition declined to 79.4 and 45.3%, respectively, during the 12th week posttreatment. For steers treated at 600 µg (AI)/kg, mortality of adult horn flies, Hematobia irritans L. (Diptera: Muscidae), declined from 16.9% during week 2 to 3.1% during week 7 postinjection. The blood from steers treated at 1,200 µg (AI)/kg resulted in a similar decline in mortality of blood fed adult horn flies from 29.4% during week 1 to 4.0% during week 7. The 600 µg (AI)/kg treatment provided complete control of larval horn flies in the manure for 9 wk, whereas the 1,200 µg (AI)/kg injection gave complete control for 14 wk posttreatment. The doramectin gel formulation provided long-lasting delivery of doramectin to cattle and extended control of lone star ticks and larval horn flies. Such a simple and inexpensive formulation could be useful in tick eradication programs by reducing the frequency of gathering cattle.

Steers were treated with doramectin or eprinomectin by daily oral capsule for 28 consecutive days. The level of doramectin in the serum of steers treated at 200 µg/kg/d reached a maximum of 104.0 ± 22.1 ppb at day 21 and declined from 93.3 ± 20.5 ppb on the final day of treatment to below detectable by day 56. Steers treated at 50 µg/kg/d reached a maximum level of doramectin in the serum of 24.7 ± 1.2 ppb on day 21 and declined from 24.7 ± 0.6 ppb on the final day of treatment to less than detectable on day 42. Both doramectin dosages provided 100% control of estimated larvae (EL) of Amblyomma americanum (L.) (Acari: Ixodidae) throughout the 28-d treatment period. Daily oral treatment with eprinomectin at a dosage of 200 µg/kg for 28 consecutive days produced a maximum concentration in the serum of 41.6 ± 11.0 ppb at day 14. On the final day of eprinomectin treatment, the serum concentration was 38.3 ± 5.9 ppb. Seven days later at day 35, eprinomectin was not detectable in the serum. For steers treated at 50 µg/kg/d for 28 consecutive days, the serum level of eprinomectin reached a maximum of 10.0 ± 3.0 ppb on day 28 and was undetectable on day 35. Both eprinomectin dosages provided complete control of EL of A. americanum during the 28-d treatment period. Because eprinomectin is efficacious against A. americanum at lower serum levels in cattle and is eliminated from the serum at a more rapid rate than either doramectin or ivermectin, it provides advantages for use in applications such as the medicated bait for control of ticks on white-tailed deer and could have potential for use in the Cattle Fever Tick Eradication Program.