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The abundance of mymarid parasitoids attacking the two-spotted leafhopper (Sophonia rufofascia [Kuoh and Kuoh]), a polyphagous pest recently adventive to Hawaii, was monitored using yellow sticky cards deployed in several areas on the islands of Kauai and Hawaii. The yellow cards captured Chaetomymar sp. nr bagicha Narayanan, Subba Rao, & Kaur and Schizophragma bicolor (Dozier), both adventive species, and Polynema sp. Haliday, which is endemic to Hawaii (Hymenoptera: Mymaridae). The former two species were most abundant at all sites. On Kauai, there was a negative correlation between the captures of C. sp. nr bagicha and those of Polynema sp. Throughout the season, the increase in parasitoid numbers generally followed the increase in leafhopper numbers. C. sp. nr. bagicha and S. bicolor showed distinct habitat preferences. Removal of Myrica faya Aiton, an invasive weed that is a highly preferred two-spotted leafhopper host, decreased the overall numbers of captured parasitoids, but led to a twofold increase in the ratio of trapped parasitoids/hosts in weed-free areas.

The leafhopper Sophonia rufofascia (Kuoh & Kuoh) is a recent invasive pest attacking a wide variety of plant species in Hawaii. We surveyed the distribution and parasitism of its eggs in a number of natural and agricultural habitats on the islands of Kauai, Oahu, and Hawaii. Egg density was fairly low, with egg distribution affected both by plant species and plant habitat. Approximately 40% of S. rufofascia eggs, averaged over all plants and sites, were parasitized by Chaetomymar sp. nr. bagichi Narayanan, Subba Rao, & Kaur; Schizophragma bicolor (Dozier); and Polynema sp. Haliday (Hymenoptera: Mymaridae). Percentage parasitism varied widely among different plant species and habitats. C. sp. nr. bagichi was the most abundant and widely distributed species, but the parasitoid guild varied depending on plant and on habitat. The implications of these results on decisions regarding classical biological control of twospotted leafhopper in Hawaii are discussed.

We performed a series of laboratory experiments to determine the effects of shade, soil moisture, and soil compaction on the selection of pupation habitats by wandering late-instar Oriental fruit flies, Bactrocera dorsalis (Hendel). Larvae showed a strong preference toward pupating in shaded rather than brightly lit areas, in moist rather than dry soil, and in soil with larger particle sizes. These behavioral preferences are likely to lead to clumped distribution of Oriental fruit fly pupae in natural habitats. The implications of this for management of localized populations by chemical and biological methods are discussed.

Mating behavior of post-diapause Colorado potato beetles, Leptinotarsa decemlineata (Say), was observed within an overwintering site, a rotated potato field, newly colonized potato plants, and under laboratory conditions. The influence of spring mating on beetle flight in the presence and in the absence of host plants was investigated using a computer-linked flight mill system. Diapause was terminated simultaneously in male and female beetles, and the first matings were observed as early as within the first 24 h after the beetles emerged from the soil (60–90 DD accumulated). The beetles mated within the overwintering site, the potato field, and the fields rotated out of potatoes. Mating status did not affect flight behavior of overwintered beetles; however, unfed beetles displayed higher flight activity than fed beetles. Most flight activity took place soon after flight muscle regeneration, and then declined sharply by the 5th day after flight initiation. Mating in or near overwintering sites soon after diapause termination might be an important factor in providing gene flow between insecticide-resistant and insecticide-susceptible Colorado potato beetle populations, and should be considered in designing resistance management plans.

Colorado potato beetle dispersal and reproduction was investigated under field and laboratory conditions. Movement and mating of newly emerged summer-generation Colorado potato beetle adults was monitored in the field using a mark-recapture technique, and beetle mating within experimental plots was recorded. The number of degree-days (DD) required for the beetles to become reproductive was tested in an environmental chamber using 10°C as a developmental threshold. A computer-linked flight mill system was used to quantify the influence of mating on the flight behavior of male and female beetles. Adult dispersal started within the first 24 h after eclosion from the pupae, but a significant proportion of newly emerged beetles stayed close to the place of their larval development until reaching reproductive maturity. The beetles required at least 34 DD before mating produced viable offspring, and females did not start laying eggs until a minimum of 51 DD after eclosion. Mating had a pronounced effect on beetle flight, decreasing flight activity of the females and increasing flight activity of the males. Enhancing gene flow between beetles surviving on transgenic plants and susceptible beetles in refugia should be advantageous in managing beetle resistance to transgenic plants.

Laboratory experiments were conducted to compare relative fitness of strains of Colorado potato beetle resistant and susceptible to Bacillus thuringiensis subsp. tenebrionis Cry3A toxin. Net replacement rates and intrinsic rates of population increase were calculated for resistant and susceptible populations. During the experiment, susceptible males on average copulated 13.3 6 1.5 times, whereas resistant males copulated only 8.0 6 1.0 times. Susceptible females produced an average of 824.2 6 68.1 eggs and 590.9 6 58.5 larvae, which was significantly .484.6 6 48.0 eggs and 334.9 6 39.7 larvae produced by an average resistant female. As a result, both net replacement rate and intrinsic rate of increase were reduced for the resistant population. Furthermore, twice as many susceptible beetles as resistant beetles survived overwintering diapause. Our results clearly indicate that relative fitness of resistant individuals is reduced in the absence of B. thuringiensis in the environment. Therefore, relaxation of selection pressure through refugia and insecticide rotation will favor decrease in the frequency of resistant alleles in beetle populations.

Sperm precedence in the Colorado potato beetle, Leptinotarsa decemlineata (Say), was investigated using phosphoglucomutase (Pgm) allozymes as genetic markers. Females were mated to 2 males carrying different Pgm alleles, and the proportion of offspring sired by each male was determined by cellulose acetate gel electrophoresis. Our results indicate that Pgm alleles in the Colorado potato beetle are inherited in the Mendelian fashion, and there is no change in sperm utilization over time. We also were able to confirm that sperm precedence in this insect is incomplete, with approximately equal to 72% of the larvae fathered by males at the 2nd mating. Possible implications of incomplete sperm precedence for insecticide resistance management are discussed.

Adults of full-sib Colorado potato beetle families were separated into 3 groups fed on different diets: transgenic potato foliage, potato foliage treated with a foliar formulation of B. thuringiensis endotoxin (12.37 μg of Cry3A δ-endotoxin per 1 μl of mixture), and untreated potato foliage. After feeding for 3 h, all the beetles were placed on a computer-linked flight mill system. The number of beetles that flew, duration of each flight, and the number of flights for each beetle were recorded. Feeding on transgenic foliage had a strong negative effect on the proportion of beetles that flew, as well as the average number of flights per flying beetle. Mean flight duration was not influenced by the beetle diet, but interaction between family and diet was highly significant, with pronounced family effects observed for the beetles fed on standard and treated foliage. Beetles from families that performed the longest flights when fed on untreated foliage performed the shortest flights when fed on transgenic foliage. Suppression of beetle flight as a result of endotoxin ingestion could keep beetles within transgenic fields, thus increasing selection pressure toward development of physiological resistance. One possible way to reduce this pressure is to provide refugia for susceptible beetles in close association with fields planted to transgenic potato.

Laboratory strains of Colorado potato beetle, Leptinotarsa decemlineata (Say), physiologically resistant and susceptible to Bacillus thuringiensis (Berliner) subsp. tenebrionis Cry3A toxin were reared to adults on caged potato plants. Influence of three different diets (transgenic potatoes, regular potatoes, and regular potatoes followed by the transgenic potatoes) on beetle mortality, fecundity, and flight behavior were tested under laboratory conditions. A computer-linked flight mill system was used to quantify beetle flight, and dissections were performed to determine the level of flight muscle development. Susceptible beetles continuously fed on transgenic foliage suffered heavy mortality, did not develop flight muscles, and did not produce any eggs. Resistant beetles continuously fed on transgenic foliage were capable of flight and reproduction; however, it took them longer to initiate flight behavior, and their fecundity was lower than fecundity of other treatments. In both strains, detrimental effects became significantly less severe when the beetles were allowed to feed on regular foliage prior to toxin ingestion. In the resistant strain, ingestion of Cry3A toxin significantly increased flight activity, indicating that physiological resistance was probably reinforced by the behavioral escape from toxic environments. No such response was observed for susceptible beetles. When fed on regular foliage, resistant Colorado potato beetles engaged in significantly fewer flights than susceptible beetles. Behavioral differences between resistant and susceptible beetles observed in the present study are likely to affect gene flow between transgenic crops and adjacent refugia, and should be taken in consideration when designing resistance management plans for transgenic potato crops.

A recently synthesized kairomone blend, based on the volatiles produced by potato (Solanum spp.) plants, has been demonstrated to be attractive to both adult and larval stages of the Colorado potato beetle, Leptinotarsa decemlineata (Say) (Coleoptera: Chrysomelidae). It was subsequently formulated in a viscous inert carrier for field applications and showed potential for aggregating beetles in treated areas of the field. We investigated effects of this kairomone formulation on the potato aphid, Macrosiphum euphorbiae (Thomas) (Homoptera: Aphididae). The response of both winged and wingless adults to natural potato foliage and synthetic kairomone was tested in a Y-tube olfactometer. Aphid response to untreated potato foliage, foliage treated with the kairomone blend, and foliage treated with blank inert carrier also was tested in petri dishes. In addition, aphid densities on field plots treated with kairomone and blank inert carrier were compared with the control plots. The untreated potato foliage was found to be attractive to wingless, but not winged, potato aphids. In the olfactometer, the foliage treated with synthetic Colorado potato beetle kairomone was not attractive to either winged or wingless aphids. In petri dishes, aphids avoided leaflets treated with both kairomone formulation and its blank carrier. There was no statistical difference between any treatments compared in the field.

The two-spotted leafhopper, Sophonia rufofascia (Kuoh and Kuoh), is an exotic pest from South-East Asia that attacks a wide variety of plant species in Hawaii. Myrica faya Aiton is an aggressive exotic weed that displaces and excludes native plants in Hawaiian forests. It has been argued that because of the high nutritional quality of its foliage, M. faya might facilitate leafhopper invasion of native Hawaiian ecosystems that were originally dominated by the endemic tree Metrosideros polymorpha (Gaudichaud). In the present study, we quantified suitability of M. faya and M. polymorpha as ovipositional hosts for S. rufofascia. Overall, leafhoppers preferred to deposit their eggs into the foliage of M. faya. M. faya presence in the area did not affect leafhopper oviposition on M. polymorpha. Foliar pubescence provided good protection of hirsute morphotypes of M. polymorpha. At the same time, glabrous M. polymorpha morphotypes were quite suitable for leafhopper oviposition. There was no difference in the abundance of leafhopper eggs along a precipitation gradient. Our results confirm that invasion of native Hawaiian forests by the weed M. faya will facilitate their invasion by S. rufofascia. Because of the broad host range characteristic of the two-spotted leafhopper, this build-up may adversely affect a number of endemic plant species growing in native forests.

An effective lure-and-kill trap is a potentially important instrument in monitoring and controlling oriental fruit flies, Bactrocera dorsalis (Hendel). A number of experiments were performed in an orchard of commercial guava, Psydium guajava L., to determine how fly captures are affected by combining visual and olfactory stimuli, and by the timing of trap deployment relative to host phenology. Baiting sticky Ladd traps with hydrolyzed liquid protein significantly increased the number of captured flies. Mostly male flies were caught in the absence of mature guava fruit, whereas mostly female flies were caught when ripe fruit was abundant. These results suggest that an effective oriental fruit fly trap should include both visual and olfactory lures, and that proper timing of trap deployment can be an important factor in monitoring female abundance in oriental fruit fly populations.