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We evaluated five herbivore-induced plant volatiles plus a male-produced pheromone as attractants for adult green lacewings in Washington apple orchards in 2008. We found at least five attractants or combinations of attractants were attractive to the three most abundant green lacewing species in our trials. Chrysopa nigricornis and Chrysopa oculata were attracted to the combination of methyl salicylate and iridodial with iridodial alone being the second best attractant. Chrysoperla plorabunda was found in lower numbers than C. nigricornis and C. oculata, but did exhibit a significant attraction to benzaldehyde. In mid-summer, we added the herbivore-induced plant volatile squalene to the study and found it to be exceedingly attractive, but only to male C. nigricornis. Whether alone or in combination, squalene attracted 4–5-fold more C. nigricornis than any other compound tested. Our data have revealed C. nigricornis to be an abundant orchard predator that can be readily monitored with squalene-baited traps. Despite the obvious promise of HIPVs in biological control programs, we urge caution in their deployment as large-scale attractants, at least until further studies have investigated potential disruption of natural enemy population dynamics.

The minute pirate bugs, Orius insidiosus (Say) and Orius pumilio (Champion) (Hemiptera: Heteroptera: Anthocoridae), are closely related species known to be sympatric in north Florida. Here, male and female genitalia, DNA sequences, and the effects of within- and between-species pairings on egg production and egg development were examined to develop a better understanding of the relationship between these two species. Interspecific matings between the two species did not result in viable progeny. Although there were gross similarities in the morphology of the male parameres (external genitalia) between the two species, the cone in O. pumilio was much broader with a greater spiral twist and the flagellum was longer than in O. insidiosus. Correspondingly, there were differences in the morphology of the copulatory tubes of the females of the two species. In O. insidiosus, the organ was somewhat longer than in O. pumilio and oriented parallel to the abdominal midline, while the copulatory tube in O. pumilio tilted slightly towards the midline. Additionally, the copulatory tube for O. pumilio included a sclerotized basal mound that was not present in O. insidiosus. These morphological differences suggest that successful copulation between these species could be difficult. In contrast to conspecific matings, interspecific matings resulted in few or no eggs laid over a period of two weeks and no viable progeny. Comparison of the 18S ribosomal gene ITS-1 sequences between the two species demonstrated only 91% homology. When yolk protein contents were examined to determine whether reproductive physiology had shifted to full egg production, interspecifically mated females contained amounts of yolk protein comparable to that in fed, but unmated females; this was less than 10% of the yolk protein previously found in fed and conspecifically mated females. These findings together confirm that O. insidiosus and O. pumilio are indeed two separate species.

Orius diespeter Herring was described in 1966 based on two specimens collected in western British Columbia, Canada. The original description relied mainly on color of the hemelytra to distinguish this species from Orius tristicolor (White), a related species common in western North America. Orius diespeter is shown here to have variation in color; hemelytra coloration ranges from entirely dark, to dark with contrasting white on the basal half of the corium. Specimens of O. diespeter with white markings are easily confused with O. tristicolor. Orius diespeter is separated from O. tristicolor by having shorter dorsal setae, a shorter copulatory tube, and a shorter flagellum of the paramere. The distribution of O. diespeter in North America is updated to include most of the northern states of the United States, as well as western and southeastern provinces and territories of Canada. We suggest that early to mid-1900′s records for O. tristicolor in the northeastern United States and eastern Canada ac...

The potato psyllid, Bactericera (=Paratrioza) cockerelli (Sulc) (Hemiptera: Triozidae), is a major pest of potato. We examined the role of chemical signals in sex attraction, assessing male and female response to male- and female-produced volatile chemicals. In laboratory olfactometer assays, potato psyllid males were attracted to odorants emitted from live females and from solvent extract of females. These results indicate that the female-produced chemicals responsible for attracting males may be isolated by means of insect extractions. Males were also attracted to volatile chemicals from males and extracts of males, providing the first example of male-male attraction in the Psylloidea. Males exposed simultaneously to odorants from conspecific females and males were preferentially attracted to female odorants, suggesting the presence of a female-specific sex attractant for males. Potato psyllid females avoided volatile chemicals emitted by females and extracts of females and by volatile chemicals emitted by males and extracts of males. Possible explanations for avoidance of conspecifics by females are discussed. This study is the first report of male attraction to volatile chemicals emitted by females and female extracts in the Triozidae and more specifically in the potato psyllid.

Potato tuber worm (PTW), Phthorimaea operculella (Zeller), is a world-wide pest of potato. In rustic stores, PTW larvae can infest 100% of stored tubers. Treatment of tubers in rustic stores with the PTW granulovirus (PoGV) has been demonstrated to protect stored tubers. This is the first study to show the effects of PoGV for protection of tubers stored in refrigerated warehouse conditions. Tubers were treated by dipping in aqueous suspensions of PoGV or water. An estimated 0.0819 larval equivalents of virus or 1.88×109 viral occlusion bodies were deposited on each kilogram of tubers. They were held at 16°C for 11 days before lowering the temperature by 0.5°C per day until 10°C was reached. The tubers were stored at this temperature for 53 days. Mean numbers of infested tubers at the end of the assay was affected by both pre-infestation rate and virus treatment. Mean numbers of infested tubers in the control treatment was 3 tubers per chamber higher than in the virus treatment providing strong ev...

The potato psyllid, Bactericera cockerelli (Sulc), is a pest of potato, tomato, and some other solanaceous vegetables and has also been incriminated in the transmission of a bacterial pathogen, Candidatus Liberibacter solanacearum, resulting in a serious disease known as ‘zebra chip’. Although there are several reports of fungal pathogens in psyllids, there are none from B. cockerelli, nor have any fungi been evaluated against it. Five isolates of fungi, one Beauveria bassiana, two Metarhizium anisopliae and two Isaria fumosorosea, were bioassayed against B. cockerelli on potato leaves under ideal conditions for the fungi. All applications were made with a Potter spray tower. With the exception of concentration-effect studies, all other applications were made using 107 conidia/mL in a 2-mL aqueous suspension. All isolates except B. bassiana, produced 95–99% mortality, corrected for control mortality, in adults 2–3 days after application of conidia and 91–99% in nymphs 4 days after application. Th...

The seminal work of Stern and his coauthors on integrated control has had a profound and long-lasting effect on the development of IPM programs in western orchard systems. Management systems based solely on pesticides have proven to be unstable, and the success of IPM systems in western orchards has been driven by conservation of natural enemies to control secondary pests, combined with pesticides and mating disruption to suppress the key lepidopteran pests. However, the legislatively mandated changes in pesticide use patterns prompted by the Food Quality Protection Act of 1996 have resulted in an increased instability of pest populations in orchards because of natural enemy destruction. The management system changes have made it necessary to focus efforts on enhancing biological control not only of secondary pests but also of primary lepidopteran pests to help augment new pesticides and mating disruption tactics. The new management programs envisioned will be information extensive as well as time sensitive and will require redesign of educational and outreach programs to be successful. The developing programs will continue to use the core principles of Stern and his co-authors, but go beyond them to incorporate changes in society, technology and information transfer, as needed.

The predatory true bug Anthocoris confusus Reuter is native to Europe and Asia. Scattered records for this species in North America date from 1929. In 2007–2008, we collected adults and nymphs of A. confusus from deciduous trees in western Washington State. This is the second North American record for A. confusus from west of the Rocky Mountains, and is the first record from the western United States. Specimens were collected from European beech (Fagus sylvatica; Fagaceae) and linden (Tilia sp.; Tiliaceae). The linden trees were heavily infested with the aphid Eucallipterus tiliae. The presence of adult and immature bugs, and the occurrence of the species at the collecting site in consecutive years, suggests that A. confusus is established at this location. We summarize North American records for A. confusus, briefly discuss host plant records, and list traits used to separate A. confusus from other Anthocoris spp. Additional predatory Heteroptera collected from linden and European beech included...

Poor understanding of natural enemy movement between cover crop and crop habitats has limited effective use of cover to enhance biological control of pest arthropods in agricultural systems. To address this problem, we used an egg-albumin immunomarker sprayed on a legume cover crop to monitor movement by generalist predators from the cover crop into the canopy of pear trees in a Central Washington State pear orchard. Generalist predators in four taxa (Heteroptera, Coccinellidae, Chrysopidae, Araneae) were collected from both cover crop and pear tree canopy, and tested using enzyme-linked immunonoassay (ELISA) methods to determine if the marker was present. In the three years of study, > 90% of arthropods collected from the cover crop had acquired the marker, indicating that we had excellent coverage and marking of arthropods with the solution. Between 17 and 29% (depending upon the year of study) of the approximately 2000 specimens collected from the tree canopy were also found to be marked, which is evidence that a percentage of the generalist predator community in the tree canopy had originated from or had visited the legume cover crop. These specimens included spiders and immature insects, which presumably colonized the tree either by walking up the tree trunk or (for spiders) by ballooning into the canopy. Some care must be taken in applying this technology or in interpreting results, due to unknown effects of the marker on arthropod behavior, and to questions of whether the marker might transfer from marked to unmarked insects as they interact in the field. Despite these caveats, the technology described here provides a new tool for assessing the effects of habitat management on movement of generalist predators in crop systems.

Beating tray and sweep net samples from apple and pear orchards in south-central Washington State were used to obtain information on life history and phenology of orchard-associated spiders. Cardboard shelters placed in the orchards in the fall and collected during the winter yielded information on spider overwintering. Data were obtained for 43 species in 28 genera and 12 families. The eight most abundant species were Pelegrina aeneola (Curtis 1892), Meioneta fillmorana (Chamberlin 1919), Oxyopes scalaris Hentz 1845, Theridion neomexicanum Banks 1901, Misumenops lepidus (Thorell 1877), Xysticus cunctator Thorell 1877, Philodromus cespitum (Walckenaer 1802), and Sassacus papenhoei Peckham & Peckham 1895. Each was represented by more than 690 specimens. Salticidae, Philodromidae, and Linyphiidae were represented by the largest number of species. Most species appear to have univoltine life cycles in the study area. Species matured at different times during the season between spring and fall. Twenty-seven species utilized cardboard shelters for overwintering, but some common spiders failed to do so and apparently use alternative locations. Some species overwintered in a broad range of developmental stages, whereas other species overwintered in only one or two instars.

The predatory true bugs Anthocoris antevolens White and A. musculus (Say) (Hemiptera: Heteroptera: Anthocoridae) are geographically widespread species in North America having broadly overlapping ranges. The two species are similar in coloration, size, host-plant use, and general appearance of the male genitalia. They are separated in keys by characteristics of the pubescence on the hemelytra: A. antevolens, pubescence long and dense; A. musculus, pubescence short and sparse. However, the extensive variability in this trait, in combination with similarities in other traits, has led to questions about whether A. antevolens and A. musculus are actually distinct species. We compared behavioral, morphological, and molecular genetic traits among specimens collected from four geographic regions, whose appearance would identify them as A. musculus (from three populations: Maine, Michigan, Montana) or as A. antevolens (from one population: central Washington). We included for comparison results for three populations of A. antevolens shown in earlier publications to differ in behavior, morphology, and mitochondrial DNA. Our results showed that identifications made using pubescence traits often failed to parallel variation in other characteristics, notably appearance of the male genitalia, mating success, and DNA sequences. In sum, our results indicate that variation among populations of A. antevolens in morphological, behavioral, and genetic traits may often exceed differences in those same traits between A. musculus and A. antevolens, if identifications are made using available keys.

The pear psylla, Cacopsylla pyricola (Forster) (Hemiptera: Psyllidae), and related psyllids are important pests of pear (Pyrus spp.) worldwide. Many of these pests are thought to be partially controlled by predatory insects. To improve our understanding of the predator species that attack pear psylla, we developed monoclonal antibodies (MAbs) against this pest for predator gut content studies. Mice were immunized with homogenates of nymphal, adult, and egg stages of pear psylla. A mouse immunized with nymph homogenate showed high activity against all three antigen types and was used for MAb development. From 952 hybridomas screened, 35 showed good activity to pear psylla and low activity against nontarget arthropods. Four MAbs were retained: two from immunoglobulin M (IgM)-secreting hybridomas, both with high activity against all stages of psylla except young eggs, and two immunoglobin G-secreting hybridomas, both with high activity against psylla eggs and gravid adult females. Using one of the IgM-MAbs, pear psylla remains were detected in the predatory bugs Anthocoris tomentosus Pericart (Heteroptera: Anthocoridae) and Deraeocoris brevis (Uhler) (Heteroptera: Miridae) in laboratory feeding trials. Digestion half lives typically exceeded 24 h and were dependent on meal size and predator life stage. Gut content analysis of 970 field-collected D. brevis and Anthocoris spp. showed that the proportion which fed on psylla averaged 59% and that percentage closely tracked the density of pear psylla nymphs during three seasons. The utility of these antibodies for the study of trophic interactions and habitat management in relation to biological control of pear psylla is discussed.

Pear psylla, Cacopsylla pyricola (Förster) (Hemiptera: Psyllidae), is a pest of pears, Pyrus L. (Rosaceae), throughout North America and western Europe. Previous studies in our laboratory showed that males of the overwintering form (winter morphotype) were attracted to volatile chemicals from pear shoots infested with post-diapause females. The current study shows that males of the summer morphotype also are attracted to volatiles from female-infested host material. Older females (8–10 d old) were significantly more attractive to males than younger (2–5 d old) females. Both virgin and mated females attracted male psylla. Volatiles from female summerforms attracted males even in the absence of host-plant material, and both living and freshly killed females were attractive. Our results indicate that female C. pyricola emit a volatile sex attractant, and the results of the studies further define the life-history conditions in female pear psylla that lead to male attraction.

A companion study showed that male pear psylla, Cacopsylla pyricola (Forster) (Homoptera: Psyllidae) were attracted to volatiles from pear shoots infested with post-diapause females. The present study compared the behavioral response of males to diapause and post-diapause females. Assays were done using a Y-tube olfactometer. We collected male and female winterform psylla from pear orchards at regular intervals between late October (early diapause) and late February (post-diapause). Female-infested shoots were not attractive to males until the February samples, coinciding with ovarian maturation and onset of mating in the field. A second set of assays was done in which we manipulated diapause status in the laboratory either by exposing psylla to a long-day photoperiod or by treating insects with an insect growth regulator, fenoxycarb. In the photoperiod experiments, both short-day and long-day males preferentially selected long-day (post-diapause) females over short-day (diapause) females. Fenoxycarb-treated males preferred fenoxycarb-treated (post-diapause) females over untreated (diapause) females; untreated males showed no preferences. Results support observations made elsewhere that male winterform pear psylla perceive and are attracted to volatile odors associated with pear shoots infested with post-diapause females.

Anthocoris antevolens White (Hemiptera: Heteroptera: Anthocoridae) is a widespread predatory bug in North America that exhibits substantial geographic variation in coloration, body measurements, size and shape of the male genitalia, pubescence, and sexual behavior. Earlier behavioral studies with three populations (including two populations that are sympatric in central Washington) showed that there was limited or no successful mating between insects from nonlike populations, despite vigorous mating attempts by males. The current study shows that males from those three populations diverge also in size and shape of claspers, length of the phallus, body measurements, and pubescence. Divergence extends to the two sympatric populations. Analysis of mitochondrial DNA shows that phenotypic divergence is associated with genetic divergence. Results reported here, in combination with the earlier published mating trials, support statements made elsewhere by us that A. antevolens is actually a complex of an unknown number of externally similar species.

Post-diapause winterform pear psylla, Cacopsylla pyricola (Forster) (Homoptera: Psyllidae), exhibit a highly clumped distribution in late winter in pear orchards. The behaviors leading to clumped distributions in this species are unknown, but could include aggregation for mating activities. Choice tests and assays with an olfactometer were done to test whether male psylla of the overwintering morphotype are attracted to pear shoots infested by post-diapause females and to shoots previously occupied by females. Paired choice tests in small arenas showed that males accumulated on pear shoots currently occupied or previously occupied by females if those shoots were paired with uninfested shoots or shoots previously occupied only by males. Assays with an olfactometer showed that males were attracted to volatile odors from female-infested or previously infested shoots. The exact source of the attractants (i.e., the female psylla, the pear shoot, or a combination of these sources) remains to be determined.

Seven native plants (four shrubs, two perennial herbs, and a woody vine) common in sagebrush steppe habitats of eastern Washington were sampled for predatory and parasitic arthropods. Sagebrush steppe is a common natural habitat adjacent to apple and pear orchards in that part of the state. Many predatory arthropod species found on the native plants also occur in adjacent orchards; some of these species were particularly abundant on the plants when they were flowering. Other species found on the native plants rarely occur in adjacent orchards. Orius tristicolor (White, 1879) was the most abundant of the natural enemies that also occur in orchards. Other predatory Hemiptera also found in adjacent orchards included Deraeocoris brevis (Uhler, 1904), Nabis alternatus Parshley, 1922, and Geocoris spp. Coccinellidae, Chrysopidae, and Hemerobiidae were not common on the native plants, but one or more species in each family that commonly occur in orchards were collected. Spiders found on the native plants that al...

Psyllids (Hemiptera: Pyslloidea) are phloem-feeding insects comprising eight Hemipteran families (Burckhardt and Ouvrard 2012). Several psyllid species are major agricultural pests, including pear psylla, Cacopsylla pyricola (Forster) (Hemiptera: Psyllidae), and potato psyllid, Bactericera cockerelli (Sulc) (Hemiptera: Triozidae). C. pyricola is a pest of cultivated pear, Pyrus communis L. (Rosaceae) because it produces abundant honeydew which causes fruit russetting, provides and medium for the growth of sooty mold and increases labor costs during harvest (Westigard and Zwick 1972). B. cockerelli is a pest of Solanaceous crops including potato and tomato and is the vector of “Candidatus Liberibacter solanacearum,” the pathogen associated with zebra chip disease of potato (Munyaneza 2012). Both psyllids are primarily controlled using insecticides, but current research efforts seek to develop ecologically based strategies to manage these pests. All psyllids (Hemiptera: Psylloidea) have an obligate relationship with the bacterial endosymbiont, Carsonella ruddii (Gamma Proteobacterium) (Thao et al. 2000). Carsonella is transovarially transmitted and is housed within specialized host cells called bacteriocytes which form aggregates called bacteriomes (Chang and Musgrave 1969, Thao et al. 2000). This endosymbiont produces essential amino acids that are lacking in the insect’s diet, and elimination of this endosymbiont using antibiotics leads to death of the insect (Baumann 2005, Nakabachi et al. 2006). Because Carsonella is vital to the survival of psyllids, novel control strategies for psyllid pests including C. pyricola and B. cockerelli could be developed by targeting this endosymbiont (Rio et al. 2004, Douglas 2007, Crotti et al. 2012). Paramount to discovering ways to manipulate Carsonella is the ability to obtain accurate estimations of Carsonella populations. A recent study by Cooper and Horton (2014) indicated that bacteriomes of female psyllids were larger than those of males, suggesting that females may harbor more Carsonella or other bacteriome-associated endosymbionts than do males. If so, then insect sex represents an important source of biological variation that must be accounted for when estimating Carsonella populations in psyllids. The objectives of our study were to 1) develop methods using fluorescence in situ hybridization and quantitative polymerase chain reaction (qPCR) to estimate Carsonella populations in C. pyricola and B. cockerelli, 2) compare Carsonella populations between female and male C. pyricola of varying ages (fifth-instar nymph to 21-d-old adult), and 3) document in both psyllid species the presence of Carsonella in varying ages of oocytes.

Anthocoris antevolens White (Heteroptera: Anthocoridae) is a widespread predatory bug in North America commonly associated with deciduous trees and shrubs. Unpublished observations showed that there is considerable geographic variation in male genitalia in this species and that the variation may lead to reproductive isolation among geographically separated populations. We show that male bugs from two sympatric populations in the Yakima Valley, Washington, one occurring on oak (Quercus garryana Douglas) and the other collected from willow (Salix sp.), differed in size and shape of the phallus and clasper. Mating trials showed that males from the oak source successfully inseminated females from the oak source in 75% of pairings; insemination success for males from the willow source paired with females from the willow source was somewhat lower at 62%. In nonlike crosses (oak × willow, willow × oak), males failed to inseminate the female in 100% of pairings, despite vigorous mating attempts by the ma...

Mating behavior was compared among three populations of Anthocoris antevolens White (Heteroptera: Anthocoridae). Two of the three populations are sympatric in the Yakima Valley, Washington, and are known to differ in length of the setae on the hemelytra and in characteristics of the male's genitalia. The third population occurred 120 km west of the Yakima populations. All possible inter- and intrapopulation crosses were studied. Males attempted to mate females in all crosses and were as rapid in initiating mating attempts in interpopulation crosses as in intrapopulation crosses. Mating success, defined to be insemination of the female, varied between 64 and 92% in intrapopulation crosses, but only between 0 and 21% in interpopulation crosses. The crosses between the two sympatric populations never resulted in insemination. Females in all crosses resisted mating attempts by males. Resistance behavior included hunching of the abdomen to prevent insertion of the clasper by the male, use of a hind leg to block male attempts to insert the clasper, and attempts to dislodge the male. For two of the populations, female resistance increased when paired with a male from a different population than when paired with a male from her population; females from the third population showed similar levels of resistance in interpopulation and intrapopulation crosses. Our results support the idea that A. antevolens is actually composed of an unknown number of reproductively isolated cryptic species.

Mating is necessary to bring about ovarian maturation in females of Anthocoridae and related taxa (Cimicidae). The objectives of this study were to determine how forced delays in mating affect extent and rate of oocyte development, duration of the preoviposition period, and levels of lipid reserves in three species of Anthocoris. Extent of oocyte development by unmated females differed among the three species. In unmated A. tomentosus, the basal oocyte failed to show any increase in size with increasing female age, whereas oocytes in unmated A. nemoralis and A. whitei exhibited some growth beginning 2 days after eclosion. One consequence of these differences among species is that a forced delay in mating (of 3 or 10 days) had less of an effect on A. whitei and A. nemoralis than on A. tomentosus, in terms of the length of the preoviposition period measured from the time of mating. Mated females of A. nemoralis and A. whitei grew larger oocytes than unmated females within 2 days of mating, whereas the same phenomenon took 4 days in A. tomentosus. Embryos became visible in the eggs of mated A. nemoralis and A. whitei 2–3 days after mating, compared with 5 days after mating for A. tomentosus. Mature eggs with egg caps were visible within 3, 4, and 6 days after mating for A. nemoralis, A. whitei, and A. tomentosus, respectively. In all three species, unmated females 10 days after eclosion had significantly higher levels of lipids allocated to nonreproductive tissues than similarly aged females that had been mated on the day of eclosion, suggesting that there was a trade-off between allocation of resources to eggs and allocation to somatic reserves.

Beneficial arthropods were sampled using beat trays in 10 pear and 8 apple orchards in Washington and Oregon, USA. One border of each orchard was adjacent to non-agricultural land (extra-orchard habitat). Beneficial arthropods were also sampled on 45 species of plants in extra-orchard habitats adjacent to study orchards. Orchard samples were taken monthly at 2 or 3 distances (depending upon size of the orchard) from the edge adjacent to extra-orchard habitat. An overall mean of 33.8 beneficial arthropods was taken per 26-tray sample (43.8% spiders; 37.8% predaceous insects; and 18.5% parasitoids). In May, July, and August, densities of beneficial arthropods declined significantly as distance from extra-orchard habitat increased. The decline was most evident in spiders and parasitoids; no trend was noted for predaceous insects. Most of the decline occurred between 0–60 and 60–120 m into the orchard, with no significant decline between 60–120 and 120+ m. These results are consistent with the idea that some taxa of beneficial arthropods moved into orchards from extra-orchard habitat. The most common predaceous insects in orchards were Miridae (32.3% of beneficial insects), Coccinellidae (11.1%), Chrysopidae (6.9%), and Hemerobiidae (5.7%). Important parasitoids were Trechnites insidiosus (7.6% of beneficial insects) and Pnigalio flavipes (2.3%). The families Linyphiidae, Salticidae, Oxyopidae, Philodromidae, Theridiidae, and Clubionidae together comprised 87.3% of total spiders. Twenty-two taxa of spiders and 22 taxa of beneficial insects collected in orchards were also collected on plant species outside of the orchards. The predatory insects Orius tristicolor , Deraeocoris brevis , and Nabis alternatus and the spiders Misumenops lepidus and Oxyopes scalaris were collected on the largest number of extra-orchard plant species. Common parasitoids of orchard pests were never collected from extra-orchard host plants.

Anthocoris nemoralis (F.) (Heteroptera: Anthocoridae) is native to the western Palearctic region and is among the most widespread geographically of all Anthocoris species in Europe. The predator originally established in North America as a consequence of at least one unintentional introduction occurring sometime before 1960 and an intentional introduction made in the early 1960s to control a non-native psyllid pest in pear orchards. Recent collecting efforts suggest that A . nemoralis has expanded its geographic range and host plant range. It is now found in western North America from southern California north into British Columbia. An eastern population located on the Niagara peninsula was reported in the late 1950s and was collected from that location at least until the late 1970s. Old and New World populations of A . nemoralis appear to prefer plant species that host psyllid prey. In North America, A . nemoralis has been recorded from 13 plant genera, of which 11 host psyllids. This percentage is much higher than the percentage of tree and shrub genera that host psyllids, suggesting that A . nemoralis in North America has preferentially colonized plants that host psyllids, including plants that do not occur naturally in the native Old World range of A . nemoralis . Several of the plant genera are hosts to newly arrived psyllids from South America and Australia. Concerns have been expressed that the introduced predator in North America may adversely affect native anthocorids, particularly species that occur in pear orchards: A. antevolens White, A . tomentosus Pericart, and A . musculus (Say). Overlap in plant genera used by four native anthocorids and the introduced A . nemoralis was highest between A . nemoralis and two mostly western species, A . antevolens and A . tomentosus . Detailed surveys of native tree and shrub species in North America that host psyllids should be done to determine actual extent of range expansion (geographical and ecological) by A . nemoralis , and to provide more information about competition between native anthocorids and A . nemoralis .

Effects of mowing frequency on ground cover composition and on numbers of predators, parasitoids, and select phytophagous arthropods in the ground cover of three reduced-insecticide pear orchards were determined. Concurrent samples taken in the tree canopy (with beating trays) and in the herbicide strips on the orchard floor (with pitfall traps) tested whether counts of natural enemies in these two habitats were also affected by mowing regime. A reduction in frequency of mowing from two to three times per month (= control) to once per month or once per growing season led to increased cover of grasses, broadleaf plants, and broadleaf plants in flower. Sweep net samples of natural enemies in the ground cover were dominated numerically by spiders (Araneae), parasitic Hymenoptera, and predatory Heteroptera, with lesser numbers of other taxa (Syrphidae, Neuroptera, Coccinellidae). Predators and parasitoids showed substantial increases in numbers associated with decreased mowing frequency. Sweep net counts of aphids, Lygus spp. (Heteroptera: Miridae), and leafhoppers/planthoppers, all potential prey of predators, also increased significantly with decreased mowing frequency. In the pitfall samples, only the European earwig (Forficula auricularia L.) (Dermaptera: Forficulidae) exhibited a change in counts associated with mowing treatment; numbers of earwigs in pitfall traps declined as mowing frequency decreased. For the beat tray samples, mean tray counts for most natural enemy taxa were higher in the less frequently mowed plots, but significantly (P < 0.05) so only for two taxa: spiders and a predatory mirid, Deraeocoris brevis (Uhler) (Heteroptera: Miridae). It remains to be determined whether biological control of pests in the tree canopy can be enhanced by manipulating mowing frequency. Questions raised by this study include whether there is extensive movement by natural enemies between the ground cover and tree canopy, and whether plot size affects the likelihood of showing that mowing frequency influences predator densities in the tree canopy.

Overwintering shelters composed of cardboard bands were placed on pear and apple trees located in central Washington state to monitor overwintering by predatory arthropods and by two pest taxa. A subset of bands was sampled at regular intervals between late summer and mid-December to determine when taxa began to enter bands. The remaining bands were left undisturbed until collection in mid-December to determine the numbers and types of arthropods overwintering on tree trunks in these orchards. More than 8,000 predatory arthropods were collected from bands left undisturbed until mid-December, dominated numerically by Acari (Phytoseiidae) [Galendromus occidentalis (Nesbitt), Typhlodromus spp.], Araneae, and Neuroptera (Hemerobiidae, Chrysopidae). Predatory mite numbers were higher in bands placed in apple orchards than bands placed in pear orchards. The Araneae were particularly diverse, including >3,000 spiders representing nine families. Less abundant were Heteroptera, including a mirid [Deraeoco...

Assays were done in the laboratory and field to monitor the response of Pacific coast wireworm,Limonius canusLeConte, to food baits. A glass-plate assay was used in laboratory trials to study movement of wireworm larvae through soil in response to several food baits, including germinating seeds of grains, rolled oats [Avenu sauvaL. (Poaceae)], carrot [Daucus carotaL. (Umbelliferae)], and potato [Solanum tuberosumL. (Solanaceae)]. Studies were also done with these baits to determine effectiveness under field conditions. In both laboratory and field trials, germinating seed of wheat [Triticum aestivumL. (Poaceae)] and barley [Hordeum vulgareL. (Poaceae)] ranked higher in response by larvae than the remaining food baits. In the glass-plate assays, 65–70% of wireworms contacted the wheat or barley seed baits within a 2-h assay period. Corn [Zea maysL. (Poaceae)] seed and sliced carrot were also effective, with 60% of larvae contacting the baits. Rice [Oryza sativaL. (Poaceae)], rye [Secale cerealeL. (Poaceae)], and potato were contacted by 30–45% of larvae. In the majority of assays, contact with the bait occurred within 30 min of the start of the assay. Trail lengths varied substantially among larvae (0–70 cm). The field studies showed that all food baits captured more wireworms than unbaited traps. A second assay conducted in the laboratory showed that moistened rolled oats were contacted with a higher probability if oats were aged 72 h following wetting (51% of larvae contacted the bait) than oats used immediately following wetting (28% of larvae). Field trials using baits composed of different volumes of rolled oats showed little evidence of a dose response in capture rates ofL.canus, although all baits captured more wireworms than unbaited traps. These studies showed thatL.canusis attracted to food baits in both laboratory and field trials, and that baits may prove useful to monitor populations of this pest in the field.

Potato psyllid, Bactericera cockerelli (Sulc) (Hemiptera: Triozidae), is an economic pest of solanaceous crops in North and Central America, and in New Zealand. Four genetic haplotypes of the psyllid have been identified in North America. Three of these haplotypes (Central, Western, and Northwestern) are common on potato crops within the major potato-growing regions of Idaho, Oregon, and Washington. Within this growing region, a weedy perennial nightshade, Solanum dulcamara (bittersweet nightshade), has been identified to be an important overwintering host and spring or summer source of psyllids colonizing potato fields. It is unclear whether bittersweet nightshade is a highly suitable host plant for all three haplotypes known to occur in the Pacific Northwest. The objective of the present study was to examine developmental traits and adult body size of all three haplotypes of psyllids reared on potato and bittersweet nightshade. Averaged over haplotype, development times were longer for psyllids reared on nightshade than potato. Duration of the preoviposition period, egg incubation requirements, nymphal development time, and total developmental time averaged 7.4, 5.9, 23.5, and 29.5 d on nightshade and 4.9, 5.5, 22.3, and 27.9 d on potato, respectively. The largest host effects were found for the Central haplotype, which exhibited a substantially extended (by over 5 d) preoviposition period on nightshade compared with potato. Averaged over host plant, nymphal and total development times of the Northwestern haplotype were longer (25.5 and 31.1 d, respectively) than those of the Western and Central haplotypes. The Northwestern haplotype was largest in overall body size, while the Central haplotype had the smallest overall body size, irrespective of host plant. Both sexes exhibited this trend.

Potato psyllid, Bactericera cockerelli (Sulc) (Hemiptera: Triozidae), is a serious pest of solanaceous crops in North and Central America and New Zealand. This insect vectors the bacterium that causes zebra chip disease of potato (Solanum tuberosum L.). Four distinct genetic populations, or haplotypes, of B. cockerelli have been identified. Three of the haplotypes may co-occur in potato fields in the Pacific Northwest of United States. Solanaceous weeds, including the perennial Solanum dulcamara (bittersweet nightshade), may provide refuge for psyllid populations which then migrate to potato crops. This study tested whether fecundity, fertility (% egg hatch), and adult longevity of potato psyllid were affected by host plant (S. dulcamara or potato) and whether these reproductive traits were similar among the three haplotypes that are most common in the Pacfic Northwest: Northwestern, Central, and Western. We hypothesized that the locally resident haplotype (Northwestern), which is known to overwinter extensively on S. dulcamara, would show relatively higher fitness on nightshade than the other two haplotypes. Fecundity differed significantly among haplotypes, with an average lifetime fecundity of 1050, 877, and 629 eggs for Northwestern, Western, and Central females, respectively. Egg hatch was significantly reduced in psyllids reared on bittersweet nightshade (61.9%) versus potato (81.3%). Adult psyllids lived longer on nightshade than on potato, averaging 113.9 and 108.4 d on nightshade and 79.0 and 85.5 d on potato for males and females, respectively. However, the longer life span of psyllids on nightshade than potato failed to lead to higher fecundity, because females on nightshade often ended egglaying well before death, unlike those on potato. There was no evidence for any of the fitness traits to suggest that the locally resident haplotype (Northwestern) performed relatively better on nightshade than the other two haplotypes. Lastly, we examined whether mating between psyllids of different haplotypes affected sperm transfer and egg hatch rates. Females of the Northwestern haplotype failed to produce viable eggs when mated by males of either the Western or Central haplotypes.

Cardboard bands were placed on pear and apple trees at each of three sites to act as overwintering shelters for spiders. Bands were placed on the trees in late August, at three heights on the tree. One-third of the bands was collected in January to determine what taxa of spiders overwintered in the shelters. The remaining bands at each site were collected and replaced at weekly intervals between late August and early December to monitor phenology of movement into the shelters. More than 2,900 spiders in 10 families were recovered from the winter-collected set of bands. Spiders were collected from all three sampling heights in the trees. The majority of spiders were juveniles, although adults of some Salticidae [especially Pelegrina aeneola (Curtis) and Phanias sp.] were fairly common. The dominant families were Philodromidae (primarily Philodromus spp.) and Salticidae (primarily P. aeneola), comprising 66 and 28%, respectively, of the total specimens. In the weekly collections, >5,600 bands were sampled during the study producing >6,000 spiders represented by 12 families and 30 identified genera. Dominant taxa in the weekly collected bands included Philodromus cespitum (Walckenaer), P. aeneola, Xysticus spp. (Thomisidae), Sassacus papenhoei Peckham and Peckham (Salticidae), Phidippus spp. (Salticidae), and Anyphaena pacifica Banks (Anyphaenidae). Of these taxa, Xysticus spp., S. papenhoei, and A. pacifica were very uncommon in the winter-collected bands, and we infer from these results that these spiders used the bands as temporary refuges only, and overwintered elsewhere. Data obtained from the weekly collected bands suggested that Philodromus spp., Dictyna spp., P. aeneola, and Cheiracanthium mildei L. Koch entered overwintering shelters during the interval between mid-October and mid- to late November. Pear and apple blocks at the same site were more similar in community composition than a common crop species at two different sites. More spiders were recovered from bands placed in the unmanaged and organically managed orchards than from apple and pear blocks that received insecticides during the growing season.

The influence of male and female body size on copulation duration and probability of insemination was determined for Anthocoris whitei Reuter allowed to mate at two temperatures. Copulation duration decreased significantly with increasing male length or increasing relative size (male length divided by female length). Female length had no effect on copulation duration. We interrupted copulation at 20 or 40 min at both 25 and 15 °C to determine the interacting effects of male size, temperature, and copulation duration on probability of insemination. Insemination probabilities increased with increasing male size, increasing temperature, and increased duration of copulation. Large males were more successful than small males at inseminating females at cool temperatures and for severely shortened copulations. Results are consistent with the hypothesis that males of this species experience physical difficulties either in achieving intromission or in forcing sperm through the aedeagus, and that larger body size in males lessens these difficulties.

Summary 1 Many apple growers in Washington State, U.S.A. use mating disruption (MD) for control of codling moth, Cydia pomonella (Linnaeus). Fewer applications of synthetic, broad-spectrum insecticides are made in MD orchards than in orchards under conventional (C) management. Spider abundance and diversity in MD, C and certified organic (O) orchards were compared. Spiders inhabiting the trees (arboreal), the understory vegetation, and the ground surface were studied. 2 Total arboreal spider density and total understory spider density were significantly higher in O orchards than in MD and C orchards. Many species occurred in both the trees and the understory. 3 Arboreal, visually orientated, hunting spiders and arboreal ambushers/runners were significantly more abundant in O orchards compared to C and MD orchards. Visual hunters were significantly more abundant in MD compared to C orchards. Numbers of spiders in two other guilds (web-makers and nocturnal hunters) showed no statistical differences with respect to orchard management type. 4 The highest density of ground surface-dwelling spiders occurred in one of the O orchards. Two C orchards had higher densities than any MD orchard. Ground surface species were distinct from those in the understory and the trees. 5 With one exception, an orchard's arboreal fauna was most similar to that of another orchard under the same type of pest management. Three exceptions were noted among comparisons of the understory faunas. The ground surface-dwelling fauna of one O orchard was distinctive, whereas that in the second O orchard was similar to the C and MD orchards. 6 Reduced use of synthetic, broad-spectrum insecticides in MD orchards did not result in arboreal spider densities comparable to those found in O orchards. A contributing factor may be that all species were univoltine. Spider populations may thus be severely reduced by even a small number of synthetic, broad-spectrum insecticide applications and the time required for recovery may be lengthy.

Occurrence of Anthocoris tomentosus Pericart, A. antevolens White, A. whitei Reuter, and Deraeocoris brevis (Uhler) in non-orchard habitats is described for areas adjacent to the pear growing regions of Yakima, WA. The four species were found on a number of tree and shrub species, especially willow, cottonwood, oak, alder, aspen, poplar, and bitterbrush. The four predators differed in degree of specialization. A. whitei was found almost exclusively on antelope bitterbrush (Purshia tridentata Pursh), apparently in close association with an unidentified psyllid. The other two anthocorids were more generalized, but differed in occurrence on some tree species. Adult and immature A. antevolens were common on oak, cottonwood, and poplar. Conversely, A. tomentosus was comparatively uncommon on these species, but was more abundant than A. antevolens on the neighboring willows; immatures of A. tomentosus were never recovered from oak. Adult and immature D. brevis were collected from several species not shown to support populations of Anthocoris spp., suggesting that the mirid is more of a generalist than the anthocorids. Anthocoris spp. were rare in apple orchards, whereas D. brevis was common there. A. tomentosus and A. antevolens showed distinct seasonal changes in plant use. Both species congregated on willow catkins beginning in March, but began to appear on summer hosts (oak, cottonwood, alder, aspen, poplar) in May and June. Some of the movement from willow may have been a result of the disappearance of a univoltine psyllid from this host plant. Traps composed of corrugated cardboard were placed at different sites to collect overwintering predators. A. antevolens and D. brevis were more broadly distributed among plant species than A. tomentosus or A. whitei (the latter restricted to pear and bitterbrush). A. antevolens was very abundant in traps collected from poplar and cottonwood, apparently because both tree species are important sources of late-summer prey for this predator. Other miscellaneous Anthocoridae and Deraeocoris spp. were collected while sampling, and lists of these species are provided. Orius tristicolor (White) was common at several sites, and was easily the most abundant anthocorid in overwintering traps at one intensively sampled orchard. This species was particularly abundant in traps placed in peach trees. Overwintering sex ratios of D. brevis, Anthocoris spp., and O. tristicolor were moderately to strongly female-biased.

The predatory bug Anthocoris nemoralis (F.) is a common species native to Europe that has become established in several areas of North America. The objectives of this study were to determine whether North American and European insects differed in aspects of mating activity and reproduction. We compared mating preferences, mating propensities, and some life history traits between a European (England) and North American (San Francisco Bay area) population of A. nemoralis; the North American population colonized the source locale apparently between 10 and 30 yr ago. In no-choice and choice assays, the insects showed no preference for mating with insects from the same source population. Both types of assays indicated that insects from the two sources differed in mating propensities: UK females were less likely to mate during a 30-min assay than females from California (irrespective of male source); and California males were less likely to mate than males from the UK (regardless of female source). Mor...

In laboratory studies, suspensions of killed and live ice-nucleating microorganisms were used to decrease the supercooling capacity of the winter form of pear psylla, Cacopsylla pyricola (Foerster) (Hemiptera: Psyllidae). Dry, untreated adults supercooled extensively before they froze at −22.7 °C. Application of 1000 ppm of a preparation of the killed ice-nucleating bacterium, Pseudomonas syringae Van Hall 1902 (Pseudomonadaceae), significantly decreased the adults’ supercooling capacity causing some individuals to freeze at temperatures as high as −3.9 °C. Topical application of several live microorganisms also reduced the supercooling capacity of adults significantly; Pseudomonas putida (Trevisan 1989) was the most effective, causing more than 80% of C. pyricola adults to freeze at −15 °C or higher. Furthermore, the temperature of crystallization of adults treated with P. putida remained significantly higher than controls for at least lid post-treatment. Application of ice-nucleating microorganisms also reduced the capacity of adults to survive short-term exposure to high subzero temperatures comparable to a mild frost. Realization of this approach for biological control of pear psylla will require the development of methods for the delivery of microorganisms to overwintering adults under field conditions.

Five weekly applications of Beauveria bassiana (Balsamo) Vuillemin, a genetically engineered isolate of Bacillus thuringiensis Berliner (Raven®), and aldicarb (Temik®) were compared for control of Colorado potato beetle, Leptinotarsa decemlineata (Say) in an irrigated desert cropping system. B. thuringiensis was applied using low and high label rates (1.17 and 7.01 ha -1 ). B. bassiana was applied at 5 x 10 13 spores ha -1 . Aldicarb (Rhone-Poulenc), applied at 3.37 kg a.i. ha - 1 provided the greatest beetle control and potato yields (45 metric tons ha -1 ), but overall lowest biodiversity in nontarget organisms, particularly predatory Heteroptera. Low and high rates of B. thuringiensis produced fair to excellent beetle control, yielded 33 and 40 metric tons ha -1 and enabled good survival in predatory Heteroptera and other nontargets. Plots treated with B. bassiana resulted in poor control of beetles prior to row closure after which fair to good control was achieved. Yield in the Beauveria-treated plots was 33 metric tons ha -1 and effect on biodiversity was comparable to the Bt-treated plots. The lowest number of over-wintering adult L. decemlineata was found in the plots treated with bacteria and fungi (0.68-0.84 adults/0.03 m -3 of soil) and the highest was found in control and aldicarb plots (3.44 and 1.84 adults/0.03 m 3 of soil). Aphids and leafhoppers showed higher densities in plots treated with microbial control agents, but were eliminated from plots treated with aldicarb.

Pear psylla, Cacopsylla pyricola (Foerster) (Homoptera: Psyllidae), is one of the key insect pests in North American pear production. In some growing areas, more than 50% of dollars spent to control arthropod pests in commercial pear are directed specifically at controlling this species. Control measures require accurate and timely information about dispersal, onset of egg-laying in spring, densities in the orchard, and age composition of the population. To meet these ends, a number of sampling methods have been developed to monitor pear psylla, the most common being (for pest management purposes) visual inspection of spurs and foliage for nymphs and eggs, and use of beat trays to monitor adults. Action thresholds have been developed for counts obtained with either method. However, threshold estimates are fairly narrowly defined, referring to a somewhat limited group of pear cultivars, type of injury to be prevented, and pest management program being used. Further refinement has been difficult because of an incomplete understanding of psylla's spatial distribution, seasonal changes in spatial distribution, and unknown or seasonally changing action thresholds. Beat trays and visual inspection of foliage have also been used to monitor pear psylla in various types of research projects, including studies of dispersal and biological control. Other sampling tools used in research include sticky traps, suction traps, and water pan traps. Density estimates obtained by these different sampling methods tend be positively correlated, albeit with high levels of unexplained variation. For counts obtained by sticky traps, much of the unexplained variation can be attributed to flight activity of the insect, which is known to depend (at a minimum) on sex, morphotype, reproductive status, time of year, time of day, leaf fall, and weather. Thus, if sticky traps are to be used in a pest management program for pear psylla, it must be recognized that counts on traps will include both density and (potentially large) behavioral components. I conclude this review with suggestions about the type of research that would improve monitoring techniques for this pest and assist eventually in developing a more effective control program.

Effects of photoperiod, time of year, temperature, and an insect growth regulator (fenoxycarb) on ovarian development rate in overwintering pear psylla, Cacopsylla pyricola (Foerster), were determined. Winterform pear psylla were collected from the field at intervals between October and February, and reared at 20 °C and one of three treatments: short-day photoperiod, long-day photoperiod, or short-day photoperiod + fenoxycarb. Insects were then dissected at intervals to score ovarian development. Baseline scores (i.e., ovarian development in the field on date of collection) increased very slowly between October and February. By mid-February, only about 20% of insects in the field were categorized as having postdiapause status based upon ovarian development. In the laboratory, time required for insects to reach postdiapause status decreased between the October and February collection dates. Number of days necessary for 50% of the long-day insects to reach postdiapause status was approximately 2 weeks in October, 6 days in December, and < 2 days in February. Short-day insects also required fewer than 2 days in February, but required > 2 weeks in the October and December samples. Our results suggested that insects collected in January and February had completed diapause but that ovarian development was subsequently prevented in the field by low temperatures. Fenoxycarb caused rapid ovarian development even in October-collected insects; rate of development was only slightly more rapid in the February-treated psylla.

In the Columbia Basin region of the Pacific Northwest, the green peach aphid, Myzus Persicae (Sulzer), is the predominant vector of the potato leafroll virus to potato plants, Solanum tuberosum L. Potato plants inoculated with the virus may develop tubers expressing net necrosis before or during storage, which can significantly reduce a crop's commercial value. In the field, prophylactic pesticides have been used traditionally to suppress aphid populations, thereby preventing inoculation and the advent of net necrosis. Out of the field, storage management of infected tubers has played a key part in managing the incidence of net necrosis. To identify potential tradeoffs between costs of spraying pesticides to control aphid populations and marketing activities involving storage management, data are analyzed from an extensive USDA-ARS field experiment. A probit model corrected for spatial correlation is used to predict the probability that individual tubers expressed net necrosis. The model is jointly conditioned on the inoculation interval (which is the time after planting that a plant was inoculated by viruliferous aphids), the tuber storage period, and the tuber weight. Consistent with previous empirical work, over the inoculation interval the probability of net necrosis monotonically increases to a maximum at ≍90 d and then tends to decrease thereafter. The empirical model reveals new results, showing that net necrosis probabilities increase with longer storage periods and are notably higher for larger tubers. Jointly, these findings enable us to identify pest management tradeoffs that can help reduce the incidence of net necrosis to acceptable levels.

Attempts at using Perillus bioculatus (F.) for control of Colorado potato beetle, Leptinotarsa decemlineata (Say), have been hampered by an incomplete understanding of the predator’s over-wintering biology. This study determined the effects of photoperiod and life stage of prey (Colorado potato beetle) on tendency for adult females to enter reproductive diapause, duration of the preoviposition period, and mortality of females. Perillus bioculatus showed an increasing tendency to enter diapause rather than to initiate reproductive activities as day length decreased. Females that were fed large beetle larvae (mid to late fourth instar) showed a significant increase in the number of individuals entering diapause compared with females that were fed a mix of beetle eggs and small larvae (first to third instar). Probit analysis was used to estimate the photoperiod that caused 50% of females to enter diapause; these estimates were 15L:9D for females feeding on large larvae, and 14.5L:9.5D for females feeding on eggs and small larvae. Females that were fed large larvae also showed a longer preoviposition period and had a slightly significant higher rate of mortality than those fed eggs and small larvae.

The effect of photoperiod on induction of reproductive diapause was determined for 3 species of predatory bugs inhabiting the pear and apple growing regions of the Pacific Northwest. Females of Anthocoris tomentosus Pericart, A. antevolens White (Anthocoridae), and Deraeocoris brevis (Uhler) (Miridae) were more likely to enter reproductive diapause (characterized by undeveloped ovaries and well-developed fat body) under short-day conditions than under long-day conditions. Critical photoperiods were between 16:8 and 15:9 (L:D) h in D. brevis, and between 15:9 and 14:10 [L:D] h in A. tomentosus . Results for A. antevolens were less clear because females in this species often failed to reproduce even under long-day conditions (18:6 and 16:8 (L:D) h). A small number of A. tomentosus and A. antevolens that failed to mature ovaries also failed to accumulate large fat reserves. Duration of the preoviposition period in nondiapausing insects was shortest in A. tomentosus (9 d), of intermediate duration in D. brevis (10–11 d), and longest in A. antevolens (12–13 d). Overwintering sex ratios were highly biased in the 2 anthocorids (79–95% female), and were moderately biased in D. brevis (60% female). Overwintering samples of 2 other anthocorid species, Orius tristicolor (White) and A. whitei Reuter, also were female-biased (100% female for both species). Dissections of females indicated that insects having undeveloped ovaries and well-developed fat body could be collected from the field most of the summer. Numbers of teneral adults in the dissections showed peaks in late July ( A. tomentosus and A. antevolens ) and in early August ( D. brevis ).

Several horticultural oils, an insecticidal soap, neem, garlic extract, a sugar ester, and a synthetic insect growth regulator were evaluated under laboratory conditions for their ability to inhibit pear psylla’s [Cacopsylla pyricola (Foerster)] feeding and oviposition. Supreme oil significantly reduced winterform oviposition rates in both choice and no-choice assays and reduced feeding rates in no-choice assays. Supreme oil also reduced oviposition rates of summerform females in choice tests but not in no-choice tests. In addition, summerform oviposition rates were reduced significantly by application of several mineral oils (Orchex 796E, 692, and WS2928) and garlic barrier to pear foliage in no-choice tests, and by all oils, garlic barrier, and M-Pede in choice tests. Summerform feeding rates were reduced by application of mineral oils. Data suggest that "summer type" oils and other compounds may have utility in pear psylla management programs by decreasing feeding and oviposition.

Eight potato (Solanum tuberosum L.) lines and a control (cv. Russet Burbank) were screened for suitability to Colorado potato beetle, Leptinotarsa decemlineata (Say) (Chrysomelidae), and for defoliation levels in the field to determine whether laboratory-obtained measures of performance are useful for predicting defoliation. Several lines caused reduced larval growth rates and survival compared to the control. Forty-eight hour weight gains by fourth instar larvae, after adjustment for consumption rates, were reduced on three lines, suggesting that these lines had antibiosis-like effects. Lines having very low suitability in the laboratory showed very low defoliation levels in the field, whereas lines that were highly suitable in the laboratory tended to suffer extensive defoliation in the field. Correlation analyses suggested that fourth instar growth rates or larval survival rates are useful measures for predicting defoliation in the field.

Adult pear psylla, Cacopsylla pyricola (Foerster), were monitored with beat trays, yellow sticky traps, and clear sticky traps for 2 yr at 3 orchards to determine whether a general relationship exists between tray counts and sticky trap catch. Samples were also categorized according to morphotype of the insect (summerform versus winterform), diapause status of winterforms (diapausing versus postdiapause and reproductive), and sex of the insect. Most (42 of 48) of the samples indicated that trap catch varied significantly with tray count (by linear regression analysis). However, aside from the fall winterform generation, no general relationship between trap catch and tray count was noted. Results suggest that sticky trap counts often had a large behavioral or activity component that obscured density effects. These effects were especially noticeable in the spring winterform generation and the summerform generation. Factors affecting sticky trap catch included sex of the insect, reproductive status, trap color, insect age, and leaf fall. We suggest that these factors, as well as others not explored here (e.g., weather), contributed to the lack of a general relationship between tray and trap counts. Previous work indicates that either method predicts damage to the tree; thus, for pest-management decisions, both sampling methods are useful. However, for more precise questions about absolute densities of adults, we suggest that beat trays should be preferred.

Food web ecologists have long sought to characterize the trophic niches of animals using stable isotopic analysis. However, distilling trophic position from isotopic composition has been difficult, largely because of the variability associated with trophic discrimination factors (inter-trophic isotopic fractionation and routing). We circumvented much of this variability using compound-specific isotopic analysis (CSIA). We examined the (15)N signatures of amino acids extracted from organisms reared in pure culture at four discrete trophic levels, across two model communities. We calculated the degree of enrichment at each trophic level and found there was a consistent trophic discrimination factor (~7.6‰). The constancy of the CSIA-derived discrimination factor permitted unprecedented accuracy in the measurement of animal trophic position. Conversely, trophic position estimates generated via bulk-(15)N analysis significantly underestimated trophic position, particularly among higher-order consumers. We then examined the trophic hierarchy of a free-roaming arthropod community, revealing the highest trophic position (5.07) and longest food chain ever reported using CSIA. High accuracy in trophic position estimation brings trophic function into sharper focus, providing greater resolution to the analysis of food webs.

The insect growth regulator fenoxycarb prompts ovarian development in diapausing winterform pear psylla, Cacopsylla pyricola (Forster) (Homoptera: Psyllidae). We applied fenoxycarb to caged psylla in September, November, and December to test whether premature ovarian development reduced overwintering survival, spring fecundity, or spring longevity. Fenoxycarb prompted ovarian development in all treated psylla, with the largest effects occurring in the September-treated insects. Recovery of live psylla in spring was 46-95% in treated insects and 72-92% in controls; overwintered insects from the fenoxycarb treatments survived field temperatures below -20°C despite having had mature ovaries. Fecundity and longevity of psylla were the same in treated and untreated insects, indicating that overwintering with mature ovaries did not cause reduced spring egglaying capacity. Several treated insects each deposited over 1900 eggs and survived more than 120 days. Due to their more advanced development, treated insects had higher oviposition rates than controls during the first 5 days after removal from the field. The largest impact on spring fitness was due to the effects of fenoxycarb on egg hatch. Eggs deposited on clean foliage by September-treated females were less likely to hatch than eggs deposited by controls, suggesting that fenoxycarb affected developing eggs within the female. Prospects for using fenoxycarb in fall to control pear psylla appear to be limited.

Overwintering pear psylla, Cacopsylla pyricola (Foerster), were misted with water or with one of several dilute solutions of water and surfactant, and then exposed to a range of subzero temperatures for 24 h. Misted psylla had significantly greater mortality than unmisted controls. Increases in mortality occurred at temperatures as warm as −6°C, a temperature well within the range of conditions in the field. At extreme low temperatures (−18°C) there was virtually no mortality in the unmisted controls, whereas mortality approached or reached 100% in several of the misted groups. Temperatures necessary to kill 50% of insects estimated for topically treated psylla ranged between −2.6 and −12.7°C for surfactant-treated insects, and below −18°C for water-treated or control insects. The possibility of using surfactants and water for control of overwintering pear psylla is discussed.

Pear psylla, Cacopsylla pyricola Forster (Homoptera: Psyllidae), was flown in the laboratory to test hypotheses suggested by field observations. Flight durations of the same insects flown on two different days were highly correlated, suggesting that there were biological differences among insects in flight tendencies. Flight durations were similar between summerform and winterform morphotypes. Flight frequencies and durations increased between September and November collections of winterforms, results that are consistent with field observations. Long-duration (60+ min) flights were three to four times as frequent in winterforms restricted to senescing pear foliage compared to insects provided access to pear seedlings. Winterforms collected during the fall flight period from a pear orchard and an adjacent apple orchard (an overwintering habitat) showed similar flight durations. There was no correlation between flight durations and any of five body and wing measurements; body size of winterforms increased between September and November. It has been proposed elsewhere that much of the fall movement into adjacent non-pear habitats by winterforms is due to short duration non-migratory flights rather than to a true migratory flight. The lack of differences between apple- and pear-collected winterforms may be consistent with this hypothesis.

The psyllid Bactericera maculipennis (Crawford) (Hemiptera: Triozidae) often cohabits field bindweed (Convolvulus arvensis, Solanales: Convolvulaceae) and other plants with the congeneric psyllid, Bactericera cockerelli (Šulc), in the Pacific Northwestern United States. Bactericera cockerelli is a vector of "Candidatus Liberibacter solanacearum," the pathogen associated with zebra chip disease of potato (Solanales: Solanaceae). Because B. maculipennis and B. cockerelli both naturally occur on certain plants, we surveyed B. maculipennis adults collected from Washington and Idaho for presence of "Ca. L. solanacearum" to determine whether this psyllid also harbors this pathogen. Liberibacter was present in 30% of field-collected B. maculipennis and in 100% of colony-reared psyllids. Sequences of 16S rDNA and microsatellite markers revealed that "Ca. L. solanacearum" from B. maculipennis was closely related to Liberibacter haplotype B from B. cockerelli. Results of laboratory assays demonstrated that Liberibacter can be transmitted between B. cockerelli and B. maculipennis on plants within the Convolvulaceae. Potato plants challenged with Liberibacter-infected B. maculipennis did not become infected, apparently because potato is not a suitable host for the psyllid. We therefore conclude that B. maculipennis is not a direct threat to potato production, despite its association with Liberibacter. We are the first to report that "Ca. L. solanacearum" is associated with a psyllid other than B. cockerelli in North America. Results of our study demonstrate the importance of understanding the complete ecology of psyllids-including interactions with other psyllids on non-crop hosts-in predicting what crops or regions are potentially susceptible to the spread of Liberibacter.

Pear psylla, Cacopsylla pyricola Foerster, adults that had contacted substrates treated with the insect growth regulators fenoxycarb or pyriproxyfen were allowed to oviposit on untreated plants. Eggs from treated insects had a reduction in hatch for up to 2 wk after treatment. The reduction was dependent on duration of contact with the treated surface. A pyriproxyfen-impregnated yellow tape has been developed and may assist in an attract-and-sterilize approach to management of pear psylla. Contact durations of as little as 5 s with this product reduced egg hatch in psylla for 1 wk after exposure.

Sticky trap catch of pear psylla,Cacopsylla pyricola Foerster, is male biased during the reproductive generations, but not the diapausing generation. In cage studies, we monitored movement by male and female pear psylla between host plants, and tested whether reproductive and diapausing psylla exhibit similar rates of movement. We also experimentally varied sex ratio to determine whether sex ratio affected movement. Male-biased sex ratios prompted increased movement off of the original host by male psylla of the reproductive generations; no such effect was noted for diapausing insects. We interpret these results to indicate that male movements increased under male-biased conditions due to mate-searching activities. There was also evidence in two experiments that severely male-biased sex ratios prompted movement off of the original host plant by reproductive females; this effect may have been due to harassment of ovipositing females by males.