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The abundance of predatory phytoseiid mites, Typhlodromus pyri, important biological control agents of spider mite pests in numerous crops, is positively influenced by the density of leaf trichomes and tuft-form domatia in vein axils. Identification of the genetic regions controlling both trophic levels could facilitate the improvement of predatory mite habitat in breeding programs. The abundance of T. pyri and non-glandular trichomes was measured in a segregating F1 family derived from the cross of the complex Vitis hybrid, ‘Horizon’, with Illinois 547-1 (V. rupestris B38 × V. cinerea B9), finding positive correlation among traits. High density genetic maps were used to localize one major quantitative trait locus (QTL) on chromosome 1 of Illinois 547-1 associated with both predatory mite abundance and leaf trichomes. This QTL explained 23% of the variation in phytoseiid abundance and similar amounts of variance in domatia rating (21%), domatia size (16%), leaf bristle density (37% in veins and 33% in blades), and leaf hair density (20% in veins and 15% in blades). Another nine QTL distributed among chromosomes 1, 2, 5, 8, and 15 were associated solely with trichome density, and explained 7–17% of the phenotypic variation. Combined, our results provide evidence of the genetic architecture of non-glandular trichomes in Vitis, with a major locus influencing trichome densities, domatia size and predatory mite abundance. This information is relevant for breeding grapevines with a more favorable habitat for biological control agents.

Government agencies develop invasive species management programmes assuming early detection is key to successful management. Some theoretical studies confirm this intuition, while others, which restrict sampling effort to be constant in time, suggest managers are investing too heavily in sampling to detect new local invader populations. We explore whether these optimal constant-effort strategies underplay the importance of early surveillance and determine how much changing sampling effort through time reduces total management costs. Using optimal control theory to calculate time-dependent surveillance policies that minimize the total cost of sampling, eradication, and damage by the invasive, we find that the best strategies often use intense early sampling, followed by reduced sampling effort. Intense early sampling can drastically reduce costs compared with constant-effort strategies if propagule pressure from outside the managed area is low. However, if new infestations arise from frequent independent introductions from an outside source, constant strategies are cost-effective. Synthesis and applications. For invasive species that are initially present, not frequently reintroduced into the managed area, and for which surveillance is reasonably cost-effective, we recommend a simple three-phase management programme that deploys intense early surveillance until the majority of undetected populations have been discovered, followed by medium effort until most of the heavily infested areas have been cleared of the invader and finally low long-term effort to prevent infestations caused by future introductions and spread from populations that escaped surveillance. This programme captures the majority of the economic benefits from varying sampling effort continuously through time.

Drosophila suzukii (Matsumura; Diptera: Drosophilidae) is one of the most serious invasive pests of berries and cherries worldwide. Several adult monitoring systems are available to time foliar application of insecticides with the expectation of detecting the presence of D. suzukii before they infest susceptible crops. We tested this by comparing four different trapping systems based on two homemade baits, apple cider vinegar (ACV) or fermenting dough, and two fermentation volatile-based commercial lures, Scentry and Trece. Traps baited with dough or Scentry captured more D. suzukii than traps baited with ACV or Trece in blueberries and traps baited with Trece in raspberries. In blueberries, traps baited with Scentry, Trece and dough provided 11-21 d of warning prior to first detection of fruit infestation. However, these traps were not as effective in summer floricane raspberries. The Scentry lure baited traps detected D. suzukii on the same week as the first detection of fruit infestation and other trapping systems detected the fly 4 to 11 d after the first detection, suggesting the need for an improved D. suzukii detection system in raspberries. Both synthetic lures (Scentry and Trece) were significantly more selective for D. suzukii than dough bait, although the selectivity of all four tested lures/baits were relatively low at

Of the major physical factors that influence insect seasonal ecology, moisture is least understood and least appreciated. It is our premise that experimental probing of insects from diverse zones and various habitats would reveal general patterns of insect responses to moisture that are as striking as those for photoperiod and temperature. Using the paradigms of photoperiod and temperature as ecophysiological determinants of insect seasonality, we hypothesize that moisture influences insect life cycles via one or more of three mechanisms-as a token stimulus for diapause, modulator of developmental or reproductive rates, or behavioral cue for vital seasonal events. For heuristic purposes, we offer each of these hypotheses in close association with approaches for testing their validity in insects that undergo dry-season dormancy. The approaches appear appropriate for examining the role of moisture in the life histories of terrestrial invertebrates other than insects, as well as plants and microbes that have a seasonal resting stage. Elucidating moisture's role in insect seasonal cycles is critical to the development of comprehensive phenological models, improved insect management systems, and identification of novel evolutionary mechanisms for adaptation to wet-dry seasons, especially in tropical, subtropical, and Mediterranean regions.

The rate at which obliquebanded leafroller, Choristoneura rosaceana (Harris), larvae vacated feeding sites in apple, Malus domestica Borkhauser (Rosaceae), trees was determined by monitoring infested terminal foliage under field conditions. The overwintering and summer generations of C. rosaceana were monitored in two orchards in 1997 and 1998. Larvae vacated terminal feeding sites relatively frequently because 50% of the sites during the overwintering and summer generations were vacant 34 ± 6 °d (threshold = 6 °C) and 53 ± 10°d, respectively, after sites had been marked. Vacancy rates increased from the beginning to the end of the summer generation in 1997 but remained relatively constant throughout the summer generation in 1998. The differences between the 2 years were probably because of less precipitation and lower availability of actively growing terminal foliage at the end of the summer in 1997 than in 1998. Differences in larval development did not seem to contribute to differences in vacancy rate. Recolonization of growing terminals was also studied in the field by removing C. rosaceana larvae from terminals only (1997) and the entire tree (1998). In 1997 and 1998, larval recolonization of terminals and trees occurred, because 6–8 d after larvae were removed populations in removal and adjacent control trees were not significantly different. Frequent larval movement to actively growing terminal foliage with sublethal insecticide residues may increase larval survival and could slow resistance development by providing a refuge for susceptible insects.

Plum curculio, Conotrachelus nenuphar (Herbst), feeding and oviposition on apples during spring was measured for 3 yr in a heavily infested orchard in New York State. A logistic model was formulated to relate cumulative fruit injury to cumulative heat units (degree-days base 10°C [DD10]) following petal fall. Cumulative plum curculio injury was well described by the model in the trees from which data for the model were collected. However, injury progressed faster and ended earlier in smaller trees at the same site and at a different site, probably because of differences in tree architecture. Field trials showed that protection of the fruit via insecticide residue was no longer necessary after the model predicted that 40% of the cumulative plum curculio oviposition and feeding cycle had been completed (171 DD10 after petal fall). Based on historical weather records, use of the model to schedule insecticide treatments would save 1 insecticide application nearly half the time compared with a standard of 3 insecticide applications. A delay between initial plum curculio feeding and oviposition, which coincides with the petal fall, phenophase, and steadily increasing damage, which is influenced by temperatures after petal fall was observed. The effectiveness of delaying insecticide treatments until the rate of plum curculio damage was rapidly increasing was compared with treatments applied at petal fall. Delaying the 1st insecticide application resulted in higher levels of damage compared with making the 1st treatment immediately after petal fall.

Insect populations tend to be patchy in distribution. Even when the mean population density is low, there may be local patches with high densities. As a result, estimates of mean populations may provide little information about the size or intensity of local patches within the sampled area. We compared the following 3 methods of estimating local population densities of insects: (1) with moving averages, a local mean population density is estimated as the mean of samples taken within a given radius of a central point, (2) with inverse distances, local means are estimated as weighted averages of samples; each sample is given a weight proportional to a power of the reciprocal of its distance from the center of the region for which the mean is to be estimated, (3) kriging is a geostatistical algorithm for estimating local means as weighted averages of samples. Weighting is based on the spatial covariance of the samples, or the degree to which samples that are near to each other are related. The first 2 methods are relatively easy to calculate but were unreliable when used with standard parameters to estimate local Japanese beetle grub densities. When an optimum radius was used with moving averages and an optimum exponent was used with inverse distances, the advantage of ease of calculation was lost, yet both methods were still inferior to kriging in providing accurate estimates of local means.

This study examined habitat use patterns by adult whiteflies, Bemisia argentifolii Bellows and Perring, in response to predators, Delphastus catalinae (Horn), at different spatial scales. When female whiteflies were confined to small arenas with leaf discs from which they could not escape, whiteflies significantly delayed settling on leaf discs when predators were present compared to when no predators were introduced. The presence of D. catalinae altered the vertical distribution of adult whiteflies (sex ratio = 1:1) on cucumber plants; adult whiteflies moved upward faster over time within the plant canopy when predators were present mainly on the lower leaves of the plants compared to whiteflies on plants without predators. Most D. catalinae remained in the lower parts of the plants during the experiment. Therefore, we inferred that female whiteflies more quickly moved to the upper plant strata to reduce the risk of predation of their progeny; this would induce subsequent movement of males seeking mates. Introduction of D. catalinae onto a cucumber plant with high whitefly density did not cause increased dispersal of adult whiteflies (sex ratio = 1:1) into neighboring uninfested plants. The results indicate that predator-avoidance behaviors by adult B. argentifolii differed at different spatial scales. The predator-avoidance behavior may have a negative impact at the within-plant scale by inducing more whiteflies to move into upper plant strata. However, the effect of predators on the among-plant dispersal of whiteflies was not significant.

Grapevine leafroll disease threatens the economic sustainability of the grape and wine industry in the United States and around the world. This viral disease reduces yield, delays fruit ripening, and affects wine quality. Although there is new information on the disease spatial-dynamic diffusion, little is known about profit-maximizing control strategies. Using cellular automata, we model the disease spatial-dynamic diffusion for individual plants in a vineyard, evaluate nonspatial and spatial control strategies, and rank them based on vineyard expected net present values. Nonspatial strategies consist of roguing and replacing symptomatic grapevines. In spatial strategies, symptomatic vines are rogued and replaced, and their nonsymptomatic neighbors are virus-tested, then rogued and replaced if the test is positive. Both nonspatial and spatial classes of strategies are formulated and examined with and without considering vine age. We find that spatial strategies targeting immediate neighbors of symptomatic vines dominate nonspatial strategies, increasing the vineyard expected net present value by 18% to 19% relative to the strategy of no disease control. We also find that age-structured disease control is preferred to non-age-structured control but only for nonspatial strategies. Sensitivity analyses show that disease eradication is possible if either the disease transmission rate or the virus undetectability period is substantially reduced.

Cold storage can be used to slow development, facilitate accumulation of the organisms and accommodate fluctuating demand for augmentative biological control agents. Previous research suggested the possibility of improving cold storage of Trichogrammatids by recurrent warming, so we subjected Trichogramma ostriniae juveniles within Ephestia kuehniella host eggs to either 2°C constant or to 2°C with twice-weekly recurrent warming for 3 h to 20°C. Parasitoid subsamples were allowed to mature for 1–9 days before placement in cold storage for up to 8 weeks. Parasitism by parentals, progeny emergence and fecundity and longevity of progeny were measured weekly for 8 weeks. Relative to constant 2°C, recurrent warming generally improved emergence, fecundity and longevity, and all the response variables were affected by the interaction of temperature regimen, parasitoid maturity class, and cold storage duration. This implies the utility of recurrent warming to improve egg parasitoid performance and for ex...

In this study we asked whether, in the context of a trap crop system, differential predation risks among plants influence host choice patterns of adult whiteflies, Bemisia argentifolii . We investigated whether adult whiteflies avoid natural enemies inhabiting poinsettia (a cash crop) and whether this behavior can be used to increase the movement of whiteflies to cucumber (a trap crop). The potential of cucumber as a trap crop was first evaluated and we found that significantly more whiteflies were attracted to cucumber when the whiteflies were released between the two plants. However, the accumulation of whiteflies on cucumber substantially diminished if the insects had first settled on poinsettia. Under such circumstances, we investigated whether movement of adult whiteflies to cucumber could be increased by creating conditions that would cause the whiteflies that had settled on poinsettia to leave the plant. A mechanical disturbance, consisting of shaking the plant, was first used to test this hypothesis. The shaking caused more whiteflies to leave poinsettia and move onto the trap crop, compared to undisturbed whiteflies. We then asked whether the presence of natural enemies on the cash crop could induce whiteflies to leave the cash crop and move onto the trap crop. Three natural enemies were tested: two predators, Amblyseius swirskii and Delphastus catalinae , and a parasitoid Encarsia formosa . The presence of D. catalinae on poinsettia induced significantly more whiteflies to disperse to cucumber compared to poinsettia with no natural enemies, whereas A. swirskii and E. formosa did not result in a significant increase. Predator avoidance behavior by adult whiteflies should be investigated further in the context of trap cropping and other crop-habitat alterations designed to help manage whitefly abundance.

Observations suggest that the summer generation of a native, tortricid leafroller, Choristoneura rosaceana (Harris) is scarce in undisturbed, wild habitats but often abundant in managed apple orchards. We conducted experiments to determine whether these differences are attributable to differential impact of natural enemies in these two habitats and/or differences in host plant suitability. Laboratory-raised C. rosaceana larvae were implanted in dogwood (Cornus spp.) dominated wild habitats and in apple orchards to investigate habitat effects on natural enemy inflicted larval mortality. The proportion of released larvae that established feeding sites on apple trees and dogwood plants were similar. Parasitism and predation were similar in both habitats, suggesting that resources required by natural enemies were not different in these two habitats. Relative rates of parasitism by some parasitoid species differed on dogwood and apple plants when both plant species occurred in wild habitats. There was evidence that some parasitoid species were differentially abundant between the two habitats. To test whether development time or pupal weight was affected by the food source, F1 generations of larvae collected in both habitats were fed with apple and dogwood in the laboratory. Initiation of pupation occurred 3 days later if larvae consumed dogwood compared to apple; however, the food source did not affect pupal weight. These results suggest that there are opportunities to enhance conservation biological control of C. rosaceana in apple orchards.

This study evaluated whether experience of Trialeurodes vaporariorum (Westwood) (Hemiptera: Aleyrodidae) on a poinsettia cash crop, Euphorbia pulcherrima Willd. ex Koltz (Euphorbiaceae), influences the effectiveness of an eggplant trap crop, Solanum melongena L. (Solanaceae). Two whitefly strains were tested: one was reared on poinsettia (poinsettia-strain) and a second was reared on bean [Phaseolus vulgaris L. (Fabaceae)] (bean-strain). We first determined whether host experience altered the preference of adult whiteflies for eggplant and their survivorship on poinsettia. Then, we determined whether changes in the preference and/or survivorship influenced the effectiveness of the trap cropping. Adult whiteflies from both strains consistently redistributed and settled on an eggplant trap crop in significantly higher numbers compared to poinsettia. The adult survivorship of the poinsettia-strain whiteflies was slightly higher on poinsettia than on the bean-strain. In research greenhouse experiments, we found that the trap cropping consistently resulted in a decrease in the density of the poinsettia-strain whiteflies on the cash crop compared to that in monoculture. However, higher adult whitefly survivorship on eggplant than on poinsettia could compromise its effectiveness as a trap crop in poinsettia. The effectiveness of trap cropping, as reflected by the whitefly density reduction on a poinsettia cash crop, was significantly smaller than the attractiveness of the trap crop, as indicated by the whitefly abundance on an eggplant trap crop.

Non-glandular trichomes on leaves or stems are strongly positively correlated with the abundance of many predatory phytoseiid mite species. Some perennial fruit crops have few or no trichomes and overcoming this limitation of leaf habitat for natural enemy mites could improve biological control of pest mites in agricultural crops. This study evaluated whether juxtaposing plants with and without trichomes will promote more abundant natural enemies throughout an ensemble of plants. We first asked whether the pattern of increased phytoseiid retention with higher trichome densities on a single leaf “scales up” to larger plantings. For three patch sizes (1, 4 or 16 plants) of two grape varieties inoculated with phytoseiids, no strong effect of patch size on Typhlodromus pyri Scheuten abundance was observed in the trichome-rich Baco plantings or in the trichome-free Dechaunac plantings. No predator populations established in Dechaunac plantings of any size. Second, we asked whether the addition of a plant with leaf trichomes within a row (“array”) of plants lacking leaf trichomes can increase phytoseiid density throughout arrays. In both a greenhouse and a field experiment, predatory mites moved onto and established on a neighboring plant only if that plant had trichomes; phytoseiids rapidly dispersed from trichome-free plants even when the plant was the one inoculated with predators. The overall number of phytoseiids decreased over time in ensembles that included both trichome-rich and trichome-free plants in the greenhouse and the field experiments, clearly indicating that for biological control programs to be successful, all plants must express trichomes.

Habitat complexity can mediate interactions among predators and herbivores and influences arthropod population density and community structure. The abundance of many predatory mites (Acari: Phytoseiidae) is positively associated with abundance of non-glandular trichomes. We hypothesized that (1) increasing the complexity (trichome density mimicked with cotton fiber patches) of the habitat that predatory mites encounter on leaves would reduce adult dispersal from plants, and (2) increasing habitat complexity would reduce the time that mites spend walking. Typhlodromus pyri Scheuten retention on plants increased linearly in the presence of trichome mimics; mites placed on plants lacking leaf trichomes showed a behavioral response that led to active dispersal. Phytoseiid retention increased with both fiber patch size and fiber density within patches. Moving fiber patches from the underside of the leaf to the upper leaf surface did not change phytoseiid retention but did alter egg distribution, suggesting trichomes do not exclusively influence phytoseiid behavior. Phytoseiid activity level as measured by the amount of time spent walking did not decrease with the addition of fibers. Overall, increasing habitat complexity in the form of non-glandular trichomes strongly reduced T. pyri dispersal behavior; the predatory mites showed a consistent preference for complex trichome-rich habitat that was manifest both rapidly and in absence of predators. Hence, the frequently observed pattern of population-level accumulation of phytoseiids on trichome-rich plants appears to be driven by a behavioral response to the presence and abundance of non-glandular trichomes on the leaf surface manifested in the level of dispersal and/or retention. The primary implication of phytoseiid-habitat interactions for biocontrol programs is that where plants have no trichomes, T. pyri will not establish. Whether this behavioral response pattern is a general response of phytoseiids to leaf trichomes or varies with species is a question that remains unanswered.

Trap cropping, though promising, has had little evaluation in greenhouses. This study evaluated eggplant, Solanum melongena L. (Solanaceae), as a trap crop for two whitefly species, Trialeurodes vaporariorum (Westwood) and Bemisia argentifolii Bellows & Perring (both Hemiptera: Aleyrodidae), on greenhouse poinsettia, Euphorbia pulcherrima Willd. ex Koltz (Euphorbiaceae). Because the two whitefly species co-occur in greenhouses, a common trap crop for both whiteflies is desirable. When adults were provided a choice between eggplant and poinsettia in a cage, 60% of B. argentifolii and 98% of T. vaporariorum were observed on eggplant after 3 days. However, when adults were given eggplant after first settling on poinsettia, only 38% of B. argentifolii were later found on eggplant, whereas 95% of T. vaporariorum moved to eggplant. In a greenhouse experiment, eggplant did not affect either the spatial distribution or density of adult B. argentifolii on poinsettias. In contrast, eggplant changed the spatial distribution of T. vaporariorum within 3 days by attracting and retaining the adults. However, the attractiveness of eggplant did not result in a reduced number of T. vaporariorum on poinsettias compared with poinsettias in monoculture. Adult T. vaporariorum mortality was high on poinsettias and this likely caused adult density on poinsettias in monoculture to decrease as fast as that under trap cropping. A simulation model was developed to examine how adult whitefly mortality on poinsettia influences trap cropping effectiveness. When whitefly mortality was high, simulated densities were similar to the experimental data. This reveals an unexpected factor, pest mortality on the main crop, that can influence the relative effectiveness of trap cropping. Our results indicate that eggplant will not work unilaterally as a trap crop for B. argentifolii. For T. vaporariorum, attraction to eggplant might be useful as a trap crop system when whitefly mortality on the main crop is not high.

Studies were conducted from 2002 to 2005 to determine the effectiveness of reduced-risk (RR) tactics for managing key pests in 50 commercial apple orchards (114 ha) in Michigan, North Carolina, New York, Pennsylvania, Virginia, and West Virginia; and 20 peach orchards (190 ha) in Michigan, New Jersey, Pennsylvania, and West Virginia. At each apple site, a block of up to 5 ha received a seasonal program of selective RR and organophosphate-replacement insecticides, with or without pheromones for mating disruption of key lepidopteran pests of apple (codling moth, oriental fruit moth, and obliquebanded leafroller) and peach (oriental fruit moth, lesser peachtree borer, and peachtree borer). A comparison block at each site with the same variet - ies and tree training was managed using each grower's standard program of conventional insecticides (STD). Pheromone traps for lepidopteran species were hung in all plots and monitored weekly. Foliar samples were taken during the season to estimate phytophagous and predator mite densities. Red sphere traps baited with fruit volatiles were used to monitor apple maggot adults in apple orchards. Fruits were inspected for insect damage at harvest, and graded according to USDA standards. Partial budget analysis was used to assess the net profitability of RR programs to produce apples and peaches for their intended market in each state. Fruit damage at harvest caused by direct fruit pests was generally low across all blocks and treatments. There were no statistically significant differences in fruit damage or mite populations between the RR blocks, with or without pheromones, and the growers' standards. Insecticide use patterns in the RR plots represented up to 88 and 78% reduction in the amount of active ingredient applied per hectare, and an 85 and 77% decrease in their Environmental Impact Quotient for apples and peaches, respectively. However, RR programs were more expensive and generally less profitable compared with growers' standard programs. Regression analysis estimated that RR apple programs with and without mating disruption were on average $465 and $144/ha more expensive, and $544 and $159/ha less profitable, respectively, compared with standard programs. RR+MD programs for peaches cost an average $314/ha more and returned about $284/ha less than STD peach programs. ResearcH

We exposed mass-produced Phytoseiulus persimilis to 5 °C or 10 °C for 0, 6, 12 or 18 days to determine the influence of cold on the fecundity and longevity of individual predators, on their dispersal and survival patterns following storage, and on the reproductive age structure in populations of females. When P. persimilis populations were tested shortly after harvest the distribution of reproductive age classes was consistently biased towards older and non-producing females, with overall average fecundity of ∼13 eggs and longevity ∼7 days. The number of live predators gradually declined as the length of storage increased at either 5 °C or 10 °C. In contrast, the capability of predators to disperse upward was only reduced after 18 days of storage at 5 °C. The proportion of reproductively young females increased in populations that survived 18 days of storage at either 5 °C or 10 °C, and this was reflected in significantly higher mean oviposition period and fecundity than in the remaining three treatments. Our results reveal that the ability of P. persimilis females to tolerate cold storage and starvation is strongly tied to their reproductive age and that reproductively young females are capable of tolerating prolonged exposure to low temperature and starvation without compromising their quality. Fecundity of P. persimilis assessed shortly after harvest met the expectations outlined in IOBC guidelines. We found a positive linear relationship between the directly measured total fecundity and the results of a short-term (5-day) IOBC fecundity test, indicating that the IOBC test reliably predicts the reproductive potential of P. persimilis females. However, the proportion of surviving predators did not meet IOBC guidelines.

Measuring natural enemy (NE) inflicted mortality presents a serious challenge in managed habitats, such as apple orchards, where the crop-plant is frequently treated with a wide range of insecticides. Toxic residues keep natural populations of pests at too low levels to sample and prevent the use of techniques in which laboratory reared insects are released directly on foliage and used to measure NE activity. Three methods to implant obliquebanded leafroller, Choristoneura rosaceana (Harris) (Lepidoptera: Tortricidae) larvae were tested: (1) larvae placed on potted apple trees, (2) larvae placed on excised leaves inserted in florists’ waterpicks and (3) larvae placed on branches placed into water filled Polyvinyl chloride (PVC) pipes. Use of potted trees allowed accurate estimation of NE inflicted mortality; however, this method was very labor intensive. The waterpick method required less labor, but it underestimated larval mortality caused by NEs. The use of PVC pipes to hold infested branches combined the benefits of the other two methods tested. This technique was simple to use and provided accurate estimates of NE inflicted mortality.

Natural enemy (NE) inflicted mortality of the obliquebanded leafroller, Choristoneura rosaceana (Harris), was compared in apple orchards treated with reduced-risk and conventional insecticides and in adjacent unsprayed wild habitats. We hypothesized that NE inflicted mortality would be greater in plots treated with reduced-risk insecticides and in the wild habitats. Laboratory-reared larvae were exposed to NEs by placing larvae in excised foliage into the experimental plots. Nine parasitoid species were recorded, but only Actia interrupta (Diptera: Tachinidae), and the Hymenoptera Oncophanes americanus (Braconidae) and Exochus albifrons (Ichneumonidae) were abundant. Total parasitism by Hymenoptera and Diptera was equal among treatments; however, the prevalence of Hymenopteran and Dipteran parasitoids appeared to vary among orchards. Higher numbers of predators were collected in wild habitats but predation levels were not significantly different among treatments. We found no evidence that NEs were limited by fragmentation of wild habitats. Furthermore, the wild habitats harbored several plant species that are hosts for C. rosaceana . Because NE induced mortality was similar in both insecticide treatments and in unsprayed wild habitats, it is difficult to ascertain whether these results are due to the toxicity of the insecticides in the two pesticide-programs or the ecology of the natural enemies. The combination of highly mobile natural enemies and habitats treated with toxic insecticides may have masked treatment-specific differences. Results from this study do not provide evidence that the use of reduced risk insecticides in orchard blocks interspersed among blocks treated with conventional insecticides will afford opportunities for biological control of C. rosaceana .

Pupae of Encarsia formosa were cold stored to determine the influence of low temperature and the duration of exposure on their development and mortality during storage, and on the pattern of eclosion following storage. Eclosion, the process of extraction of a pharate adult from the host scale, was prevented at temperatures below 10 °C although the pupae continued to develop even at 4 °C. The middle stages of E. formosa pupae appeared to suffer lower mortality due to chilling compared to early or late pupal stages. Detrimental effects of cold, expressed as pupal mortality, accumulated and increased as temperature was lowered and duration of storage extended. When compared to parasitoids that had not been stored, eclosion of E. formosa was advanced following storage at 10 °C as pupae continued to develop during storage, and delayed following storage at 4 and 7 °C, possibly due to high mortality of late pupal stages. To determine the influence of different storage regimes on eclosion, flight and parasitism, pupae of E. formosa and Eretmocerus eremicus were exposed to a continuous (7 °C) and an acclimation (12 °C for 7 days, followed by 7 °C) storage regime. All three fitness parameters declined with increased duration of cold storage and its harmful effects accumulated and increased over time. The patterns of decline for eclosion and flight relative to storage duration were different between the two storage regimes; acclimated pupae tolerated cold better. Unlike for eclosion and flight, the pattern of decline for parasitism was similar between storage regimes. Enhanced tolerance to cold could be attributed to acclimation and/or pupal development to a stage more tolerant to low temperatures. To assess the cumulative impact of cold storage on the biological control potential of the two parasitoids, we constructed a composite quality index model by combining results from eclosion, flight, and parasitism. The pattern of decline in the index relative to storage duration resembled the decline observed for parasitism. The composite model predicts fewer, but more realistic gains from the use of the acclimation regime than those predicted by individual models.

In New York, onion [Allium cepa L. (Alliaceae)] fields often border woods or other vegetable fields. Because onion maggot adults, Delia antiqua (Meigen) (Diptera: Anthomyiidae), spend a significant portion of their time outside of onion fields, surrounding habitat may affect patterns of fly activity and oviposition within onion fields. To better understand these patterns throughout the onion-growing season, first-, second-, and third-flights maggot adult (male and female) activity was monitored using yellow sticky cards. Half of the monitored fields bordered woods, whereas the other half bordered other onion or vegetable fields. Within all fields, yellow sticky cards were placed at five distances along a transect beginning at the onion field edge extending into the field center. First-flight male and female adult activity was greatest along onion field edges and was especially high along edges bordering woods. This pattern diminished during the second flight and was absent during the third. To determine if spatial patterns of onion maggot oviposition by first-flight onion maggots were similar to first-flight adult activity patterns, potted onion plants were placed in onion fields that bordered or did not border woods in late May and early June 2003. The number of eggs laid in the soil at the base of each plant was recorded. Unlike spatial patterns of first-flight adult activity, oviposition patterns were not affected by bordering habitat or distance from the field edge. Based on the activity of onion maggot adults in onion fields, future and existing control strategies should consider targeting first-flight adults along field edges rather than across entire fields, especially in fields that border woods. In contrast, based on spatial patterns of oviposition within onion fields, controls targeting onion maggot larvae should be applied on a fieldwide basis.

One component of developing a systematic approach for deployment of trap crops is to understand how the trap crop modifies pest behavior. Glossy-leafed collards, Brassica oleracea L. var. acephala (Brassicaceae), were evaluated as a potential trap crop for diamondback moth, Plutella xylostella (L.) (Lepidoptera: Plutellidae), because they are attractive to P. xylostella adults and are a poor host for P. xylostella larvae compared to cabbage, Brassica oleracea L. var. capitata . We used large field plots to measure the changes in adult, egg, and larval P. xylostella densities in cabbage when the trap crop was planted in the field. Furthermore, we planted the trap crop in dispersed and concentrated spatial arrangements to determine the impact of trap crop arrangement on the behavior of P. xylostella . In 2002, results showed that the presence of collards within a cabbage field reduced larval density on cabbage. In 2003, neither trap crop arrangement had a significant impact on P. xylostella larval density on cabbage. Adult moths aggregated in proximity to collards in 2002, but not in 2003. Egg and larval data in both years in all treatments showed that total oviposition was highest near a central release point, indicating that females lay many eggs before dispersing very far when suitable host plants are available. The mean direction of P. xylostella movement and oviposition from a central release point was not consistent or correlated to wind direction. Plant size of the trap crop in relation to the main crop and environmental factors may have been responsible for the inconsistent effectiveness of the trap crop.

Natural predation is an important component of integrated pest management that is often overlooked because it is difficult to quantify and perceived to be unreliable. To begin incorporating natural predation into sweet corn, Zea mays L., pest management, a predator survey was conducted and then three sampling methods were compared for their ability to accurately monitor the most abundant predators. A predator survey on sweet corn foliage in New York between 1999 and 2001 identified 13 species. Orius insidiosus (Say), Coleomegilla maculata (De Geer), and Harmonia axyridis (Pallas) were the most numerous predators in all years. To determine the best method for sampling adult and immature stages of these predators, comparisons were made among nondestructive field counts, destructive counts, and yellow sticky cards. Field counts were correlated with destructive counts for all populations, but field counts of small insects were biased. Sticky cards underrepresented immature populations. Yellow sticky cards were more attractive to C. maculata adults than H. axyridis adults, especially before pollen shed, making coccinellid population estimates based on sticky cards unreliable. Field counts were the most precise method for monitoring adult and immature stages of the three major predators. Future research on predicting predation of pests in sweet corn should be based on field counts of predators because these counts are accurate, have no associated supply costs, and can be made quickly.

A 3-year demonstration study was conducted in four western New York apple orchards to evaluate current approaches of sustainable pest management in representative commercial orchards. Pests that could be tolerated were regulated by natural antagonists, including predatory mites that were introduced to supplement endemic populations, while those with lower tolerance levels were managed with a schedule of selective pesticides, e.g., insect growth regulators and horticultural mineral oil. Pesticide application decisions (timing and materials) were made on the basis of current state extension guidelines, which involved a combination of protectant and threshold-based sprays determined through timely scouting and sampling procedures. Only non-toxic or minimally toxic pesticides to the principal mite and aphid predators were applied in the orchards. By the third season, effective conservation biological control of European red mite was achieved in all orchards, and fruit quality at harvest was equal or superior to that in comparison blocks managed using the growers’ conventional practices.

Plants with leaves having numerous trichomes or domatia frequently harbor greater numbers of phytoseiid mites than do plant with leaves that lack these structures. We tested the hypothesis that this pattern occurs, in part, with Typhlodromus pyri because trichomes increase the capture of pollen or fungal spores that serve as alternative food. Using a common garden orchard, we found that apple varieties with trichome-rich leaves had 2–3 times more pollen and fungal spores compared to varieties with trichome-sparse leaves. We also studied the effects of leaf trichome density and pollen augmentation on T. pyri abundance to test the hypothesis that leaf trichomes mediate pollen and fungal spore capture and retention and thereby influence phytoseiid numbers. Cattail pollen (Typha sp.) was applied weekly to mature ‘McIntosh’ and ‘Red Delicious’ trees grown in an orchard and, in a separate experiment, to potted trees of the same varieties. ‘McIntosh’ trees have leaves with many trichomes whereas leaves on the ‘Red Delicious’ trees have roughly half as many trichomes. With both field-grown and potted trees, adding cattail pollen to ‘Red Delicious’ trees increased T. pyri numbers compared to ‘Red Delicious’ trees without pollen augmentation. In contrast, cattail pollen augmentation had no effect on T. pyri populations on ‘McIntosh’ trees. Augmentation with cattail pollen most likely supplemented a lower supply of naturally available alternative food on ‘Red Delicous’ leaves and thereby enhanced predator abundance. These studies indicate that larger populations of T. pyri on pubescent plants are due, in part, to the increased capture and retention of pollen and fungal spores that serve as alternative foods.

A basic tenet of integrated pest management (IPM) is that many crop plants can tolerate some threshold level of leaf injury from foliar pests before the crop is affected. In practice, foliar pests are monitored, and pesticides are used only when pests reach a density that is thought to cause too much damage. Sound monitoring methods for many pests have been developed, but our understanding of plant responses to pests is weak. A problem is that pest thresholds are usually used independently for each pest, and do not take into account other factors that affect the crop. We propose that in apple trees; (1) foliar pest injury primarily reduces leaf carbohydrate production and effects of multiple pests are additive, and (2) the effects of foliar pests and other factors on the crop can be integrated by the balance of the tree's carbohydrate supply from the leaves to the demands for crop and tree growth. A dry matter production model developed by Lakso and Johnson in 1990 and subsequently expanded was tested as an integrator of the effects of pests, environmental variations, and cultural practices (initially crop load adjustments) on fruit development. The model simulated the measured effects of European red mites (Panonychus ulmi Koch) on apple fruit growth at different crop levels. Simulations suggest that a threshold response of fruit growth to foliar pests occurs with light crop load, but may not at high crop loads. This is in agreement with empirical studies of pest stress interactions with tree crop load. The model provides a plant-based integration of multiple foliar pests, environment and cultural practices of apples.

Phytoseiid mites, both in agricultural and natural systems, can play an important role in the regulation of herbivorous mites. Host plant traits, such as leaf pubescence, may influence the dynamics between predator and prey. In this study, we examined the influence of leaf surface characteristics (leaf pubescence and two-spotted spider mite webbing) on the behavior of two species of predatory mites, the generalist Typhlodromus pyri and the spider mite specialist Phytoseiulus persimilis. In laboratory trials, T. pyri females consistently spent more time and deposited more eggs on leaf discs from trichome-rich apple varieties compared to relatively trichome-poor varieties. A similar result was found when the choice involved trichome-rich and trichome-poor apple varieties planted into the same pot where leaves were allowed to touch so that the mites could freely move from leaf to leaf. To further explore the effect of structure created by pubescence and to remove possible confounding effects of chemical cues, we added cotton fibers to trichome-free bean leaves. T. pyri females consistently spent more time and deposited more eggs on the side of a glabrous bean leaf with artificial cotton fibers versus the side without added fibers. When given a choice between two densities of cotton fibers, T. pyri females consistently selected the highest density of available fibers in which to to reside and oviposit. T. pyri also preferred cotton fiber configurations in which it could move underneath and access the plant surface. The artificial pubescent leaf was also used to test the effect of leaf hairs and two-spotted spider mite webbing on the behavior of P. persimilis. P. persimilis females preferred residing and ovipositing on surfaces with cotton fibers or two-spotted spider mite webbing than on bean leaf areas without these structures. When presented a choice between cotton fibers or webbing, the behavior of P. persimilis females depended on the cotton fiber density. In a mixed-variety apple orchard, we investigated the relationship between leaf pubescence and phytoseiid density under field conditions. We found a highly significant, positive relationship between density of trichomes on leaves and abundance of T. pyri, whereas spider mite prey numbers were uniformly low and unrelated to trichome density. These field results suggest that the behavioral responses found in our laboratory experiments have population consequences.

Predaceous arthropods are frequently more abundant on plants with leaves that are pubescent or bear domatia than on plants with glabrous leaves. We explored the hypothesis that for some predatory mites this is because pubescence affords protection from intraguild predation. In laboratory experiments, we tested whether apple leaf pubescence protected Typhlodromus pyri eggs from predation by western flower thrips, Frankliniella occidentalis. To investigate the effect of pubescence further, we added cotton fibers to trichome-free leaves. We also determined whether webbing produced by Tetranychus urticae protected Phytoseiulus persimilis eggs from predation by F. occidentalis. Predation by thrips on T. pyri eggs oviposited on field-collected pubescent "Erwin Bauer" apple leaves was significantly less than on glabrous "Crittenden" apple leaves. Phytoseiid eggs oviposited in the cotton fibers were preyed upon significantly less than those on the trichome-free bean disk. Increasing the cotton fiber density from 5 to 20 fibers only slightly further reduced predation by thrips on T. pyri eggs. Thrips fed upon significantly fewer P. persimilis eggs oviposited in Te. urticae webbing than eggs oviposited on a surface that differed only in the absence of Te. urticae web. We conclude that a complex leaf topography reduces intensity of intraguild predation in this system.

A cornerstone of spatial ecology is the quantification of the patchy nature of animal and plant populations in space. By using spatial covariance, total covariance, and quantile variance, we found that patchiness of Japanese beetle grub populations varied more between years than between fairways at a central New York golf course. We also observed that populations tended to shrink and swell around patches with perennially low density, that locations with perennially low grub density were associated with high soil organic matter content, and that locations with frequently high grub density were associated with intense adult beetle activity in the vicinity.

Insect populations tend to be patchy, and the nature of the patches is a critical component of ecology. Predator-prey interactions, coexistence of competing species, survival of rare species as habitat is destroyed, and damage to crops are just a few examples of spatially-dependent ecological processes. For want of tractable quantitative approaches, understanding of spatial ecology has lagged far behind recognition of its importance. We assert that a quantitative foundation of a spatial ecology involves the reification of patches as objects of study. We introduce two new measures of patch dynamics: total covariance for comparing degrees of patchiness between populations, and quantile variance for quantifying the constancy of dispersion patterns through time. These new measures, in combination with the long-established spatial covariance from geostatistics, comprise a rudimentary toolbox for reification of patches and empirical field studies in spatial ecology.

To determine whether diverse populations and biotypes of Chrysoperla carnea (Stephens) (Neuroptera: Chrysopidae) can be mass-produced and stored under uniform conditions, we assessed reproduction in five North American populations, four from the carnea biotype and one from the mohave biotype. Non-diapause adults from the carnea biotype varied significantly in only one aspect of reproduction, viz., the preoviposition period, whereas the duration and rate of oviposition, as well as fecundity, did not vary significantly. Relative to the carnea populations, the mohave population typically had delayed oviposition and a lower rate of oviposition; however, its oviposition period was long, and thus its fecundity differed only from that of the most productive carnea populations. The shelf-life (= survival during storage, and subsequent survival and reproduction after storage) was evaluated for four populations of the carnea biotype. Survival of diapausing adults during the first 18 weeks of storage was high among all four populations; adults from three populations also showed high survival after 35 weeks of storage. A high incidence of females from all four populations laid some fertile eggs after being stored for up to 31 weeks or longer. After six or more weeks of storage, average fecundity was high and ranged from ∼400–900 eggs/female. Duration of storage (up to 39 weeks) was a significant determinant of fecundity in two of the four populations. In practice, diverse populations of C. carnea can be efficiently mass-produced (with or without storage) under uniform conditions in the insectary. Thus, the choice of which populations to mass-produce and use in augmentation can be based primarily on the characteristics (e.g., climate, habitat, crop) of the intended area of release, rather than on considerations concerning mass-rearing.

The survival of Heterorhabditis bacteriophora Oswego Poinar, Steinernema carpocapsae NY001 Weiser, and S. glaseri NC1 Steiner varied in relation to the bulk density of a sandy loam soil. Survival of H. bacteriophora decreased linearly with time (4–70 d) and quadratically with increasing bulk density, whereas S. glaseri survival decreased linearly with time, but increased quadratically with increasing bulk density. Survival of S. carpocapsae decreased quadratically with time, but was unaffected by bulk density. H. bacteriophora and S. glaseri infected larvae of the greater wax moth, Galleria mellonella (L.) for up to 10 wk after soil inoculation, and the incidence of infection showed no significant variation in relation to bulk density or time. In contrast, infection rate by S. carpocapsae increased with bulk density and decreased with time. The combined effects of soil texture and bulk density on movement these of nematode species generally decreased as the bulk density of 3 soil textures increased. However, the degree to which soils of high bulk density reduced movement differed among species and soil textures: H. bacteriophora was the least restricted; whereas, S. carpocapsae was the most restricted. All 3 species moved significantly more in sandy loam, than in loam or silty clay loam. Although movement was reduced at relatively high bulk densities, survival of the 3 nematode species was high. Rates of movement and infection by the nematodes were strongly correlated with the amount of soil pore space having dimensions similar to or greater than the diameters of the nematodes. In a sandy loam soil, H. bacteriophora moved at least 18 cm within 4 d of soil inoculation across all bulk densities tested, whereas S. carpocapsae moved only 9 cm at the 3 lower densities and

The North American Free Trade Agreement (NAFTA) and the General Agreement on Tariffs and Trade (GATT) have focused attention on risk assessment of potential insect, weed, and animal pests and diseases of livestock. These risks have traditionally been addressed through quarantine protocols ranging from limits on the geographical areas from which a product may originate, postharvest disinfestation procedures like fumigation, and inspections at points of export and import, to outright bans. To ensure that plant and animal protection measures are not used as nontariff trade barriers, GATT and NAFTA require pest risk analysis (PRA) to support quarantine decisions. The increased emphasis on PRA has spurred multiple efforts at the national and international level to design frameworks for the conduct of these analyses. As approaches to pest risk analysis proliferate, and the importance of the analyses grows, concerns have arisen about the scientific and technical conduct of pest risk analysis. In January of 1997, the Harvard Center for Risk Analysis (HCRA) held an invitation-only workshop in Washington, D.C. to bring experts in risk analysis and pest characterization together to develop general principles for pest risk analysis. Workshop participants examined current frameworks for PRA, discussed strengths and weaknesses of the approaches, and formulated principles, based on years of experience with risk analysis in other setting and knowledge of the issues specific to analysis of pests. The principles developed highlight the both the similarities of pest risk analysis to other forms of risk analysis, and its unique attributes.

Laboratory assays were used to compare the ability of commercially produced Trichogramma spp. to parasitize eggs of the obliquebanded leafroller, Choristoneura rosaceana (Harris), in the laboratory and field. Trichogramma platneri Nagarkatti parasitized more obliquebanded leafroller eggs per egg mass than did Trichogramma pretiosum Riley or Trichogramma minutum Riley produced by either of 2 insectaries. T. minutum produced at 1 insectary caused significantly more host mortality by host feeding and repiercing than by parasitism. Variation in parasitoid performance from different insectaries and among shipments from the same insectary was common. Young egg masses were more heavily parasitized than old egg masses. Parasitism increased as the number of conspecific female Trichogramma spp. placed on the same host increased, but the number of eggs parasitized per female decreased. Exposure of host egg masses to female Trichogramma spp. prevented additional oviposition in the same egg mass by conspecific, ovipositionally experienced females but had no effect on parasitism by conspecific, ovipositionally naive females. The method used to attach sentinel egg masses to foliage influenced parasitism rates. Moistening the leaf with water and adhering the egg mass to the moistened leaf had the least impact. Inundative releases of Trichogramma spp. into an apple orchard paralleled laboratory assays by showing greater parasitism of obliquebanded leafroller egg masses by T. platneri than with T. minutum . However, extreme differences observed in field performance between the 2 species was not predicted from the assays.

Effect of atmospheric permeation with synthetic sex pheromone on the behavior and control of obliquebanded leafroller, Choristoneura rosaceana (Harris), was studied in small and large plots in commercial apple orchards. Synthetic sex pheromone significantly reduced the ability of male moths to locate pheromone-baited traps and tethered females; however, no differences were found among 3 pheromone rates. Location of pheromone dispensers within the tree canopy did not alter the number of males locating pheromone-baited traps and mating tethered females. Obliquebanded leafroller activity was greatest in the upper positions of the tree canopy and no edge effect was observed around perimeters of large disrupted blocks. The presence of gravid feral females, mated tethered females, high larval densities, and fruit damage within large pheromone disrupted blocks indicate obliqubanded leafrollers mate in orchards treated with synthetic sex pheromone. However, fruit damage caused by obliquebanded leafroller larvae was similar in pheromone, pheromone plus insecticide, and insecticide treatments.

Fruit maturity, quality, calcium concentration and economic value of `Starkrimson Delicious' (Malus domestica Borkh.) apples, under a range of crop levels and European red mite [Panonychus ulmi (Koch)] cumulative mite-days (CMD), were best explained by local surface regression models involving CMD and crop load. Fruit from trees with low CMD and a light crop (125 fruit/tree, about 20 t/ha) were the most mature at harvest. Those fruit had higher ethylene concentrations, starch pattern indices, soluble solids concentrations, and watercore incidence at harvest than fruit from trees with low CMD and a normal crop (300 fruit/tree, about 40 t/ha), or with high CMD at any crop level. Those fruit also had higher incidences of watercore and internal breakdown after 4 months of cold storage. Calcium concentrations in fruit increased as crop load and CMD increased. Whole-canopy net CO2 exchange rate per fruit related better to fruit quality and calcium concentrations than either crop load or CMD alone, but was always a much worse predictor than local surface regressions. Low CMD and normally cropped trees had the highest crop value; lightly cropped trees had an intermediate crop value; while high CMD and normally cropped trees had the lowest crop economic value. Crop load should be considered when defining action thresholds for mites, and harvest schedules for apples should reflect crop load and mite populations on apple trees.

The hypothesis was tested that effects of late-season European Red Mite (ERM) [Panonychus ulmi (Koch)] injury on apple (Malus domestica Borkh.) fruit development are better explained by carbon physiology than by pest densities. Midseason ERM populations were allowed to develop in mature semi-dwarf `Starkrimson Delicious'/M26 trees with moderately heavy crops, then were controlled with miticides at different mite-day (activity of one mite per leaf for 1 day) levels as estimated by weekly leaf sampling. The range of final mite-days was from 250 to 2100 on individual trees. Seasonal fruit growth patterns were monitored. Diurnal whole-canopy net CO2 exchange rate (NCER) was measured in eight clear flexible balloon whole-canopy chambers on several dates before and after mite infestations. Mite injury reduced fruit growth rates. Leaf and whole-canopy NCER were reduced similarly. Late season fruit growth and final fruit size were correlated with accumulated mite-days, but were better correlated to whole-canopy NCER per fruit. Fruit firmness, color, soluble solids and starch ratings showed no correlation to mite-days. Number of flower clusters per tree and final fruit per tree the following year were not related to accumulated mite-days, but final fruit per tree the following year were better correlated to whole-canopy NCER per fruit. These results generally supported the hypothesis.

The hypothesis that carbon balance is the basis for differences in responses by lightly and normally cropped apple trees to European red mite (ERM) [Panonychus ulmi (Koch)] damage was tested. Mature `Starkrimson Delicious' (Malus domestica Borkh.)/M.26 apple trees were hand-thinned to light (125 fruit/tree, about 20 t/ha) or normal (300 fruit/tree, about 40 t/ha) target crop levels and infested with low [1000 CMD) target levels of ERM. A range of crop loads and CMD was obtained. Mite population density, fruit growth, leaf and whole-canopy net CO2 exchange rates (NCER) were measured throughout the growing season of 1994. Leaf area and vegetative growth per tree were also measured. Yield and final mean fruit size were determined at harvest. Return bloom and fruiting were determined the following year. Total shoot length per tree was not affected by crop load or mite damage. ERM reduced leaf and whole-canopy NCER. Normally cropped trees showed fruit weight reduction earlier and more severely than lightly cropped trees with high mite injury. Variation in final fruit weight, return bloom and return fruiting was much better related to whole-canopy NCER per fruit than to CMD.