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In June of 2013 an application of dinotefuran on an ornamental planting of European linden trees (Tilia cordata Mill. [Malvales: Malvalceae]) in a shopping mall parking lot in Wilsonville, Oregon provoked the largest documented pesticide kill of bumble bees in North America. Based on geographic information systems and population genetic analysis, we estimate that between 45,830 and 107,470 bumble bees originating from between 289 and 596 colonies were killed during this event. Dinotefuran is a neonicotinoid that is highly effective in exterminating and/or harming target pest insects and non-target beneficial insects. Analysis to detect the concentration of pesticides in flowers that received foliar application revealed that the minimum reported dinotefuran concentration of a sampled T. cordata flower was 7.4 ppm, or in excess of 737% above the LC50 of the beneficial pollinator, the honey bee (Apis mellifera Linnaeus, 1758 [Hymenoptera: Apidae]). Furthermore, sampled Vosnesensky bumble bees (Bombus vosnesenskii Radoskowski, 1862 [Hymenoptera: Apidae]) were found to have an average dinotefuran concentration of 0.92 ppm at the time of death, which exceeds the maximum LC50 of A. mellifera (0.884 ppm). Our study underscores the lethal impact of the neonicotinoid pesticide dinotefuran on pollinating insect populations in a suburban environment. To our knowledge, the documentation and impact of pesticide kills on wild populations of beneficial insects has not been widely reported in the scientific literature. It is likely that the vast majority of mass pesticide kills of beneficial insects across other environments go unnoticed and unreported.

Organic vegetable farmers rely heavily on labor-intensive tillage for weed management, which adversely affects soil health and harms beneficial insects that consume crop pests and weed seeds. Using cover crop residues as a weed-suppressive mulch enables some reduction in tillage, and combining this tool with recently developed organic herbicides may further enhance weed suppression in vegetable production. However, organic herbicides may also adversely affect beneficial insects, and their nontarget effects are unknown. Here, we examine the combined impacts of cultural and chemical tools on weed cover while monitoring activity of beneficial epigeal insects and measuring rates of weed seed biological control to assess potential nontarget effects of organic herbicides. In a 2-yr experiment, we compared three cover crop mulch treatments and three organic herbicide treatments (capric/caprylic acid, corn gluten meal, and herbicide-free) in a reduced-tillage system. Organic herbicides led to no reductions in beneficial insect activity nor weed seed biocontrol. In both years, capric/caprylic acid herbicide and cover crop mulches reduced weed pressure relative to a fallow control treatment, whereas corn gluten meal had no effect. In year 2, a combination of cover crop mulch with organic herbicide had the greatest weed suppression relative to the fallow control. Integrated weed management is a perpetual challenge, but our results suggest that organic herbicides used in concert with cover crop mulch may enhance weed control and reduce the need for tillage, with limited collateral damage to natural enemies.

Berry crops are increasingly produced in high tunnels, which provide growers with the opportunity to extend their production season. This is particularly beneficial for the northern region of the United States with short and unpredictable growing seasons and where rainfall limits fruit quality. However, little is known about the effect of high tunnels on the community of pests, natural enemies, or pollinators, especially in berry crops, and there are few reports of the insect community in raspberries in this region. We compared the abundance of these insects during two growing seasons in field-grown and tunnel-grown floricane and primocane producing raspberries through direct observation and trapping at five sites in southwestern and central Michigan. We found eight key pests, including spotted wing Drosophila, leafhoppers, and thrips, and seven key natural enemies including parasitoid wasps, spiders, and lacewings, that were common across all sites. Pest populations were up to 6.6 times higher in tunnels, and pests typical of greenhouse systems became more dominant in this environment. Natural enemies observed on plants under tunnels were also more abundant than in the field, but this trend was reversed for natural enemies trapped on yellow sticky cards. There was also a reduction of both honey bees and wild bees under the high tunnels, which was balanced by use of commercial bumble bees. These data not only provide much-needed information on the phenology of the insect community on raspberry plantings, they also highlight the entomological implications of protected raspberry culture.

Neonicotinoid residues can be present in soybean vegetative tissue, prey insects, and flower tissues, possibly making them toxic to pollinators and natural enemies. Baseline information on the toxicity of neonicotinoids to beneficial insects other than pollinators through multiple routes of insecticide exposure is limited. The objectives of this study were 1) to evaluate the toxicity of thiamethoxam to the hemipteran predator, Orius insidiosus Say, exposed to residues through treated vegetative tissue and insect prey, and 2) to evaluate the effect of thiamethoxam on the abundance of this predator species in soybean fields. Predators were exposed to thiamethoxam in soybean leaves and Aphis glycines Matsumura using a systemic bioassay. Abundance of the predator was evaluated in thiamethoxam seed-treated fields during two different soybean seasons. Our results indicate that concentrations required to kill >50% of the evaluated insects were higher than the concentrations that the insects are likely to encounter in the field. Consumption of A. glycines by O. insidiosus was affected at 10 ng/ml and 5 ng/ml of thiamethoxam at 24 h of evaluation. There was significant mortality for O. insidiosus at 24 h after exposure to thiamethoxam-treated aphids at these concentrations. In soybean fields, there were no significant differences in O. insidiosus number between the plots treated with thiamethoxam and the control. Thiamethoxam may have significant effects on the predators if O. insidiosus feeds on early soybean vegetative tissue or contaminated prey. These results suggest that the compatibility of thiamethoxam with IPM programs for A. glycines needs further evaluation.

Industrialized farming practices result in simplified agricultural landscapes, reduced biodiversity, and degraded species-interaction networks. Thus far, most research assessing the combined effects of farming systems and landscape complexity on beneficial insects has been conducted in relatively diversified and mesic systems and may not represent the large-scale, monoculture-based dryland agriculture that dominates many regions worldwide. Specifically, the effects of farming systems on forbs, bees, and their interactions are poorly understood in highly simplified dryland landscapes such as those in the Northern Great Plains, United States, an area globally important for conventional and organic small grain, pulse, forage, and oilseed production. During a 3-yr (2013–2015) study, we assessed 1) the effects of dryland no-till conventional and tilled organic farming on forbs, bees, and bee–flower networks and 2) the relationship between natural habitat and bee abundance. Flower density and richness were greater in tilled organic fields than in no-till conventional fields, and forb community composition differed between farming systems. We observed high bee diversity (109 taxa) in this highly simplified landscape, and bee abundance, richness, and community composition were similar between systems. Compared with tilled organic fields, bee–flower interactions in no-till conventional fields were poorly connected, suggesting these systems maintain relatively impoverished plant-pollinator networks. Natural habitat (11% of the landscape) did not affect small-bodied bee abundance in either farming system but positively affected large-bodied bees within 2,000 m of crop-field centers. In highly simplified agricultural landscapes, dryland organic farming and no-till conventional farming together support relatively high bee diversity, presumably because dryland organic farming enhances floral resources and bee–flower networks, and no-till management in conventional farming provides undisturbed ground-nesting habitats for wild bees (Hymenoptera: Apoidea).

Reconstructing prairie vegetation in row crop-dominated agricultural landscapes may contribute to several ecosystem services, including the biological control of insect pests, such as the soybean aphid Aphis glycines Matsumura. The influence of the amount and configuration of reconstructed prairie vegetation on the delivery of ecosystem services was investigated in several small catchments at Neal Smith National Wildlife Refuge in Iowa. Treatments include catchments entirely in row crops under a no-till, corn-soybean (Zea mays L.-Glycine max [L.] Merrill) rotation, catchments with 10% of the land in prairie located at the base, and catchments with 10 or 20% of the land in multiple contour strips of prairie. During 2009 and 2011 growing seasons, we measured abundance and diversity of aphidophagous insect predators in response to treatment and habitat type (i.e., soybean, prairie). In 2011, we further studied the biological control of soybean aphids by artificially infesting uncaged and caged plants to prevent exposure from predators. While aphidophagous predators were more abundant in prairie, populations of key aphid predators did not significantly differ among treatments. Biological control of the soybean aphid did not differ among treatments or with distance from prairie. Our results suggest that prairie strips, in addition to providing soil and water quality benefits, may increase the populations of beneficial insects, but may not directly impact biocontrol. We propose several hypotheses to explain why we did not observe more soybean aphid predation with the increased abundance of aphidophagous predators in catchments containing prairie.

Native plants attractive to beneficial insects may improve the value of buffer strips by increasing biodiversity and enhancing the delivery of insect-derived ecosystem services. In a 2-yr field experiment, we measured the response of insect communities across nine buffers that varied in plant diversity. We constructed buffers with plants commonly found in buffers of USDA-certified organic farms in Iowa (typically a single species), recommended for prairie reconstruction, or recommended for attracting beneficial insects. We hypothesized that the diversity and abundance of beneficial insects will be 1) greatest in buffers composed of diverse plant communities with continuous availability of floral resources, 2) intermediate in buffers with reduced species richness and availability of floral resources, and 3) lowest in buffers composed of a single species. We observed a significant positive relationship between the diversity and abundance of beneficial insects with plant community diversity and the number of flowers. More beneficial insects were collected in buffers composed of species selected for their attractiveness to beneficial insects than a community recommended for prairie restoration. These differences suggest 1) plant communities that dominate existing buffers are not optimal for attracting beneficial insects, 2) adding flowering perennial species could improve buffers as habitat for beneficial insects, 3) buffers can be optimized by intentionally combining the most attractive native species even at modest levels of plant diversity, and 4) plant communities recommended for prairie reconstruction may not contain the optimal species or density of the most attractive species necessary to support beneficial insects from multiple guilds.

We evaluated the efficacy of attractive toxic sugar baits (ATSB) in the laboratory and field with the low-risk active ingredient dinotefuran against mosquito populations. Preliminary laboratory assays indicated that dinotefuran in solution with the sugar baits was ingested and resulted in high mortality of female Culex quinquefasciatus Say and Aedes aegypti Linnaeus. Field studies demonstrated >70% reduction of mosquito populations at 3 wk post-ATSB application. Nontarget feeding of seven insect orders—Hymenoptera, Lepidoptera, Coleoptera, Diptera, Hemiptera, Orthoptera, and Neuroptera—was evaluated in the field after application of attractive sugar baits (ASB) on vegetation by dissecting the guts and searching for food dye with a dissecting microscope. Nontargets were found stained with ASB 0.9% of the time when the application was applied on green nonflowering vegetation. Only two families were significantly impacted by the ASB application: Culicidae (mosquitoes) and Chironomidae (nonbiting midges) of the order Diptera. Pollinators of the other insect orders were not significantly impacted. No mortality was observed in the laboratory studies with predatory nontargets, wolf spiders or ground beetles, after feeding for 3 d on mosquitoes engorged on ATSB applied to vegetation. Overall, this novel control strategy had little impact on nontarget organisms, including pollinators and beneficial insects, and was effective at controlling mosquito populations, further supporting the development of ATSB for commercial use.

The squash bug, Anasa tristis (DeGeer) (Hemiptera: Coreidae), is an indigenous pest of squash and other cucurbits. Pesticides can control squash bug populations although many small-scale growers in the Southeast seek alternative methods of management. Cultural control methods, including varying the planting date and farmscaping, are not well understood under southeastern conditions. The goal of farmscaping is to increase natural ecosystem functions to aid in the control of pest populations. In the summers of 2014 and 2015, field plots of squash, separated by a minimum of 150 m were organized in a split-split plot design, with floral resources at the whole-plot level and varied planting date at the subplot level. Data were collected on squash bug abundance and fruit yield (kg), and abundance of potential natural enemies of A. tristis. Plots with added floral resources had fewer squash bug adults than plots without added floral resources in four of eight possible year × site × planting date combinations. Furthermore, the site in 2014 which had a reduction in squash bug adult abundance also had an increase in the abundance of potential enemies, including spiders, ground beetles, and predaceous Hemiptera. There were additional instances when potential natural enemy abundance was greater in resource-enhanced plots, but they were not associated with sites that had a reduction in yield loss or squash bug abundance. The use of floral resources to attract natural enemies and beneficial insects merits further investigation.

The cabbage seedpod weevil, Ceutorhynchus obstrictus (Marsham), is an alien invasive pest of canola, Brassica napus L., in North America. Field populations of both adults and larvae are known to be aggregated in their distributions, but the causal mechanism for this clustering is not understood. We investigated the hypothesis that spatial distributions of C. obstrictus adults, larvae, and their parasitoids were directly or indirectly related to host plant quality as indicated by leaf tissue nutrient contents. During the years of 2005 and 2007, these insect populations were sampled in a grid pattern in three commercial fields of B. napus located near Lethbridge, Alberta, Canada. Leaf samples were collected from plants in each grid plot and analyzed for nutrient contents. Spatial patterns and associations among the collected variables were analyzed using Spatial Analysis by Distance IndicEs software. We observed significant spatial associations among C. obstrictus adults, larvae, and parasitoids. T...

Increases in agricultural conversion are leading to declines in native grasslands and natural resources critical for beneficial insects. However, little is known regarding how these changes affect pollinator diversity. Land use types were categorized within 300 m and 3 km radii of pollinator sampling locations in Brookings County, SD. Pollinator abundance and species richness were regressed on the proportion of the landscape dedicated to row crops, grass and pasture, forage crops, small grains, and aquatic habitats using variance components modeling. Row crops had a negative effect on bee abundance at 300 m, after fixed effects modeling accounted for outliers skewing this relationship. At 3 km, corn positively affected bee abundance and richness, while soybean acreage decreased species richness. The landscape matrix of outlying sites consisted of large monocultured areas with few alternative habitat types available, leading to inflated populations of Melissodes and Halictidae. Syrphids had a positive parabolic relationship between diversity and row crops, indicating potential for competitive exclusion from intermediate landscapes. Unlike other studies, landscape diversity within 300 m was not found to significantly benefit pollinator diversity. Within especially agriculturally developed areas of the region, high abundances of pollinators suggest selection for a few dominant species. There was no effect of forage crops or aquatic habitats on pollinator diversity, indicating that less highly managed areas still represent degraded habitat within the landscape. Incorporating pollinator-friendly crops at the farm level throughout the region is likely to enhance pollinator diversity by lessening the negative effects of large monocultures.

Crapemyrtle is a common landscape planting that is a resource subsidy for beneficial insects. Field studies were conducted to determine the influence of crapemyrtle flower color on the population abundances and predator-prey dynamics of the herbivorous Frankliniella species and the predator Orius insidiosus. Adults and immatures of predator and prey were highly anthophilous, preferring white 'Acoma' flowers compared with lavender 'Apalachee', red 'Carolina Beauty', and pink 'Choctaw'. The predator was aggregated with its prey in a density-dependent manner: the adults by preferring the crapemyrtle clones also preferred by the thrips and the nymphs by direct tracking or as a function of increased prey and fecundity. Acoma was best for preference and buildup of O. insidiosus populations, and it was the only clone where there was no buildup in thrips populations. Two species of Karnyothrips (Thysanoptera: Phlaoethripidae), predators of small insects, were common in Tillandsia usneoides, an epiphyte on the crapemyrtle. Crapemyrtle is a bridge to enhance populations of O. insidiosus during summer months when there are few other hosts in the southern USA.

Native wasps were sampled from 33 lowbush blueberry (Vaccinium angustifolium) fields and adjacent forests in eastern Maine during the summers of 1997 and 1998. Sampling was conducted along a horizontal transect that bisected the field/forest interface using two methods: window-pane traps suspended at varying heights (1, 7, and 14 m above the ground) and ground-level malaise traps. The objectives of this study were to assess (1) the spatial distributions of wasp species assemblages associated with the two distinct habitats and (2) the potential interactions of wasp species assemblages across the blueberry/forest landscape. Wasp samples from the two trap types collected different wasp species assemblages, each of which were consistent across the 2 yr. Both methods documented lower abundances of wasps in blueberry fields in comparison with adjacent forests. Window pane traps at varying heights identified statistically significant but remarkably minor differences in height even at the highest traps in the middle of blueberry fields in both years of the study. The malaise traps detected distinct species assemblages whose horizontal distributions differed substantially from each other. Distributions ranged from those that were trapped exclusively in the forest, through those that were evenly distributed across the landscape, to taxa that were almost exclusively found in the blueberry field centers. Our results suggest that forest and edge habitats may be important refugia for wasp species assemblages that contribute to regulation of blueberry insect pest populations. Detailed knowledge of specific taxa should assist in the management of the blueberry/forest landscape for the conservation and enhancement of beneficial insects.

The use of insectary plants in agroecosystems to provide floral resources for enhancing natural enemy activity is an increasingly used practice, but candidate flowering plant species are not always screened for their attractiveness to key arthropods in the system being studied. In the work presented here, the relative attractiveness of four species of insectary plants to beneficial and pest insect species was assessed by observing the relative frequencies of flower visits to replicated blocks of the insectary flowers in two Oregon broccoli fields. The four plant species tested were alyssum (Lobularia maritima L. Desv.), coriander (Coriandrum sativa L.), buckwheat (Fagopyrum esculentum Moench), and phacelia (Phacelia tanacetifolia Benth.). Predatory hoverflies (Syrphidae) were identified to species, where possible, because of their previously observed importance as aphid predators in broccoli fields in the study area. The other beneficial insect groups observed were in the families Apidae, Coccine...

Codling moth, Cydia pomonella (L.), and redbanded leafroller, Argyrotaenia velutinana (Walker), are two key tortricid orchard pests in Minnesota. Field trials were conducted during 2001 and 2002 in Minnesota apple orchards to determine seasonal phenology of C. pomonella and A. velutinana and to evaluate two popular trap designs (Pherocon 1CP or 1C “Wing” trap versus Pherocon VI “delta” trap) for monitoring both species. Trap performance was determined by comparing the number of males captured, date of first moth capture, and the capture of nontarget beneficial insects. For C. pomonella, two distinct flight periods were recorded, suggesting two generations per year in Minnesota. Emergence and flight activity of first generation C. pomonella began at ≈110 degree-days (DD) base 10°F. This corresponded to apple bloom in southern Minnesota. The delta trap captured significantly more C. pomonella males than the wing trap (Pherocon 1CP version). For A. velutinana, three flight periods were recorded at a...

Recent advances in weed control technology have changed how vegetational diversity can be managed in agroecosystems. This 2-yr study assessed the impact of altering the timing of herbicide application in herbicide-resistant field corn on the European corn borer, Ostrinia nubilalis (Hubner), and on the beneficial insects that prey on O. nubilalis egg masses. Treatments in this study were intended to allow weed presence in the field for varying periods of time, but control the weeds before crop yield was negatively impacted. Effects on O. nubilalis oviposition were assessed directly by counting egg masses and indirectly by assessing damage to corn stalks resulting from O. nubilalis infestations. The impact of weeds on the main generalist predators in this system was quantified through direct counts and predation trials on sentinel egg masses. In this study, altering the timing of herbicide application in herbicide-resistant field corn did not appear to affect the oviposition preference of O. nubilalis or the beneficial insects that prey on its egg masses. End-of-season stalk comparisons showed no differences in O. nubilalis infestation levels among the treatments. Predation on sentinel egg masses showed few significant differences among treatments, and predator densities were only rarely significantly different by treatment and showed no evident trends. Thus, our data suggest that under the conditions of this experiment, manipulating herbicide applications to minimize O. nubilalis damage is not a viable management technique in field corn.

Evidence for field attraction by beneficial insects to synthetic herbivore-induced plant volatiles (HIPVs) is presented. Three synthetic HIPVs (methyl salicylate, (Z)-3-hexenyl acetate, (E)-4,8-dimethyl-1,3,7-nonatriene) were evaluated in a Washington state hop yard during April–October 2002 for attractiveness to beneficial insects. The predatory mirid, Deraeocoris brevis (Uhler), and the anthocorid, Orius tristicolor (White), were attracted to sticky cards baited with (E)-3-hexenyl acetate, while the geocorid, Geocoris pallens Stal., and hover flies (Syrphidae) were attracted to methyl salicylate-baited cards. The coccinellid, Stethorus punctum picipes (Casey), was attracted to both HIPVs in July and September. The (E)-4,8-dimethyl-1,3,7-nonatriene did not attract any beneficial insects. Lygus hesperus Knight, Leptothrips mali (Fitch), Anagrus spp., other Miridae, Coccinellidae, and parasitic Hymenoptera were not attracted to the three HIPVs tested. The possible exploitation of HIPVs in enhancin...

Nontarget arthropod populations were monitored in both transgenic and nontransgenic corn and soybean fields in western and central Ohio. A total of 24 fields, 12 corn and 12 soybean, were inspected weekly from late June through mid August. Half of the cornfields were Bacillus thuringiensis (Bt) hybrids and half of the soybean fields were Roundup Ready (RR). Sweep net samples in soybean fields and unbaited Pherocon AM yellow sticky traps in both soybean and cornfields were used to collect nontarget arthropods. Soil samples were also taken from all 24 fields to compare soil mite populations. A select group of 15 readily identifiable arthropods composed mainly of beneficial insects commonly found in field crops, were recorded in weekly sweep net and sticky trap samples for later analysis. Sweep net data from soybean fields revealed no significant differences in nontarget arthropods. Yellow sticky trap data from soybean and corn fields found significantly more green lacewing adults (Chrysopa spp.) in six pooled non-RR soybean fields, significantly more rove beetles in one non-Bt cornfield, and significantly more Orius spp. in one Bt cornfield. There were also significantly more soil inhabiting mites at one non-RR soybean field. Based on the abundance of these arthropod populations in paired transgenic and nontransgenic fields, few negative effects on the 15 nontarget arthropods selected can be directly associated with transgenic soybean and corn crops in Ohio.

Four different corn, soybean, and wheat cropping systems were established in small replicated plots and simultaneously in larger (4-hectare) unreplicated fields. Each system was subject to distinct tillage practices, fertility programs, and methods of pest control, based on methods currently in use on farms in the Mid-Atlantic region of the United States. Ground-dwelling arthropods (mostly Carabidae and spiders) were sampled during the fourth and sixth growing season after the establishment of the plots, and foliar insects (pest and beneficial) and pest damage were sampled on corn in the sixth growing season. Overall, beneficial arthropod populations were lowest and corn pest insect populations (especially Western corn rootworms, Diabrotica virgifera virgifera LeConte) were highest in the simplest, most intensively managed continuous corn system, which had annual use of soil insecticides. Generally ground-dwelling species were higher in soybeans than in corn, and in no-till than in deep-tilled crops. Growers wishing to enhance populations of beneficial insects should consider predominantly no-till cropping systems with several different crops in the rotation and minimal insecticide use. For both ground and foliar sampling, patterns of abundance among systems and crops in the small replicated plots generally followed those observed in the large fields, but numbers of spiders and carabids collected per pitfall trap were generally much higher in the large fields.

The red imported fire ant, Solenopsis invicta (Buren), is an invasive species in the southern United States and is expanding its range westward to California and eastward up the Atlantic Coast. This voracious predator can reach extremely high densities and have widespread effects once it invades an ecosystem. We conducted a 2-yr sampling study and a series of greenhouse and field experiments to document the impact of red imported fire ants on beneficial insects in cotton. We found that the densities of 12 of 13 natural enemies sampled on cotton plants in 1999, and 8 out of 8 sampled in 2000, were negatively correlated with the densities of foraging fire ant workers. Red imported fire ants reduced the survival of lady beetles (Coccinella septempunctata L., and Hippodamia convergens Guerin-Meneville) (Coleoptera: Coccinellidae) by 50% and green lacewing larvae (Chrysoperla carnea Stephens) (Neuroptera: Chrysopidae) by 38% in greenhouse experiments. Fire ants did not, however, reduce the survival of spiders (Oxyopidae, Thomisidae, and Clubionidae). We used a commercially available fire ant bait to suppress fire ant populations in cotton fields during the 2000 growing season and compared the densities of beneficial arthropods in treated versus control fields. Densities of lady beetles, spiders, and big-eyed bugs (Heteroptera: Geocoridae) were significantly higher in fields with suppressed fire ant populations than in fields with relatively large fire ant populations. The effect of fire ants on minute pirate bugs (Heteroptera: Anthocoridae) was inconsistent, and populations of damsel bugs (Heteroptera: Nabidae) and hooded beetles (Coleoptera: Anthicidae) were not affected by fire ant suppression. The results of this study suggest that red imported fire ants are major intraguild predators of important beneficial arthropods in cotton.

Native plant and beneficial insect associations are relatively unstudied yet are important in native habitat restoration programs aimed at improving conservation biological control in perennial crops such as wine grapes. Beneficial insects (predators, parasitoids, pollinators) attracted to 10 species of flowering native wild buckwheat (Eriogonum spp.) in central Washington were identified and counted on transparent sticky traps. Combining all categories of beneficial insects, the mean number per trap ranged from 48.5 (Eriogonum umbellatum) to 167.7 (Eriogonum elatum). Three Eriogonum spp. (E. elatum, Eriogonum compositum, and Eriogonum niveum) attracted significantly more beneficial insects than the lowest-ranked species. E. niveum attracted greatest numbers of bees and parasitic wasps, and E. elatum was highly attractive to predatory true bugs and beneficial flies. Blooming periods of Eriogonum spp. extended from mid April to the end of September. This study demonstrates the attraction of beneficial insects to native flowering buckwheats and suggests their potential as a component of habitat restoration strategies to improve and sustain conservation biological control in Washington viticulture.

Establishing flowering plants in and around fields to provide pollen and nectar resources for natural enemies has shown promise as a strategy to enhance biological control of crop pests. Natural enemies are selective in their flower feeding, however, and show preferences for certain plant species. In this study the relative attractiveness of 11 flowering plant species to aphidophagous hoverflies (Diptera: Syrphidae) was evaluated at the Oregon State University Vegetable Research Farm. Six of these plant species were also evaluated at two other farm sites. Of the 12 species of hoverflies collected, Meliscaeva cinctella (Zetterstedt), Toxomerus marginatus (Say), Toxomerus occidentalis (Curran), Sphaerophoria sulfuripes (Thomson), and Scaeva pyrastri (L.) were common to all three sites. Attractiveness of flowering plants to foraging hoverflies was assessed by conducting timed observations of feeding-visit frequencies. Flowering periods varied between plant species and comparisons were made only for plant species flowering on a particular date. Relative attractiveness of plant species to hoverflies differed between dates and sites. Among early-season flowering species, coriander, Coriandrum sativum (L.), was fed from most frequently. Among late-season flowers, yarrow, Achillea millefolium (L.), fennel, Foeniculum vulgare (Miller), and Korean licorice mint, Agastache rugosa (Fischer & C. A. Meyer) were fed from most frequently. These results help in the selection of plants to enhance biological control, but final selection of plants for this purpose requires considering flower, natural enemy, and pest phenologies, and pollen and nectar quality and availability.

A faunal sUlVeywas conducted to find possible biological control agents for Parlhenium hysterophorus L. (Asteraceae),a serious annual weed in many parts of the world, particularly Queensland, Australia, and India. Between 1977 and 1991, most of the plant's native range in North Americawas sulVeyedfrom bases at Monterrey and Cuernavaca, Mexico, and Temple, TX. Two hundred and sixty-twophytophagous arthropod species were collected on P. hysterophorus by various methods including hand picking,dissection, rearing, and sweep- ing; 144 of these species were found to feed on the plant at some stage of their life cycle. The orders represented most abundantly were Coleoptera (33.2%), Homoptera (22.9%), Lep- idoptera (20.2%), and Hemiptera (18.3%). Twofungal pathogens, Puccinia abrupta Dietel and Holwayvariety partheniicola (Jackson)Parmelee and Pucciniamelampodii Di'eteland Holway, were also obselVed. An index of similarity was used to make pairwise comparisons between the phytophagous arthropod communities on different plant taxa. These comparisons showed that the fauna of P. hysterophorus is most similar to that of ragweeds (Ambrosia spp.). Six insect species that were shown to be stenophagouswere shipped to Australiafor further testing and possible field release. One of the fungal pathogens underwent host-range testing in the United Kingdom and was released in Australia.

Lygus bug, Lygus hesperus Knight, and beneficial insect populations ( Orius sp., Geocoris spp., and Nabis spp.) were quantified in alfalfa strips, which were interplanted within cotton fields. The propensity of alfalfa strips to retain lygus bugs, thereby keeping them out of cotton, and the utility of alfalfa strips as a reservoir for beneficial insects were evaluated from May to August in 1990 and 1991. The following three alfalfa cutting strategies were examined: (1) uncut alfalfa, (2) a 28-d strip-cut treatment, and (3) a 35-d strip-cut treatment. Insect populations were quantified in both the newer alfalfa growth and the older alfalfa growth of the strip-cut treatments. Lygus bug densities were significantly higher in the uncut treatment than in the other treatments, peaking at 520 per 1.9 m2 in 1990 and 350 per 1.9 m2 in 1991. Lygus bug levels in the strip-cut treatments were low in the newer alfalfa growth (averaging 41.8 per 1.9 m2) and only slightly higher in the older alfalfa growth of the 28-d strip-cut treatment (averaging 65.3 per 1.9 m2). Populations were relatively constant within these three treatments throughout the season. However, in the older growth of the 35-d cutting regime, Lygus bug populations averaged 103 per 1.9 m2. Densities of beneficial insects were also higher in the uncut than the strip-cut treatments, but the higher predator densities apparently did not offset the high Lygus bug population increase. The uncut treatment also lacked Lygus bug egg and nymphal mortality from the alfalfa cutting as compared with the strip-cut treatments. The less frequent cutting, in the 35-d compared with the 28-d treatment, probably also allowed for a buildup of the Lygus bug population. Lygus bug instar distribution, sex, and predator species were also examined in these treatments. It appears that to optimize Lygus bug management, while still producing high densities of predacious insects, strip-cut alfalfa should be used and cut on a 28-d schedule.

Sweetpotato whitefly, Bemisia tabaci (Gennadius), has recently become a pest of peanut in the southern United States. Limited observations in grower fields had identified differences in infestation among cultivars. We wished to determine whether selected cultivars grown commercially in this region resisted whitefly infestation and whether parasitism by aphelinid parasitoids differed among cultivars. Five cultivars were evaluated in summer 1992 and six in summer 1993. In 1992, ‘Florunner’ supported the greatest populations of red-eye nymphs and ‘Southern Runner’ supported the lowest populations. Encarsia nigricephala Dozier was the most common parasitoid (53.0% of all parasitoids reared), followed by Encarsia transvena (Timberlake) (25.6%), and Encarsia pergandiella Howard (18.3%). Parasitism was uniformly high and species composition on the five cultivars did not differ. In 1993, ‘Southern Runner’ supported the greatest populations of all immature whitefly stages except red-eye nymphs. ‘Marc I’ supported the lowest levels of whitefly infestation. E. nigricephala was extremely abundant in 1993 (85.3% of all parasitoids reared), followed by E. pergandiella (9.8%), and E. transvena (4.7%). Eretmocerus nr. californicus was found in low numbers in both years. Again, in 1993, parasitism was high on all cultivars (up to 100% by the end of September), and no differences were noted in the parasitoid composition among the six cultivars. Whitefly infestation was light in these noninsecticide-treated peanut plots, most likely because of natural control by native aphelinid parasitoids, and other beneficial insects.

Insect pollination of commercial annonaceous crops is variable among localities and poorly understood. To gain basic information for use in pollinator management programs, we studied the nitidulids that pollinate commercially grown sugar apples ( Annona squamosa L.) and atemoyas ( A. squamosa X A. cherimola P. Miller) in Florida. Only flowers visited by nitidulids set fruit. We found nine species of nitidulid flower visitors, seven of which pollinated. Carpophilus mutilatus Erichson was the most important pollinator in terms of efficacy and abundance, followed by C. fumatus Boheman and Haptoncus luteolus (Erichson). The Annona flowers, which are protogynous, are entered by the beetles usually during the female phase. Peak entry into atemoya flowers occurs in the morning (0700–0900 EST) and into sugar apple flowers both in morning (0700–1100) and evening (1700–2100). The beetles remain inside up to 22 h, until the flowers senesce and the stamens fall. In 1989, natural fruit set ranged from 0–29% of sampled flowers per day in atemoya groves and from 0–10% of flowers per day in sugar apples. Percentage of fruit set is correlated with numbers of nitidulids in the flowers.

This research was designed to determine corn earworm, Helicoverpa zea (Boddie), biology in irrigated food corn and identify beneficial insects and diseases associated with them. We were interested in determining the period of oviposition and feeding by corn earworms to understand when corn is most vulnerable to feeding damage from larvae for designing pest management tactics. These data were collected on corn during pollination and kernel development. Oviposition began with appearance of the first silks but did not peak until late July after silks were dry and continued until late in the dough growth stage. Most eggs were laid on the distal third of silks. After eclosion, larvae quickly moved to the basal third of silks usually under the husk. Larvae began feeding on kernels as third instars appeared. They penetrated 9 and 15 cm into the ear, respectively, in each of the 2 yr. Deep penetration of the ear occurred in August as kernels hardened. Larvae could not eat these hard kernels, therefore, they simply took bites out of many kernels (nipped), which lowers the quality of corn for food processing. Only 1% of the corn earworms were parasitized or infected with disease organisms.

Since 1980, >16 million parasites of Hypera postica (Gyllenhal) were distributed across the United States as part of the Alfalfa Weevil Biological Control Program. Two species of internal parasites, one of the larval stage, Bathyplectes anurus (Thomson) and one of the adult stage, Microctonus aethiopoides (Loan), were released in the largest numbers. A detection survey conducted by the USDA, Animal and Plant Health Inspection Service, found that a second larval parasite, Bathyplectes curculionis (Thomson), had already spread throughout alfalfa-growing areas in the United States. Later, an establishment survey successfully recovered parasites in nearly half of the >700 counties where releases were made. Results from an evaluation survey indicated that the number of alfalfa weevil parasite species collected in surveyed fields in Iowa, Missouri, and Nebraska more then doubled from 1.3 to 3.0. Parasitism rates also increased in these states, whereas insecticide usage declined. However

The alfalfa leafcutting bee, Megachile rotundata (Fabricius), is used to pollinate alfalfa, Medicago sativa L., for seed production in the United States and Canada. It is difficult to reliably sustain commercial M. rotundata populations in the United States because of problems with disease, parasites, predators, and unexplained mortality. One possible explanation for early immature mortality is that, relative to floral availability, superfluous numbers of bees are released in alfalfa fields where resources quickly become limited. Our objective was to determine how M. rotundata density affects bee nesting, pollination efficiency, and reproductive success. Various numbers of bees were released into enclosures on an alfalfa field, but only 10-90% of released female bees established nests. Therefore, a "bee density index" was derived for each enclosure from the number of established females and number of open flowers over time. As the density index increased, significant reductions occurred in the number of pollinated flowers, number of nests, and number of cells produced per bee, as well as the percentage of cells that produced viable prepupae by summer's end and the percentage that produced adult bees. The percentage of cells resulting in early brood mortality (i.e., pollen balls) significantly increased as the density index increased. We conclude that bee nest establishment, pollination efficiency, and reproductive success are compromised when bee densities are high relative to floral resource availability. Open field studies are needed to determine commercial bee densities that result in sustainable bee populations and adequate pollination for profitable alfalfa seed production.

Synthetic male lures are commonly used to monitor and mass trap pestiferous fruit flies (Diptera: Tephritidae: Dacinae). However, there has been much dispute as to the nontarget impacts of such lures on beneficial and native insects. To evaluate nontarget attraction effects, traps baited with Cue-Lure and methyl eugenol were maintained and emptied weekly in a range of native and non-native forest and commercial orchard and backyard sites on Hawaii and Maui Islands. Lure trap captures were compared against those from unbaited control traps and traps artificially baited with decaying fruit flies to mimic the effect of accumulation of dead trapped target flies in male lure traps. Cue-Lure did not attract nontargets, and methyl eugenol attracted low but significant numbers of five species of flower-associated insects (honey bees, syrphid flies, nitidulid beetles, and endemic crambid moths) and two endemic Hawaiian species of sciarids (Diptera) and mirids (Hemiptera). Saprophagous nontargets, mostly Diptera, were abundant and diverse in traps baited with decaying flies and in male lure traps where accumulation of dead flies occurred but not in male lure traps with few or no fruit fly captures. Most of the previously published records of attraction to methyl eugenol are shown to actually be secondary attraction to decaying fruit flies. Endemic nontargets were collected in native and adjacent forest, but almost exclusively invasive species were attracted to traps placed in non-native habitats. Attraction of flower-associated species may be minimized if methyl eugenol traps are placed in trees after flowering season in orchards.

Seven synthetic herbivore-induced plant volatiles (HIPVs) and a mixture of nonanal + (Z)-3-hexen-1-ol were field tested for their ability to attract beneficial insects in an open cotton field. Eleven species of the main natural enemies of insect pests in cotton fields were studied. Significantly greater numbers of the ladybird beetle Coccinella septempunctata were trapped on (Z)-3-hexenyl acetate-baited cards than on others that were HIPV baited or the control cards. Erigonidium graminicolum was attracted to traps baited with nonanal, (Z)-3-hexenyl acetate, and methyl salicylate (MeSA). The predatory bug Deraeocoris punctulatus was only attracted to traps baited with octanal. The predatory bug Orius similis responded to traps baited with 3,7-dimethyl,1,3,6-octatriene, nonanal, (Z)-3-hexenyl acetate, nonanal + (Z)-3-hexen-1-ol, and MeSA. Dimethyl octatriene, nonanal + (Z)-3-hexen-1-ol, and octanal significantly attracted the syrphid fly Paragus quadrifasciatus. The ladybird beetle Propylaea japonica, the green lacewing Chrysopa sinica, the bigeyed bug Geocoris pallidipennis, the syrphid fly Epistrophe balteata, and the parasitic wasp Campoletis chlorideae did not respond to any of the HIPVs tested. These results are discussed with regard to the potential of HIPVs as tools for recruiting natural enemies into cotton fields.

The numbers and distributions of pine engraver, Ips pini (Say), predators, and secondary subcortical associates responding to racemic ipsdienol in Wisconsin were analyzed over 4 yr with regard to date, height in the canopy, and distance from the margin of previously killed trees. The largest difference in response patterns between predators and I. pini was in seasonal occurrence. Most I. pini were caught late in the season, whereas most predators were caught much earlier. Additional differences were observed in spatial distributions and time by space interactions. These results suggest that subtle behavioral or developmental (or both) shifts may allow some bark beetles to temporarily escape from predators that exploit scolytid pheromones as kairomones. Factors contributing to discrepancies between predator and prey trap catch can also be exploited in pest management. Semiochemically based control treatments can be scheduled to greatly reduce the proportion of beneficial insects caught without substantially reducing efficacy. Additionally, this information can be used to improve population estimates of predators and guide natural enemy introduction strategies.

The close affiliation between the honey bee industry and commercial pollination of U.S. crops is described, followed by a literature review that demonstrates why insufficient numbers of honey bees may be available to support adequate crop pollination services in the near future. Recent recommendations offering different methods to increase numbers of crop pollinators (continued honey bee research, establishment of management habitats, and development of additional non-honey bee pollinators) are described, and the positive and negative characteristics of each proposal are discussed. The status of crop pollination is then reviewed in some detail, followed by a recommendation to combine pollinator studies into one collaborative pollination program focused on producing the maximum number of efficient crop pollinators in the shortest possible time frame.

Aphidophagous coccinellid beetle populations were sampled by sweep net from 1969 to 1985 in small grain fields in eastern South Dakota. The assemblage of coccinellids consisted of six species: Hippodamia eonvergens Guerin-Meneville, H. tredecimpunctata tibialis (Say), H. parenthesis (Say), Coleomegilla maculata (DeGeer), Coccinella transversoguttata Faldermann, and Cycloneda munda (Say). H. convergens was the most abundant coccinellid, followed by H. tredecimpunctata , H. parenthesis , Coleomegilla maeulata , Coccinella transversoguttata , and Cycloneda munda in rank order of abundance. Seasonal patterns of population increase differed among species. At all sites, populations of each species fluctuated unpredictably among years and independently of populations of other species. Assemblage structure at a site changed unpredictably from year to year, but the extent of change was constrained. Averaged over years, there were distinct differences in the structure of coccinellid species assemblages at geographically separated sites. Although assemblage structure varied from year to year at a site, there was no evidence of systematic change in structure at any site over the years of the study. A technique was proposed for evaluating the effect of introduced predators on coccinellid species assemblages.

In four trials conducted in 1986 and 1987, inundative releases of the parasitic wasp Diglyphus begini (Ashmead) reduced Liriomyza trifolii (Burgess) populations in greenhouse marigolds grown for seed to approximately zero within 8 wk of the first release, and they remained at that level for the duration of the crop. The parasitoid populations within the greenhouses were a direct result of the releases and subsequent reproduction and not because of migration. Releases of Encarsia formosa Gahan and Chrysoperla carnea Stephens may have been responsible for the maintenance of Trialeurodes vaporariorum Westwood, Aphis gossypii Glover, and Myzus persicae Sulzer at acceptable levels in three of four trials. Spot applications of Bacillus thuringiensis successfully controlled Lepidoptera species. Under successful biological control conditions, the upper foliage of the plants at the end of the trials sustained leafminer damage of 0–1.2 mines per leaf.

Seven species of insects including ground beetles, tiger beetles, earwigs, and the red imported fire ant, Solenopsis invicta Buren, were identified in laboratory feeding trials as pupal predators of velvetbean caterpillar, Anticarsia gemmatalis Hubner. The survivorship and predation of velvetbean caterpillar pupae were studied in soybean fields in Louisiana. Two descriptive categories of predatory feeding action were identified, “partial” and “complete”. Predation was the principal mortality factor, accounting for 52.5 to 95.2% mortality in plots with fire ants. The red imported fire ant was a primary predator, accounting for 77.5 to 96.5% of total predator mortality for pupae under the soil surface in plots with fire ants. Our studies also indicated that the red imported fire ant seemed to reduce other ground-dwelling pupal predators of velvetbean caterpillar.

To describe parasitoids of grape berry moth, Endopiza viteana Clemens, infested grapes were collected during two seasons in three grape habitats: wild grapes (the native host), organically managed commercial vineyards, and conventionally managed commercial vineyards. Three species of egg and larval parasitoids were prominent among the (eight) species collected. Trichogramma pretiosum Riley, an egg parasitoid, was collected only during the second season when E. viteana populations were high and was responsible for a large proportion of parasitoid-induced mortality that season. The larval parasitoids Glypta mutica Cushman and Apanteles polychrosidis Viereck caused low levels of mortality during both seasons. All of the major parasitoid species were collected in each habitat type. Neither levels of parasitism nor the number of parasitoid species collected were consistently higher in the more diverse wild grape habitat compared with the two grape monocultures, although on average, levels of parasitism were slightly higher in the wild grape habitat. G. mutica was responsible for a higher proportion of the overall parasitism in the wild than in the cultivated habitats, whereas A. polychrosidis was responsible for a higher proportion of the parasitism in the cultivated habitats. The proportion of overall parasitism contributed by T. pretiosum was equivalent across habitats. Gated E. viteana cohorts were used to estimate generational mortality in the egg and larval stages. Parasitoids were responsible for 12–42% mortality in three cohorts. Total mortality for the egg and larval stages was between 63 and 72%. The parasitoid complex and resulting level of parasitism at individual sites are influenced by factors independent of those we used to define the habitat types. No generalizations can be made about the expected species composition or level of parasitism in any of the habitats examined.

Egg parasitism of Heliothis zea (Boddie) and other lepidopterous pests was monitored in a field trial of processing tomato cultivars in 1981 and in several late-season commercial fields of processing tomatoes in the Sacramento Valley of California in 1983, 1985, and 1986. Four species of Trichogramma were present: T. pretiosum Riley, T. thalense (Pinto & Oatman), T. deion Pinto & Oatman, and T. brevicapillum Pinto & Platner. Actual parasitism of H. zea eggs exceeded 83% in all fields monitored in 1985 and exceeded 62% in most fields monitored in 1986. Manduca spp. and Trichoplusia ni (Hubner) eggs were also commonly parasitized by Trichogramma spp. The high levels of H. zea egg parasitism recorded in these commercial fields indicates that the current economic threshold, which is based on the abundance of white H. zea eggs, can be increased to account for the mortality caused by Trichogramma . Procedures to incorporate H. zea egg parasitism into the current integrated pest management program for processing tomatoes are proposed. Acceptable fruit quality at harvest in fields that exceeded the current economic threshold during the growing season provides additional support for increasing the threshold. The effect of insecticide applications on H. zea egg parasitism is discussed.

The South American weevil Neohydronomus affinis Hustache was first released in North America as a biological control for waterlettuce, Pistia stratiotes L., at Kreamer Island, Lake Okeechobee, Fla., on 29 April 1987. Releases were made at six additional sites in southern Florida. Periodic observations at several of these sites indicate the weevils have become established and are dispersing. At some sites, weevil-infested plants are exhibiting symptomology typical of plants in other countries where N. affinis has been used successfully to control this aquatic weed.

Pecan, Carya illinoensis (Wangenh.) K. Koch, orchards provide an important habitat for the red imported fire ant, Solenopsis invicta Buren, and orchards from middle to southern Georgia were heavily infested. Honeydew produced by blackmargined aphids, Monellia caryella (Fitch), on pecans was an important source of carbohydrate food for S. invicta , which were found foraging at 9-m heights in trees. Mowing of orchard ground cover caused a change in the ratio of S. invicta on the ground to that in trees but was not correlated with outbreaks of M. caryella in trees. S. invicta was a major predator of eggs, larvae, and pupae of a green lacewing, Chrysoperla rufilabris (Burmeister), and of the pupae of Allograpta obliqua (Say) in pecans but had little effect on the eggs of Hippodamia convergens Guerin-Meneville. A close mutualistic relationship between S. invicta and the mealybug Dysmicoccus morrisoni (Hollinger) was discovered. S. invicta promoted the development of colonies of D. morrisoni on callus tissue located on the main stem of trees by covering the colony with soil and debris, by defending the colony, and by collecting honeydew.

Under greenhouse conditions there is a direct relationship between the density of glandular trichomes on aphid-resistant potato clones ( Solanum tuberosum x S. berthaultii , F3 and S. berthaultii ) and the adverse effectson 11 aphidophagous species. These negative effects include a reduction in adult coccinellid searching time, a decrease in the distance newly hatched chrysopid and coccinellid larvae move, and a decrease in the number of eggs Chrysopa oculata oviposit on highly pubescent foliage. Survival of the parasitoid Aphidius matricariae decreases when adults are exposed to moderate and high densities of glandular pubescence. However, the severe negative effects observed under greenhouse conditions are attenuated in the field. Field studies show that natural enemies and moderate levels of glandular pubescence are compatible mortality factors in the management of aphids on potatoes. Thus, although these greenhouse and laboratory studies elucidate the behavioral responses of natural enemies to glandular trichomes, they inadequately predict the effects of glandular pubescence on beneficial insects in the field.