A roadmap for ladybird conservation and recovery.

Ladybirds (Coleoptera: Coccinellidae) provide services that are critical to food production, and they fulfill an ecological role as a food source for predators. The richness, abundance, and distribution of ladybirds, however, are compromised by many anthropogenic threats. Meanwhile, a lack of knowledge of the conservation status of most species and the factors driving their population dynamics hinders the development and implementation of conservation strategies for ladybirds. We conducted a review of the literature on the ecology, diversity, and conservation of ladybirds to identify their key ecological threats. Ladybird populations are most affected by climate factors, landscape composition, and biological invasions. We suggest mitigating actions for ladybird conservation and recovery. Short-term actions include citizen science programs and education, protective measures for habitat recovery and threatened species, prevention of the introduction of non-native species, and the maintenance and restoration of natural areas and landscape heterogeneity. Mid-term actions involve the analysis of data from monitoring programs and insect collections to disentangle the effect of different threats to ladybird populations, understand habitat use by taxa on which there is limited knowledge, and quantify temporal trends of abundance, diversity, and biomass along a management-intensity gradient. Long-term actions include the development of a worldwide monitoring program based on standardized sampling to fill data gaps, increase explanatory power, streamline analyses, and facilitate global collaborations.

Las catarinas (Coleoptera: Coccinellidae) proporcionan servicios que son críticos para la producción de alimento, y juegan un papel ecológico como fuente de alimento para depredadores. Sin embargo, la riqueza, abundancia y distribución de catarinas están en peligro debido a muchas amenazas antropogénicas. La carencia de conocimiento sobre el estatus de conservación de la mayoría de las especies y los factores que inciden en su dinámica poblacional dificulta el desarrollo e implementación de estrategias de conservación para las catarinas. Realizamos una revisión de la literatura sobre la ecología, diversidad y conservación de catarinas para identificar sus amenazas ecológicas clave. Las poblaciones de catarinas fueron afectadas mayormente por factores climáticos, composición del paisaje e invasiones biológicas. Proponemos acciones de mitigación para la conservación y recuperación de catarinas. Acciones a corto plazo incluyen programas de ciencia y educación ciudadana, medidas de protección para la recuperación de hábitat y de especies amenazadas, prevención de la introducción de especies no nativas y el mantenimiento y restauración de áreas naturales y la heterogeneidad del paisaje. Acciones a mediano plazo implican el análisis de datos obtenidos de programas de monitoreo y colecciones de insectos para desenmarañar el efecto de las diferentes amenazas a las poblaciones de catarinas, comprender el uso del hábitat por taxa de los que se tiene conocimiento limitado y cuantifica las tendencias temporales de la abundancia, diversidad y biomasa a lo largo de un gradiente de intensidad de manejo. Acciones a largo plazo incluyen el desarrollo de un programa de monitoreo a nivel mundial basado en muestreos estandarizados para subsanar la falta de datos, incrementar el poder explicativo, optimizar los análisis y facilitar colaboraciones globales.

Effects of insecticides on malacostraca when managing diamondback moth (Plutella xylostella) in combination planting-rearing fields.

The combination of crop planting and animal rearing in the same area is popular. However, if the methods of planting and rearing are not appropriate, it will result in losses and the disruption of pest management. The toxicities of 17 insecticides to Plutella xylostella, Eriocheir sinensis, and Procambarus clarkii were tested. The recommended maximum field doses were used in 2 d and 4 d bioassays, and the levels of resistance of P. xylostella to insecticides were determined. Of five insecticides that had relatively low toxicity to E. sinensis and P. clarkii, spinetoram and MbNPV showed the best control efficacy of P. xylostella, followed by tetrachlorantraniliprole, chlorantraniliprole, and avermectin. P. xylostella had relatively little resistance to spinetoram, MbNPV, chlorantraniliprole, and avermectin. Therefore, we concluded that the best insecticides suitable for combination planting and rearing fields (cauliflower-crab or cauliflower-crayfish) were spinetoram and MbNPV, followed by chlorantraniliprole and avermectin. Other insecticides, such as emamectin benzoate, indoxacarb, and chlorfenapyr were effective at controlling P. xylostella, but they were not suitable for use in combination planting and rearing fields because of their high toxicity to crabs and crayfish.

Assessing the risk of insecticides to Actinopterygii in the combination of ecological planting and rearing.

In order to study the co-existing environment of pests and economic animals, the toxicity of 15 insecticides to Plutella xylostella, Monopterus albus, and Paramisgurnus dabryanus was tested. Combined with the recommended maximum doses in the field and bioassay, the results showed that for the three insecticides that were of relatively low toxicity to M. albus and P. dabryanus, spinetoram showed the best control effect on P. xylostella, followed by chlorfenapyr and chlorantraniliprole. However, P. xylostella showed a relatively high resistance to chlorfenapyr. Therefore, the best insecticide suitable for the fields with the cauliflower-finless eel or cauliflower-loach planting and rearing combination was spinetoram, followed by chlorantraniliprole and chlorfenapyr. Other insecticides such as emamectin benzoate, Bacillus thuringiensis (Bt), matrine, and so on were effective against the diamondback moth, but they were not suitable for use because of their high toxicity to the finless eel and loach.

Predator Performance and Fitness Is Dictated by Herbivore Prey Type Plus Indirect Effects of their Host Plant.

Animals, including herbivores and predators, use diet-mixing to balance their macro- and micronutrient intake. Recent work demonstrated that lady beetles fed only pea aphids from fava beans had reduced fitness caused by a deficiency of dietary sterols. However, beetles redressed this deficit by eating fava bean leaves. In the current study we used Coccinella septempunctata as a model to test the hypotheses that pea aphids are a poor sterol resource independent of their host plant, and that fava beans produce low quality prey regardless of aphid species. Additionally, we tested the reproductive rescue capacity of alfalfa and barley foliage compared to fava, and profiled the sterols of phloem exudates, foliage, and aphids reared on these different hosts. Beetle fecundity and egg viability was significantly better when provided pea aphids reared on alfalfa (compared to fava beans) and green peach aphids reared on fava plants. Alfalfa and barley leaves were not consumed by beetles and did not support beetle reproduction. The sterol profile of aphids largely reflected their host plant phloem. However, green peach aphids from fava acquired 125-times more sterol than pea aphids from fava. Our findings show how the sterol content of different host-plants can affect the third trophic level. Our results suggest that 1) prey quality varies depending on prey species, even when they occur on the same plant, 2) plant species can mediate prey quality, 3) host plant-mediated effects on prey quality partially drive omnivory, and 4) diet-mixing benefits growth and reproduction by redressing micronutrient deficits.

Herbivory improves the fitness of predatory beetles.

While many predatory arthropods consume non-prey foods from lower trophic levels, little is known about what drives the shift from predator to omnivore. Predatory lady beetles often consume non-prey foods like plant foliage and pollen. One species, Coccinella septempunctata, eats foliage to redress sterol deficits caused by eating sterol-deficient prey. Here we explore how omnivory benefits lady beetle fitness. We reared seven species of lady beetles-from five genera distributed across the tribe Coccinellini-on pea aphids in the presence or absence of fava bean foliage; pea aphids have very low sterol content. Foliage supplements lengthened the development times of four species and decreased survival to adulthood of two species; it had no effect on adult mass. We mated beetles in a 2 × 2 factorial design (males with or without foliage paired with females with or without foliage). For each species, we observed a profound paternal effect of foliage supplements on fitness. Females mated to foliage-supplemented males laid more eggs and more viable eggs compared to females mated to non-supplemented males. Foliage-supplemented males produced 2.9-4.6 times more sperm compared to non-supplemented males for the three species we examined. We analysed the sterol profile of four beetle species reared on pea aphids-with or without foliage-and compared their sterol profile to field-collected adults. For two laboratory-reared species, sterols were not detected in adult male beetles, and overall levels were generally low (total ng of sterol/beetle range: 3-33 ng); the exception being Propylea quatuordecimpunctata females (total ng of sterol/beetle range: 50-157 ng). Laboratory-reared lady beetle sterol content was not significantly affected by the presence of foliage. Field-collected beetles had higher levels of sterols compared to laboratory-reared beetles (2,452-145,348 ng per beetle); cholesterol and sitosterol were the dominant sterols in both field-collected and laboratory-reared beetles. Our findings indicate that herbivory benefits lady beetle fitness across the Coccinellini, and that this was entirely a paternal effect. Our data provide a rare example of a nutritional constraint impacting fitness in a sex-specific manner. It also shows, more broadly, how a nutritional constraint can drive predators towards omnivory.

Mechanism of the different metabolome responses between Plutella xylostella and Pieris rapae treated with the diamide insecticides.

Diamide insecticides, such as chlorantraniliprole, cyantraniliprole, and tetrachlorantraniliprole, are a new class of insecticides that selectively target insects by affecting calcium homeostasis. While this class of insecticides are effective on a wide range of insect pests, the toxicities of diamide insecticides vary among species and life stages. In this study, we addressed the mechanism underlying the different responses of Plutella xylostella and Pieris rapae to diamide insecticides. The susceptibility to insecticides of P. xylostella and P. rapae larvae was assessed 2 and 4 days after exposure to chlorantraniliprole, cyantraniliprole, and tetrachlorantraniliprole. P. xylostella larvae treated with distilled water (Group A), chlorantraniliprole (Group B), cyantraniliprole (Group C), and tetrachlorantraniliprole (Group D) and P. rapae larvae treated with distilled water (Group E), chlorantraniliprole (Group F), cyantraniliprole (Group G) and tetrachlorantraniliprole (Group H) were subjected to metabolomics analysis. The differential metabolites in the B vs. F, C vs. G, and D vs. H groups were analyzed, followed by pathway enrichment analysis. Chlorantraniliprole, cyantraniliprole, and tetrachlorantraniliprole all showed high toxicities for P. xylostella and P. rapae larvae. P. rapae larvae were more sensitive to the diamide insecticides than P. xylostella larvae. There were 65 overlapped differential metabolites between P. xylostella and P. rapae larvae treated with these three diamide insecticides. Pathway analysis showed that the differential metabolites were closely related with fatty acid biosynthesis and metabolism-related pathways. The differential regulation of fatty acid biosynthesis and metabolism may contribute to the different response to diamide insecticides in P. xylostella and P. rapae.

Prey nutrient content creates omnivores out of predators.

The proximate forces that create omnivores out of herbivores and predators have long fascinated ecologists, but the causal reasons for a shift to omnivory are poorly understood. Determining what factors influence changes in trophic position are essential as omnivory plays a central role in theoretical and applied ecology. We used sevenspotted lady beetles (Coccinella septempunctata) to test how prey nutrient content affects beetles' propensity to engage in herbivory. We show that beetles consuming an all-prey diet demonstrate normal growth and development, but suffer a complete loss of fitness (spermatogenic failure) that is restored via herbivory and supplementation with phytosterols and cholesterol. Furthermore, we show that lady beetles possess a state-dependent sterol-specific appetite and redressed their sterol deficit by feeding on foliage. These results demonstrate that predators balance their nutrient intake via herbivory when prey quality is low, and reveal a selective force (sterol nutrition) that drives predatory taxa to omnivory.

An Assessment of the Physiological Costs of Autogenous Defenses in Native and Introduced Lady Beetles.

Many lady beetles expel an autogenously produced alkaloid-rich 'reflex blood' as an antipredator defense. We conducted an experiment to determine whether there was a measurable fitness cost associated with the daily induction of this defensive behavior, and whether costs differed between native (Coccinella novemnotata Herbst (Coleoptera: Coccinellidae)) and invasive species (Coccinella septempunctata L. (Coleoptera: Coccinellidae) and Harmonia axyridis (Pallas) (Coleoptera: Coccinellidae)). Newly mated females were provided a restricted or unrestricted amount of aphids and were bled for 10 d. We measured the mass of reflex blood produced and the total number and viability of eggs laid per day. The amount of reflex blood released per day increased for C. septempunctata at the restricted level and did not change for any other species-diet level combination. We did not detect a significant cost of reflex bleeding on the quantity or viability of eggs laid by any species, even at the restricted aphid level. Remarkably, bled individuals at the ad libitum level laid significantly more viable eggs compared to controls. All species laid significantly fewer total eggs (49-69% fewer) at the low versus high aphid level. These results demonstrate that while resource scarcity has a negative impact on fecundity, repeated use of the reflex bleeding defense system does not. These results support the findings of other reports and strongly suggest that adult lady beetles incur no measurable physiological costs related to the induction of the reflex-bleeding defense.

Interactions of Coccinella novemnotata (Coleoptera: Coccinellidae) and Coccinella septempunctata (Coleoptera: Coccinellidae) While Foraging for Aphids.

The importation and establishment of Coccinella septempunctata L. (Coleoptera: Coccinellidae) in North America purportedly caused the displacement and local extirpation of the native ninespotted lady beetle, Coccinella novemnotata Herbst (Coleoptera: Coccinellidae), across most of its former range, and several reports have shown that C. septempunctata maintains competitive advantages over C. novemnotata. We investigated the role of aphid density on the retention time of these two species on fava bean plants, and the effect of con- versus heterospecific pairings of adult beetles on the foraging behavior of C. novemnotata. We found that aphid density did not affect C. novemnotata's retention time, but did affect the retention time of C. septempunctata, which left plants without aphids significantly faster than C. novemnotata. Additionally, C. septempunctata females left plants significantly faster than their male counterparts, whereas we observed no difference between the two sexes for C. novemnotata. Our test of pairs of beetles showed that C. novemnotata were together on plants more frequently than conspecific pairs of C. septempunctata and heterospecific pairs of beetles, and that all beetles were more likely to be found together on the aphid-infested plant versus the non-infested plant regardless of the pairs' composition. These results show that C. novemnotata spend more time foraging for aphids when aphids are scarce compared with C. septempunctata, and that C. novemnotata is less tolerant of occupying plants inhabited by C. septempunctata versus a conspecific beetle, adding additional mechanisms whereby C. septempunctata could outcompete C. novemnotata in the field.

The Influence of Exotic Lady Beetle (Coleoptera: Coccinellidae) Establishment on the Species Composition of the Native Lady Beetle Community in Missouri.

The diversity and abundance of native lady beetles (Coccinellidae) in North America has declined in recent decades. This decline is often correlated with the introduction and establishment of exotic lady beetle species, including Coccinella septempunctata L. and Harmonia axyridis Pallas, suggesting that exotic species precipitated the decline of native lady beetles. We examined species records of native coccinellids in Missouri over 118 yr and asked whether the species composition of the community experienced a shift following the establishment of the exotic species. We found that the contemporary native coccinellid community is different from the community that was present nearly a century ago. However, there was no evidence for a recent abrupt shift in composition triggered by the establishment of exotic species. Instead, our data suggest that the native lady beetle community has been undergoing consistent and gradual change over time, with some species decreasing in abundance and others increasing. While not excluding exotic species as a factor contributing to the decline of native lady beetle species, our findings suggest that other continuous factors, like land use change, may have played a more influential role in determining the composition of the native coccinellid communities within our region.

Intraguild Interactions of Native and Introduced Coccinellids: The Decline of a Flagship Species.

The decline of Coccinella novemnotata Herbst, the ninespotted lady beetle, across North America has been attributed to the introduction of Coccinella septempunctata L. It has been suggested that C. septempunctata negatively impacted C. novemnotata through a combination of mechanisms. We investigated the effects of scramble competition and intraguild predation between groups of C. septempunctata and C. novemnotata. A novel aspect of these experiments for this species combination was that we provided beetles the option to cannibalize conspecifics or predate on heterospecifics (i.e. intraguild predation); thus, we were able to compare interspecific versus intraspecific competition. Increasing prey density resulted in significantly lower rates of intraguild predation on C. novemnotata by C. septempunctata. Percentage survival of C. novemnotata grouped with C. septempunctata at low and high aphid densities was 6 and 61%, respectively. For our second study, we increased the spatial complexity and volume of the assay system, and provided prey ad libitum. C. novemnotata survival from first-instar to adult was significantly lower than C. septempunctata survival when grouped heterospecifically (43 vs 61% survival, respectively). Finally, we conducted a study to determine if hungry larvae discriminate conspecific versus heterospecific larvae by testing whether they predated selectively on the basis of species, which they did not appear to do. We conclude that C. novemnotata larvae suffer greater rates of intraguild predation from C. septempunctata compared with cannibalism, that this difference appears to be due to size asymmetry between the two species, and that local conditions impact the severity of intraguild predation by C. septempunctata.

Negative effects of pesticides on wild bee communities can be buffered by landscape context.

Wild bee communities provide underappreciated but critical agricultural pollination services. Given predicted global shortages in pollination services, managing agroecosystems to support thriving wild bee communities is, therefore, central to ensuring sustainable food production. Benefits of natural (including semi-natural) habitat for wild bee abundance and diversity on farms are well documented. By contrast, few studies have examined toxicity of pesticides on wild bees, let alone effects of farm-level pesticide exposure on entire bee communities. Whether beneficial natural areas could mediate effects of harmful pesticides on wild bees is also unknown. Here, we assess the effect of conventional pesticide use on the wild bee community visiting apple (Malus domestica) within a gradient of percentage natural area in the landscape. Wild bee community abundance and species richness decreased linearly with increasing pesticide use in orchards one year after application; however, pesticide effects on wild bees were buffered by increasing proportion of natural habitat in the surrounding landscape. A significant contribution of fungicides to observed pesticide effects suggests deleterious properties of a class of pesticides that was, until recently, considered benign to bees. Our results demonstrate extended benefits of natural areas for wild pollinators and highlight the importance of considering the landscape context when weighing up the costs of pest management on crop pollination services.

Egg Predation by the Introduced Lady Beetle, Coccinella septempunctata (Coleoptera: Coccinellidae), Lowers Mortality but Raises Relative Risk for the Native Lady Beetle, Coccinella novemnotata.

Populations of the native ninespotted lady beetle, Coccinella novemnotata Herbst, have undergone precipitous declines in North America following the establishment of the exotic sevenspotted lady beetle, Coccinella septempunctata L. Recent volunteer efforts have made it possible to establish colonies of the now-rare C. novemnotata and test mechanisms contributing to its decline. We evaluated the relative frequencies of intraguild predation and cannibalism of eggs between these two species. A single C. novemnotata or C. septempunctata adult was exposed to conspecific and heterospecific eggs in either the presence or absence of pea aphids. The study revealed two expected results: 1) eggs of C. novemnotata were consumed more frequently than eggs of C. septempunctata by both species, and 2) egg consumption was higher when aphids were absent, independent of predator and egg species. There were also two unexpected results from the study: 1) the asymmetry between egg predation rates was higher when aphids were present, and 2) higher predation rates on C. novemnotata eggs in the absence of alternate prey was due to a relatively higher rate of intraspecific cannibalism. This implies that C. novemnotata would have suffered higher egg mortality rates before the invasion of C. septempunctata, but even though the aggregate rate of egg predation on C. novemnotata eggs is lower post-invasion, it is still significantly higher than the aggregate rate of predation of C. septempunctata eggs. This differential pattern of asymmetric predation could contribute to habitat compression and the overall decline of C. novemnotata.

Development times and age-specific life table parameters of the native lady beetle species Coccinella novemnotata (Coleoptera: Coccinellidae) and its invasive congener Coccinella septempunctata (Coleoptera: Coccinellidae).

To determine if differences in life history parameters contribute to native species exclusion, immature development times, larval survivorship, reproductive life history parameters, and age-specific life tables were determined for two populations (eastern United States and western United States) of ninespotted lady beetles (Coccinella novemnotata Herbst) and one population of sevenspotted lady beetles (Coccinella septempunctata L.). Developing larvae were provided an ad libitum diet of pea aphids (Acyrthosiphon pisum Harris) at a constant temperature of 25°C. The first and fourth larval stadia of C. novemnotata were significantly longer than that of C. septempunctata, as was their total development time from egg to newly eclosed adult. Stage-specific developmental mortality was low for both species and did not exceed 7% for the entire development period. The preoviposition period of the two C. novemnotata populations was significantly shorter (15-20%) than that of C. septempunctata. C. novemnotata from both locations laid significantly fewer total eggs than C. septempunctata (34-40% fewer) over the 31-d test period, and also fewer eggs per day (37-43% fewer). The net reproductive rate of the C. novemnotata populations was 42-50% lower than that of C. septempunctata as was C. novemnotata's intrinsic rate of natural increase (rm: 0.1716 and 0.1840 vs. 0.1959 for western and eastern C. novemnotata and C. septempunctata, respectively).

Effect of prey limitation on competitive interactions between a native lady beetle, Coccinella novemnotata, and an invasive lady beetle, Coccinella septempunctata (Coleoptera: Coccinellidae).

The size and geographic distribution of Coccinella novemnotata Herbst populations have been decreasing rapidly across North America closely following the establishment, spread, and population growth of the invasive seven-spotted lady beetle, Coccinella septempunctata L. To determine whether intraguild predation and competition for prey may be partially responsible for the decline, we paired first-instar larvae of two populations of C. novemnotata (eastern and western) with first-instar C. septempunctata at low or high aphid densities. Survival of both C. novemnotata populations was significantly lower when larvae were paired with C. septempunctata, and western C. novemnotata exhibited significantly lower survival compared with the eastern population. This relationship depended on aphid density with the greatest survival of both C. novemnotata populations occurring at the high aphid density. Both male and female C. novemnotata weighed less on the day of eclosion when paired with C. septempunctata as compared with pairings with conspecifics. In a second test, C. septempunctata and C. novemnotata instars were varied at the start of the trial and C. novemnotata survival to adulthood in the presence of C. septempunctata was dependent of the instar of C. novemnotata used to initiate the experiment. C. novemnotata exhibited higher rates of survival and weighed significantly more on the day of eclosion when C. novemnotata was older than its C. septempunctata partner. These results suggest that interspecific competition including intraguild predation by C. septempunctata may contribute to C. novemnotata population declines, but that the intensity of this impact may vary across C. novemnotata populations.

Genetics of color polymorphism in the pea aphid, Acyrthosiphon pisum.

The genetic basis of color polymorphism is explored in the pea aphid, Acyrthosiphon pisum (Harris) (Homoptera: Sternorrhyncha), in which two color morphs have been described (pink or green). Laboratory crosses and a Mendelian genetic analysis reveal that color polymorphism in pea aphids is determined by a single biallelic locus, which we name colorama, with alleles P and p, pink being dominant to green. The putative genotypes are Pp or PP for pink morphs, and pp for green morphs. This locus is shown to be autosomal. Last, there was no evidence of influence of the direction of the cross on color inheritance, thus showing that cytoplasmic effects and/or maternally-inherited symbionts play no role in the inheritance of color polymorphism in pea aphids. The existence of a simple genetic determinism for color polymorphism in a system in which genetic investigation is possible may facilitate investigations on the physiological and molecular mechanisms of genetically-based color morph variation, and the establishment of a link between this locus and fitness in a range of ecological conditions.

Transect sampling to enhance efficiency of corn rootworm (Coleoptera: Chrysomelidae) monitoring in corn.

Crop monitoring for adult corn rootworms, Diabrotica virgifera virgifera LeConte and Diabrotica barberi Smith and Lawrence, remains the best means to assess fields at risk from this pest if replanted to corn, Zea mays (L.). Improvements in sampling methodology, including the development of a sequential sampling plan, have reduced the minimum sampling time required to make a management decision to 20 min or less per field per visit. However, many growers and crop consultants still find this time commitment a constraint to repeated scouting. A common currently used sampling method involves systematically covering most of the field following a "W" pattern. The feasibility of replacing the current sampling pattern with a simpler and less time-consuming transect (straight line) pattern was assessed. When sampling methods were compared, computer simulations demonstrated that treatment decisions based on transect sampling would have an acceptably low error rate averaging 10% over a range of realistic corn rootworm densities (0-2 adults per plant). This error rate represented a decrease in accuracy of <1% compared with systematic sampling. Field trials using transect, systematic, and random sampling in each field were used to compare the categorization of adult corn rootworm densities into "above" or "below" threshold with a sequential sampling plan. Efficiency measured in time to reach a decision, number of corn plants evaluated, and time divided by plants observed were compared between sampling methods. The three methods did not differ significantly in the number of plants evaluated or in the categorization of corn rootworm populations. Transect sampling resulted in a significantly shorter time divided by plants observed (38 s), than either systematic (78 s), or random sampling methods (166 s). Based on these results transect sampling reduces sampling time 51% compared with systematic sampling and thus could be used to reduce total sampling times substantially.

Enumerating lepidopteran species associated with maize as a first step in risk assessment in the USA.

Pest management can have substantial impacts on non-target species both within and outside the units being managed. Assessment of these impacts is hampered by the lack of even the most basic checklist of the species present in most systems. The maize agroecosytem is of particular interest because of the large area covered and the intensity of widely varying forms of pest management. In this study a database of lepidopteran species that occur within the maize agroecosystem in the United States was compiled. The process was initiated by developing a list of plants present in maize using published sources and the first-hand knowledge of "weed" experts. This list of plant species associated with maize was then cross-listed with lepidopteran host feeding records using published sources. Finally, phenological profiles and conservation rankings were added. Although our list is not exhaustive, we found 132 plant species in 33 families associated with maize, and 229 lepidopteran species in 21 families that feed on these plants. The database of plants and lepidopteran species can be a starting point for assessment of risk to non-target Lepidoptera in maize from chemical control, biological control, and the use of transgenic Bt maize. The lepidopteran species associated with maize were found to be significantly less imperiled, as measured by their conservation rankings, than lepidopteran species as a whole in all habitats. This finding suggests that rare or endangered lepidopteran species are unlikely to be impacted by pest management in maize. Based on the likely lack of impact of pest management in maize on individual species, future studies should focus on potential impacts on the ecological services that lepidopteran species provide.

Interspecific variation in the escape responses of aphids: effect on risk of predation from foliar-foraging and ground-foraging predators.

A series of laboratory experiments was conducted to determine the effect of interspecific differences on prey defensive behavior on the susceptibility of two aphid species (Acyrthosiphon pisum and A. kondoi) to a ground-foraging predator, Harpalus pennsylvanicus, and a foliar-foraging predator, Coccinella septempunctata. These organisms are representative of a biologically and economically important predator/prey system in alfalfa. The primary defensive behavior of both aphid species toward C. septempunctata was to "drop" from the plant. Both aphid species were significantly more likely to drop from the plant in the presence of C. septempunctata. However, when C. septempunctata was present, a significantly lower proportion of A. kondoi individuals dropped (0.42 ± 0.07) compared to A. pisum (0.73 ± 0.08). As a result of their lower propensity to drop from the plant A. kondoi individuals are significantly more likely to be consumed by C. septempunctata. Conversely, the higher propensity of A. pisum individuals to drop increased their susceptibility to ground-foraging predators. When A. pisum was the prey species, ground-foraging predators made a significant contribution to overall aphid suppression and there was a significant synergistic interaction between ground and foliar-foraging predators. When A. kondoi was the prey there was no interaction between the predator species. As either a cause or consequence of its higher propensity to drop, A. pisum seems to be more adapted for survival and dispersal off the plant. In comparison to A. kondoi individuals, A. pisum individuals relocate plants more quickly (63 ± 41 s vs. 164 ± 39 s), disperse farther (18 ± 1.7 cm vs. 13 ± 0.66 cm), and survive longer (37 ± 2.0 h vs. 25 ± 2.0) off the plant. This study demonstrates the importance of prey defensive behavior in determining the susceptibility of a prey species to a multiple-predator complex.