Promoting arthropod biodiversity to increase ecosystem services through ecological intensification is a challenge for agriculture. And recent evidence suggests that standard pesticide applications not only harm natural enemies but may also fail to deliver long-term pest control solutions. To fuel ecological intensification and build predictive frameworks for pest management incorporating estimates of pest abundance, natural enemy abundance and their associated interactions is essential. Within this framework, there is a need to shift the focus from a single pest and predator to consider the community of predatory arthropods that interact with communities of prey. We took a network-based approach to investigate community interactions of predatory arthropods that feed on key pests and alternative prey in cotton over a three-year period. We merged prey activity, generalist predator communities collected from cotton canopies, and reconstructed trophic interactions with DNA detection frequencies estimated from molecular gut content analysis. Overall, many predator diets overlap, resulting in similar foraging patterns on groups of cotton pests. Moreover, predation on key cotton pests, such as stink bugs and white flies, was low. Therefore, ecological intensification that increases specialized arthropod predators within the community should improve biological control service delivery.

Among the many ecosystems services of winter covers, winter legumes have an advantage over winter grain covers by fixing N that may be used by subsequent crops. A 5-yr study was conducted to compare the biomass yields of five leguminous winter cover crops [Austrian winter pea (Pisum sativum L.), fava bean (Vicia fava L.), narrow-leaf lupin (Lupinus angustifolius L.), cahaba vetch (Vicia spp.), crimson clover (Trifolium incarnatum L.)] plus rye (Secale cereale L.) and determine the effects of these winter cover crops either harvested or left on the soil on subsequent biomass sorghum [Sorghum bicolor (L.) Moench] and cotton (Gossypium hirsutum L.) yields at two field locations in Georgia. Lupin produced between 4.16 and 9.54 Mg ha(-1) biomass, approximately two to four times more than any other cover at both locations every year. Lupin, followed by vetch and winter pea had the greatest positive effect on biomass sorghum yields. Biomass-sorghum yields after lupin cover were not significantly different whether biomass was retained on the soil by rolling or removed. Seed cotton yields were higher after lupin and vetch . Significantly higher sorghum and cotton yields occurred for rolled covers with crimson clover, winter pea, and fava bean. Averaged over the years and locations, lupin biomass produced approximately 143 kg ha(-1) N, more than any other cover. The study suggests that harvested or grazed lupin or vetch covers could give similar benefits to summer row crops compared with traditionally leaving the cover on the soil.

Precision agriculture (PA) is the application of management decisions based on identifying, quantifying, and responding to space-time variability. However, knowledge of crop pest responses to within-field environmental variability, and the spatial distribution of their natural enemies, is limited. Quantitative methods providing insights on how pest-predator relationships vary within fields are potentially important tools. In this study, phloem feeders and their natural enemies, were observed over two years across 81 locations within a field of the perennial feedstock grass in Georgia, USA. Geographically weighted regression (GWR) was used to spatially correlate their abundance with environmental factors. Variables included distance to forest edge, Normalized Difference of Vegetation Index (NDVI), slope, aspect, elevation, soil particle size distribution, and weather values. GWR methods were compared with generalized linear regression methods that do not account for spatial information. Non-spatial models indicated positive relationships between phloem-feeder abundance and wind speed, but negative relationships between elevation, proportions of silt and sand, and NDVI. With data partitioned into three seasonal groups, terrain and soil variables remained significant, and natural enemies and spiders became relevant. Results from GWR indicated that magnitudes and directions of responses varied within the field, and that relationships differed among seasons. Strong negative relationships between response and explanatory factors occurred: with NDVI during mid-season; with percent silt, during mid-, and late seasons; and with spider abundance during early and late seasons. In GWR models, slope, elevation, and aspect were mostly positive indicating further that associations with elevation depended on whether models incorporated spatial information or not. By using spatially explicit models, the analysis provided a complex, nuanced understanding of within-field relationships between phloem feeders and environmental covariates. This approach provides an opportunity to learn about the variability within agricultural fields and, with further analysis, has potential to inform and improve PA and habitat management decisions.

Wild bees are major contributors to pollination of economically important crops. However, widespread habitat conversion to agriculture and pesticide exposure are associated with declines in wild bee abundance and biodiversity. A growing number of studies have investigated the incorporation of a variety of flower species in agroecosystems to augment resource and habitat availability to wild bees and pollination of nearby crops. Here we investigated if wildflower strips containing Gaillardia pulchella Foug. (Asteraceae) in 2018 and G. pulchella, Rudbeckia hirta L. (Asteraceae), and Monarda citriodora Cerv. ex Lag. (Lamiaceae) in 2019 could promote pollinator abundance and pollination of nearby peanut and cotton. We used bee bowls in crop fields to capture bees and identified the pollen on the bees. We captured a total of 291 bees in peanut and 89 bees in cotton that were comprised of 2 families (Apidae and Halictidae) with 10 species represented from these families. The species in peanut were comprised mostly of Melissodes communis Cresson and Melissodes bimaculatus Lepeletier (Apidae). The bee species in cotton was comprised of mostly Lasioglossum reticulatum Robertson (Halictidae), M. communis, and M. bimaculatus. At peak abundance in peanut, 48% of bees bore both G. pulchella and peanut pollen. At peak abundance in cotton, 37% of bees bore 1 or more wildflower strip pollen and cotton pollen. Throughout the season, 62% of the bees captured in cotton had unidentified pollen from surrounding sources. These results indicate that the wildflower buffers had provided pollinators and bee foragers to these crops in early season. By studying bee foraging between crop fields and wildflower strips based on identification of pollen grain on bee bodies, we showed the potential to increase pollination in crop fields through the provision of floral resources throughout the growing season.

Since its invasion of the southeastern United States in 2009, the bean plataspid or kudzu bug, Megacopta cribraria (F.) (Hemiptera: Plataspidae), has become an agricultural pest of soybean, Glycine max (L.) Merrill (Gardner et al. 2013, J. Entomol. Sci. 48: 355–359; Lahiri and Reisig 2016, J. Integrated Pest Manage. 7: 1–6; Ruberson et al. 2013, J. Appl. Zool. Entomol. 48: 3–13). The use of chemical-based arthropod control is the dominate means of controlling this pest (Lahiri and Reisig 2016). However, this practice can harm nontarget species including Paratelenomous saccharalis (Dodd) (Hymenoptera: Platygastridae), an egg parasitoid of M. cribraria in the kudzu bugs' native range. Paratelenomous saccharalis was first discovered in the southeastern United States in 2013, but only populations in southern Georgia and Florida have established (Gardner and Olson 2016, J. Entomol. Sci. 51: 325–328; Gardner et al. 2013; Medal et al. 2015, Florida Entomol. 98: 1250–1251). Therefore, alternative less toxic control methods are needed. One method of control is the use of biopesticides in an integrated pest management (IPM) strategy (Lahiri and Reisig 2016). Biopesticides are derived from natural materials and are less toxic than conventional pesticides; they are more pest specific, and smaller quantities are needed for control. Our objectives were to (a) determine the influence of the biopesticides Azera, Neem, and Pyganic on all life stages of M. cribraria in soybean and (b) determine the influence of these biopesticides on P. saccharalis sampled from naturally occurring M. cribraria egg masses in soybean.The study was conducted on the University of Georgia Lang experimental farm in Tifton, GA. Soybean (variety AG 6931) was planted 7 May 2014 in an area 13.7 m by 16 rows. Four treatments were randomly assigned in plots of 3.4 m by eight rows with four replications. Biopesticides were applied to the plots on 23 July at 4.10 L/ha for Azera (MGK, Minneapolis, MN) and Pyganic (MGK, Minneapolis, MN) and 2.34 L/ha for Neem (Certis, Columbia, MD). GOS (Georgia Organic Solutions, LLC) spray clean (0.95 L) was also applied to the biopesticide plots. No biopesticides were applied to the control plots. Megacopta cribraria adults and nymphs were sampled from the four middle rows, two rows alternated per sampling date, with a sweep net 38 cm in diameter for 7.31 m of rows. Egg masses were sampled by collecting a single egg mass from each sample location. Weekly sampling began on 8 July and was every 3 days after the pesticides were applied for a total of seven sampling dates. Kudzu bug developmental stages were identified and recorded in the laboratory. Egg masses were held in an environmental chamber (12:12 h [L:D]; 25 ± 2.0°C; 50 ± 10% relative humidity) for emergence of kudzu bugs or parasitoids.All data were analyzed using SAS statistical software (SAS Institute Inc., Cary, NC). The effect of date, treatment, and their interactions on the density of eggs, nymphs, and adults was tested with analysis of variance using Tukey's honestly significant difference (HSD) to separate significantly different means. Chi-square analyses were used to compare percentage of eggs and egg masses parasitized and those not parasitized by P. saccharalis among treatments.There were significant interactions between date and treatment on the density of M. cribraria third instars (Table 1). The density of third instars was higher in Pyganic than in the other treatments but only on 31 July. No interactions between date and treatment were found for the density of adults, egg masses, and second, fourth, and fifth instars (Table 1). There was a significant effect of date on the density of adults, egg masses, and first, second and fourth instars, but not fifth instars (Table 1). The density of adults was higher on 16 July than on all other sampling dates (Fig. 1). Egg mass density increased over the first three sampling dates, peaking on 22 July and remaining at this density over the later sampling dates (Fig. 1). The density of first instars was higher on 25 July than on all other sampling dates (Fig. 2). The density of second instars was higher on 23 July than on 8 and 15 July (Fig. 2). The density of fourth instars was higher on 31 July than on any other sampling date (Fig. 2). Treatment had a significant effect on the density of second instars and egg masses (Table 1). The density of second instars was significantly lower in the Azera and Neem treatments than in the control and the Pyganic treatments (Fig. 3). The density of egg masses was significantly lower in the Azera treatment than in the control, Neem, and Pyganic treatments (Fig. 3).There was a significant influence of treatment on the percentage parasitism of M. cribraria eggs (χ2 = 36.94, df = 3, P < 0.001) and egg masses (χ2 = 40.04, df = 3, P < 0.001). Parasitism was highest in the control, intermediate in the Neem, lower in the Azera, and lowest in the Pyganic treatment (Fig. 4). There was no significant influence of treatment on the percentage of eggs of M. cribraria not parasitized (χ2 = 6.38, df = 3, P = 0.095; Fig. 4). There was a significant influence of treatment on the percentage of M. cribraria total eggs (χ2 = 10.49, df = 3, P = 0.015), those hatched (χ2 = 8.80, df = 3, P = 0.032), and those not hatched (χ2 = 12.62, df = 3, P = 0.006). A higher percentage of eggs was found in the control than in the biopesticide treatments (Fig. 5). A lower percentage of eggs hatched, and a higher percentage of eggs did not hatch in the Azera treatment (Fig. 5). The least percentage of eggs not hatched was found in the Pyganic treatment (Fig. 5).We found that Neem and especially Azera had a negative effect on the density of second instars of M. cribraria in soybean, with almost 100% fewer numbers of these instars compared with the control. Neem treatments showed a 50% reduction in the density of second instars in soybean compared with the control. The number of M. cribraria egg masses was also lowest in the Azera treated soybean, and the number of M. cribraria eggs that did not hatch was highest in the Azera-treated soybean compared with the control and other biopesticide treatments. This suggests that Azera may be effective in reducing M. cribraria eggs and second-instar nymphs in soybean. However, Azera-treated soybean had fewer parasitized M. cribraria eggs and egg masses than the control and Neem treatment. Given the reduction in second instars treated with Neem and Neem's lower negative effect on egg and egg mass parasitism, Neem may be the most suitable alternative control method for M. cribraria in an IPM management strategy. The benefits of Neem as a biopesticide have been reviewed in Unsal (2019, Turkish J. Agric. Food Sci. Tech. 7: 1415–1423). Laboratory assays of Azera show high mortality of brown marmorated, Halyomorpha halys (Stål) (Hemiptera: Pentatomidae), and other stink bug adults and nymphs, but field studies in pepper and tomato indicated no effect on these pests (Morehead and Kuhar 2017, J. Pest Sci. 90: 1277–1285). To the best of our knowledge, this is the first report of Azera as a biopesticide of kudzu bugs. The Pyganic biopesticide had the lowest parasitized M. cribraria eggs and egg masses and had no effect on any M. cribraria life stage, suggesting the use of Pyganic may not be a suitable strategy for M. cribraria control in soybean. No control of the crucifer flea beetle, Phyllotreta cruciferae (Goeze) (Coleoptera: Chrysomelidae), on canola and brown marmorated and other stink bugs on pepper and tomato has been found (Briar et al. 2018, Phytoparasitica 46: 247–254; Morehead and Kuhar 2017), but the compound has been effective against whiteflies, Bemisia tabaci (Gennadius) (Hemiptera: Aleyrodidae), in squash (Razze et al. 2016, J. Econ. Entomol. 109: 1766–1771) and had no effect on the whitefly predator Delphastus catalinae (Horn) (Coleoptera: Coccinellidae) when the predator was released 5 days after pesticide application.

Stink bugs (Hemiptera: Pentatomidae) are economic pests of a variety of fruit crops across the southeastern USA, and damage by stink bugs to peaches is common. The landscape surrounding orchards may influence stink bug distribution and dispersal into this commodity, but such patterns may vary over the growing season. Accordingly, stink bug control should be targeted seasonally towards habitats that effectively reduce or prevent damage to peach. In this study, we used pheromone-baited traps to characterize distribution patterns of 2 stink bug species, Euschistus servus (Say) and Euschistus tristigmus (Say) (both Hemiptera: Pentatomidae), in peach orchards and surrounding habitat over 2 seasons at 3 sites in central Georgia, USA. In addition, we used Spatial Analysis by Distance Indices to identify significant aggregations of each species over the duration of the growing seasons. Adults captured in traps differed by species, and distribution patterns varied by habitat and wk sampled. Euschistus servus was commonly found in peaches, whereas E. tristigmus was not. Regardless of orchard or yr, adult E. servus tended to avoid woodland habitat, whereas E. tristigmus tended to prefer this habitat type. Both species increased later in the season in peach orchards with significant spatial aggregations of each detected at all orchards. However, the wk in which aggregations were detected varied by orchard and yr. Across all orchards, E. servus adults clustered mainly in peach trees adjacent to pecan, as well as pine, fallow, and kudzu habitat. Adult E. tristigmus aggregated primarily in woodland, pine, and pecan habitat. Seasonal distribution patterns of E. servus and E. tristigmus suggest that control measures may need to be implemented on a fine spatial scale across peach and non-crop habitats.

Stink bugs (Hemiptera: Pentatomidae) are significant pests of cotton and soybeans in the southeastern United States with annual control costs exceeding $14 million in these crops. Three of the most prominent stink bug pests are the southern green (Nezara viridula), brown (Euschistus servus) and green (Chinavia hilaris) stink bugs. To determine trophic linkages between generalist arthropod predators and these pests, species-specific 16S molecular markers were designed and used to detect the presence of prey DNA in predator gut-contents. Over 2700 predators were collected over two growing seasons in cotton and soybean in southern Georgia in 2011 and 2012 and screened for stink bug DNA. Trophic linkages were analyzed relative to prey availability, crop type and field location. The frequency of stink bug DNA in predator guts was negligible on E. servus (0.23%) and C. hilaris (0.09%). Overall gut content detection of N. viridula was 3.3% and Geocoris sp. (Hemiptera: Geocoridae), Orius sp. (Hemiptera: Anthocoridae) and Notoxus monodon (Coleoptera: Anthicidae) were the primary predators. This contrasts with previous studies that reported a much more diverse suite of predators consuming stink bugs with much higher frequency of gut-content positives. The discrepancy between studies highlights the need for replicating studies in space and time, especially if the goal is to implement effective and durable conservation biological control in integrated pest management.

The economically important brown stink bug, Euschistus servus (Say) (Hemiptera: Pentatomidae), is a native pest of many crops in southeastern United States and insecticide applications are the prevailing method of population suppression. To elucidate biological control of E. servus populations, we investigated two egg predators' (red imported fire ants, Solenopsis invicta Buren (Hymenoptera: Formicidae), and Geocoris spp. (Hemiptera: Geocoridae)) responses to both local and landscape factors that may have influenced their combined ability to cause mortality in immature E. servus. We estimated the density of fire ants and Geocoris spp. on four major crop hosts-maize, peanut, cotton, and soybean-in 16 landscapes over 3 yr in the coastal plain of Georgia, USA. Both Geocoris spp. and fire ant populations were concentrated on specific crops in this study, maize and soybean for Geocoris spp. and peanut and cotton for fire ants, but the percentage area of specific crops and woodland and pasture in the landscape and year also influenced their density in focal fields. The crop specific density of both taxa, the influence of the percentage area of specific crops and woodland in the landscape, and the variability in density over years may have been related to variable alternative resources for these omnivores in the habitats. Despite the variability over years, differential habitat use of fire ants and Georcoris spp. may have contributed to their combined ability to cause E. servus immature mortality.

Studies show that agricultural land requires investment in the habitat management of non-cropped areas to support healthy beneficial arthropods and the ecosystem services they provide. In a previous small plot study, we manually counted blooms over the season, and found that plots providing greater numbers of flowers supported significantly higher pollinator populations over that of spontaneous weed plots. Here, we examined the potential of deploying an inexpensive small unmanned aerial vehicle (UAV) as a tool to remotely estimate floral resources and corresponding pollinator populations. Data were collected from previously established native wildflower plots in 19 locations on the University of Georgia experimental farms in South Georgia, USA. A UAV equipped with a lightweight digital camera was deployed to capture images of the flowers during the months of June and September 2017. Supervised image classification using a geographic information system (GIS) was carried out on the acquired images, and classified images were used to evaluate the floral area. The floral area obtained from the images positively correlated with the floral counts gathered from the quadrat samples. Furthermore, the floral area derived from imagery significantly predicted pollinator populations, with a positive correlation indicating that plots with greater area of blooming flowers contained higher numbers of pollinators.

Marginal agricultural land provides opportunities to diversify landscapes by producing biomass for biofuel, and through floral provisioning that enhances arthropod-mediated ecosystem service delivery. We examined the effects of local spatial context (adjacent to woodland or agriculture) and irrigation (irrigation or no irrigation) on wildflower bloom and visitation by arthropods in a biofeedstocks-wildflower habitat buffer design. Twenty habitat buffer plots were established containing a subplot of Napier grass (Pennisetum perpureum Schumach) for biofeedstock, three commercial wildflower mix subplots, and a control subplot containing spontaneous weeds. Arthropods and flowers were visually observed in quadrats throughout the season. At the end of the season we measured soil nutrients and harvested Napier biomass. We found irrespective of buffer location or irrigation, pollinators were observed more frequently early in the season and on experimental plots with wildflowers than on weeds in the control plots. Natural enemies showed a tendency for being more common on plots adjacent to a wooded border, and were also more commonly observed early in the season. Herbivore visits were infrequent and not significantly influenced by experimental treatments. Napier grass yields were high and typical of first-year yields reported regionally, and were not affected by location context or irrigation. Our results suggest habitat management designs integrating bioenergy crop and floral resources provide marketable biomass and habitat for beneficial arthropods.

We conducted a field study to determine seasonal egg parasitism rates of the kudzu bug Megacopta cribraria (F.) on the kudzu plant, Pueraria montana (Lour.) Merr. var. lobata (Willd.) Maesen et Almeida ex Sanjappa and Pradeep, in Tokyo, Japan, during the period from May 2014 to September 2014. The eggs of M. cribraria per 1 m2 of kudzu at four locations in Tokyo were collected weekly and parasitism rates were assessed. Eggs of M. cribraria were laid on the kudzu plant from May to September. Megacopta cribraria eggs were parasitized by two parasitoid species, Paratelenomus saccharalis (Dodd) and Ooencyrtus nezarae Ishii. Paratelenomus saccharalis first appeared in May, and its parasitism rates peaked in July and September. Ooencyrtus nezarae first appeared in June and its parasitism rates peaked in July. Except for one location which could not be statistically analyzed because of the small sample size, occurrence of parasitism by P. saccharalis and O. nezarae in M. cribraria egg masses was independent at one location and positively associated at two locations, suggesting that the use of host egg masses by P. saccharalis and O. nezarae is not mutually exclusive. Parasitism rates by P. saccharalis and O. nezarae were significantly lower for egg masses parasitized by both species than for those parasitized by a single species. The proportion of males among O. nezarae progeny was significantly higher for egg masses parasitized by O. nezarae together with P. saccharalis than for those parasitized by O. nezarae alone. These results suggest that parasitism of host egg masses by the two species is influenced by their interspecific interactions.

Producers in the southeastern USA face significant crop losses from the stink bugs Nezara viridula (L.), Euschistus servus (Say), and Chinavia hilaris (Say) (all Hemiptera: Pentatomidae). Cotton, peanut, and soybean are major agronomic crops and host plants of stink bugs in the region. We conducted a field plot study to measure the relative longevity of adult, unmated N. viridula males and females caged on peanut, cotton, and soybean to test three hypotheses: (1) differences in mortality are associated with differences in host plant food suitability, (2) mortality rates increase with age, and (3) males have higher mortality than females. Using survival analysis, we found that the sex of the individual did not affect survival rates on any of the three host plants. Survival was significantly higher in cotton and soybean than in peanut. Mortality rates increased with age in peanut, but not in soybean or cotton. The frequency of canopy temperatures above 35 °C was higher in peanut than in soybean. Peanut appears to be a less than ideal habitat in terms of canopy temperature and/or food quality for N. viridula adults. Both, cotton and soybean were equally suitable food resources for N. viridula adults prior to maturation of the plants.

The success of parasites can be impacted by multi-trophic interactions. Tritrophic interactions have been observed in parasite-herbivore-host plant systems. Here we investigate aspects of multi-trophic interactions in a system involving an entomopathogenic nematode (EPN), its insect host, and host plant. Novel issues investigated include the impact of tritrophic interactions on nematode foraging behavior, the ability of EPNs to overcome negative tritrophic effects through genetic selection, and interactions with a fourth trophic level (nematode predators). We tested infectivity of the nematode, Steinernema riobrave, to corn earworm larvae (Helicoverpa zea) in three host plants, tobacco, eggplant and tomato. Tobacco reduced nematode virulence and reproduction relative to tomato and eggplant. However, successive selection (5 passages) overcame the deficiency; selected nematodes no longer exhibited reductions in phenotypic traits. Despite the loss in virulence and reproduction nematodes, first passage S. riobrave was more attracted to frass from insects fed tobacco than insects fed on other host plants. Therefore, we hypothesized the reduced virulence and reproduction in S. riobrave infecting tobacco fed insects would be based on a self-medicating tradeoff, such as deterring predation. We tested this hypothesis by assessing predatory success of the mite Sancassania polyphyllae and the springtail Sinella curviseta on nematodes reared on tobacco-fed larvae versus those fed on greater wax moth, Galleria mellonella, tomato fed larvae, or eggplant fed larvae. No advantage was observed in nematodes derived from tobacco fed larvae. In conclusion, our results indicated that insect-host plant diet has an important effect on nematode foraging, infectivity and reproduction. However, negative host plant effects, might be overcome through directed selection. We propose that host plant species should be considered when designing biocontrol programs using EPNs.

Since its invasion of the southeastern United States in 2009, the bean plataspid or kudzu bug, Megacopta cribraria (F.) (Hemiptera: Plataspidae), has become an agricultural pest of soybean, Glycine max (L.) Merrill (Ruberson et al. 2013, J. Appl. Zool. Entomol. 48: 3–13; Gardner et al. 2013, J. Entomol. Sci. 48: 355–359), initiating studies to determine potential biological control agents. Surveys of kudzu, Pueraria montana var. lobata (Willd.) Maesen & S. Almeida, in the more northern counties of Georgia in 2010, 2011, and 2012 found no parasitized kudzu bug egg masses and also concluded that occasional generalist predators and pathogens did not appear to effectively control this species (Ruberson et al. 2013; Zhang et al. 2012, Environ Entomol. 41:40–50). However, in 2013, an egg parasitoid identified as Paratelenomus saccharalis (Dodd) (Hymenoptera: Platygastridae) by Walker A. Jones (USDA-ARS) and confirmed by Elijah J. Talamas (USDA, Smithsonian Institution, Washington, DC) was found in kudzu bug eggs in kudzu initially in northcentral Georgia, where parasitism rates ranged from 47.5% to 95% (Gardner et al. 2013). This parasitoid was subsequently reported from kudzu bug eggs in Alabama, South Carolina, Mississippi (Gardner et al. 2013), southern Georgia (P. Roberts and D.M.O. pers. obs.), and Florida (Medal et al. 2015, Fla. Entomol. 98: 1250–1251). However, since its initial discovery in 2013, the parasitoid has only been found in southern Georgia and Florida, presumably because of natural mortality factors impacting its ability to overwinter in the more northern areas of its reported range. Epizootics of the entomogenous fungus Beauveria bassiana (Balsamo) Vuillemin were also observed and confirmed in soybean fields, kudzu patches, or both in several locations in South Carolina (pers. commun. D. Greene and J. Greene, Clemson University), and North Carolina (pers. commun., E. Scocco Niland, Wingate University). High mortality rates of overwintering kudzu bug adults

The adoption of transgenic Bt cotton has, in some cases, led to environmental and economic benefits through reduced insecticide use. However, the distribution of these benefits and associated risks among cotton growers and cotton-growing regions has been uneven due in part to outbreaks of non-target or secondary pests, thereby requiring the continued use of synthetic insecticides. In the southeastern USA, Bt cotton adoption has resulted in increased abundance of and damage from stink bug pests, Euschistus servus and Nezara viridula (Heteroptera: Pentatomidae). While the impact of increased stink bug abundance has been well-documented, the causes have remained unclear. We hypothesize that release from competition with Bt-susceptible target pests may drive stink bug outbreaks in Bt cotton. We first examined the evidence for competitive release of stink bugs through meta-analysis of previous studies. We then experimentally tested if herbivory by Bt-susceptible Helicoverpa zea increases stink bug leaving rates and deters oviposition on non-Bt cotton. Consistent with previous studies, we found differences in leaving rates only for E servus, but we found that both species strongly avoided ovipositing on H. zea-damaged plants. Considering all available evidence, competitive release of stink bug populations in Bt cotton likely contributes to outbreaks, though the relative importance of competitive release remains an open question. Ecological risk assessments of Bt crops and other transgenic insecticidal crops would benefit from greater understanding of the ecological mechanisms underlying non-target pest outbreaks and greater attention to indirect ecological effects more broadly.

Counts of salivary sheaths and salivary flanges have been widely used in studies of feeding behavior and crop damage of pestiferous stink bugs (Hemiptera: Pentatomidae) and other sheath-feeding Hemiptera. While salivary flanges can effectively predict crop damage by stink bugs, previous studies have assumed that food consumption (e.g., ingestion) and preference can also be inferred from flange data. Yet this assumption has remained untested. We investigated the relationship between the number of stink bug salivary flanges and consumption of cotton bolls for two important agricultural pest species: Nezara viridula (L.) and Euschistus servus (Say). We inferred food consumption rates from measures of relative growth rate and excreta quantity. To measure excreta, we quantified the color intensity, or chromaticity, of excreta using digital image analysis. We found a positive relationship between growth rate and the number of flanges for fifth instars of E. servus. However, we found no relationship between growth or excretion and the number of flanges for all stages of N. viridula and for E. servus adults. Our results indicate that counts of salivary flanges should not be used to infer food consumption or preference in studies on N. viridula and E. servus adults, but can be used in studies of E. servus nymphs. Species- and stage-specific differences in the relationship between consumption and salivary flanges suggests distinct feeding strategies among species and stages; such differences may be potentially important in determining crop damage from pestiferous stink bugs.

1. Herbivory often induces systemic plant responses that affect the host choice of subsequent herbivores, either deterring or attracting them, with implications for the performance of both herbivore and host plant. Combining measures of herbivore movement and consumption can efficiently provide insights into the induced plant responses that are most important for determining choice behaviour. 2. The preferences of two frugivorous stink bug species, Nezara viridula and Euschistus servus between cotton plants left undamaged or damaged by Helicoverpa zea and Heliothis virescens larvae were investigated. A novel consumer movement model was used to investigate if attraction rates or leaving rates determined preferences. Stink bug consumption rates were measured using salivary sheath flanges. Finally, the systemic induction of selected phenolic‐based and terpenoid secondary metabolites were measured from heliothine herbivory on developing cotton bolls, to investigate if they explained stink bug feeding responses. 3. Heliothine herbivory did not affect the N. viridula feeding preference. However, we found opposing effects of H. zea and H. virescens herbivory on the behaviour of E. servus . Avoidance of H. zea ‐damaged plants is not obviously related to phenolic or terpenoid induction in cotton bolls; whereas a preference for H. virescens ‐damaged plants may be related to reductions in chlorogenic acid in boll carpel walls. 4. The present results highlight the inferential power of measuring both consumer movement and consumption in preference experiments and combining behavioural responses with phytochemical responses. Furthermore, while plant‐mediated interactions among herbivorous insects are well studied, interactions among frugivorous species specifically have been poorly documented.

Although conservation tillage is widely believed to be an agricultural management practice effective for increasing soil carbon (C) accretion and associated soil quality, there is limited research to determine whether conservation tillage increases net C accretion versus simply altering the distribution of C content by soil depth. We implemented conservation farming practices (winter cover cropping plus strip tillage) for a nonirrigated corn (Zea mays L.) production system in the southeastern coastal plain of Georgia, United States, that had been previously managed under a conventional plow and harrow tillage regime. Total soil C and nitrogen (N) were measured on samples collected from 0 to 65 cm (0 to 25.6 in) at 57 sites before and after five years under conservation farming practices. Crop yield, winter and summer aboveground crop biomass production, and biomass C and N content were also measured annually at each site. Soil C increased an average of 20 Mg ha(-1) (8.9 tn ac(-1); 6 to 62 Mg C ha(-1) [2.6 to 27.6 tn C ac(-1)], depending upon slope position) and was associated with a N increase of 2 Mg ha(-1) (0.89 tn ac(-1)). Although 72% to 80% of the C accretion was in the top 35 cm (13.8 in), 3 to 6 Mg C ha(-1) (1.3 to 2.6 tn C ac(-1)) was accreted from 35 to 65 cm (13.8 to 25.6 in). The soil C accreted during the study amounted to 36% of the net biomass C produced. Corn yield increased 2,200 kg ha(-1) (1,964 lb ac(-1)) depending upon slope position (1,200 to 2,500 kg ha(-1) [1,071 to 2,232 lb ac(-1)]) during the same time. Analysis indicated that soil C content from 15 to 35 cm (5.9 to 13.8 in) was the soil parameter primarily associated with corn yield. Season rainfall from planting to corn silking stage for both corn production years was the lowest in the past 45 years (20 to 25 cm [7.8 to 9.8 in] below the net crop demand) suggesting that soil C-mediated increase in plant-available soil water was a mechanism contributing to improved corn yield. Calculated estimates (from soil clay, sand, and C content) of increased soil water holding capacity suggest that C accretion in the top 35 cm (13.8 in) of soil potentially increased water storage enough to supply up to four days' worth of additional crop water demand. These results indicated that conservation farming practices can increase soil C and N accretion in degraded sandy soils of the humid southeastern United States coastal plain, and that increased soil C may potentially mitigate the deleterious effects of short-term rainfall deficits in nonirrigated production systems.

Helicoverpa zea (Boddie) is a major insect pest of corn and other agricultural crops. An improved understanding of semiochemcials that control adult behavior is needed to develop alternative control measures. In this study, overnight SPME collection of volatiles from corn ears enclosed in Teflon bags in the field at two stages of development were made. C8–C10 aldehydes, a C8-alcohol, C6–C9 alcohol acetates, and numerous monoterpenes, sesquiterpenes, sequiterpene alcohols, and geosmin were identified after thermal desorption and GC/MS. Structural assignments of the alcohol acetates, Z-3-hexenyl acetate, 2-heptyl acetate, 2-nonyl acetate, and 4-nonyl acetate, the monoterpenes, α- and β-ocimene, and geosmin were made by analysis of standards that were purchased or prepared in the laboratory. All other assignments were based on published Kovat’s retention time indices (KI) and mass spectra. Pair-wise comparison of the relative amounts of each component between two groups of corn ears defined by silk weight did not identify significant differences, thus it is unknown whether or not silk weight impacted volatile emission composition and rate. To our knowledge three compounds detected in SPME collections, 2-heptyl acetate, 2-nonyl acetate, and 4-nonyl acetate have not been previously reported in corn ear or silk volatiles. Their impact on the flight response of gravid earworm females was evaluated in a flight chamber. No significant response to the individual compounds or a blend of all three was observed. Thus, their impact on moth behavior remains uncertain.