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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. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM PUBLISHER]

Highlights: [•] Aridelus rufotestaceus lived longer on flowers and 5% honey solution than on water. [•] Feeding on Indian blanket and 5% honey solution increased production of mature ova. [•] Body sugars of the wasps were similar after feeding on the treatments for 24h. [Copyright &y& Elsevier]

Outbreaks of non-target pests associated with transgenic Bt cotton threaten the economic and ecological benefits of the technology in cotton-producing countries. In the southeastern USA, stink bug pests, namely Nezara viridula L. and Euschistus servus Say (both Heteroptera: Pentatomidae), have recently become severe problems associated with Bt cotton, requiring continued insecticide use. However, the causes of non-target pest outbreaks remain unclear. Release from competition with Bt-susceptible pest species, in addition to other mechanisms, may contribute to increased stink bug populations in Bt cotton. We investigated the competitive interactions between the two stink bug species and the Bt-susceptible pests Helicoverpa zea (Boddie) and Heliothis virescens Fabricius (both Lepidoptera: Noctuidae) on non-Bt cotton. We tested for competition effects on stink bug growth rates in no-choice experiments at two spatial scales: a single cotton boll and a branch with multiple developing bolls. Although caterpillars of the two species had equivalent effects on resource availability, they had distinct effects on stink bug growth rates. Fourth instar H. zea reduced growth rates of both stink bug species by 60% when caged on a single cotton boll and reduced growth rates of only E. servus by 36% when caged on a cotton branch. In contrast, H. virescens had no effect on stink bug growth rates. Resource competition was apparent in the interactions between H. zea and E. servus, but interference competition may have contributed to the interactions as well. Competitive release of stink bug populations in Bt cotton is possible, and should be more likely for E. servus than for N. viridula. Understanding the causes of non-target pest outbreaks in Bt cotton will contribute to improved environmental risk assessments of future releases of Bt cotton and related transgenic crops. [ABSTRACT FROM AUTHOR]

1. Vegetative buffers in agricultural landscapes can provide a range of important ecological services, including conservation of native flora and fauna, enhancement of biological pest control and reduction of agrochemical drift. Typically, studies addressing the impact of such vegetative elements focus on one particular benefit. We investigated whether the benefits of field margins that had been established for conservation of northern bobwhite quail Colinus virginianus populations extended to the enhancement of biological pest control in adjacent conservation tillage cotton fields. 2. Densities of a selection of insect species and the predation and parasitism rates of insect pest species were measured in first- and second-year field margins established for bobwhite quail as well as in an adjacent cotton crop. 3. Second-year field margins yielded higher densities of all species sampled, with the exception of staphylinids and cotton aphids. Despite this, thrips and their predator, Orius insidiosus, were the only species that were also more abundant in the adjacent cotton field. Tachinids and Trichogramma and Lygus species, appeared to prefer the field margin vegetation over the cotton. 4. Overall, the impact of second-year margins on the cotton crop did not significantly differ from first-year margins with regard to pest occurrence or biological control. 5. Analysis of the sugar content in Meteorus autographae, a generalist parasitoid of Lepidoptera larvae, suggested that this species is severely food-limited in the field margins established for bobwhite quail. 6. Synthesis and applications. This study shows that field margins designed to specifically benefit bobwhite quail may be unsuitable for providing other ecological services. By making small adjustments in the vegetative composition of these field margins, such as adding early season nectar-producing plants, it may be feasible to combine biodiversity and pest-control benefits and thereby optimize the overall ecological services to be gained. [ABSTRACT FROM AUTHOR]

Compares the lifetime patterns of carbohydrate and lipid metabolism between starved and sucrose-fed parasitoid wasp. Synthesis of trehalose and glycogen; Egg maturation rate; Average number of eggs carried by female wasps.

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. [ABSTRACT FROM AUTHOR]

Nitrogen (N) is one of the most critical chemical elements for plant and animal growth, exerting a variety of bottom-up effects. Development and oviposition of the beet armyworm, Spodoptera exigua (Hübner) (Lepidoptera: Noctuidae), were studied in relation to varying N fertilization levels (42, 112, 196, and 280 p.p.m.) in cotton [ Gossypium hirsutum L. (Malvaceae)]. Low N fertilization of cotton plants led to reduced plant biomass and a lower percentage of N in leaf blades and in leaf petioles. Development of S. exigua larvae fed with plants with reduced N applications (42 and 112 p.p.m.) was prolonged relative to treatments receiving higher N fertilization. Almost all larvae reared on artificial diets underwent only five instars before pupation. However, most larvae reared on cotton plants, irrespective of N levels, experienced a supernumerary sixth larval instar. Furthermore, significantly more larvae reared on lower N cotton plants underwent supernumerary development compared to larvae reared on higher N cotton plants. Life-time feeding damage per larva ranged from 55 to 65 cm2, depending on the nutritional quality of the food plant, although the differences were not statistically significant. Larvae distinguished between cotton plants with various nutritional qualities and fed preferentially on higher N plants. Female moth oviposition choice was also affected by host plant nutritional quality: cotton plants with higher N levels were preferentially chosen by S. exigua females for oviposition. The mechanisms of these effects are unclear, but they can have important implications for population dynamics and pest status of beet armyworms in the field. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

The rapid adoption of genetically engineered (GE) plants that express insecticidal Cry proteins derived from Bacillus thuringiensis (Bt) has raised concerns about their potential impact on non-target organisms. This includes the possibility that non-target herbivores develop into pests. Although studies have now reported increased populations of non-target herbivores in Bt cotton, the underlying mechanisms are not fully understood. We propose that lack of herbivore-induced secondary metabolites in Bt cotton represents a mechanism that benefits non-target herbivores. We show that, because of effective suppression of Bt-sensitive lepidopteran herbivores, Bt cotton contains reduced levels of induced terpenoids. We also show that changes in the overall level of these defensive secondary metabolites are associated with improved performance of a Bt-insensitive herbivore, the cotton aphid, under glasshouse conditions. These effects, however, were not as clearly evident under field conditions as aphid populations were not correlated with the amount of terpenoids measured in the plants. Nevertheless, increased aphid numbers were visible in Bt cotton compared with non-Bt cotton on some sampling dates. Identification of this mechanism increases our understanding of how insect-resistant crops impact herbivore communities and helps underpin the sustainable use of GE varieties. [ABSTRACT FROM AUTHOR]