Influence of Weed Manipulation in Field Borders on Brown Stink Bug (Hemiptera: Pentatomidae) Densities and Damage in Field Corn

Within-field spatial patterns of Euschistus servus and Nezara viridula (Hemiptera: Pentatomidae) in field corn

A complex of stink bugs, primarily the brown stink bug, Euschistus servus (Say) (Hemiptera: Pentatomidae) , and the southern green stink bug, Nezara viridula (L.) (Hemiptera: Pentatomidae) , are the most damaging insect pests of field corn, Zea mays L., in the southeastern United States. Characterizing the spatial patterns of these highly mobile, polyphagous pests is critical for developing efficient and effective sampling plans. In 2021 and 2022, stink bugs and their injury were assessed biweekly from emergence through R2 in 20 corn fields. The spatial analysis by distance indices (SADIE) showed that aggregation patterns were identified primarily in adult populations of both E. servus and N. viridula, and in nymphal populations of both species to a lesser extent. Aggregation patterns were also identified in early vegetative injury, but not in ear injury assessed at R2. The spatial association of stink bugs and their injury varied with corn phenological stage. A lack of spatial association between stink bug populations early in the season and vegetative injury suggests a need for intensive sampling, particularly in fields with increased residue from cover crops. Results of this study illustrate the variability in spatial patterns of stink bugs in corn, which can help to improve sampling plans for decision-making in IPM programs.

Characterizing the Spatiotemporal Distribution of Three Native Stink Bugs (Hemiptera: Pentatomidae) across an Agricultural Landscape

Simple Summary

Stink bugs (Hemiptera: Pentatomidae) are highly mobile pests that forage on, and damage, a variety of crops. Habitats that surround farms, such as forests, wetlands, and pastures may play a role in the location of stink bugs and their movement into crop fields. Here, stink bugs were trapped weekly across an 18 km² agricultural landscape, and we characterized their distribution, as well as patterns of aggregation by habitat. Brown stink bugs (Euschistus servus) were most often captured in crop fields and the timing of aggregations often corresponded to food availability. Dusky stink bugs (Euschistus tristigmus) were primarily captured in forest, and only occasionally in crop fields. Green stink bugs (Chinavia hilaris) were found in both crop fields and non-crop habitat. Control of stink bugs may require management plans that consider movement not only within crop fields, but also the surrounding habitat.

Abstract

Stink bugs (Hemiptera: Pentatomidae) are polyphagous pests that cause significant economic losses to a variety of crops. Although many species have been documented to aggregate within agricultural fields, much less is known regarding the timing and distribution of adults and nymphs within and between surrounding non-crop habitat. Therefore, we explored the spatiotemporal distribution of Euschistus servus (Say), Euschistus tristigmus (Say), and Chinavia hilaris (Say), three species of North American origin, and examined whether distribution patterns varied between species according to habitat. Stink bugs were monitored weekly for three years within an 18 km² grid of pheromone-baited traps. We tested whether habitat affected distribution patterns, used spatial analysis by distance indices (SADIE) to identify aggregations, and visualized distributions with interpolated maps. Overall, E. servus adults were captured in crops, whereas E. tristigmus adults and nymphs were mainly captured in forests. Accordingly, distribution patterns of E. tristigmus were relatively stable over time, whereas aggregations of adult E. servus varied over space, and the timing of aggregations reflected the phenology of major crops. Chinavia hilaris was most often captured in forest, followed by crop habitat. Pest management strategies for stink bugs may require an area-based management approach that accounts for movement in agricultural fields and surrounding habitat.

The Impact of Brown Stink Bug (Hemiptera: Pentatomidae) Damage during the Seedling Stage on Field Corn Growth and Yield

Brown stink bug, Euschistus servus (Say) (Hemiptera: Pentatomidae), is a common insect that can infest corn fields in the Mid-South and Southeastern U.S. Infestations and damage are sporadic, thus little research has been conducted on the impact of brown stink bug infesting corn seedlings. Two experiments were conducted in eleven commercial corn fields in the Mississippi Delta to evaluate the impact of damage from natural stink bug infestations during the seedling stage (<V4) on corn yield and growth during 2018 and 2019. Single plants and 3-meter sections of the row were marked at each location. Plant damage for the single plant experiment was rated on a 0-3 scale and every single plant was given a damage rating based on visible symptomology. As damage severity increased, plant height and yield decreased. Some plants with the most severe damage did not produce any grain. At each location, sections of row (plots) with 0%, 10%, 20%, 30%, or 40% damaged plants were identified. All levels of damaged plants resulted in lower yield compared to the nondamaged control. These results demonstrate the brown stink bug infestations during the seedling stage (<V4) can reduce corn yield. The magnitude of yield reductions can be dependent on several factors including the severity of damage to individual plants and the percentage of plants with damage within the field. Although detecting infestations with current scouting methods is difficult, fields should be scouted and infestations managed to minimize yield loss.

Brown Stink Bug (Hemiptera: Pentatomidae) Damage to Seedling Corn and Impact on Grain Yield

Brown stink bugs, Euschistus servus, are an important early-season pest of field corn in the southeastern United States. Feeding in the early stages of corn development can lead to a number of growth deformities and deficiencies and, ultimately, a reduction in yield. An observational and two experimentally manipulated trials were conducted in 2017 and 2018 to 1) determine optimal timing for assessing brown stink bug damage, 2) assess the level of damage from which yield compensation can occur, and 3) examine the relationship between brown stink bug density and early-season damage and yield. Fields were identified with infestations of brown stink bugs and a damage rating system for early stages of corn was established. Varying rates of brown stink bug densities were introduced using field cages and damage was assessed throughout the season. The density and duration of stink bug infestations were critical factors for damage potential, with each day of active feeding per plant resulting in a loss of ~14 kg/ha in yield. The level of damage in early stages of corn was categorized into easily identifiable groups, with only the most severe damage leading to a reduction in yield. Moderate and minimal feeding damage did not result in yield loss. This study emphasizes the need for early and frequent scouting of corn to determine the risk of damage and yield loss from brown stink bugs. Results from this study can be used to help develop management programs for brown stink bugs in the early vegetative stages of field corn.

Reevaluating the Economic Injury Level for Brown Stink Bug (Hemiptera: Pentatomidae) at Various Growth Stages of Maize

Economic yield loss and reduction in grain quality from brown stink bug, Euschistus servus (Say), feeding injury in early and late stages of maize, Zea mays (Poales: Poaceae, Linnaeus), development was assessed in Virginia and North Carolina in 2018 and 2019. Varying levels of stink bug infestations were introduced to seedling maize (V2-early stage), and a range of late-stages of maize, including 1) the last stage of vegetative development (V12/V14), 2) prior to tasseling, 3) at tasseling (VT), and 4) across all tested late growth stages. Euschistus servus infestation levels included 33, 67, and 100% of maize seedlings, and 25, 50, 100, and 200% of plants during later stages. Infestations were maintained on seedling maize for 7 d, and 8 or 16 d in reproductive stages. Infestation level in seedling maize had an impact on grain yield. Infestation level and growth stage both had an impact on grain yield in reproductive maize. The percentage of discolored kernels was also affected by infestation level, but not growth stage. Regression analysis between grain yield and infestation level indicated that the average economic injury level is 7% in seedling maize (7 bugs/100 plants) and 12% (12 bugs/100 plants) from the last vegetative stages (V12/V14) through pollination (VT). The economic injury level in the late vegetative stages is only applicable when infestations are present for an extended period of time (16 d), emphasizing the need for continued scouting of maize throughout the season to make informed management decisions.

Baseline Flight Potential of Euschistus servus (Hemiptera: Pentatomidae) and Its Implications on Local Dispersal

The brown stink bug, Euschistus servus (Say), is a damaging pest of multiple crops in the southeastern United States. In addition to crops, both the weedy field borders and wooded areas of a typical farmscape in this region harbor E. servus host plants, many of which are temporally and spatially limiting in availability or nutritional suitability. Therefore, local dispersal is required so that individuals efficiently track and utilize host resources. This research sought to establish the baseline flight capacity of adult E. servus across the season in relation to body weight, sex, and plant host use with a flight mill system. Across this 2-yr study, among the individuals with a flight response in the flight mill, 90.1% of individuals flew in a range of >0-1 km, with an individual maximum flight distance of 15.9 km. In 2017, mean total distance flown varied across the season. Except for the individuals collected from corn in 2019, during both 2017 and 2019, the highest numerical mean flight potential occurred soon after overwintering emergence and a relatively low flight potential occurred during the cropping season. Individuals collected from wheat, corn, and early season weeds lost a higher proportion of body weight after flight than did individuals from soybean and late season weeds. The baseline dispersal potential information generated from this study can be extrapolated to the farmscape level aiming to develop, plan, and implement E. servus management programs.