Location: Crop Protection and Management Research2013 Annual Report
1a. Objectives (from AD-416):
1. Determine biological, ecological, and structural mechanisms driving stink bug population dynamics in the southeastern region of the United States. 1.A. Study the role of landscape make-up on populations of stink bugs. i. Confirm the sequence of habitats used by the stink bugs Nezara viridula and Euschistus servus in southern Georgia prior to colonization of cotton. ii. Estimate the parameters (net reproductive rate and interpatch movement) in our simple patch model that predicts stink bug colonization of cotton, and fit the model using data. iii. Using the parameterized model, predict the effects of landscape structure on the colonization of cotton by these stink bugs and test the model predictions. 1.B. Evaluate semi-field bioassays for the effects of relative crop quality on major crops used simultaneously by stink bugs. 1.C. Determine the role Bt technology and concomitant reduction in insecticide use and both Bt-targeted and non-targeted inter-specific insect pest interactions on pest invasiveness. 1.D. Assess survival of stink bug egg masses in soybean, cotton, and peanut. 1.E. Identify uncultivated host plant sources of stink bugs for cotton. 2. Develop and test bio-based management systems for stink bugs that are widely adaptable to various cropping systems in the southeastern region of the United States. 2.A. Evaluate non-chemical management practices that reduce populations of overwintering stink bugs such as through the use of controlled burns in woodland understory. 2.B. Determine the effectiveness of pheromone traps to capture stink bugs in a trap crop. 2.C. Determine the ability of a habitat of nectar-producing plants to provide food to natural populations of stink bug parasitoids. 2.D. Determine the effectiveness of a multifunctional habitat to serve as a trap crop for stink bugs and a site for conservation and feeding for bees and other insect pollinators and natural enemies of stink bugs. 3. Assess the ability of various southeastern region winter crops (legumes and small grains) to host a diversity and abundance of beneficial and pest species, and to determine the impact that these insects have on crop protection and damage in continuous cropping systems. 3.A. Determine the host plant affinity of the strains of fall armyworm to winter grain species grown in the southeastern U.S. 3.B. Determine the relative benefit of grasses, legumes, and winter weeds as early season habitat for beneficial arthropods and their relay into later planted sorghum. 4. Using knowledge gleaned about insect enemies, evaluate the use of trained parasitoid wasps in detection of aflatoxin concentrations in peanuts at the peanut grading stage.
1b. Approach (from AD-416):
Map and ground-truth aerial photos and collect data on stink bug 5th instar density over time in corn, cotton, soybean and peanut in four landscapes to estimate parameters (habitat colonization and net reproductive rate) of an existing simple patch model and confirm sequence of host use for stink bugs. Conduct a study on stink bug longevity for Bt cotton, RR cotton, peanut and soybean using plant cages. Use data on relative longevity of stink bugs and data from previous studies on relative stink bug preference for crops to further parameterize the model. Conduct studies on competition between stink bugs and heliothines at the cotton boll and branch scales and on stink bug feeding and oviposition preference for heliothine damaged and undamaged cotton plants. Volatiles and plant tissue will be analyzed for herbivore anti-feedants. Stink bug eggs will be placed as sentinels in Bt cotton, RR cotton, peanut and soybean to obtain data on egg mortality. Occurrence and abundance of stink bugs will be assessed for uncultivated host plants of stink bugs adjacent to cotton fields. Data on density of overwintering populations of stink bugs will be collected in agricultural fields with managed low intensity burns under the woodland and in fields with no woodland burns. Data on density of a stink bugs will be collected in soybean trap crops with and without stink bug pheromone capture traps in agricultural farmscapes. Data will be collected on stink farmscapes with and without a habitat of nectar-producing plants. Data will be collected on stink bug density and damage to cotton in agricultural farmscapes with and without a multifunctional habitat with plant species for trapping stink bugs and other plants for providing resources to natural enemies of these pests. Data will be collected on density of specific sorghum pest and beneficial insects and predation and parasitism rates of pests in both the winter cover crops and subsequent summer crops. Volatiles from aflatoxin infested and uninfested peanuts will be collected and analyzed using GC-MS and a strong volatile correlate to aflatoxin infested peanuts will be identified. Data on the ability of wasps to detect aflatoxin infested peanuts at the grading stage will be collected using the portable 'wasp hound'.
3. Progress Report:
The third year of a study of the effects of landscapes on stink bug populations in southern Georgia was conducted (Objective 1). All of the field data in the regional analysis and all of the data for parameterization of the model predicting stink bug populations in cotton have been collected. Analyses are ongoing. The third year of a study to determine the ability of a multifunctional trap cropping system in peanut-cotton plots was conducted (Objective 2). The trap cropping system included a trap crop, i.e., soybean, a nectar-producing plant, i.e., buckwheat, and stink bug pheromone capture-kill traps. Stink bugs were much lower in cotton with the trap cropping system compared to cotton without this system. The second year of a study to determine incidence of field predation on stink bugs by arthropod predators in soybean and cotton using DNA gut-content analysis was conducted (Objective 2). Big-eyed bugs, minute pirate bugs, and striped lynx spiders were three of the dominant predators in these crops. The first year of a study to determine the ability of barrier walls to deter movement of stink bugs from peanut into cotton was conducted (Objective 2). The walls were established at the peanut-cotton interface. The four treatments included: a 6 ft. vinyl wall, a 2 ft. vinyl wall, sorghum sudangrass, and a control. Stink bugs were lower in cotton with a 6 ft. vinyl wall at the crop-to-crop interface compared to control cotton. Stink bug density was similar for the 2ft. vinyl wall treatment and the control treatment. Sorghum sudangrass deterred movement of stink bugs into cotton, but was not as effective as the 6 ft. vinyl wall. Bioassay of seven cultivars of oats, including black oats, revealed no significant strain affinity of fall armyworm (FAW) across this crop. Both the corn and rice strain of FAW exhibited virtual equal affinity for this cohort of cultivars.
1. Colonization of stink bug pests in farmscapes in the coastal plain of southeastern United States. Peanut-cotton farmscapes are composed of peanut and cotton fields whose edges interface with each other. An understanding of spatial distribution and movement of stink bugs in these farmscapes in the coastal plain of the southeastern United States is critical for developing management strategies to control these pests. ARS scientists in Tifton and Byron, Georgia showed that corn, peanut, and cotton served as good host plants for the brown stink bug and the southern green stink bug. These two stink bugs develop in corn and peanuts and then move into cotton at the crop-to crop interface where they feed on cotton bolls. Corn did not serve as a host plant for the green stink bug. Even though peanut is a poor host plant for the green stink bug, adults still move into cotton at the peanut-cotton interface. In summary, all stink bugs move along field edges as they colonize cotton. Growers and other researchers are beginning to adopt and test trap cropping systems at field edges for management strategies for stink bugs.
2. Non-crop sources of stink bug pests in farmscapes in the coastal plain of southeastern United States. Farmscapes in the coastal plain of the southeastern United States are surrounded by woodland habitats. Thus, it’s important to determine if any non-crop plants in these habitats are sources of stink bugs moving into crops in these farmscapes. ARS scientists in Tifton and Byron, Georgia and University of Florida and University of Georgia collaborators showed that black cherry, uncultivated pecan, mimosa, beggarweed, pokeweed, and elderberry occur in woodland habitats and are sources of stink bugs dispersing into corn, peanut, and cotton. Some growers in the region are currently destroying, via herbicide applications and bulldozing, non-crop host plants in woodland habitats to eliminate or reduce populations of stink bugs in their crops.
3. Although the bioassay of FAW on cultivated oats yielded a non-specific affinity, it did reveal significant differences in host plant resistance among the oat cultivars. The cultivar, 'Florida 501' exhibited significantly higher levels of resistance compared to the other cultivars, and black oats exhibited significantly more susceptibility than common oats.
Olson, D.M., Wackers, F., Haugen, J. 2012. Threshold detection of boar taint chemicals using parasitic wasps. Journal of Food Science. 77:356-361. DOI:10.1111/j.1750-3841.2012.02883x.