Location: Crop Protection and Management Research2011 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
In fiscal year 2011, several studies were conducted to understand the insect ecology of major insect pests in the southeastern region and subsequently test some sustainable systems for management of these pests. The first year of a study to determine the potential for stink bugs to disperse from chinaberry and pokeweed adjacent to cotton fields was conducted (Objective 1). Various species of stink bugs were found to feed on these two uncultivated host plants. The first year of a study to assess the efficacy of stink bug capture traps, and a trap crop to reduce dispersal of stink bugs from peanut into cotton was conducted in an on-farm peanut-cotton field (Objective 2). The results from the test suggest that stink bug capture traps work best in controlling stink bugs when used in combination with a trap crop of soybean. The first year of a study to determine the possibility of increasing parasitization of stink bug adults by providing them with milkweed weed nectar was conducted (Objective 2). It was determined that many species of stink bug parasites fed on milkweed nectar in the field. Results from the field test indicate that parasitization of southern green stink bugs was higher in plots where milkweed plants were available. Laboratory tests indicate that longevity of one of the parasites of stink bug was increased when feeding on milkweed nectar. The first year of a sentinel study to determine race specificity of fall armyworm was established at three sites in the region (Objective 3). Each site was planted to a different base crop which included corn, bermuda grass and oats. Additionally, 15 pots of each species were embedded as sentinel species in the base crop for a period of 6 weeks from oat boot stage onward. Fall armyworm larvae were collected from each sentinel crop while adult moths were collected in pheromone traps and from a field sweep of each base crop. Fall armyworms were separated from other collected taxa and prepared for genetic analysis. The second year of a study of the effects of landscapes on stink bug populations in southern Georgia was completed (Objective 1). Comparisons of two regions in southern Georgia differing in scale of production of corn indicated that the higher corn region always had more stink bugs in corn, peanut, and cotton than in the region with less corn. Stink bugs in soybean were similar in both regions. Overall, peanuts and cotton tend to have lower numbers of stink bugs than corn and soybean in both regions. The exception was one peanut field in one year which had numbers of stink bugs and estimates of their survival as high as those in soybean in both regions. Estimates of survival indicate that there were regional differences in survival in peanut and cotton with higher survival in the high corn region. There were also regional differences in fire ants. More fire ants were found in the low corn region, but over all crops in both regions the numbers were always highest in peanut and cotton than in soybean and corn.
Ni, X., Da, K., Buntin, G., Cottrell, T.E., Tillman, P.G., Olson, D.M., Powell, R., Lee, R.D., Wilson, J.P., Scully, B.T. 2010. Impact of brown stink bug (Heteroptera: pentatomidae) feeding on corn grain yield components and quality. Journal of Economic Entomology. 103:2072-2079. DOI:10.1603/EC09301.