Location: Southeast Watershed Research
2020 Annual Report
Objectives
1. Determine biological, ecological, and structural mechanisms driving stink bug population dynamics in landscapes composed of agricultural (e.g., corn, peanut, cotton, and soybean) and non-agricultural habitats to design management strategies for stink bugs in the Southeastern Region of the United States.
1.A. Determine the seasonal occurrence and biology of stink bugs in non-crop habitats in agricultural landscapes.
1.B. Determine stink bug dispersal from non-crop hosts into cotton and the impact on cotton in terms of boll injury.
1.C. Investigate the potential for host-associated differentiation (HAD) in parasitoids of stink bug adult, nymph and egg stages.
1.D. Deploy use of Long-term Agricultural Research (LTAR) sites and eco-informatics to establish causal relationships between environmental and geospatial data, management strategies, and pest control success in vegetable crops such as cucurbits, fruiting vegetables, onions, cabbage, leafy greens and sweet corn.
2. Develop and test biologically-based management strategies, including augmentative releases of parasitoids, trapping insect pests with pheromone traps, elimination of non-crop sources of stink bugs, biopesticides, and multifunctional trap cropping systems, to monitor and/or control native and naturalized stink bugs and the invasive kudzu bug and the brown marmorated stink bug in the Southeastern Region of the United States.
2.A. Determine the efficacy of augmentative releases of kudzu bug parasitoids in reducing kudzu bug populations.
2.B. Monitor populations of the newly invasive brown marmorated stink bug using pheromone-baited stink bug traps.
2.C. Determine the effect of selected biopesticides on the kudzu bug in soybean.
2.D. Examine the utility of eliminating non-crop host plants of stink bugs along field edges for reduction of stink bug dispersal into cotton.
2.E. Evaluate the effectiveness of using a soybean trap cropping system to manage stink bugs attacking cotton.
Approach
Collect data on the seasonal occurrence, development and feeding and mating behavior of stink bugs in known and potential non-crop habitats surrounding row crops in 10-12 agricultural landscapes. Conduct a study of stink bug dispersal from known non-crop hosts into cotton and their impact on cotton boll injury in 6-8 agricultural landscapes. Conduct a study on the presence of host-associated differentiation in parasitoids of stink bug adults, nymphs and eggs collected in cotton and soybean fields and from nearby known non-crop host plants. Conduct a study on the effects of augmentative releases of an exotic kudzu bug egg parasitoid on kudzu bug density in 10 kudzu patches in North and South Georgia and nearby soybean fields. Monitor populations of the newly invasive brown marmorated stink bug north of the Coastal Plain in Georgia using pyramid stink bug traps baited with lures and map its distribution and spread in Georgia. Conduct studies in experimental plots on selected biopesticide effects on kudzu bug populations in soybean. Conduct a study on the elimination of known non-crop host plants of stink bugs along 6 cotton field edges on stink bug dispersal into the cotton field. Conduct a study in a grower’s peanut-cotton farmscape on the effect of a soybean trap cropping system on the density of stink bugs attacking cotton.
Progress Report
FY2020 concludes this 5-year research project to assess seasonal occurrence and biology of stink bugs in non-crop hosts(Objective 1.A). Data on number of brown marmorated stink bug (BMSB) in pheromone-baited traps continues to be collected throughout Georgia and Alabama (Objective 2.B). Data has been collected by ARS reseachers at Tifton, Georgia, on dispersal of stink bugs from non-crop hosts into cotton.
Accomplishments
1. Influence of within-field environmental and ecological factors on phloem-feeding insects. Reductions in agricultural reliance on broad spectrum pesticides could occur with the site-specific information on pest and natural enemy location within a field and their association with environmental variables (e.g. topographic, edaphic and Normalized Difference Vegetation Index (NDVI) as a measure of plant health) and predator-prey interactions. Over 3 sampling dates (early, mid- and late season) and two years, ARS researchers at Tifton, Georgia, and University of Georgia, collaborators determined the abundance and spatial distribution of phloem-feeding crop pests and their natural enemies in a geo-referenced field planted with a bioenergy feedstock grass, Miscanthus x giganteus. ARS researchers at Tifton, Georgia, and University of Georgia collaborators also conducted molecular gut content analysis (MGCA). Spatial and temporal models and geographical weighted regression analyses indicated that elevation, slope, southeastern aspects, percentage of silt at 0-15 cm soil depth, NDVI, wind speed, and the abundance of spiders and insect predators were related to the abundance of phloem-feeding pests. The relationship between these variables and phloem feeders varied over space and time, but confidence in coefficient values was high across locations in the field, suggesting that precision management across sites would have to be specifically timed. MGCA indicated that spiders are feeding on both phloem feeders and dipteran species as alternative prey. These results will help guide designing of detailed experiments that include habitat management schemes that promote increases in the abundance, diversity and biological control efficacy of natural enemy species given the predicted ‘hot spots’ of phloem-feeders in the field.
2. Wildflower buffers at crop field edges to promote increases in the abundance and diversity of wild bee pollinators. In 2019, a total of 123 bees comprised of 12 species from 2 families were captured by ARS researchers at Tifton, Georgia, in adjacent maize, peanut and cotton representing a Shannon Diversity Index of 2.15 and applying the effective number of species [exp (2.15)], corresponds to a community with 9 equally-common species. This formula allows comparison of diversity within and among communities over time. A total of 47 bees were captured in corn and 22% of these bees had both corn and wildflower pollen. A total of 47 bees were captured in peanut and 55% of these bees had peanut and wildflower buffer pollen. A total of 29 bees were captured in cotton, and 24% of these bees had cotton and wildflower pollen. These results by ARS researchers at Tifton, Georgia, suggest that the wildflowers are providing bee pollinators to the crops and the potential for crop pollination.
3. The invasive brown marmorated stink bug (BMSB) has expanded into the Piedmont and Coastal Plains Regions of Georgia and Alabama. Because the diversity of natural enemies attacking this pest is unknown in these states, a team of biological control research scientists from ARS Tifton, Georgia, the University of Georgia, Clemson University, and Auburn University deployed BMSB egg masses as sentinels in orchards, row crops, and vegetables. Ten species of tiny parasites killed BMSB eggs. Prevalence of parasite species emerging from BMSB eggs was mainly specific to the habitat in which they were placed. Two new parasite species, Trissolcus basalis and Trissolcus solocis, were discovered parasitizing BMSB eggs. Percentage parasitism of BMSB egg masses by the former species ranged from 50-100% in habitats with egg masses of the southern green stink bug and BMSB. T. solocis is a new and rare species that may become more prevalent in areas in which BMSB have become established. Grasshoppers, big-eyed bugs, predatory stink bugs, fire ants, and spiders preyed on BMSB eggs. For one year of the study, percent parasitism was higher for blueberry compared to other crops except for peach and apple. Percent predation (70-100%) was higher in soybean and cotton than in other crops both years. Generally, predation was higher than parasitism. In conclusion, native stink bug parasitoids and predators are serving as biological control agents of BMSB eggs in the southeastern US.
Review Publications
Tillman, P.G., Cottrell, T.E. 2019. Comparison of two insect-collecting devices for trapping stink bugs (Hemiptera: Pentatomidae). Journal of Entomological Science. 54(4):409-416. https://doi.org/10.18474/JES18-131.
Balusu, R., Talamas, E., Cottrell, T.E., Toews, M., Blaauw, B., Sial, A., Buntin, D., Fadamiro, H., Tillman, P.G. 2019. First record of Trissolcus basalis (Hymenoptera: Scelionidae) parasitizing Halyomorpha halys (Hemiptera: Pentatomidae) in the United States. Biodiversity Data Journal. https://doi.org/10.3897/BDJ.7.e39247.
Tillman, P.G., Toews, M., Blaauw, B., Sial, A., Cottrell, T.E., Talamas, E., Buntin, D., Joseph, S., Balusu, R., Fadamiro, H., Lahiri, S., Patel, D. 2020. Parasitism and predation of sentinel eggs of the invasive brown marmorated stink bug, Halyomorpha halys (Hemiptera: Pentatomidae) in the southeastern US. Biological Control. 145(2020)104247. https://doi.org/10.1016/j.biocontrol.2020.104247.
Khadka, A., Hodges, A., Leppla, N., Tillman, P.G. 2020. The effects of relative humidity on Halyomorpha halys (Stal) (Hemiptera: Pentatomidae) egg hatch, nymph survival and adult reproduction. Florida Entomologist. 103(1):136-138. https://doi.org/10.1653/024.103.0424.
Sabbatini Peverieri, G., Mitroiu, M., Bon, M., Balusu, R., Benvenuto, L., Bernardinelli, I., Fadamiro, H., Falagiarda, M., Fusu, L., Grove, E., Haye, T., Hoelmer, K.A., Lemke, E., Malossini, G., Marianelli, L., Moore, M.R., Pozzebon, A., Roversi, P., Scaccini, D., Shrewsbury, P., Tillman, P.G., Tirello, P., Waterworth, R., Talamas, E. 2019. Surveys of stink bug egg parasitism in Asia, Europe and North America, morphological taxonomy, and molecular analysis reveal the Holarctic distribution of Acroclisoides sinicus (Huang & Liao) (Hymenoptera: Pteromalidae). Journal of Hymenoptera Research. 74: 123-151. https://doi.org/10.3897/jhr.74.46701.
