Location: Southeast Watershed Research
2024 Annual Report
Objectives
1. Assess spatial and temporal distribution of the invasive brown marmorated stink bug (BMSB) and whitefly species and their natural enemies relative to environmental and ecological factors in cropping systems and on host plants in surrounding natural areas and field borders and develop a model that will guide decisions on pest management. [NP304, C3, PS3A, 3B and 3C]
1.A. Determine the spatial and temporal distribution of the whitefly, Bemisia tabaci, relative to environmental factors within cropping systems and nearby non-crop hosts in field borders and adjacent natural areas.
1.B. Determine the suitability of treatments with low risk to beneficial insects such selective insect growth regulator insecticides, predatory mites, and biochemical insecticides, to manage the whitefly, Bemisia tabaci.
2. Evaluate parasitism and predation of BMSB and indigenous stink bugs by parasitoids and predators in crop and non-crop habitats. [NP304, C3, PS3A, 3B and 3C]
2.A. Assess parasitism and predation of BMSB and indigenous stink bugs by parasitoids and predators in orchard, vineyard, vegetable, and row crop farmscapes and non-crop hosts in nearby woodlands in the southeastern USA.
2.B. Develop floral habitat to enhance biological control of BMSB and indigenous stink bugs in farmscapes.
3. Develop optimal native wildflower habitat and other floral resources near crop fields for provisioning of resources and refuge sites that increase pollinator abundance, diversity, and pollination of nearby crops, such as initially in cotton and peanut, with potential applications to other pollinator-dependent crops. [NP304, C3, PS3A, 3B and 3C]
3.A. Determine the abundance and diversity of wild bee pollinators utilizing mixed wildflowers, cover crops, cropping systems and field borders, and naturally occurring areas to determine which species is utilizing which floral resource.
4. Improve current and evaluate novel weed management techniques for traditional and organic row, vegetable, and perennial cropping systems produced throughout the southeastern United States.
4.A. Determine if applications of various organic herbicides can provide economic weed control.
4.B. Evaluate interactions between prohexadione calcium and various postemergence herbicides when applied as a tank-mixture.
5. Develop a better understanding of the influence edaphic and environmental factors have on the fate of chemical and non-chemical weed control practices to improve crop and ecological safety while maintaining grower profitability and sustainability.
5.A. Determine the thermal stability and activation energy of various organic herbicides in aqueous solution.
5.B. Quantify the impact drying time has on the movement of herbicides applied over-the-top of mulch covered vegetable beds.
5.C. Assess the potential use of an organic soil amendment for reducing residual herbicide injury to Brassica carinata.
Approach
The spatial and temporal distribution of the whitefly, Bemisia tabaci, and its natural enemies relative to environmental factors will be assessed in cropping systems (row; corn, cotton, peanut, soybean, and vegetable; squash, pepper, eggplant, etc. crops), and on host plants in borders and natural areas. Treatments of low risk to beneficial insects (2 insect growth regulators, 4 species of predatory mites, and 2 biochemical insecticides) will be evaluated for their suitability to control whitefly outbreaks. Also, the spatiotemporal patterns of indigenous stink bugs and the invasive brown marmorated stink bug, Halyomorpha halys, will be assessed in 2-3 orchard, row crop, and non-crop habitats. Sampling will be conducted using whole plant and drop cloth samples and stink bug traps. Evaluation of parasitism and predation of stink bug eggs will be assessed using natural and sentinel egg masses in crop and non-crop hosts in 2-3 blueberry, apple, peach, and pecan orchards, 2-3 grape vineyards, 2-3 vegetable farms, and 2-3 row crop farms. Abundance, diversity, and potential for crop pollination by wild bee pollinators will be assessed. Sampling will be conducted using blue vane bee traps and sweep netting in wildflowers, cover crops, crops, field borders, and natural areas. Species of bees will be identified. Metabarcoding will be used on pollen samples collected from each species to determine which species is utilizing which floral resource. The potential for utilizing organic herbicides in economical weed management programs will be assessed in various runner-type peanut cultivars and 6-8 common and troublesome weed species in greenhouse and field experiments. Tank-mixtures of prohexadione calcium (plant growth regulator) and 2-4 postemergence herbicides will be evaluated in 2-3 runner-type peanut cultivars and 6-8 weed species in greenhouse and field experiments. The influence of edaphic and environmental factors on chemical and organic weed control products will be assessed on 8-10 herbicides in row, specialty, and non-crop areas.
Progress Report
The third year of a study to assess spatial and temporal distribution of BMSB (Brown Marmorated Stink Bug) in orchards in the farmscape and non-crop hosts in nearby woodlands collected has been completed (Objective 1.A). The fourth year of a study to assess spatial and temporal spatial and temporal biocontrol of sentinel and wild BMSB eggs has been completed (Objective 2.A). The second year of a study to develop floral habitat to enhance biological control of stink bugs has been completed (Objective 2.B). Second year of determining the spatial and temporal distribution of the whitefly, Bemisia tabaci, relative to environmental factors within cropping systems and nearby non-crop hosts in field borders and adjacent natural areas completed (Objective 1.A.). Second year of determining the suitability of treatments with low risk to beneficial insects such selective insect growth regulator insecticides, predatory mites, and biochemical insecticides, to manage the whitefly, Bemisia tabaci complete (Objective 1.B). Second year of developing an optimal native wildflower habitat and other floral resources near crop fields for provisioning of resources and refuge sites that increase pollinator abundance, diversity, and pollination of nearby crops completed (Objective 3.A).
Accomplishments
1. Trapping the invasive brown marmorated stink bug (BMSB) in Cropping Systems.. The BMSB damages fruit in orchards and field crops and is often found within nearby woodlands. Traps baited the lures that are attractive the BMSB can be used to monitor this pest. However, efficiency of trapping BMSB may vary depending on trapping strategy (live versus dead capture), location (on ground or in tree canopy), and changes in capture over the day. ARS researchers at Tifton, Georgia compared capture of BMSB within fruiting plants for each trap strategy, trap location and time of day collected. More BMSB were captured in kill traps than live traps. Capture of live adult was higher in tree trap than in ground traps. More live adults were captured from 8am – noon, with the fewest captured from noon – 6pm. A better understanding of stink bug activity in the field allows for improved trapping and, possibly, improved timing of treatment applications.
2. Low wind speeds and small disturbances during harvest causes whitefly movement between plants. Bemisia tabaci, also called the sweet potato whitefly, is a pest in agriculture crops and can spread plant diseases in those crops. While it is known that wind can disperse whiteflies within and between crops, it was unknown how low wind speeds, and small disturbances during harvest, from the picking of certain crops, effected the movement of whiteflies between plants. Wind tunnel experiments were conducted at low wind speeds (0-1mph, 1-2mph, 2-3mph, 3-4mph, and 4-5mph) on plants with different levels of whitefly infestations. ARS researchers at Tifton, Georgia also conducted tests in cucumber fields to determine what effect the disturbance of harvesting cucumbers had on movement of whiteflies within those fields. Even at low levels of infestation (0-5 adult whiteflies per leaf) low wind speed (0-1mph) caused an increase of dispersal of whiteflies to adjacent plants. Movement between plants increased with increased wind speed and increased adult whitefly per leaf. Whiteflies not only moved downwind but moved against the wind to upwind plants. Disturbances from simulated picking in cucumber field caused whiteflies to move to adjacent plants and to plants in other rows. This research illustrated how whiteflies spread increases within infested fields with little disturbance. Even with low wind speed, low infestation rates, and small harvesting disturbances whiteflies can spread within a grower’s field even against the wind. This information will inform growers to not expect that infestation with move with the wind and if outbreak spots are found in a field that infestation can spread in any direction with little disturbance. (Objective 1.A)
3. Comparison of control of whitefly using insect growth regulator insecticides, predatory mites, and biochemical insecticides in field and laboratory setting.. ARS researchers at Tifton, Georgia believe there is increasing interest in finding ways to control insect pests that are considered low risk to beneficial insects. Insect growth regulators, predatory mites, and biochemical insecticides are some of the options considered low risk to beneficial insects. Eight treatments consisting of two insect growth regulators (IRGs) (pyriproxyfen and buprofezin), four predatory mite species (Amblyseius swirskii, Amblyseius andersoni, Neoseiulus cucumeris, and Neoseiulus californicus), and two biochemical insecticides (EcoVenger® and Azaguard TM) were applied for two consecutive years in cotton. A negative control (no application) and a positive control, consisting of a reduced risk industry standard insecticide (acetamiprid), were also conducted. The chemicals were additionally tested in a spray chamber to determine their effectiveness under more controlled conditions. Of the chemicals tested, EcoVenger®, was the most effective against all life stages of whitefly. In the laboratory, IRGs were found to be most effective against early instars with little to no control at later instar stages of development. Predatory mites in field plots led to a decrease in whitefly eggs in all predatory mite treatments. This experiment showed stakeholders that whitefly control can be achieved with reduced risk treatments. Predatory mites should be released early in infestations to control whitefly eggs. IRGs should also be applied early to target first and second whitefly instars. (Objective 1.B)
4. Comparison of whitefly control of possible candidate predatory mites raised on whiteflies versus augmentative release populations. Predatory mites that are used to control whiteflies are not raised on whiteflies when they come from the predatory mite suppliers. While control of whitefly eggs was found in field releases of Amblyseius swirskii, Amblyseius andersoni, Neoseiulus cucumeris, and Neoseiulus californicus in a previous study, laboratory observations of whitefly egg reduction was low from these predatory mites when tested directly from the supplier. It is possible that initial populations did not cause the reduction in eggs found in that previous field study. The future generations from the augmentative released population might need to learn that whitefly eggs are a food source before whitefly population control can been achieved. An experiment is currently being conducted by ARS researchers at Tifton, Georgia to test initial populations from the predatory mite supplier versus future generations of those predatory mites raised on whiteflies to determine the difference in control from these populations. This experiment will conclude before the end of the fiscal year. Results from this experiment will help growers understand why there might be a delay in whitefly control from augmentative application of predatory mites and which predatory mites are best suited for controlling and surviving on whitefly populations. (Objective 1.B)
Review Publications
Tillman, P.G., Grabarczyk, E.E., Kesheimer, K., Balusu, R. 2023. Seasonal density and parasitism and predation of Halyomorpha halys (Stal) and indigenous stink bugs (Hemiptera: Pentatomidae) in a field crop agroecosystem in the southeast US. Journal of Economic Entomology. https://doi.org/10.1093/jee/toad159.
Grabarczyk, E.E., Querejeta, M., Tillman, P.G., Wallace, R.D., Barnes, B., Meinecke, C., Villari, C., Gandhi, K., Laforest, J., Elliott, M., Schmidt, J.M. 2023. Molecular analysis of three material types to reveal biodiversity of joro spider (trichonephila clavata) trophic interactions and web contents. Frontiers in Ecology and Evolution. 11. Article 1177446. https://doi.org/10.3389/fevo.2023.1177446.
Tillman, P.G., Grabarczyk, E.E., Kesheimer, K.A., Cottrell, T.E. 2024. Trapping strategy and diel periodicity affect capture rate of Halyomorpha halys (Hemiptera: Pentatomidae) in agroecosystems. Environmental Entomology. 53(2):237-248. https://doi.org/10.1093/ee/nvae010.