Location: Insect Behavior and Biocontrol Research
2024 Annual Report
Objectives
1. Develop strategies for optimal use of biological control agents against invasive weeds such as air potato and Chinese tallow tree based on research that improves our understanding of factors that determine weed abundance, including biotic and abiotic elements and climatic region.
1.A. Determine the role of native natural enemies attacking a biological control agent (Caloptilia triadicae) in its introduced range.
1.B. Determine presence and importance of air potato leaf beetle chemical communication pathways to improve air potato biological control.
2. Develop and refine biologically-based control strategies for invasive insects such as the Argentine cactus moth, Harrisia cactus mealybug, and Old World bollworm, focusing on the use of parasitoids and disrupting pheromone cues.
2.A. Determine release factors that increase successful establishment of the parasitoid Apanteles opuntiarum against the Argentine cactus moth.
2.B. Determine the effectiveness of released control agents Anagyrus cachamai and/or A. lapachosus to control the Harrisia cactus mealybug (HCM) in Puerto Rico.
2.C. Determine the effectiveness of disrupting pheromone communication between gregarious cactus moth larvae as a sustainable management tactic for this pest in commercial cactus production areas.
2.D. Determine whether parasitoids that attack native Helicoverpa zea will also be successful against the potentially invasive Helicoverpa armigera.
3. Develop sustainable management strategies such as “push-pull” technology for controlling invasive whiteflies in vegetable production using naturally repellent plants, plant chemicals, trap plants, and green leaf volatiles together with natural enemy refuge plants.
3.A. Identify companion plants, products and chemical compounds that a) repel whiteflies and determine their efficacy in limiting pest dispersal into crops (“push” factors), as well as b) identify plants and products capable of attracting whiteflies into trap crops to facilitate control (“pull” factors).
3.B. Evaluate companion or refuge plants that “attract and reward” important whitefly predators.
3.C. Develop an integrated cropping system combining “push-pull” crops or plant products with natural enemy refuges for sustainable biologically-based control of whiteflies.
Approach
Invasive insect pests and weeds are among the most serious problems facing agricultural and natural ecosystems throughout the United States. This project plan describes research to improve implementation of biologically based tactics for non-pesticide management of insect pests and weeds through a better understanding of the pest species’ biology and interactions with host plants and natural enemies, as well as development of optimized approaches, technologies and strategies. One area of research will address improvement of techniques to enhance release success, establishment and impact of biological control insect species against invasive weed species such as the air potato and Chinese tallow tree. Another area of research focuses on the development of an integrated cropping system for control of whiteflies in vegetable crop systems using ‘push’ components consisting of naturally repellent plants or plant compounds, in conjunction with ‘pull’ components that consist of trap crops, complemented by refuge plants to attract and reward natural enemies. Finally, the use of host specific parasitoids for the protection of native cacti from the invasive Argentine cactus moth and the Harrisia cactus mealybug, and protection of crops from the potentially invasive Old World bollworm, will be studied. Therefore, the plan is expected to serve several stakeholders and customers, including researchers at land grant institutions, government and non-governmental organizations, growers, ranchers and commodity groups, and small-scale farmers and organic producers. The outcomes of this research project will improve the sustainability of agricultural production, reduce reliance on pesticides and reduce the environmental degradation caused by invasive pest species.
Progress Report
For Objective 1, progress was made by ARS researchers at Gainesville, Florida with impact surveys being conducted for Subobjective 1A and lure development completed for Subobjective 1B. Results for Subobjective 1a, indicated minimal levels of impact to Chinese tallow tree from Caloptilia triadicae. Results for Subobjective 1B determined a 2-compound blend that could be deployed in the field to aggregate populations of air potato beetles onto target plants. The significant accomplishments on Subobjective 1A and 1B will result in the improvement of biological control for the invasive weeds Chinese tallow and air potato. Progress has also been achieved on Objective 2. For Subobjective 2C, studies determined that 1st, 2nd, and 3rd instars cactus moth were highly responsive to the trail pheromone and would likely be controlled, while 4th and 5th instars did not follow the trail pheromone. Outcomes for Subobjectives 2A and 2B have been significantly delayed due to slow progress towards the permitting of the biological control agents. Research is ongoing and release permits are progressing towards submission and approval. For Subobjective 2D, laboratory experiments with H. zea parasitoids, especially Cotesia marginiventris, are on-going. Under Objective 3, Subobjective 3B, progress was made by determining the response of two whitefly predators to attractive blends of green leaf volatiles. Blends of green leaf volatiles optimized for the attraction of whiteflies were attractive to the predatory mirid Macrolophus praeclarus. However, this blend was not attractive to the natural enemy Delphastus catalinae. The use of these green leaf volatile blends for monitoring and trapping whiteflies may also improve the biological control of whiteflies in vegetable production.
Accomplishments
1. Development of lures to aggregate air potato in the field. Air potato is a non-native invasive weed spreading across the southeastern United States, and because of its invasive nature, the air potato leaf beetle was introduced to help control this plant. The air potato beetle has been very successful at controlling the plant; however, some patches of the weed seem to be able to avoid detection and feeding from the beetle. Studies by ARS researchers at Gainesville, Florida have identified highly attractive, plant produced chemicals that can attract and aggregate populations of the air potato beetle to these uncontrolled patches. Lures were developed and deployed in the field resulting in increased densities and damage to the target weed. These lures can be deployed by land managers to improve the outcomes of their air potato biological control program.
2. Formation of invasive plant and honeybee working group. ARS researchers at Gainesville, Florida in collaboration with the USDA Office of the Chief Scientist, multiple state universities, and USDA-APHIS, an Invasive plant control and bee forage workgroup, has been formed to facilitate discussion between the diverse group of stakeholders and land managers interested in the interactions between honeybees and invasive plants. This working group is seeking to provide scientifically based, empirical data to regulatory agencies, to provide the latest science about invasive weeds impacts and managements, utilization of invasive weeds by honeybees, and to explore needs to address the recovery of invaded habitats. Additionally, the working group is developing key messaging on integrated habitat management and how several disciplines and/or stakeholders can cooperate for better natural habitat management in the southeastern United States.
3. Response of different cactus moth instars to applications of trailing pheromone. The continued expansion of the Argentine cactus moth continues to threaten cultivated and native cactus throughout the southern United States. Experiments were conducted by ARS researchers at Gainesville, Florida to determine if cactus moth larvae could be controlled through application of their trail pheromone. Application of the trail pheromone can disrupt the normal behavior of the larvae and significantly increase mortality. Studies determined that 1st, 2nd, and 3rd instars were highly responsive to the trail pheromone and would likely be controlled, while 4th and 5th instars did not follow the trail pheromone. These results indicate the importance of timing treatment. If the larvae are too old, they will not be controlled by applications of the trail pheromone.
4. Sweetpotato whitefly and natural enemy attraction to green leaf volatiles blends. Sweetpotato whitefly, Bemisia tabaci, is a major insect pest of vegetables in the field and in high tunnel production. Research was conducted by ARS researchers at Gainesville, Florida to determine if compounds that were attractive to sweetpotato whitefly were also attractive to natural enemies. Attractive blends of green leaf volatiles were assayed against two economically important predators of sweetpotato whitefly. It was determined that blends that were optimized for attraction of sweetpotato whitefly also attracted female Macrolophus praeclarus. However, this blend was not attractive to either male or female Delphastus catalinae. The deployment of this attractive lure will enhance sweetpotato whitefly monitoring and will likely result in enhanced biological control from M. praeclarus.
Review Publications
Fouad, H.A., Gomes Da Camara, C.A., Martins De Moraes, M., Tavares, W.D., Legaspi, J.C., Zanuncio, J.C. 2023. Insecticidal and repellent activities of four essential oils against Sitophilus zeamais (Coleoptera: Curculionidae). Dose Response. 21(4). https://doi.org/10.1177/15593258231210263.
Legaspi, J.C., Kanga, L.H., Haseeb, M., Simmons, A.M. 2023. Assessing the status of “push-pull” technology in worldwide agriculture and forestry. Subtropical Agriculture and Environments. 74:1-12.
Gaffke, A.M., Romero, M.I., Alborn, H.T. 2023. What is more important to host-seeking entomopathogenic nematodes, innate or learned preference?. Agriculture Journal. 13(9):1802. https://doi.org/10.3390/agriculture13091802.
Bowers, K.E., Hight, S.D., Miller, N.W., Gaffke, A.M., Taylor, J.E. 2024. Use of non-native, invasive tree logs for commercial mushroom production. Invasive Plant Science and Management. https://doi.org/10.1017/inp.2024.12.
Griesheimer, J.L., Martini, X., Minteer, C., Hight, S., Gaffke, A.M. 2024. Beetle herding: optimizing the biological control of the invasive air potato vine using attractive semiochemical lures. Chemoecology. https://doi.org/10.1007/s00049-024-00405-6.