Location: Agroecosystem Management Research
2024 Annual Report
Objectives
OBJECTIVE 1: Determine the environmental predictors of stable fly outbreaks and dispersal.
Subobjective 1A: Identify and model environmental variates associated with stable fly population dynamics.
Subobjective 1B: Model stable fly population dynamics in differing climatic zones.
OBJECTIVE 2: Investigate stable fly larval habitats to develop improved management strategies that protect livestock from stable flies.
Subobjective 2A: Characterize the temporal and spatial dynamics of physical and biological parameters associated with stable fly developmental substrates.
Subobjective 2B: Identify and develop stable fly larvicides and assess their sustainability.
OBJECTIVE 3: Identify stable fly attractants and repellents for use in strategies to protect livestock from stable flies.
Subobjective 3A: Identify novel stable fly attractant compounds from host animals and larval development sites (substrates).
Subobjective 3B: Develop long acting formulations with spatial and contact repellency.
Subobjective 3C: Identify and develop novel stable fly oviposition deterrents.
Subobjective 3D: Incorporate products developed in 3A-3C into a comprehensive Push-Pull strategy for managing stable fly infestations and improving animal well-being.
Approach
Stable flies are among the most important arthropod pests of livestock and, with changing climate and agronomic practices, are poised to expand their roles as pests and disease vectors. Their painful bites reduce livestock productivity, annoy companion animals, and interfere with recreational activities. Recent estimates of the economic impact of stable flies on cattle industries in the United States exceed $2 billion. Current management technologies are unable to effectively manage stable flies. This project proposes to address the development of novel technologies for managing stable fly populations and their impact on livestock using basic and applied research. Basic research will address developmental biology and population dynamics. Applied research includes chemical control strategies, repellants for protecting animals, and attractants for improving the efficacy of trapping devices. Combined, these efforts will improve our ability to monitor stable fly populations, identify and manage larval developmental substrates, and protect livestock from their painful bites. Successful completion of this project will improve livestock productivity and producer’s profits, as well as reduce livestock stress and disease.
Progress Report
This is the final report for project 3042-30200-011-00D titled “Management of Stable Flies to Improve Livestock Production”. A new project will replace the current one in fiscal year (FY) 2025.
All milestones in Objective 3 have been completed with novel attractant compounds identified from several stable fly developmental environments all over the world (United States, Brazil and Costa Rica) and new effective natural product-based repellent candidate compounds discovered with stronger and longer effectiveness than the gold standard repellent, DEET, and other traditional pesticides being used for biting fly control currently. A 3-year Push-Pull field trial has demonstrated that the combination of using attractant baited mass trapping and topical application of repellent formulation on cattle provided the same level of control as found while using the traditional insecticide (permethrin), but with no resistance developed as found from insecticide application) and with a one-third lower material cost. Technology transferred of developing the first attractant impregnated stable fly tap trap was developed with a research partner, and the product showed significant stable fly population reduction in feedlot field trials with over one million stable flies caught and more than 70% of animal stress reduction observed. The newly discovered coconut free fatty acid repellent compounds acids (decanoic and dodecanoic acid, either individual or blends) are considered as effective as DEET (the golden standard in repellents), but broader applications to many other blood-sucking pests, such as mosquitoes, ticks, bedbugs, etc. These newly discovered repellent compounds have been further applied to repel some urban pests like cockroaches and scorpions. Recently, coconut fatty acid repellent has been used in snail eradication program by the quarantine and eradication invasive snail program of Animal and Plant Health Inspection Service (APHIS) with significant improvement in prevention and control. Furthermore, the starch-pectin formulation of coconut fatty acids has been demonstrated as an effective stable fly oviposition deterrent from the field trials carried out in Costa Rica, with over 90% reduction of egg-laying in stable fly larval development sites.
For Objective 2, characterization of the temporal and spatial dynamics of physical and biological parameters associated with stable fly developmental substrates was completed. In 2023, a new scientist was hired and completed some of the tasks from the original milestones (the DNA from stable fly adult gut contents and larval development substrates extracted, processed, and sequenced for microbial community composition). New milestones were proposed and approved in developing novel RNA interference (RNAi)and MicroRNA-based biopesticides. RNAi with double-strained RNA of Vacuolar-type ATPase is successfully developed as the new generation of biopesticides and were tested on larvae and adults by microinjection for adults and feeding/soaking for larvae on their effectiveness against stable flies. The mortality and knockdown of target gene of RNAi on both larvae and adults were demonstrated, which will be further investigated.
The discoveries of these novel natural product based repellent compounds have further helped U.S. small businesses to secure Federal funding for their product development through collaborations (3 companies). It has also been used to develop repellent impregnated U.S. soldier uniforms and novel repellent releasing devices to help U.S. military personnel prevent mosquito attacks and disease transmission (Deployed War Fighting Program).
Accomplishments
1. Environmentally sound stable fly control. Stable flies are one of the most important arthropod pests of livestock that reduce cattle weight gain and milk production leading to annual economic losses of more than $3 billion to the United States cattle industry. Together with biting fly control professionals (entomologists and cattle producers in Nebraska), ARS scientists in Lincoln, Nebraska, developed the first Push-Pull control strategy in suppression of biting fly attacks on livestock animals, ranked as Number 1 Agricultural Products in Nebraska. The efficacy in controlling stable fly biting reached the same level as observed from the use of a traditional pesticide (permethrin) during the 3-year field trials. The method developed may provide a novel control strategy for organic cattle growers who are fighting against stable flies.
2. Invasive snails cause significant losses of flowers in nurseries and other agricultural products in the U.S. Novel application of repellent against snails. In collaborating with USDA-APHIS, (Animal and Plant Health Inspection Service), ARS scientists in Lincoln, Nebraska, developed botanical-based repellent formulations (catnip and coconut fatty acids) that have been further applied in the eradication programs for invasive snail control with significant reduction in invasive snail hitchhiking with sea containers at the United States international shipping ports and garden nurseries (New York, Florida and Hawaii). Prototype repellent products are being tested in the field with over 5 days of repellency observed.
Review Publications
Wang, H., Zhao, X., Tan, L., Zhu, J.J., Hyten, D. 2024. Crop DNA extraction with lab-made magnetic nanoparticles. PLOS ONE. 19(1). Article e0296847. https://doi.org/10.1371/journal.pone.0296847.
Zhu, J.J., Wang, H. 2024. Semiochemicals and natural repellents in biting fly management. Current Opinion in Insect Science. 64. Article 101223. https://doi.org/10.1016/j.cois.2024.101223.