Location: Agroecosystem Management Research2011 Annual Report
1a. Objectives (from AD-416)
Objective 1. Develop push-pull strategies for managing stable flies in agricultural systems. Sub-objective 1A. Identify stimuli that influence fly orientation and distribution. Sub-objective 1B. Develop a push-pull strategy utilizing identified attractants and repellents as components to manage flies. Objective 2. Refine the application of larval control of stable flies by studying maggot distribution, manipulation of larval habitat, and geographic extent of control required. Sub-objective 2A. Examine the causes for clumped distribution of maggots within a breeding site. Sub-objective 2B. Examine modification of soil microflora to reduce larval stable fly populations in concentrated breeding habitats. Sub-objective 2C. Determine effective radius of larval control required to see reduction below economic threshold on an individual property. The purpose of this project is to develop tools for reducing the impact of stable flies on livestock production. Three entomologists are assigned to this project, each supported by a full time research technician and one or two part time students. These scientists are members of the Agroecosystem Management Research Unit (AMRU). The AMRU is a diverse research unit with soil scientists, agronomist, agricultural engineer, and microbiologists completing the staff. The scientists assigned to this project interact with co-workers having expertise in spatial statistics, soil chemistry and physics, soil microbial ecology, and chemical synthesis and formulation to accomplish the mission of the unit.
1b. Approach (from AD-416)
Methodologies to achieve the objectives: 1) Examine the morphology and structure of sensory organs of stable fly adults and larvae. 2) Electrophysiological techniques will be used to identify attractant constituents associated with host animals (breath and skin emissions, etc.) and oviposition substrates (livestock animal manures and decomposing organic matter such as silage, rotting hay, and grass/alfalfa clippings) 3) Identify and evaluate novel repellents on stable fly populations. 4) Use visual and landscape features to develop a spatiotemporal model of stable fly dispersion that will describe and predict habitat use and suitability for larvae and adults. 5) Develop formulations of identified attractants and repellants for field application. 6) Reduce stable fly populations in confined and pastured cattle with Push-Pull strategy. 7) Take a holistic approach to reduce the development of immature stable flies by examining the biological, chemical, and physical characteristics of larval developmental sites and develop tools to modify these sites to render them unsuitable for stable fly development. Though this research will be directed at a better understanding of the stable fly habitat, other filth flies developing in similar habitats will be examined. 8) The limits of chemical and physical properties on survival of both stable flies and house flies will be studied in the laboratory. 9) Patterns of stable fly and house fly larval dispersal in relation to physical and chemical factors will be studied in the laboratory. 9) Mark release recapture studies will be performed in the field to study stable fly larval dispersal. 10) Antibiotics and food preservatives will be tested in the in the laboratory and then the field to determine their effect on stable fly survival. 11) Self marking technique will be usedat stable fly larval development sites to study the dispersal distances from these sites.
3. Progress Report
Chemical Ecology. Behavioral responses of stable flies to newly identified volatile attractants associated with their hosts were characterized in behavioral studies. Traps baited with attractants caught significantly more flies than those without attractants. Additional compounds were identified that stimulate female stable flies to lay their eggs. Two stable fly repellent formulations were evaluated on cattle and provided 5-7 hours of protection. An encapsulated formulation of catnip developed in a collaborative project reduced the number of eggs laid by stable flies by over 95% and inhibited larval growth by 90%. Methods for incorporating attractants, oviposition stimulants, and repellants into stable fly control technologies are being explored. Laboratory studies on stable fly larval developmental substrates. Effects of electrical conductivity, a measure of dissolved salt concentrations, on the development of immature stable flies were examined by adding 14 inorganic salts to the standard laboratory diet. Differences in electrical conductivity had little effect upon stable fly development; however, some salts, sodium chloride for example, inhibited larval development while others, such as potassium chloride, had little effect. In studies varying the moisture content of diets, stable fly larvae preferred substrates with about 70% moisture, but were capable of completing development in substrates with 25 - 80% moisture. The addition of ammonium bicarbonate, a food preservative, to the laboratory diet nearly doubled the number of pupae produced per pan. Microbial communities in natural stable fly developmental substrates. Studies were initiated to examine microbial succession in stable fly developmental habitats and associate changes in microbial communities with stable fly phenology. Preliminary results indicate that enteric bacteria predominate during the decomposition stages when immature stable fly populations are highest. Relative numbers of enteric bacteria and immature stable fly density decrease as the substrate decomposes. These studies are on going. Stable fly dispersal. Results of mark-release-recapture studies conducted in 2010 indicated that adult stable fly survival and dispersal were highest in June and then both decreased in July and further decreased in August. Young, unfed flies were more likely to be recaptured than were older flies that had fed on sugar or blood prior to release. Although still in progress, replication of that study in 2011 has substantiated those results thus far. The mean time from release to recapture was 1.8 days and 90% of the recaptured flies were collected in the first 2 days after release. Half of the recaptured flies were collected more than 2.3 kilometers from their release point. Control of stable flies in their developmental sites. The efficacy of an insect growth regulator, Cyromazine, for controlling stable flies in winter hay feeding sites was evaluated. When a granular formulation was applied at the rate of 0.5 g of active ingredient per meter-square, stable fly adult emergence was reduced by more than 90%. Stable fly emergence from the treated sites was reduced for at least 8 weeks.
1. An insect growth regulator controls immature stable flies. Manure and waste hay residues associated with winter feeding of livestock are important sources stable flies in the central US. Active microbial communities in these residues degrade most insecticides rapidly and options for controlling stable flies developing in them have been elusive. ARS researchers in Lincoln, Nebraska demonstrated that the insect growth regulator Cyromazine can provide economical, season long control of stable flies in winter hay feeding sites with a single, spring time, application. This provides the first practical solution for controlling stable flies in this habitat and should have a major role in reducing production losses attributable to this fly which are estimated to be greater than $2 billion per year for the US cattle industry.
Zhu, J.J., Dunlap, C.A., Behle, R.W., Berkebile, D.R., Wienhold, B.J. 2010. Repellency of a wax-based catnip-oil formulation against stable flies. Journal of Agricultural and Food Chemistry. 58:12320-12326. DOI: 10.1021/jf102811k.