Location: Agroecosystem Management Research2013 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. Several stable fly attractants associated with cattle and their environments were identified including 1-octen-3-ol, phenol, p-cresol and m-cresol. Addition of these compounds to standard stable fly traps increases catch rates 2-4 fold in feedlot and other livestock environments. A microencapsulated formulation of catnip that deters stable fly and house fly oviposition under field conditions was developed and evaluated. An oil-based formulation of catnip oil that protects cattle from stable flies for 24 hours and horn flies for 20 hours was developed as well. A blend of natural compounds was identified from food grade vinegar that attracts house flies in agricultural environments. Larval functional morphology. Scanning electron microscopy was used to characterize and compare sensory receptors on the surface of 1st, 2nd, and 3rd instar stable fly and house fly larvae. Physical and chemical characteristics (pH, moisture content, electrical conductivity, temperature, ammonium, and nitrate) of larval substrates were characterized. Larval community ecology. Natural substrates from stable fly larval habitats including manure, silage, and hay feeding site residues were collected. Metagenomic analyses will be used on these samples to characterize the microbial communities associated with larval substrates and nutrition. A sterile meridic larval diet for stable flies was developed. Several microbial and protozoan symbionts of stable fly larvae tentatively identified as trypanosomatids, gregarines, and spiroplasmids have been observed. We are in the process of isolating and characterizing these organisms, several of which may be new species. Adult phenology. Spatial-temporal dispersion patterns of nine years of stable fly trapping data from a 25 trap grid located on 4,000 hectares of land in northeastern Nebraska were characterized. Trap catches varied greatly on temporal and spatial scales. The number of flies collected by traps was correlated with that of neighboring traps up to an inter-trap distance of 2 kilometers. Seasonal patterns of trap catches differed greatly among traps as close as 10 kilometers of each other. Some traps collected over 80% of their total annual catch by early September whereas others had collected less than 20% at that time. The analysis indicated that the 25 traps used was the minimum number needed to evaluate spatial and temporal trends in stable fly populations over the 4,000 hectare property. A morphometric analysis of flies emerging from cattle winter hay feeding site residues and samples of the adult population collected on sticky traps indicated that the flies emerging from the hay feeding sites were significantly larger than those in the general adult population. This result indicates that larval developmental sites other than winter hay feeding sites are contributing large numbers of flies to the general stable fly population.
1. Stable fly larvae are dependent upon bacteria in their natural habitats for growth and survival. Previous attempts to rear them aseptically have either failed or yielded small, stunted, adults. ARS scientists in Lincoln, Nebraska developed a sterile diet for stable fly larvae. Larval development on this diet was not delayed and adults were of normal size. Development of this diet opens the door for future studies on the nutritional requirements of stable fly larvae and the role microbial communities play in fulfilling those nutritional needs.
Friesen, K.M., Johnson, G.D. 2013. Stable fly phenology in a mixed agricultural-wildlife ecosystem in northeast Montana. Environmental Entomology. 42(1):49-57. DOI:ORG/10.1603/EN12231.