Location: Agroecosystem Management Research2012 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 used at stable fly larval development sites to study the dispersal distances from these sites.
3. Progress Report:
Chemical Ecology. Four manure associated stable fly attractants were identified and behavioral activities of stable flies were characterized in response to each. Trap catches were enhanced by the addition of attractants and synergistic effects were observed. Attractants associated with oviposition sites were identified and shown to enhance oviposition response of gravid stable flies in field trials. A microencapsulated formulation of the catnip oil based stable fly adult repellent was developed. This formulation repels adult stable flies, deters oviposition, and has larvicidal activity. Field efficacy tests of an oil-based catnip formulation were conducted with pasture cattle. The repellant reduced the number of stable flies on treated animals by 80% relative to untreated animals and exhibited 24 hours of residual activity. Repellants and attractants will be incorporated into a push-pull strategy for managing stable flies (Subobjectives 1a and 1b). Larval functional morphology. The ultrastructure of the larval integument was examined with scanning electron microscopy. The morphology, localization, and density of receptor structures were characterized. The morphology, cytology, and physiological function of distinct regions of the larval digestive system were characterized. These studies contribute to understanding how stable fly larvae orient themselves in their environment and locate suitable microhabitats (Subobjective 2a). Larval community ecology. Studies to assess the microbial community profile and function in natural larval substrates were initiated. Eleven larval habitat types from three locations were sampled weekly. Stable fly larvae were dissected and examined for symbiotic organisms. Several symbionts were observed and we are currently working on isolating, characterizing, and culturing those organisms. Metagenomic analyses of larvae and substrates will be performed. Pupae are being isolated and monitored for the emergence of parasitic wasps and beetles. Stable fly larvae are dependent upon the microbial community in their habitats for nutritional resources. Understanding microbial community structure of substrates suitable and unsuitable for larval development will permit modifications favoring the unsuitable condition (Subobjective 2b). Studies are continuing on the use of Insect Growth Regulators for the control of stable flies in larval developmental sites. Adult phenology. Seasonal variation of adult stable fly size was examined. Size was correlated with population level trends. Larger flies were collected when populations were increasing compared with those collected when populations were decreasing. This indicates that nutritional resources of larval developmental sites have a role in controlling population levels (Subobjective 2b). Adult stable fly monitoring programs continue at the Meat Animal Research Center (Clay County, Nebraska), second year, and Agricultural Research and Development Center (Saunders County, Nebraska), twelfth year. Mark-Release-Recapture studies to evaluate the effects physiological age on dispersal were completed and studies on the effects of landscape features were initiated (Subobjective 2c).
1. Managing stable flies organically. Stable flies are a major pest insects for cattle producers and no stable fly repellants are currently available for use in organic production settings. An encapsuled formulation of catnip oil was developed by ARS scientists in Lincoln, NE to control immature stable flies developing in animal wastes. The formulation deters female flies from depositing their eggs and inhibits larval development under field conditions. A single application is effective for 5-7 days. This is the first botanical-based product for the control of immature stable flies. The formulation, once registered, will provide an effective stable fly control option for organic cattle producers.
Doud, C.W., Taylor, D.B., Zurek, L. 2012. Dewatered sewage biosolids provide a productive larval habitat for stable flies and house flies (Diptera: Muscidae). Journal of Medical Entomology. 49(2):286-292. DOI: HTTP://DX.DOI.ORG/10.1603/ME11158.