Flies Impacting Livestock, Poultry and Food Safety

NON-TECHNICAL SUMMARY: Muscoid flies are among the most important pests in livestock and poultry production systems. Two species in particular, house fly (Musca domestica) and stable fly (Stomoxys calcitrans), are responsible for damage and control costs in excess of a billion dollars per year in the United States. In addition to the direct damage these flies inflict upon livestock, their presence as a byproduct of confined livestock and poultry operations has been repeatedly cited as a common nuisance, especially when the flies enter the vicinity of human habitations and urban environments. Lawsuits, zoning limitations and animosity between farmers and homeowners have resulted. Both of these flies use manure or manure mixed with vegetative materials for larval developmental sites. In spite of their ubiquitous presence, importance as pests, and association with diseases of humans and livestock, our knowledge of the biology of these species is seriously wanting and available control technologies remain inadequate. House flies are considered to be the primary nuisance pest associated with dairy and other confined animal operations. These flies are capable of carrying more than 65 disease organisms that affect humans and animals such as the virulent Escherichia coli strain O157:H7. In poultry production, house flies can transmit Salmonella. With their painful bites, they can reduce weight gains of cattle on finishing rations up to 20%. It has been estimated that stable flies caused $432 million dollars in losses, primarily to confined livestock, in the US. Stable flies have emerged as primary pests of pasture cattle as well, doubling their economic impact. The proposed research is technically feasible and the expertise to accomplish the objectives of this project exists within the university and USDA-ARS systems. However, expertise is widely dispersed with few states having more than one livestock entomologist and many having none. A Multistate project will serve to coordinate this research effort, maximizing synergy and minimizing duplicated effort. Given the dispersal potential for these flies as well as varying cultural and climatic conditions throughout North America, multistate collaborations are necessary to address many of the issues of biology and control of muscoid flies. Successful completion of this project will provide a better understanding of the interactions between livestock production systems and the life cycles of pestiferous flies. Exploitation of these interactions will provide economically feasible and environmentally friendly technology for reducing the impact of flies on livestock production and human health. The project will provide quantitative data to analyze fly borne spread of pathogens from animal production systems into the urban environment and the ability to assess the risk of fly-borne illness associated with different production techniques and distances from production facilities. The project will develop new control technologies for flies. These technologies will be disseminated to producers to reduce the abundance of muscoid flies thereby increasing the health and quality of livestock and reducing their economic impact.

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APPROACH: <BR> Objective 1: <BR>Subobjective 1. Characterize stable fly origins and dispersal <BR>C. Dispersal of Stable Flies <BR>Historical weather and first date of stable flies appearance on traps will be evaluated to estimate when northerly dispersal of stable flies is most likely to occur. Alsynite traps will be deployed along the putative northeasterly dispersal routes. Traps will be operated during the dispersal period and the number of flies caught recorded. Weather frontal systems will be identified and traps will be operated daily at least two days before and after the arrival of frontal systems. Correlation of trap collections with weather parameters will be assessed. The proportion of 3x and 5x traps in each of the study areas will be compared to the passage of frontal systems as confirmed by changes in barometric pressure, temperature and wind direction. Response of stable flies of different physiological states to changes in barometric pressure (Wellington 1945) will be assessed in the laboratory. <BR>D. Determine overwintering dynamics of stable fly throughout the USA Studies will be conducted to duplicate overwintering in the laboratory. Subsamples will be removed at intervals and held at 20 C for adult emergence. Reiterations will be run with smaller temperature increments until the optimal temperatures and limits for stable fly larvae to extend their larval stage and the upper limits of how long the larval stage can be extended have been identified. Overwintering temperature profiles will be compared to those observed in artificial overwintering sites fitted with temperature sensors to evaluate the potential for overwintering even if we fail to observe natural overwintering. <BR>Objective 3. <BR>B.Control and economic impact of adults <BR>Treated targets (TTs) will be evaluated on 2-4 small farms with 150 or fewer animals in each cooperating state. One meter square targets will be soaked until saturated in 0.1% lambda-cyhalothrin or water. TTs will be deployed for 2-3 months once the action threshold of 100-300 stable flies/Alsynite trap/day is reached. Alsynite traps and leg counts will be used to evaluate the effects of TTs on stable fly populations. Upon completion of the study, targets will be bioassayed to determine residual toxicity. <BR><BR>Subobjective 2: <BR>Develop house fly control and resistance management tactics A. <BR>Biological control with pteromalid parasitoids Natural parasite populations will be monitored with screen bags of sentinel house fly pupae. Bags are placed at each farm and replaced weekly. After exposure, emerged flies will be counted and recorded. Remaining pupae will be held for 3 weeks, emerged flies will be counted and parasites identified. Naturally occurring house fly pupae will be collected and transported to the laboratory each week. Pupae will be handled as above. <BR>C. Conduct nationwide survey for insecticide resistance Cooperators across the USA will submit house flies and obtain detailed histories of insecticide use, from one to five facilities (dairy, poultry or hog) across their state. Files would be brought back to the laboratory and eggs would be collected. Emerging flies would be used for bioassays by the lab making the collections.