Flies Impacting Livestock, Poultry and Food Safety

NON-TECHNICAL SUMMARY: House and stable flies are among the most important pests in livestock and poultry production systems and 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. Law suits, zoning limitations and animosity between farmers and home owners have resulted. Both of these flies use manure or manure mixed with vegetative materials to lay their eggs resulting in contact with disease agents. 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 ineffective. House 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 among flocks; and the spotting of eggs with fly specks, reduces the eggs' market value. With their painful bites, stable flies 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 each year, primarily to confined livestock, in the US and they have emerged as primary pests of pasture cattle as well, doubling their economic impact.

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APPROACH: 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. Sampling will begin 2-3 weeks prior to the estimated date and continue until local production of the second generation is observed. Alsynite traps will be deployed along the putative northeasterly dispersal routes through NW TX, OK, KS, NE, IA, MN, IL, IN, TN and NY. Traps will be operated semi-weekly during the dispersal period and the number of stable flies caught will be recorded. Weather will be monitored to identify frontal systems approaching the study area; traps will be operated daily at least two days before and after the arrival of frontal systems. Fresh stable fly specimens will be dissected to assess physiological status. Correlation of trap collections with weather parameters will be assessed. Three and five fold increases in trap rates (flies/trap-day) will allow two levels of discrimination of the strength of the data. Starting in the summer of 2007 we will begin a nationwide survey of insecticide resistance in house flies, using both bioassays and genotyping of the alleles involved in insecticide resistance. We anticipate evaluating one class of insecticides each year starting with pyrethroids (permethrin and cyfluthrin).