S1060: Fly Management in Animal Agriculture Systems and Impacts on Animal Health and Food Safety

(Multistate Research Project)

Status: Active


Federal funding priorities are focused on major issues of national concern, climate change, food safety, food security, biofuels, and obesity. Entomologists play a key and vital role in helping to solve many of these national concerns by evaluating the potential impact of climate change on insect populations and how these changes can threaten the health and well being of humans and animals, and compromise the nations safe and secure food supply. Few insects are more influenced by anthropogenic effects than nuisance and pest flies; the house fly, stable fly, horn fly, face fly and blow flies. There is a significant body of literature on the biology and economic impact of these pests but this multidisciplinary project examines closely predictive models influencing pest distribution in light of climate change, the effects of the microbial community of pest populations, and the dispersal of pathogenic microorganisms that compromise a safe and secure food supply. Advances developed in the course of this project will lead to the development of new and innovative pest management technologies to mitigate these threats.

Biting and nuisance flies are among the most important pests in livestock and poultry production systems. These flies are responsible for damage and control costs in excess of a billion dollars per year in the United States (e.g., see Taylor et al. 2012). 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 nuisance, especially when flies enter the vicinity of human habitations and urban environments. Law suits, zoning limitations and animosity between farmers and home owners have resulted (Thomas and Skoda 1993). 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. The recent sequencing of the house fly genome (underway), and future sequencing of the stable fly genome (planned) offer great potential for the identification of new opportunities for managing these pests.

House flies are considered to be the #1 nuisance pest associated with dairy and other confined animal operations (Geden and Hogsette 1994, Hinkle and Hickle 1999). House flies are capable of carrying more than 65 disease organisms that affect humans and animals (Greenberg 1971), such as the virulent Escherichia coli strain O157:H7 (Sasaki et al. 2000). In poultry production, house flies can transmit Salmonella among flocks; and the spotting of eggs with fly specks may reduce the eggs market value. Stable are among the most serious pests of cattle worldwide. With their painful bites, they can reduce weight gains of cattle on finishing rations up to 20% (Campbell et al. 1977). The total impact to U.S. cattle industries is estimated to exceed $2 billion dollars annually (Taylor et al. 2012). Given the economic importance of nuisance and biting flies, control of their populations is critically important. For decades insecticides have provided economical control of these pests. However, the evolution of insecticide resistance compromises the control achieved in many locations around the USA.

Stable flies develop as maggots in a wide array of decomposing organic matter, including soiled animal bedding and soiled feed debris that accumulates wherever cattle are confined (Moon, 2002). Populations build exponentially by continuous reproduction from spring to fall in northern temperate localities (Beresford and Sutcliffe, 2010; Taylor et al., 2012). Dairy farm surveys indicate calf hutch bedding is a prominent source of stable flies around dairies (Schmidtmann, 1988), and choice of bedding material can minimize stable fly production (Schmidtmann, 1991). More recently, it has also become apparent that feed debris and manure that accumulate during winter are important sources of stable flies, especially where overwintered debris piles remain intact into the following summer (Broce et al., 2005; Talley et al., 2009; Taylor and Berkebile, 2011).

The face fly is the primary pest of pastured cattle in most state north of the 35th parallel. Adult face flies overwinter in attics and out-buildings and colonize cattle in the spring (Karfsur and Moon 1997). The face fly feeds on lachrymal and mucosal secretions of the eyes and nose of cattle. Gravid flies lay eggs exclusively in fresh cattle dung pats, and the life cycle can be completed in as little as 14 days. When face flies are abundant, cattle change grazing habits, which often results in poor utilization of pasture. In addition to the annoyance and irritation associated with its feeding habits, the face fly is the primary means of transmission of Moraxella bovis, the causative agent of infectious bovine keratoconjunctivitis (IBK), also known as pinkeye (Glass et al. 1982, Glass and Gerhardt 1983, Krasfur and Moon 1997). Face fly infestations were estimated to cause annual losses of more than $53 million (Drummond et al. 1981). Action threshold levels of 10-15 flies per face were established to reduce the spread of pinkeye and maximize animal comfort (Krafsur & Moon 1997). In the northeast face fly numbers often exceed 100 flies per face.

The horn fly is an obligate blood-sucking parasite of cattle and is considered a serious pest of pastured cattle in US (Drummond 1988). Horn fly feeding annoys cattle, alters their grazing habits, and decreases both milk production and weight gains. Horn fly numbers as high as 10,000 per animal have been reported and they feed 10 to 12 times per day. Horn flies oviposit exclusively in fresh dung, and they do so immediately after it has been deposited (Bruce 1964). The fly can complete development in 9-12 days, with 50% adult survival at 5 weeks. Horn flies diapause beneath dung pats during the winter months. Horn fly control leads to increased milk production and calf growth (Johnsson and Mayer, 1999). Unlike other kinds of flies that just visit cattle for brief moments, adult horn flies reside on their host animals, which makes then especially vulnerable to control. Organic dairy farmers rely on essential oil repellents to alleviate horn fly problems, but success of these products is limited. Horn flies have been incriminated in the transmission of bovine mastitis, also known as summer mastitis (Oliver et al. 1998, Gillespie et al. 1999, Edwards et al. 2000). In NC, 53% of horn flies collected from cattle were positive for S. aureus, and 39% of the cows were positive for the same genotype found in the flies (Anderson et al. 2012).

In 2003, the Northeastern IPM Center Livestock and Field Crop working group created a list of prioritized needs (http://northeastipm.org/work_livepriority.cfm). The group indicated that the development of new integrated management of key pests of livestock and poultry in confined and pasture settings was a top priority with specific reference to stable fly breeding and migration in pasture systems and fly control methods for pasture and feedlot situations. Ten of the working groups 17 assessed needs and seven of the top 10 directly referred to muscid flies, including house flies, stable flies, and face flies as top priorities. The objectives of the current proposal address 10 of the 17 needs. Coordinated extension of the research outcomes derived from this proposal to stakeholders will address 2 additional priorities of this working group.

In 2001, research and extension needs for IPM of arthropods of veterinary importance that were identified as part of a USDA sponsored workshop in Lincoln, Nebraska nearly 20 years ago (Geden and Hogsette 1994) were reevaluated, updated, and the updated document is now available at: http://www.ars.usda.gov/Services/docs.htm?docid=10139 . This document describes the IPM needs of eight animal commodity groups including poultry, dairy, beef cattle, and swine. For each of these commodity groups, muscid flies are noted as a very significant pest, and the working group makes strong recommendations for increased research and extension efforts to reduce the considerable economic losses resulting from pest activities. This workgroup also noted the decline to critical levels of extension personnel nationally, particularly related to domestic animal production. Increasing coordination and collaboration among veterinary entomologists nationally is needed to more efficiently disseminate research findings and management recommendations.

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. The project will develop new control technologies for biting and nuisance flies and will assess the fly resistance to insecticides that are currently available or under development. New technological innovations and comprehensive pest management information will be disseminated to producers through a multistate coordinated effort to provide the broadest reach for project outcomes thereby increasing the health and quality of livestock and reducing the economic impact of these pest flies.

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.

This project will replace the existing S-1030 project Flies impacting livestock, poultry and food safety. Most of the recent work cited below has been the result of previous projects in this series.
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