Insect and Manure Management in Poultry Systems: Element Relative to Food Safety and Nuisance Issues

NON-TECHNICAL SUMMARY: Egg and chicken meat production facilities present habitats that produce enormous numbers of house flies and darkling beetles House flies and darkling beetles are a nuisance to neighboring residents, and are potential spreaders of enteric pathogens This project examines how different ways of storing and utilizing poultry manure will affect insect breeding potential, how fly control can be better accomplished at the sources, and how neighbors can monitor nuisance flies in residential environments.

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APPROACH: <BR> Objective (1): An evaluation of outdoor composting will be conducted. In these systems the producer moves manure out of the facility every two days. We will sample manure for house flies and darkling beetles monthly during the time period that beetles are active. Furthermore, additional compost samples will be removed to the laboratory and evaluated for house fly breeding potential. Suitability of commercial and experimental fly traps for monitoring abundance of house flies and blow flies will be examined through comparative studies. Baited jug traps, white sticky cylinders and baited pyramid traps will be compared by placing replicates of each design at 10-m intervals in proximity to known sources of house flies. The traps will then be rotated among positions over consecutive days according to a Latin square design. Relative efficiency will be evaluated by comparing mean daily catch rates of males and females of each species of fly. Using these methods poultry operations with a history of nuisance fly outbreaks will be targeted. To address the dichotomy between on farm thresholds and nuisance fly thresholds the fly population densities will be monitored inside and outside the facility. Resident nuisance threshold will be established and correlated to the fly densities within the facility. Working with the farm, an IPM program will be formed to reduce fly nuisance complaints. <P>
Objective (2): Research on prospective new classical biological control agents of house flies will be conducted. Lines of Eurasian pteromalid wasps that were recently obtained from Russia and Kazakhstan will be compared to counterparts already present in the US. The Eurasian lines appear to be Muscidifurax raptor, Spalangia endius, S. cameroni and S. nigroaenea. Reproductive isolation among Eurasian and North American lines will be evaluated directly by reciprocal crosses (MN), and indirectly by comparing mitochondrial and nuclear DNA sequences. Temperature requirements, reproductive capacity, searching abilities and host ranges of the different lines will be evaluated in the laboratory using standard methods. Performance of lines that appear to be promising will be tested against house flies under field conditions. Assays for insecticide resistance will be developed that utilize a serial dilution of technical-based insecticides applied to filter papers. Adult house flies will be assayed for susceptibility to permethrin, cyfluthrin, tetrachlorvinphos, dimethoate and methomyl. Both adult and larval darkling beetles will be assayed for susceptibility to tetrachlorvinphos, carbaryl and cyfluthrin, the only registered materials. House fly and darkling beetle resistance status will be determined for a minimum of 5 farms (poultry). Determination of darkling beetles to instar is difficult. Larvae will sieve sized to obtain mid to late instar specimens. These will serve as representatives in the larval resistance assay. An additional group of larvae will be held in the laboratory for adult emergence. Darkling beetle adults are fairly long lived (3-12 months), therefore, we will test beetles 1-3 weeks after adult emergence. <P>

PROGRESS: 2001/10 TO 2006/09<BR>
Objective (1): Field studies of different cleanout methods in caged-layer barns indicated partial cleanouts minimized level of subsequent house fly resurgence, but complete cleanouts minimized darkling beetle populations. Surveys of rural residents in two MN counties indicated odds of being annoyed by house flies increased with matching counts of house flies on sticky traps at respondents' residences. Laboratory studies nutritive value of artificial media for house flies indicated time of fermentation but not autoclaving had modest effects on nutritional quality; and the longer the fermentation, the lower its value. Differences in value were only weakly related to measures of aerobic and anaerobic bacterial densities. Objective (2): Lab experiments with three different pteromalid wasps from MN, Russia and Kazakhstan indicated females of each species readily mated with conspecific males, regardless of geographic origin. Host preference studies showed that M. raptor, S. cameroni and S. endius from all regions readily attacked and reproduced on pupae of house fly, stable fly, black dump fly, and horn fly, whereas reproduction was lower on a sarcophagid flesh fly, Sarcophaga bullata. New World and Old World lines of S. cameroni and S. endius were equally productive, but a Florida strain of M. raptor had slightly greater reproductive capacity than Old World counterparts. Studies of acquisition and retention by house flies of porcine reproductive and respiratory syndrome virus (PRRSv) showed flies were readily contaminated by feeding on blood, oropharyngeal washings and nasal washings from viremic pigs. The virus did not replicate in the flies; rather, levels per fly (log scale) declined at rates that were proportional to temperature. In a separate study, house flies dispersing from a swine unit undergoing a PRRS virus outbreak averaged 1.8 km per day, and rates of virus contamination diminished with distance. Modeling indicated that log-density of contaminated flies was well approximated as a decreasing, linear function of radial distance. Densities of contaminated flies decreased by 10-fold (1 log10-unit) every 0.59 km (0.37 mi) from the source. An 8-week study of house fly control methods compared (1) screening of ventilation inlets in side walls, (2) cyfluthrin applied to walls and floors, (3) screening and cyfluthrin in combination, and (4) no treatment (negative control). Fly screens best reduced house fly (and mosquito) densities inside the screened rooms, followed by screens + cyfluthrin, cyfluthrin alone, and untreated control. No differences were observed among treatments in mean numbers of fly specks per spot card, or levels of CO2, temperature and relative humidity. Results indicate well-maintained inlet screens effectively excluded house flies and mosquitoes, yet did not materially impede ventilation.
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IMPACT: 2001/10 TO 2006/09<BR>
Poultry producers can better anticipate the effects of different cleanout methods on insect populations associated with their caged-layer barns. County public health authorities now have a tool for setting and enforcing house fly nuisance thresholds for rural communities. Knowledge of how far PRRS virus-contaminated house flies can spread into the surrounding landscape will allow pork producers to plan isolation distances to achieve desired levels of biosecurity, and will serve as a model for analysis of fly borne spread of enteric bacteria and other pathogens that threaten animal and public health.