The efficacy of entomopathogenic nematodes for controlling housefly infestations of intensive pig units.

The efficacy of the entomopathogenic nematodes Steinernema feltiae and Heterorhabditis megidis after formulation into a housefly bait was compared with a commercial bait formulation of methomyl for the control of houseflies in a U.K. pig farm. The housefly infestation was confined to the farrowing unit, which consisted of ten farrowing houses, where two adjacent houses were sequentially re-stocked with pregnant sows at weekly intervals. Shortly after re-stocking, one house was baited with one of the nematode species and the other with methomyl. Significantly fewer flies (P < 0.05) were counted in the houses baited with either S. feltiae or H. megidis than those baited with methomyl. The efficacy of S. feltiae sprayed on to the manure was also compared with methomyl bait. Counts of houseflies carried out in the farrowing cycle before this treatment were not significantly different (P > 0.05); however, significantly fewer flies (P < 0.05) occurred after S. feltiae was sprayed. The efficacy of encapsulated S. feltiae was also compared with methomyl bait and no significant difference was observed (P > 0.05).