Efficacy of Entomopathogenic Nematodes Utilized for Control of Stable Flies (Stomoxys Calcitrans) at Round Bale Feeding Sites

Abstract

The stable fly is one of the most important livestock pests in the United States. The flies inhabit feedlots, high density livestock enclosures, dairies and hay bale feeding sites in cattle pastures. Accumulated organic materials provide excellent habitat for the stable fly to develop and complete their life cycle. The impact of the fly on the livestock, particularly cattle, causes problems for producers. A method of biological control with entomopathogenic nematodes was tested against first, second and third larval instars of the stable fly. Four distinct treatment groups were chosen on the basis of susceptibility trials. They were two single EPN genera treatments and two combined EPN genera treatments. The single genera treatments were designated as 0:1 S:H and 1:0 S:H. The combined EPN genera treatments included 1:2 S:H and 2:1 S:H. The S:H ratios refer to composition of Steinernema spp.(S) to Heterohabditis spp. (H). In all lab trials the combined EPN genera treatments increased stable fly mortality when compared to the single genera EPN treatments. Finally the information collected in the lab was administered in field trials at 8 round hay bale feeding sites in north-central Oklahoma. Based on these trials EPN treated trap site showed stable fly adult emergence to be lower in comparison to control trap sites at the same feeding sites. EPN are naturally occurring throughout the U.S. and can be administered in the field with conventional methods of spraying. Results from the trials illustrate that while control from EPN cannot compare to commercially available insecticides for stable fly mortality these naturally occurring EPN can provide background suppression that could potentially be incorporated into a sound IPM program.