Gustave D. Thomas

Effects of Stable Flies (Diptera: Muscidae) on Weight Gains of Grazing Yearling Cattle

Abstract Differences in weight gains caused by stable flies, Stomoxys calcitrans (L.), on grazing yearling steer/calves averaged 0.2 kg per steer in a 3-yr study on canyon range pastures in West Central Nebraska. Stable fly numbers averaged 0.85 per front leg on treated calves and 3.64 per front leg on control calves. In 2 of the 3 yr after the grazing trials were completed, the calves were placed in a feedlot and fed a finishing ration. Compensatory gain did not occur in the feedlot after the stable fly stress was removed.

Resistance Status of House Flies (Diptera: Muscidae) from Southeastern Nebraska Beef Cattle Feedlots to Selected Insecticides

The status of resistance to three insecticides (permethrin, stirofos, and methoxychlor), relative to a laboratory-susceptible colony, was evaluated in field populations of house flies, Musca domestica L., collected from two beef cattle feedlots in southeastern Nebraska. Topical application and residual exposure to treated glass surfaces were suitable methods for determining the resistance status of house flies to permethrin, stirofos, or methoxychlor. However, in most cases, residual exposure was more sensitive in resistance detection (i.e., higher resistance ratios). The field populations tested were moderately resistant to permethrin (RR = 4.9-fold and RR = 7.3-fold, for topical application and residual exposure, respectively) and extremely resistant to stirofos and methoxychlor (not accurately quantifiable because of low mortality at the highest possible concentrations or doses). Probable explanations for the resistance status of these house fly populations and implications for global feedlot fly management are discussed.

The influence of blood meals on accumulation of arachidonic acid by adult stable flies

Abstract We investigated the influence of blood meals on accumulation of the polyunsaturated fatty acid (PUFA), 20:4n-6, by adult stable flies, Stomoxys calcitrans (L.). The fatty acid compositions of phospholipids (PLs) and triacylglycerols (TGs) prepared from adult male and female stable flies that had been maintained either with or without blood meals were determined, and incorporation of exogenous radioactive fatty acids into tissue lipids of adults was monitored. The major PL components were 16:0, 16:1, 18:1 and 18:2n-6. Two C 20 PUFAs, 20:4n-6 and 20:5n-3 were associated with PLs in the 1–5% range. The major TG components were 14:0 and 16:1. Although absence of the normal adult blood meals influenced the overall fatty acid profiles of male and female stable flies, proportions of C 20 PUFAs in PLs of blood-fed flies were not substantially higher than proportions of C 20 PUFAs in their sucrose-fed counterparts. The fatty acid incorporation studies indicate that the ability to incorporate exogenous fatty acids is decreased in older adult stable flies. We conclude that the larval stages of stable flies are more important for accumulation of C 20 PUFAs than the adult stages.

A Review of Natural Mortality and Enemies of the Stable Fly (Diptera: Muscidae) in Missouri

This review article summarizes the most significant results of research on mortality factors affecting populations of the stable fly, Stomoxys calcitrans (L.), in Missouri.