Submitted to: Southwestern Entomologist
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: October 12, 1995
Publication Date: N/A
Interpretive Summary: The horn fly is a widely distributed introduced pest of cattle that reproduces by laying eggs in fresh cattle manure. Maggots hatch from these eggs and feed on manure for 3-4 days before turning into the pupal stage, the stage from which adult flies emerge. Adult horn flies bite cattle and feed on blood that oozes from the wound. Horn fly attacks can interfere with the normal feeding activity of cattle, resulting in reduced weight gains and less milk production. Economic losses caused by horn flies in the cattle industry are estimated to be in excess of $876 million annually. Insecticides are usually used to control adult flies, but during the last few years, some of these chemicals have lost their killing power because of the development of resistance in the pests. There are several species of predatory beetles that live in cattle manure and feed on immature stages of dung-breeding flies. If the efficiency of these existing predators could be improved by introducing new species from other countries, then populations of horn flies might be reduced with less use of chemical pesticides. This study reports the results of research to evaluate the effects of predation on immature stages of the horn fly by a predator beetle from Argentina. This beetle was effective in reducing horn fly populations under the study conditions, and it was more effective against the larval and pupal stages of the horn fly than the egg stage.
Technical Abstract: Hister bruchi Lewis, a histerid species from Argentina, was evaluated in the laboratory to determine its potential as a biological control agent for immature stages of the horn fly, Haematobia irritans (L.). When immature stages of the horn fly were exposed to varying numbers (one to five) of adult beetles, horn fly population reductions were significantly greater at tall levels compared with controls. However, increasing the predator-prey ratio greater than 1:50 had no significant effect on numbers of prey consumed by the beetles. This South American predator was more effective on the larval-pupal stages of the horn fly than on the egg stage.