Strategies for controlling house fly populations resistant to cyromazine

Abstract

The objectives of this study were to compare, from both biological and economic viewpoints, the impact of various control strategies and evaluate their effect on cyromazine-resistant Musca domestica L., and beneficial house fly pupal parasitoids on caged-layer farms (240,000 hens) in Argentina. The strategies evaluated were: chemical, chemical + cultural, and chemical + cultural + biological (integrated management). The products used were: cyromazine 1% and 50%, DDVP, azamethiphos with and without z-9-tricosene, lime, and the parasitoids Spalangia endius Walker and Muscidifurax raptor Girault & Sanders. In the absence of control measures, fly density increased quickly and the average parasitism rate was 12%. When only chemical control was used, fly populations were reduced to ca. 40/grid and parasitism averaged 2%. When topical cyromazine was used in conjunction with cultural control (lime), fly populations were reduced more rapidly than those treated with cyromazine 1% feed-through. With the subsequent use of parasitic wasps, high parasitism levels were observed and house flies were reduced to tolerance levels in the shortest time. From an economic and biological point of view, the best treatment for house flies resistant to cyromazine was biological + cultural + chemical with localized applications of topical cyromazine.