EVALUATION OF FIELD PROPAGATION OF MUSCIDIFURAX-ZARAPTOR (HYMENOPTERA, PTEROMALIDAE) FOR CONTROL OF FLIES ASSOCIATED WITH CONFINED BEEF-CATTLE

The parasitic wasp Muscidifurax zaraptor Kogan & Legner was mass-reare d in the field to control house flies, Musca domestica L., on two Nebr aska beef cattle confinements. About 50,000 freeze-killed house fly pu pae were exposed to a single release of M. zaraptor in the field. Plac ement of six additional cohorts of 50,000 freeze-killed pupae at the r elease sites at 2-wk intervals resulted in a mean parasite emergence o f 56.4% over the study period. Mean fly mortality of 37.3 and 25.9% oc curred in sentinel pupae placed around the perimeter of two release si tes, compared with 3.9% for two control sites. We demonstrated a negat ive correlation between host reduction in sentinel cohorts and distanc es the cohorts were placed from parasite release sites. However, data indicated that other environmental factors also influenced the success of M. zaraptor in locating sentinel hosts. Correlation between mortal ity in sentinel pupae and numbers of parasites released was not eviden t. Temperatures above almost-equal-to 28-degrees-C appeared to reduce the effectiveness of M. zaraptor.