Submitted to: Journal of Invertebrate Pathology
Publication Type: Peer reviewed journal
Publication Acceptance Date: 8/1/2001
Publication Date: N/A
Citation: Interpretive Summary: The use of fungal pathogens to control insect pests is a long-term goal of many laboratories worldwide. This paper discusses fungal pathogens of flies that affect pastured cattle in Denmark; these flies are debilitating to cattle, and their constant annoyance of the cattle can reduce the rate of weight gain or reduce milk production in addition to any diseases that they may transmit to cattle. This study surveyed the occurrence of fungal pathogens of cattle flies, identified these fungi, and provided new information on the natural ecology of both the flies and fungi that could contribute to the effective use of these fungi to control cattle flies. It had been thought that much of the transmission of these fungal pathogens among the susceptible populations of cattle flies occurred in stands of a weed, spear thistle, but this study provided no support for the conservation of this weed as a transmission site for the fly pathogens. The eresults suggested that it may be feasible to develop a strategy to control cattle flies with a combination of some chemical agents and conidia fungi such as BEAUVERIA BASSIANA; the majority of the fungal pathogens recorded during this study showed only limited potential for fungus-base biological control of the target cattle flies.
Technical Abstract: Cattle flies, including MUSCA AUTUMNALIS, HAEMATOBIA IRRITANS and HYDROTAEA IRRITANS, are pests of pastured cattle. A two-year study of the natural occurrence of entomopathogenic fungi in adult cattle flies and other flies associated with pastures showed that the four species included in the ENTOMOPHTHORA MUSCAE species complex (E. MUSCAE s.l.) caused epizootics in several species of flies. However, only a few specimens of cattle flies were infected by E. MUSCAE s.str. despite that cattle flies were observed to perch on spear thistles, which acted as transmission site for all four ENTOMOPHTHORA species. Transmission experiments with E. MUSCAE s.l. supported the field data. Of the two species considered host specific E. SYRPHI caused an epizootic in a muscid, and E. SCATOPHAGAE likewise could be transmitted to a muscid. This emphasizes the need for a revision of the two species. Low prevalences was recorded of another entomophthoralean, FURIA AMERICANA, and of the hyphomycetes BEAUVERIA BASSIANA and VERTICILLIUM LECANII.