Submitted to: Journal of Invertebrate Pathology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: December 18, 1998
Publication Date: N/A
Interpretive Summary: The use of fungal pathogens for the biological control of insect pests is a long-term goal of many laboratories worldwide. This paper treats a surprisingly diverse range of insect-pathogenic fungi from Denmark whose spores are produced into slime drops. These fungi were identified as a range of VERTICILLIUM and ACREMONIUM species, and their potential utility was against several important pests in Denmark (sweet potato whitefly, housefly, and lesser mealworm). The fungi that proved to be most effective against these target pests were isolated that could be identified as VERTICILLIUM LECANII, a globally distributed fungus with a well demonstrated pathogenicity for a wide range of insects. This study demonstrated that a surprisingly diverse group of these morphologically similar fungi could be isolated from insects in Denmark, and that some of these fungi were either weak pathogens or colonized dead rather than living ginsects. Some of these fungi did prove to have real potential for use in applied programs of fungal biocontrol of target pest insects in this northern European country, and it is possible that they might be useful in other parts of the world located in the high latitudes.
Hyphomycetes with conidia formed in slimy heads from hyaline mycelium were isolated from a range of insect hosts. Isolation on artificial medium and microscopic examination revealed that these fungi in many cases were not VERTICILLIUM LECANII despite a superficial resemblance to this common entomopathogen. The fungi were identified as VERTICILLIUM FUSISPORUM, VERTICILLIUM PSALLIOTAE, VERTICILLIUM LAMELLICOLA and species of ACREMONIUM. Isolates of these fungi were bioassayed against the sweet- potato whitefly (BEMISIA TABACI) and against the housefly (MUSCA DOMESTICA) to examine their entomopathogenicity. V. LAMELLICOLA was not pathogenic to insects, while varying levels of pathogenicity were shown for the other species. In general, V. LECANII was the most pathogenic species. Immature whiteflies appeared to be more susceptible to fungal infection than adult houseflies, and the host range for several of the fungi also included a coleopteran (lesser mealworm, ALPHITOBIUS DIAPERINUS).