Laboratory susceptibility of Musca domestica L. (Diptera: Muscidae) and Bactrocera tryoni (Frogatt) (Diptera: Tephritidae) to an isolate of Metarhizium anisopliae (Metsch.) Sorokin

The susceptibility of adult house flies, Musca domestica, and adult fruit flies, Bactrocera tryoni, to an isolate of Metarhizium anisopliae was tested at 20, 25 and 30 degrees C. The abdomen of each insect was inoculated with a known dose of conidia in an aqueous suspension. The insects were then incubated at high humidity for 9 days. Both species of fly started to die from the disease after 4-5 days incubation at 25 degrees C and 30 degrees C and 100% mortality was reached at these temperatures after 7-9 days. The disease developed more slowly at 20 degrees C and the final mortality for both species was just over 50% at the highest dose. Fewer than 25 conidia were needed to kill either species at 25 and 30 degrees C at 9 days. At 20 degrees C, 5896 conidia were needed to kill adult house flies and over 100 000 for fruit flies at 9 days. It is concluded that M. anisopliae may be suitable for control of both species in situations where chemical pesticides cannot be used.