Auto Inoculation of the African Invader Fruit Fly; Bactrocera invadens Drew, Tsuruta and White (Diptera: Tephritidae) with Metarhizium anisopliae, Isolate IC-20

Abstract

The potential of auto-inoculation of African invader fly (Bactrocera invadens) with Metarhizium anisopliae isolate IC-20 was assessed in a field cage experiment after the compatibility of the fungus with methyleugcnol, a male fruit fly attractant. Compatibility of the male fruit fly attractant methyleugenol with the Metarhizium isolate was tested using two methods; direct contact and exposure to volatiles. Mortality of fruit flies reached 100% in 7-12 days with LT50 of 4 days and LT90 of 8 daysrecorded in two rounds of experiments. Compatibility tests revealed that methyleugenol reduced spore germination down to 2.7% in 10 days. Dry conidia were evenly spread on velvet material covering the inside of a lynfield trap and left in a field cage in which 500 male fruit flies were released to allow auto inoculation with conidia of M. anisopliae to take place and the exposure time was set at 14 hrs. Mean spore uptake of 9.8x104 per individual fly was recorded. Results indicated the potential use of auto-inoculation of fruit flies with M. anisopliae for population suppression in the field.