Effects of autodisseminated Metarhizium guizhouense PSUM02 on mating propensity and mating competitiveness of Bactrocera cucurbitae ( Diptera: Tephritidae)

摘要

We investigated the effects of inoculation by Metarhizium guizhouense PSUM02 on mating propensity and mating competitiveness of Bactrocera cucurbitae, with a view on pest management. On day 4 postinoculation, the M. guizhouense-treated male flies had significantly lowered mating propensity and mating competitiveness, while the treated female flies had reduced mating propensity on day 4 and reduced mating competitiveness on day 5. The mating propensity and competitiveness of treated male and female flies then further declined until death. Kaplan-Meier survival analysis of treated male and female flies gave average survival times (AST) of 6.2 +/- 0.2 and 5.4 +/- 0.3 days in the mating propensity assay, and about 5.0 +/- 0.1 and 4.4 +/- 0.2 days in the mating competitiveness assay. The AST of untreated flies ranged from 12.8 +/- 0.1 to 14.7 +/- 0.2 days for comparison (observation up to 15 days). Untreated flies had decreased AST and mating characteristics when exposed to contact with treated male flies, indicating transmission of the fungal infection by such contact also to untreated male flies. Surprisingly, contact with treated female flies did not affect the AST of untreated males or females in the same cage. These results corroborate the potential for pest control by autodissemination with treated male flies, which transmit the fungus to a healthy population better than the treated female flies.