Biocidal activity of selected botanicals and Beauveria bassiana on oriental fruit fly, Bactrocera dorsalis (Diptera; Tephritidae)

Abstract

The effectiveness of aqueous extracts of four plants(Azadirachta indica, Piper guineese, Moringa oleifera and Aframomum melegueta) and aqueous  formulation of Beauveria bassiana were evaluated against larvae and pupating larvae of Bactrocera dorsalis (Hendel) (Diptera;Tephritidae) in the  laboratory. Bioassays were conducted on B. dorsalis larvae for contact and residual effects of these four botanicals and effects of soil treatments with botanicals and B. bassiana against B. dorsalis pupating larvae were assessed. Larval mortality on bioassays was recorded at 20 min intervals for 1440 minutes while adult emergence and pupating larvae mortality on treated soil were recorded after 21 days. All the extracts significantly (p<0.05) showed contact and residual effects on B. dorsalis larvae. Piper guineese recorded 100% larval mortality and was the most effective for contact toxicity while A. melegueta and A. indica recorded 87% larval mortality for residual action on B. dorsalis larvae. Effects of the extracts and B dorsalis on treated soil against pupating larvae revealed that A melegueta was the most effective among all the treatments. A. melegueta recorded 100% mortality of the pupating larvae, followed by B. bassiana recording 83.3% pupating larvae mortality with 17% adult emergence. The efficacy of A.  melegueta was comparable with cypermethrin against B. dorsalis on treated soil while B. bassiana was more effective than other plant extracts.  Therefore, the use of aqueous seed extracts of A. melegueta, A.indica, P.guineense and B. bassiana for soil applications could be incorporated in Integrated Pest Management component for the management of African invader fly in fruits orchards.

Key words: Bactrocera dorsalis, aqueous extracts, fungal pathogens, soil treatment, control