Insecticidal activity of crude extracts of three spices and commercial botanical pesticide on oriental fruit fly under laboratory conditions

Background The uses of botanical pesticides in pest management are currently on remarkable increase due to their efficacy, biodegradability, environment-friendly, and availability. Ethanol extracts of three spices ( Piper guineense , Aframomum melegueta , Zingiber officinale ) and commercial botanical pesticide AzaSol (6% azadirachtin) were assessed for contact toxicity, residual effects, and for their potential in soil application against pupariating larvae of oriental fruit fly ( Bactrocera dorsalis ) in the laboratory at ambient temperature of 27 ± 2 °C and relative humidity of 75–80%. The extracts and AzaSol were applied at 1:1.5 w/v concentration while cypermethrin was introduced as standard check and applied at 5 ml/liter of water. Results All the treatments were very effective against B. dorsalis in contact toxicity and residual affects recording 89.4–100% larval mortality at 24 h post-application. Z. officinale and cypermethrin had similar contact and residual effects on B. dorsalis , both recording 100% larval mortality at 24 h post-exposure. Piper guineense showed higher residual effects than contact effects, while A. melegueta and AzaSol showed better contact effects than residual effects against B. dorsalis larvae. AzaSol was the most effective among the botanicals in reducing the adult emergence and in enhancing larval mortality (96.7%) on treated soil followed by Piper guineense (83.3%). The efficacy of AzaSol on the treated soil was comparable to cypermethrin. All the extracts were significantly more effective than control in enhancing pupariating larvae mortality and in reducing adult emergence on treated soil. Conclusion Ethanol extracts of P. guineense and A. melegueta were highly promising against B. dorsalis on treated soil and could be adopted in soil application targeting puparia under the tree canopies as part of integrated pest management of B . dorsalis in orchards.