Phytochemical composition and insecticidal effects of native plant extracts against the mango mealybug, Rastrococcus invadens Williams (Homoptera: Pseudococcidae)

Abstract

The mango mealybug Rastrococcus invadens Williams causes enormous damage to fruit trees in Burkina Faso, with losses of up to 90% for mango trees and 53% for citrus fruits. The objective of this study was to evaluate the insecticidal effects of native plant extracts against this insect pest. The insecticidal activity and biological effectiveness of the extracts were evaluated on Petri dishes and mango leaves previously contaminated by spraying them with the native plant extracts. The experimental was a completely randomized Fischer block, and compared six doses of the hydroalcoholic extracts of A. conyzoides and H. suaveolens with abamectin 18 EC and water (control). These treatments were repeated up to ten times. The determination of the efficiency coefficients was achieved using Abbott's formula (1925). Both extracts of A. conyzoides and H. suaveolens were effective, but the one based on A. conyzoides at 50 gl -1 was the most effective with 100% mortality in 48 hours compared to 95.00% for H. suaveolens’ extract in 72 h. Their respective LC50 were 12.50 gl -1 and 17.49 gl -1, showing that A. conyzoides’ extract is more toxic to R. invadens. The high content in phenols, flavonoids, alkaloids, etc. of leafy stems of A. conyzoides and of H. suaveolens could help to sustainably control R. invadens in an integrated approach and effectively protect mango orchards.