Compared effects of Metarhizium anisopliae ICIPE 69 and Chlorpyriphos-ethyl on the mango mealybug, Rastrococcus invadens Williams (Homoptera : Pseudococcidae) and its parasitoids in western Burkina Faso

Abstract

This study was carried out to evaluate the effects of the bio pesticide Metarhizium anisopliae ICIPE 69 and the chemical pesticide Chlorpyriphos-ethyl on Rastrococcus invadens and its parasitoids Anagyrus mangicola and Gyranusoidea tebygi in orchards. A Randomized Complete Block design consisting of 5 treatments was set up in Mahon and Niampédougou. There were the untreated control, the reference chemical Chlorpyriphos-ethyl (480 g/l) and 3 doses of the bio pesticide (10⁸ conidia/ml, 10⁹ conidia/ml and 2.10⁹ conidia/ml). Live or dead mealybugs were counted on 20 leaves/mango trees before the first application of the chemicals and then successively each week for 3 to 4 weeks. Highest mortality rates of mealybugs were observed with Chlorpyriphos-ethyl (50-90%) followed by the higher dose of the bio pesticide (28-40%). The level of parasitoids expressed in log (N + 1) was low (0-0.86) on trees treated with Chlorpyriphos-ethyl compared to bio pesticide (0.15-1.86) and untreated control (0.33-1.53). Significant differences (0.047≤P<0.001) were observed between treatments after the first application of the chemicals. Although the rate of mortality of mealybugs was twice as high with Chlorpyriphos-ethyl, M. anisopliae ICIPE 69 could be an alternative to synthetic insecticides for compatibility with parasitoids.

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Keywords: Mango mealybug, biological control, entomopathogenic fungus, parasitoids, Burkina Faso