Compatibility of entomopathogenic fungi and botanicals against sucking pests of okra: an eco-friendly approach

Abstract

Background: Okra, Abelmoschus esculentus (Linn.) Moench, is one of the most important traditional vegetables in India. The crop is attacked severely by sucking pests, viz., jassid, Amrasca biguttula biguttula Ishida, and whitefly, Bemisia tabaci Genn., throughout its growth period. To control these sucking pests, different entomopathogenic fungi (EPF), viz., Beauveria bassiana, Metarhizium anisopliae, and Lecanicillium lecanii were tested alone and their 1:1 combinations with neem oil against these sucking pests and compared to Imidacloprid 17.8% SL as chemical control under field conditions during 2018 and 2019. Results: Among the EPF tested, the lowest jassid (1.16, 1.27 leaf-1) and whitefly (1.33, 0.84 leaf-1) population was recorded in plots treated with L. lecanii during the two consecutive years. Combination of L. lecanii and neem oil at half of their recommended concentrations had the lowest jassid and whitefly population among all the treatments and maximum reduction over control and at par with chemical control, i.e., Imidacloprid 17.8 SL at 0.33 ml l−1 . Moreover, all these biopesticides were found relatively safe to the polyphagous predators (Micraspis discolor, Menochilus sexmaculatus, and spiders) and at par with untreated control. In contrast, Imidacloprid 17.8 SL was the most toxic among all the treatments with the lowest numbers of spiders and ladybird beetles. Conclusion: Combination of the EPF like B. bassiana, M. anisopliae, and L. lecanii with neem oil at half of their recommended concentrations could be a viable ecofriendly option in the management of the sucking pests of okra, along with the conservation of natural enemies.