Compatibility and combined efficacy of entomopathogenic fungi and neonicotinoid insecticides against Myzus persicae (Sulzer): An ecofriendly approach

Abstract

Efficacy of different entomopathogenic fungi (EPF) Beauveria bassiana, Metarhizium anisopliae and Lecanicillium (= Verticillium) lecanii and neonicotinoid insecticides imidacloprid, thiamethoxam and acetamiprid were evaluated alone and their 1:1 combination at half-dose against Myzus persicae. Among the entomopathogenic fungi, B. bassiana was found to be the most effective, having the shortest median lethal time (LT50) of 48.17, 48.92 and 48.87 h during the period of 2018, 2019 and 2020, respectively, followed by L. lecanii (49.57, 49.45 and 50.46 h) and M. anisopliae (51.81, 51.67 and 51.63 h). Among the three neonicotinoids, acetamiprid was found to be the most effective. Combining of B. bassiana and acetamiprid at half of their recommended dose led to the shortest (22.76, 23.48 and 23.06 h during 2018, 2019 and 2020, respectively) median lethal time (LT50) followed by L. lecanii + acetamiprid (22.58, 22.68, 22.52 h) and M. anisopliae + acetamiprid (22.61, 23.82, 23.60 h). Combinations of entomopathogenic fungi and neonicotinoid insecticides led to co-toxicity coefficient values (CTC) > 1 and lower LT50 values than each one alone, indicating their compatibility and synergistic action. Combining these EPF with sub-lethal concentration of neonicotinoids could minimize the chemical insecticides input in the environment and contribute towards a greener, ecofriendly control option of this sucking pest.