Relative Toxicity of Different Insecticides to Asian Citrus Psylla (Diaphorina citri Kuwayama)

Abstract

Asian citrus psyllids Diaphorina citri (Kuwayama) act as vector of the devastating citrus disease, Huanglongbing (HLB) also known as citrus greening which is widely spread in citrus growing regions. The use of insecticides for management of citrus phylla is one of the prominent and effective method to overcome their menace. However, recently very few insecticides have been found under label claim for this pest. The present investigation was conducted in order to know the toxicity of some new chemistry insecticides against D.citri. Bioassay experiments were conducted during 2022-23. The toxicity was assessed through uptake bioassay technique for systemic insecticides by using fresh citrus twigs. The results showed that, among the five tested insecticides imidacloprid 17.8 % SL was the most effective insecticide with lowest LC50 values for both nymph and adult psyllid i. e. 0.028 and 0.032, respectively.  However, except spirotetramat 15.3 % OD,  the LC50 values of thiamethoxam 25 % WG, abamectin 1.9 % EC, fenpropathrin 30 % EC were placed within the fiducial limit of most toxic insecticide i.e. imidacloprid 17.8% SL. They are considered as at par and equally toxic to D. citri. The relative toxicity trend against the adult psylla was imidacloprid > abamectin > thiamethoxam > fenpropathrin > spirotetramat and for the nymph, the trend was imidacloprid > thiamethoxam> abamectin > fenpropathrin > spirotetramat.