Laboratory Evaluation of some Insecticides against Larval and Adult Stages of Red Palm Weevil’s Rhynchophorus ferrugineus (Olivier)

Document Type : Original Article

Authors

1 Department of Pesticide Chemistry and Toxicology, faculty of Agricultural, Alexandria University, Egypt.

2 Department of Plant Protection, faculty of Agriculture, Damanhour University

Abstract

The toxicity of eight compounds belong to different groups of  insecticides; chlorpyrifos-ethyl and dimethoate (organophosphate); methomyl (carbamate); imidacloprid (neonicotinoid); emamectin benzoate (avermectin); azadirachtin (tetranortriterpenoid), deltamethrin                       (pyrethroid) and fipronil (phenylpyrazole). was evaluated in the laboratory against larvae and adults  of the red palm weevil, Rhynchophorus  ferrugineus (Olivier), by using dipping food technique. The results showed that imidacloprid was the most toxic insecticide among the tested compounds against the larvae, followed by emamectin benzoate, deltamethrin and fipronil, whereas the LC50s were 63.6, 136.6, 290.2 and 773.78 ppm, respectively. The organophosphate insecticides, chlorpyrifos-ethyl and dimethoate were the less toxic compounds (LC50s were 2597 and 8466 ppm), against larvae. However, deltamethrin was the most toxic insecticids against the adult followed by emamectin benzoate  and imidacloprid, whereas the LC50s were 129.8, 136.6 and 287.3 ppm, respectively. The organophosphate insecticides, chlorpyrifos-ethyl and dimethoate, were still the less active compounds (LC50s were 790.4 and 11085 ppm) against the adults of R ferrugineus. The results revealed that the adults were more sensitive to most of the tested insecticides compared with larvae except for imidacloprid and dimethoate.  Moreover, by increasing time of exposure the toxicity of imidacloprid to both larvae and adults increased.
 

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