Lethal dose and time-response of some biocides affected by gamma ray for Spodoptera frugiperda (Lepidoptera: Noctuidae) controlling in maize fields

Abstract

Maize (Zea mays) field trial was done at El-Ayat district, Giza governorate to evaluate some biocide compounds (Bacillus thuringiensis (Kurs.), Emamectin benzoate and Spinosad) exposed or non-exposed to gamma ray doses (120 and 480 Gy) to potentiate its lethality for  fall armyworm, Spodoptera frugiperda (Smith) (Lepidoptera: Noctuidae) controlling purposes. Concentrations (1/2, 1/4, 1/8 and 1/16) of  the recommended doses of biocides used in current maize field trials. The evaluation parameters of lethal doses efficacy and time- response for S. frugiperda controlling were used. Spinosad treatments were considered the best dose lethality for S. frugiperda  controlling, followed by Emamectin benzoate and finally B. thuringiensis treatments. Meanwhile, Emamectin benzoate treatments gave  the least time-response lethality than other treatments aforementioned. Gamma ray dose of 480 Gy, followed by 120 Gy can potentiate  the biocide compounds of B. thuringiensis, Emamectin benzoate and Spinosad to become lethality more than the same compounds  without exposing to gamma doses and saving the dose and the time-response for controlling S. frugiperda in maize plants.