Laboratory efficacy of selected synthetic insecticides against second instar invasive fall armyworm, Spodoptera frugiperda (Lepidoptera: Noctuidae) larvae

Abstract

Maize is the most essential crop of China and its productivity has been recently endangered by the fall armyworm (FAW), Spodoptera frugiperda. Chemical pesticides are one of the most important strategies for managing FAW on a short-term basis. The seven synthetic insecticides including novel and conventional belong to four chemical group, spinetoram and spinosad (spinosyns), lambda-cyhalothrin, cypermethrin and bifenthrin (pyrethroids), abamectin (avermectins), broflinilide (diamides), were assessed for their efficiency in causing mortality to second instar S. frugiperda larvae at 24, 48 and 72 h post-treatment at five different serial concentrations (10 to 0.625 mg liter-1). The second instar S. frugiperda larvae were susceptible to the tested synthetic insecticides, however, the toxicity index of synthetic insecticides was estimated based on lethal concentration 50 (LC50), while, LC50 was calculated from the data of larval mortality. The broflanilide and abamectin proved to be the most toxic having the highest toxicity index of 100 and 78.29%, respectively, followed by cypermethrin and bifenthrin were showed toxicity index of 75.47 and 66.89%, respectively. The LC50 values were 0.606 and 0.774 mg liter-1 for broflanilide and abamectin, respectively, followed by cypermethrin and bifenthrin were showed LC50 values of 0.803 and 0.906 mg liter-1 at 72 h post-treatment. Rest of the other synthetic insecticides were showed moderate toxicity index of 42.11 to 62.09%, based on LC50 values were 1.439 to 0.976 mg liter-1 at 72 h post-treatment. The efficiency of synthetic insecticides was increased by increasing concentration level and exposure time. The screened synthetic insecticides among seven insecticides perhaps, provide basis for the development of novel insecticides for controlling S. frugiperda population after further research to evaluate and validate the laboratory results in the field.

Bioassays of Beauveria bassiana Isolates against the Fall Armyworm, Spodoptera frugiperda

“…The FAW eggs were established using a collection of larvae that were found on maize crops from Guangdong province, China, during the maize growing season. The collected larvae were cultured on an artificial diet [ 69 ] and the resultant adults were fed artificial diets of a 10% honey solution soaked into sterile cotton balls. The larvae were kept under laboratory conditions at 25 ± 2 °C, with a photoperiod of 12:12 (dark: light) and 65% ± 5% relative humidity (RH).…”

Lethal, Sub-Lethal and Trans-Generational Effects of Chlorantraniliprole on Biological Parameters, Demographic Traits, and Fitness Costs of Spodoptera frugiperda (Lepidoptera: Noctuidae)

“…The larvae of the pest eat the leaves, stalks, and flowers of cultivated plants [ 1 , 7 ]. The S. frugiperda populations are often controlled using chemical pesticides [ 8 , 9 ]. Different types of insecticides work in different ways to kill the target organisms [ 10 ].…”

Laboratory bioassay of fall armyworm (Spodoptera frugiperda) larva using various insecticides

“…Spinosad has been found as the most effective pesticide with the highest mortality of FAW larva within a very short time as explained by Cook et al (2004). Similar studies have been conducted around the world including China, Africa, Brazil and India to test the efficacy of pesticides in field and laboratory conditions to control FAW, and reported that FAW is susceptible to synthetic pesticides, however, Spinosad, Chlorantraniliprole and Emamectin benzoate causes the highest mortality compared to other synthetic pesticides (Idrees et al, 2022). Continuous application of such pesticides in the field may increase resistance against many categories of pests including FAW (Osae et al, 2022).…”