Efficacy of Selected Insecticides against Fall Armyworm, Spodoptera frugiperda (J. E. Smith) (Lepidoptera: Noctuidae), in Maize and their Impacts on Associated Parasitoids

Abstract

The fall armyworm, Spodoptera frugiperda (J. E. Smith) (Lepidoptera: Noctuidae), causes high damage on many crops, but maize is the most preferable crop. Maize is one of the most economically important crops in Ethiopia. These invasive pests af ect crop production and cause high-yield losses. Due to insecticides ef ect on non-target organisms (natural enemies), a selection of insecticides with less ef ect on natural enemies (non-target organisms) is needed. We evaluated three insecticides: Bravo-5000, Aim 10%, and Rambo, which were sprayed in the maze field of MARC based on the recommended dosage of each insecticide. The experiment was arranged in a randomized complete block design (RCBD) with three replications, each insecticide sprays at recommended dosage every seven-day interval. Rambo and Aim 10% high ef icacy than Bravo-5000 but all insecticides reduced FAW damage to the maze compared to control or untreated plants. Insecticides caused maize height dif erence between treated and untreated plants. There is no significance dif erence between leaf number of treated and untreated plants so chemical treatment did not af ect the leaf number of maize plant. There were six parasitoid species from total number of 18 parasitoids which are (Cotesia icipe, Coccygidium luteum, Netelia species, Chelonus inanitus, an unidentified sp., and Charops ater) that have emerged from FAW larvae. Based on the result, Rambo shows a high ef icacy next to Aim 10%, but Rambo (0.6% parasitism rate) caused a lower parasitism rate than Aim10% (2% parasitism rate). Non-parasitoid (0.0% parasitoids rate) result was obtained from the larvae that was collected from Bravo-5000 treated plants. Based on the results from three insecticides, Aim 10% is the most advisable insecticide by considering the toxicity of chemicals on FAW larval