Genetic variation in different field strains of fall armyworm <i>Spodoptera frugiperda</i> (Lepidoptera: Noctuidae) larvae resistance treated with two insecticides

Discriminating concentrations of the tested products, namely the diakoks (Emamectin benzoate) as well as the tracer (Spinosad), were used to determine the resistance in different strains collected from three governorates, namely Qalubia, Assiut, and Sharkia. It was revealed that diakoks insecticide was more toxic against the 4th instar larvae of the tested pest than the tracer insecticide. It was clear that the discriminating concentration (LC99) of diakoks and tracer insecticides against the baseline laboratory strain caused 82.35 and 44.12; 73.53 and 29.41 and 88.24 and 58.32% mortality in the 4th instar larvae collected from Qalubia, Assiut, and Sharkia Governorates, respectively, whereas the corresponding resistance percentages were 16.82 and 55.43; 25.73 and 70.29 and 10.87 and 40.09%; respectively. Genetic diversity in the field colony of 4th larval instars of Spodoptera frugiperda (J.E. Smith) (Lepidoptera: Noctuidae) collected from three different Egyptian Governorates compared with the baseline laboratory strain was investigated. Primer OP-A3 generated 16 fragments in the three fields colony as well as the baseline laboratory strain of S. frugiperda 4th instar larvae. Primer OP-A3 detected 16 fragments in the threefield colony as well as the baseline laboratory strain. Primer OP-A5 generated 18 fragments in the three fields colony and laboratory strain. Primer OP-B3 generated 13 fragments in the three fields colony and laboratory strain of S. frugiperda 4th larval instars. Primer OP-C15 generated 16 fragments in the three fields colony as well as the laboratory strain of the tested insect. Primer OP-D1 generated the highest number of fragments, which were 29 fragments in the three fields colony as well as the baseline laboratory insect.