Leaf dip bioassay

Insect-bioassays were conducted on 3rd instar larvae (25–30 mg weight) of F₁ generation FAW test- populations maintained in the laboratory as per the standard protocol of Insecticide Resistance Action Committee (IRAC, 2009; Method # 7). Serial dilutions of the test-insecticides were made in distilled water and maize (hybrid PMH 1) leaf pieces (~ 16 sq cm) were immersed into the test-solutions for 10 s. For control, distilled water was used. Leaf pieces were air-dried for 2 h and placed inside petri-dishes (5 cm, dia) on moistened filter paper to maintain turgidity. Individual S. frugiperda larvae were released into petri-dishes. There were 45 larvae per treatment under three replications, each comprising of 15 larvae. The treated insects were kept under 27 ± 1 °C with RH 65% and a photoperiod of 14:10 (L: D). Mortality was recorded 72-h post-treatment; morbid larvae those did not move when prodded with a brush were considered dead.