| The egg-larval parasitoid Chelonus insularis Cresson is a key parasitoid of the fall armyworm Spodoptera frugiperda (J. E. Smith) during the second field generation in the upper Magdalena River Basin, Colombia. In spite of selection pressure, the higher susceptibility of the second generation fall armyworm larvae to insecticides, compared with that of the first generation, suggests that the parasitism may be responsible for the apparent difference in susceptibility. Parasitized and non-parasitized 2nd-instar larvae of the fall armyworm were tested for susceptibility to chlorpyriphos, methomyl, cypermethrin, and Bacillus thuringiensis in the laboratory, using the leaf dip test. Parasitized larvae were up to 3.93 times more susceptible to chlorpyriphos, 3.71... |
