Does cannibalism in Spodoptera frugiperda (Lepidoptera : Noctuidae) reducethe risk of predation?

The incidence of cannibalism of larval Spodoptera frugiperda (Lepidoptera: Noctuidae) on maize under field conditions was investigated using field cag es. Cannibalism was found to account for approximately 40% mortality when m aize plants were infested with two or four fourth-instar larvae over a 3-da y period. Field trials examined the effect of larval density on the prevale nce of natural enemies of S. frugiperda. The abundance of predators (earwig s, staphylinids, other predatory beetles, and Chrysoperla spp.) was signifi cantly greater on maize plants with higher levels of larval feeding damage, while the relationship between predator abundance and number of S. frugipe rda larvae per plant was less clear. As larval damage is probably a more re liable indicator of previous larval density than numbers collected at an ev aluation, this indicates that predation risk will be greater for larvae liv ing in large groups. Parasitism accounted for 7.1% mortality of larvae in s orghum, and involved six species of Hymenoptera and Tachinidae. There was n o effect of larval density or within-plant distribution on the probability of larval attack by parasitoids. The selective benefits of cannibalism, in relation to the risk of predation and parasitism, are discussed.