Evidence of Exploitative Competition among Egg Parasitoids of Spodoptera Frugiperda (Lepidoptera: Noctuidae) in Maize

Telenomus remus and Trichogramma spp. (Hymenoptera: Platygastridae, Trichogrammatidae) are known egg parasitoids of the fall armyworm (FAW), Spodoptera frugiperda (Lepidoptera: Noctuidae) in Brazil. Parasitism of trichogrammatid on eggs of S. frugiperda has been relatively common, whereas the occurrence of T. remus in Brazilian crops has rarely been reported. Consequently, literature that gives insights about the interspecific competition among individuals of T. remus and Trichogramma spp. in the field is very scarce. Here we report the simultaneous occurrence of T. remus. Trichogramma pretiosum, and Tr: atopovirilia on eggs of the FAW in maize (Piracicaba, São Paulo, Brazil). Our findings imply that these three egg parasitoid species were engaged in exploitative competition (indirect interactions in which the depletion of resources by one species prevents the other access to them) toward eggs of S. frugiperda. Moreover. given the emergence of combinations of two and three of these parasitoid species from a single egg mass, our data strongly suggest that T. remus, Tr: pretiosum and Tr: atopovirilia were also engaged in interference competition (direct interactions among adults and/or immature individuals resulting in behavioral changes or even death of individuals). Both exploitative and interference competition may affect the population dynamics of parasitoids, with consequences for the biological control of pests. Hence, the present findings highlight the importance of determining the outcome of competition among T. remus, Tr. pretiosum and Tr: atopovirilia toward eggs of S. frugiperda in laboratory and field studies.