Parasitoids and Entomopathogens Associated with Fall Armyworm,<i>Spodoptera frugiperda</i>, in Northern Sinaloa

Abstract

Larvae of fall armyworm, Spodoptera frugiperda (J.E. Smith), were collected from 190 fields of maize (Zea mays L.) in northern Sinaloa, Mexico, during 2016 and 2017. Larvae also were collected from naturally re-growing maize plants after the rainy season. The aim of this study was to determine the natural occurrence of parasitoids and entomopathogens of S. frugiperda in this agricultural area. Taxonomic keys were used to identify parasitoids. Larvae with signs of infection by viruses, bacteria or fungi were analyzed by one-step PCR. In 2016 and 2017, the average percentages of parasitized S. frugiperda larvae in cultured maize fields were 7 and 9.3%, respectively. In contrast, in re-grown maize, 12.5 and 16.5% of larvae were parasitized, respectively. In both years, significant differences were observed in abundance of parasitism among some months. The most common parasitoids were Meteorus laphygmae Viereck (n = 862), Chelonus insularis Cresson (n = 640), and Cotesia marginiventris Cresson (n = 303), with 9.5% of total parasitism. Idiopathic mortality (2.6%) was determined throughout the study, but no entomopathogens were found in any larva collected. Parasitoids associated with S. frugiperda are well established in northern Sinaloa. But, additional studies are needed to determine their potential as biological control agents and to evaluate the possible influence of maize type on their abundance.