Prepupal and Pupal Parasitism of Helicoverpa zea and Spodoptera frugiperda (Lepidoptera: Noctuidae) by Steinernema sp. in Cornfields in the Lower Rio Grande Valley

Abstract

An indigenous Steinernema sp. (Rhabditida: Steinernematidae) nematode parasitized prepupae and pupae of corn earworm, Helicoverpa zea (Boddie), and fall armyworm, Spodoptera frugiperda (J. E. Smith), collected from fruiting cornfields in the Lower Rio Grande Valley of Texas and northern Tamaulipas, Mexico. Over a 5-yr period, 34% of all fields sampled contained parasitized corn earworm and 24.2% contained parasitized fall annyworm. Of 3,036 corn earwonn prepupae and pupae collected during this study, 11.6% were parasitized; of 1,802 fall armyworm collected, 9.3% were parasitized. Parasitism by Steinernema sp. accounted for 49.4 and 46.1% of the mortality of corn earworm and fall armyworm prepupae and pupae, respectively.