Incidence of fall armyworm (Lepidoptera: Noctuidae) parasitoids on resistant and susceptible corn genotypes

Fall army worm, Spodoptera frugiperda (J.E. Smith), larvae were collected from 24 May to 28 August 1990 and from 20 May to 17 June 1991 to determine parasitoid distribution of fall armyworm on resistant and susceptible corn genotypes. Resistant corn genotypes were 'MpSWCB-4' and 'Pioneer X304C' and susceptible genotypes were 'Pioneer 3192' and 'Cacahuacintle X's'. In 1990, Cotesia marginiventris (Cresson) was the most prevalent parasitoid in early season, parasitizing 34% of fall armyworm larvae, and it continued to be present in low numbers throughout the summer. On only one collection date (24 May 1990) did corn genotype have a significant effect on parasitism rates. On that date, significantly more C. marginiventris were reared from hosts obtained from resistant corn genotype 'MpSWCB-4' than from the other three genotypes. In 1991, Archytas marmoratus (Townsend) was the most abundant parasitoid, attacking an average of 13.6% of fall armyworm recovered. Corn genotype had a significant effect on the incidence of parasitism throughout 1991. Fall armyworm collected from the susceptible genotype 'Pioneer 3192' were parasitized significantly less frequently (8.3%) than were the larvae collected from the susceptible corn genotype 'Cacahuacintle X's' (9.8%) or the resistant genotype 'MpSWCB-4' (9.6%)