Noctuidonema guyanense (Nematoda: Aphelenchoididae): Population Profiles on Male and Female Fall Armyworm Moths²

The distribution of Noctuidonema guyanense Remillet and Silvain (Nematoda: Aphelenchoididae) populations on wild female, laboratory-reared female, and wild male moths of Spodoptera frugiperda (J. E. Smith) (Lepidoptera: Noctuidae) was determined. Populations of all life stages of N. guyanense were aggregated (P < 0.05) on abdominal segments 7–10 of wild female and moderately infested (<100 nematodes), laboratory-reared female moths. Nematodes also aggregated on abdominal segments 7–10 on heavily infested (>300 nematodes), laboratory-reared female moths, but larger populations of all mobile life stages migrated from posterior to anterior abdominal segments of a host. On wild male moths, N. guyanense populations tended to disperse along the host's abdomen, with significant aggregates of eggs and neonates on abdominal segments 8–10 and smaller aggregates of adults and juveniles on abdominal segments 1–2. Nematodes avoided colonization of the head of nearly all hosts of either sex.