Diamondback Moth (Lepidoptera: Plutellidae) Infestation and Parasitism by Diadegma insulare (Hymenoptera: Ichneumonidae) in Collards and Adjacent Cabbage Fields

Abstract

Two rows of collard greens (Brassica oleracea var. acephala L.) were planted between two cabbage fields in Bunnell, Flagler County, Florida in spring 1995. More larvae of the diamondback moth (DBM), Plutella xylostella (L.), were found on collard plants than on cabbage plants in the adjacent fields. The parasitism rate of DBM larvae collected from the collard plants reached 72% in early May and was higher than for larvae collected from the cabbage plants in adjacent fields. Parasitoids recovered from DBM larvae were mainly Diadegma insulare (Cresson). The damage to collard plants caused by DBM larvae was greater than on cabbage plants. At harvest, there was no significant difference in damage ratings of cabbage heads sampled near the middle of the field and damage to heads on rows nearest the collards. The results suggest that collard may have potential as a trap crop of DBM in cabbage fields, and that collard can play an important role in maintenance of the natural enemy, D. insulare.