Field Production of Two Species of Parasitoids of the Diamondback Moth (Lepidoptera: Plutellidae)

Abstract

Two species of parasitoids, Cotesia plutellae (Hymenoptera: Braconidae) and Diadegma insulare (Hymenoptera: Ichneumonidae), of diamondback moth, Plutella xylostella, (Lepidoptera: Plutellidae), were colonized in cages in cabbage fields west of Bunnell, Florida, from November 1996 to February 1997. Two kinds of cages were used: large-screened cages and screened laundry hampers. Both parasitoids attacked their host during the winter, completed development within the host, and increased in numbers within field cages. Parasitism of diamondback moth larvae by C. plutellae was 36-42% in laundry hampers, and 35-65% in large screened cages. The sex ratio of emerging C. plutellae was 1:1-1.2 ( f : m ) in laundry hampers and 1:0.8-1.3 in large screened cages. Parasitism of diamondback moth larvae by D. insulare was 55-90%, parasitoid adults emerged from 89% of the cocoons, and the sex ratio was 1:1.4-2.1 ( f : m ) in large screened cages. The results showed that it is possible to rear these parasitoids in field nursery cages to provide parasitoid sources for release to control diamondback moth in cabbage in Florida.