Successful Parasitization of Heliothis zea1 and Trichoplusia ni Eggs by Trichogramma23

Abstract

Laboratory and field cage studies were conducted to determine the degree of successful parasitization by selected Trichogramma stocks for the eggs of Heliothis zea (Boddie), the bollworm, and Trichoplusia ni (Hubner), the cabbage looper. The laboratory studies showed significant increases in female longevity, number of eggs successfully parasitized, and progeny production when H. zea eggs were used as hosts. Two types of field cage experiments were conducted in cotton fields. The 1st type, which had either H. zea or T. ni egg cards in a given field cage, indicated that twice as many H. zea egg cards were found. The 2nd type of experiment had both hosts in varying proportions in each cage, and showed that a higher proportion of H. zea eggs were successfully parasitized even when T. ni eggs were more abundant.