Control of the Diamondback Moth (Plutella xylostella) (Lepidoptera: Yponomeutidae) by Egg-parasitoids (Trichogramma)

10. Relationships among Density of Trichogramma chilonis (Hymenoptera: Trichogrammatidae) Released, Percentage of Parasitism, and Mortality due to Host Feeding

Abstract

Trichogramma chilonis wasps were released to 40 diamondback moth eggs per potted cabbage plant covered with net at 5 different population densities of about 0, 34, 68, 680, and 3400 wasps. At the highest density of about 3400 wasps per 40 diamondback moth eggs on a plant, an average of 45.6% diamondback moth eggs was parasitized and additively that of 50.8% was killed probably due to host feeding of wasps. Namely about 3% of diamondback moth eggs only hatched out. Thus, efficacy of Trichogramma wasps against diamondback moth eggs should be judged from not only percentage of parasitism but also host egg mortality probably due to host egg feeding, or hatchability of diamondback moth eggs.