Effect of holding diet on egg formation of tamarixia radiata (Hymenoptera: Eulophidae), parasitoid of diaphorina citri (Hemiptera: Psylloidae)

Abstract

Tamarixia radiata (Waterston) (Hymenoptera: Eulophidae), is an arrhenotokous ectoparasitoid of Diaphorina citri Kuwayama (Hemiptera: Psylloidae), vector of huanglongbing (HLB) or citrus greening disease. Mass-rearing parasitoids for augmentative biological control has created the need to find storage conditions that will optimize egg load upon release. Food provided to females during the holding period may be foremost among factors that determine the number of eggs available for oviposition following storage. Pairs of newly emerged T. radiata were provided with 8 different diet treatments: water, honey, Nu-Lure® (a proteinaceous liquid made from 44% hydrolyzed corn gluten meal), host nymphs, honey+ Nu-Lure, honey+ host nymphs, Nu-Lure+ host nymphs, and honey+ Nu-Lure + host nymphs. Female wasps were dissected after 5, 10, 15, and 20 days and mature eggs counted. An average of 4.6 eggs was observed in ovaries of newly emerged females. Honey alone was sufficient for female survival, but egg resorption took place within 5 days after emergence. The combination of honey + Nu-Lure resulted in female survivorship similar to a diet of host nymphs, but egg formation was less than with nymphs provided. Tamarixia radiata formed more eggs feeding on mixed diets (Nu-Lure+ honey+ nymphs or Nu-Lure+ nymphs) compared to nymphs alone. However no artificial diet substituted for nymphal hemolymph.