The influence of diet on egg formation in Tamarixia radiata (Waterston) (Hymenoptera: Eulophidae), a parasitoid of Diaphorina citri (Kuwayama) (Hemiptera: Psyllidae)

Tamarixia radiata, is an arrhenotokous ectoparasite of Diaphorina citri, vector of citrus greening disease or huanglongbing. The incidence of parasitism was generally low in the early growing season, suggesting a need for mass-rearing parasitoids for release, requiring temporary storage. During the holding period, food provided to females may affect the number of eggs formed in ovaries, which may influence their efficiency as a biocontrol agent upon release. In this experiment, each pair of newly emerged T. radiata was placed in a 50 ml centrifuge tube and stored in a growth chamber at 17℃. Wasps were provided with 8 different diet treatments: water, honey, Nu-Lure, host nymphs, honey+ Nu-Lure, honey+ host nymphs, Nu-Lure+ host nymphs, and honey+ Nu-Lure + host nymphs. T. radiata females under each different treatment were dissected after 5, 10, 15, and 20 d. Results showed that, an average of 4.6 eggs were observed in ovaries of newly emerged female T. radiata, so they may use reserve nutrition from larval stages to form the first clutch of eggs. Honey alone was enough to keep wasps females alive, 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 still less with nymphs provided. T. radiata formed more eggs feeding on mixed diets (Nu-Lure+ honey+ nymphs or Nu-Lure+ nymphs) compared to nymphs alone. Until now, no diet has been found as a complete substitute for nymphal hemolymph.