Evaluation of Parasitism Capacity of Megastigmus thitipornae Dogănlar & Hassan (Hymenoptera: Torymidae), the Local Parasitoid of Eucalyptus Gall Wasp, Leptocybe invasa Fisher & La Salle (Hymenoptera: Eulophidae)

Abstract

Megastigmus thitipornae Dogănlar & Hassan is the local parasitoid of Leptocybe invasa Fisher & La Salle, which is a devastating pest of Eucalyptus camaldulensis Dehn. in Thailand. This research aimed to evaluate the parasitism capacity of M. thitipornae. The experiments were undertaken in the laboratory and the greenhouse. The results from feeding adult M. thitipornae with six different diets (nine replications per treatment and ten parasitoids per replication) in the laboratory showed that diets had highly significant effects on the means of longevity of female and male parasitoids (P < 0.01, P < 0.01, respectively). A honey solution diet could extend the mean longevity of females to 9.83 ± 0.60 d (mean ± SE) and that of males to 7.83 ± 0.48 d. Estimated 50% female and male survival periods, when fed with the honey solution diet, were 8 and 4 d, respectively. The average potential fecundity (egg load) of females was 2.98 ± 0.11 eggs per female. The average female size (hind tibia length) was 0.31 ± 0.002 mm. In the greenhouse, the mean realized fecundity of females was 13.20 ± 1.95 progeny per female. M. thitipornae was identified as a synovigenic species. The progeny of this parasitoid had a male-biased sex ratio. M. thitipornae parasitized on the mature larva and pupa of the host. The single egg of this parasitoid developed as a solitary ectoparasitoid and completed its development outside the host body. The mean developmental time of M. thitipornae from the egg to the adult stage was 17 ± 0.44 d. When the above biological parameters of M. thitipornae were evaluated with those of L. invasa from a previous study, the results indicated that M. thitipornae had less parasitism capacity to control eucalyptus gall wasp (L. invasa) in Thailand.