Effects of Larval Parasitoids to Control Litchi Leafminer, Conopomorpha litchiella (Gracillariidae : Lepidoptera) in the field

Abstract

Litchi leafminer, Conopomorpha litchiella (Lepidoptera : Gracillariidae) is a microlepidoptera. They feed on lychee and longan, especially young shoots and leaves. After infesting, both of them turn brown. This may affect growth development of fruit trees. Naturally, they have been parasitised by many species of larval parasitoids. therefore, in 1995-1996 percent leaf and shoot infestation including its larval parasitoids were investigated at Chiang Ria Horticultural Research Center. Young shoots of lychee and longan were randomly checked from October to Novermber, 1996. This resulted that lychee infested shoots by C. kitchiella were 83% and 73.04% which wee higher than in longan at the same period of times. There were 59.55% and 33.35% in longan. In July the percentages of parasititisation were over 60% in lychee and 48% in longan.
six unknown species of larval parasitoids have been found. Of these are solitary ectoparasitoid which are in order Hymenoptera. Insect identification of the parasitods have not been made. species was the most effective species, compared to the others. However, all of them seem to suppress the population of C. litchiella in low insecticide spraying areas.
Percent shoot and leaf damaged by C. litchiella can be considered before making a decision to spray inbsecticedes. In addition a number of leafminer cocoon and percent parasitism should be taken into account.