Natural Enemies of the Asian Gypsy Moth (Lepidoptera: Lymantridae) in South Korea

Abstract

Thirteen season-long collections of larvae and pupae of gypsy moth, Lymantria dispar L., were made at seven forest sites near Seoul, South Korea, from 1984 to 1989 to detect the natural enemies and to determine their importance. Thirty natural enemy species were identified, including twenty that parasitized 12,388 of the 52,351 larvae and pupae reared during the study. Tachinid, braconid, and ichneumonid species accounted for >99% of this parasitism, with tachinids being more abundant than braconids, which were more abundant than ichneumonids. The braconid Cotesia melanoscelus (Ratzeburg), which parasitized 24.4% of first and second instars, was the most important parasitoid. Parasitigena silvestris Robineau-Desvoidy (Tachinidae), which parasitized 27.6% of fifth and sixth instars and 36.3% of the prepupae, was second in importance. Blepharipa schineri Mesnil, a larval-pupal tachinid parasitoid, which killed 37.5% of the pupae, is considered to be the best candidate for establishment against the moth in the United States. The nuclear polyhedrosis virus (NPV) caused the greatest mortality observed in the study, at times killing all larvae. No relationship was observed between levels of parasitism and gypsy moth population densities except for C. melanoscelus, which caused more parasitism in larger populations. Artificially created populations experienced levels of parasitism similar to those of natural populations, except for a greater abundance of C. melanoscelus in the artificial populations. Season-long parasitism rates ranged from 13.3 to 33.4% and averaged 23.7% overall versus 12% recorded in comparable studies in the United States. The great contrast in the abundance and pest status of the gypsy moth in Korea and in the United States probably relates to the large differences in parasitism.