Biology, Damage and Parasitoids of Eucalyptus Gall Wasp, Leptocybe invasa Infesting

Abstract

Leptocybe invasa has been recorded few years back in Sri Lanka from Eucalyptuscamaldulensis plantation in Maragamuwa, where no natural enemies were reported. Recentobservations revealed a decreased gall infestation and hence, the present study was conductedto investigate the biology of L. invasa, its damage to E. camaldulensis and the presence ofany natural enemies to control the infestation.

Leptocybe invasa has been recorded few years back in Sri Lanka from Eucalyptuscamaldulensis plantation in Maragamuwa, where no natural enemies were reported. Recentobservations revealed a decreased gall infestation and hence, the present study was conductedto investigate the biology of L. invasa, its damage to E. camaldulensis and the presence ofany natural enemies to control the infestation.

L. invasa was found to be the only eucalyptus gall wasp attacking Maragamuwa eucalyptusplantation during the present study period. Life cycle duration of L. invasa was 132 days onaverage. Five stages of gall development on midribs and petioles of E. camaldulensis leaveswere observed. Adult L. invasa was more active in the morning. There was no significantdifference in the abundance of L. invasa between the two seasons although they were moreabundant in the wet season. Damage index was low throughout the study period. A clearpattern in colour change from red to green in young leaves of E. camaldulensis coppices wasobserved from the initial stage. L. invasa attacked the coppices of E. camaldulensis after theyreach their typical green colour and damage increased with the development of coppices.However, damage did not further increase after coppice maturity. A total of four differentparasitoid wasps, of which only Megastigmus could be identified, were reared from leaf andshoot galls of E. camaldulensis. Megastigmus was the most abundant and mean percentparasitization was 67.00 ± 8.00. Natural enemies of L. invasa might have contributed to thedecreased gall infestation in coppices of E. camaldulensis observed recently in Maragamuwaplantation.