Biology of eucalyptus gall wasp, Leptocybe invasa Fisher and La Salle (Hymenoptera: Eulophidae).
The biology and behaviour of L. invasa on Eucalyptus tereticornis were studied in Dharwad, Karnataka, India, during 2009. L. invasa adults were active throughout the day; however, activity was most pronounced during the sunny hours (after 09:30 h and after 14:30 h). The insect laid eggs on leaf midrib, petiole and tender shoots. Damage was very severe in nursery seedlings and coppice (36.99 galls/10-cm shoot) compared to adult trees (15.67 galls/10-cm shoot). Heavy egg load due to repeated oviposition resulted in little leaf appearance and stunted growth. In severe cases, the tips of the seedlings and coppice dried up. Oviposition damage was observed even at a height of 15 m above the ground level on 6-year old trees. Oviposition was evident on buds within 3 days of bud burst. Only the females emerged from galls, which started to lay eggs, indicating thelytokous reproduction. However, a lone male was encountered during October 2008. In the laboratory, adults oviposited on midribs, petiole and tender stem of the seedling. Seedlings in glass jars exposed for oviposition showed scarring of tissue within 12-15 days after oviposition. In the greenhouse in E. tereticornis clones, the release of white ooze by adults was observed within 5-7 days, resulting in the development of the scarred tissue within 7-8 days, which turned into the typical, bump-shaped green gall within 6-8 days. The adult lived for 4.50±0.4 days without food. The stage from oviposition to adult emergence lasted 54 to 65 days.