A newly invaded eucalypt gall wasp and its parasitoid in China: identification and biology

Abstract

Abstract Gall pests have caused seriously damage to eucalyptus in recent years in China. In this study, we collected and identified the invaded eucalyptus gall wasp Ophelimus maskelli and its parasitoid Closterocerus chamaeleon for the first time in China. O. maskelli induced two types of gall shape, i.e., blister- and neoplastic-shaped galls. The blister-shaped galls were most likely induced on leaves rather on petioles and stems, while the neoplastic-shaped galls were more frequently found on petioles rather than on leaves and stems. We find that of the four solar orientations, O. maskelli significantly preferred to colonize Eucalyptus trees in the sunnier areas in south over that in west and north with significantly lower gall infestation rate detected in east. The parasitism rate of C. chamaeleon increased from 23.4% in February to 97.4% in March 2023 when the population of O. maskelli galls was low (236.8–251.4 galls/20 branches); however, when gall population increased to a high level (≈ 450 galls/20 branches), the parasitism rate significantly decreased to 26.5% in April, although it raised to 62.6% again in May. Our findings deliver insigne into development of biological control programs of O. maskelli using C. chamaeleon.