Community of parasitoids associated with occurring Gonipterus weevils in Eucalyptus, in Tasmania

An increasing number of invasive insect pests has been observed in Eucalyptus plantations outside Australia. Among these, the eucalyptus weevils Gonipterus spp. are major insect pests. Both larvae and adults feed on foliage, causing tree growth reduction and consequent economic losses. An egg parasitoid, Anaphes nitens (Girault) (Hym: Mymaridae), is the unique biological control successfully established and regulating Gonipterus spp. in many regions. However, it shows low parasitism rates in particular areas where Gonipterus platensis has established such as at high altitude eucalypt stands in the Iberian Peninsula, with high economic value. In these cases, it urges to find complementary biological control agents. In 2016, we conducted an exploratory survey, to find parasitoids associated with the native Gonipterus populations, in Tasmania (Australia), which could be later used as biological control agents. We collected from eucalypts growing on road-sides, Gonipterus individualized egg pods. Whenever, both Gonipterus larvae and an adult parasitoid emerged from the same egg pod, we used a sister larva to identify the Gonipterus species using molecular tools. Both Gonipterus spp. and parasitoid distribution through the surveyed sites/locations was determined. A distribution map and a list of egg parasitoids found associated with Gonipterus species, is provided based on our collections. Further studies on Gonipterus larvae and larval parasitoids should also be evaluated to identify other suitable biological control agents to be released outside Tasmania against Gonipterus species.