6.2 Larval parasitoids for biocontrol of invasive paropsine defoliatiors

Many countries have a large Eucalyptus plantation forest industry. In New Zealand, Eucalyptus form a small component of the plantation estate at present (FOA, 2016), but the genus is becoming increasingly important for providing speciality hardwood products. In a trend similar to other countries (Wingfield et al., 2008) but exacerbated by New Zealand’s close geographic proximity to Australia, numerous Eucalyptus pests have successfully invaded, including Chrysomelidae (Coleoptera) beetles (Withers, 2001). Of these, five are paropsines on Eucalyptus: Paropsis charybdis Stål (first found in 1916), Trachymela sloanei (Blackburn) (first found in 1976), Trachymela catenata (Chapuis) (found in 1992), Paropsisterna beata (Newman) (found in 2012) (Yamoah et al., 2016), and Paropsisterna variicollis (Chapuis) (found 2016) (Lin et al., 2017). Of all the eucalypt insect pest species, P. charybdis has been the most damaging to date, defoliating numerous species of valued Symphyomyrtus eucalypts. The biological control of P. charybis has been variable despite egg parasitoids and a ladybird being introduced, both on purpose (Enoggera nassaui Girault (Hymenoptera: Pteromalidae) and Cleobora mellyi (Mulsant) (Coleoptera: Coccinellidae) and accidentally (Neopolycystus insectifurax Girault, Hymenoptera: Pteromalidae) from Australia (Bain and Kay, 1989). Improved control is needed, especially an agent that targets the larval life stage.