Coptodisca lucifluella is a leafminer native to North Eastern America that has been recently recorded in Italy. Whereas in the native range it is detrimental to pecan-trees, the invasive populations attack black and common walnut trees in Italy. A high larval mortality has been previously reported, partially due to the activity of parasitoids. To assess if the complex of parasitoids associated to this alien pest is affected by the protocol of defence against the key walnut pest Rhagoletis completa and by the agricultural management (specialized walnut or promiscuous), three fields were chosen in the same area: two specialized walnut orchards (organic and conventional) and an organic promiscuous orchard. Percentage of parasitization was evaluated by weekly collecting samples of leaves over two years, from the earliest emergence of adults up to the last recorded larva, and parasitoids were isolated and identified. We show that several species of indigenous parasitoids have quickly adapted to this invasive pest, and that there are significant differences in the parasitization rates and in the composition of parasitoids among the three orchards. Chrysocharis spp., Neochrysocharis sp. and one species of the Pnigalio soemius complex (Hymenoptera: Eulophidae) are the most abundant parasitoids. We also collected another eulophid, Cirrospilus coptodiscae, a parasitoid native to North America that has likely host-tracked C. lucifluella. Hitherto, this parasitoid had been reared on three host species including Coptodisca splendoriferella, a closely related species often confused with C. lucifluella, parasitizing larvae in leaf mines and in host cocoons. The parasitization of the latter host stage has probably favoured the host-tracking process. Lastly, adults of C. coptodiscae showed high colour plasticity associated to different times of emergence, with lighter specimens emerging over summer and darker specimens emerging in spring.
The complex of parasitoids associated with the invasive leafminer Coptodisca lucifluella: indigenous species and a case of host-tracking / Gualtieri, Liberata; Sasso, Raffaele; Russo, Elia; Nugnes, Francesco; Gebiola, Marco; Bernardo, Umberto. - (2015). (Intervento presentato al convegno 4th International Entomophagous Insects Conference tenutosi a Torre del Mar, Spagna nel 4-9 ottobre 2015).
The complex of parasitoids associated with the invasive leafminer Coptodisca lucifluella: indigenous species and a case of host-tracking
Russo Elia;Nugnes Francesco;Gebiola Marco;
2015
Abstract
Coptodisca lucifluella is a leafminer native to North Eastern America that has been recently recorded in Italy. Whereas in the native range it is detrimental to pecan-trees, the invasive populations attack black and common walnut trees in Italy. A high larval mortality has been previously reported, partially due to the activity of parasitoids. To assess if the complex of parasitoids associated to this alien pest is affected by the protocol of defence against the key walnut pest Rhagoletis completa and by the agricultural management (specialized walnut or promiscuous), three fields were chosen in the same area: two specialized walnut orchards (organic and conventional) and an organic promiscuous orchard. Percentage of parasitization was evaluated by weekly collecting samples of leaves over two years, from the earliest emergence of adults up to the last recorded larva, and parasitoids were isolated and identified. We show that several species of indigenous parasitoids have quickly adapted to this invasive pest, and that there are significant differences in the parasitization rates and in the composition of parasitoids among the three orchards. Chrysocharis spp., Neochrysocharis sp. and one species of the Pnigalio soemius complex (Hymenoptera: Eulophidae) are the most abundant parasitoids. We also collected another eulophid, Cirrospilus coptodiscae, a parasitoid native to North America that has likely host-tracked C. lucifluella. Hitherto, this parasitoid had been reared on three host species including Coptodisca splendoriferella, a closely related species often confused with C. lucifluella, parasitizing larvae in leaf mines and in host cocoons. The parasitization of the latter host stage has probably favoured the host-tracking process. Lastly, adults of C. coptodiscae showed high colour plasticity associated to different times of emergence, with lighter specimens emerging over summer and darker specimens emerging in spring.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
