Invasive Species Compendium

Detailed coverage of invasive species threatening livelihoods and the environment worldwide

Abstract

Susceptibility variation in Eucalyptus spp. in relation to Leptocybe invasa and Ophelimus maskelli (Hymenoptera: Eulophidae), two invasive gall wasps occurring in Portugal.

Abstract

Leptocybe invasa (Fisher & LaSalle) and Ophelimus maskelli (Ashmead) are two new invasive pests, originating from Australia, which are spreading quickly in the Mediterranean countries, Africa, the Middle East and Asia. Leptocybe invasa causes typical bump-shaped galls on the leaf midribs, petioles and stems of new growth of several Eucalyptus species and O. maskelli induces small round galls on both adaxial and abaxial leaf surfaces. Field sampling was conducted with the aim to determine differences in susceptibility between E. camaldulensis and E. globulus, two host species of economic importance frequent in Portugal. Differences in susceptibility to L. invasa were found for the two species, a hybrid population and between families of Eucalyptus globulus ssp. globulus. Results demonstrated interspecific and intraspecific susceptibility variations. In order to understand the intraspecific variations, physical and chemical traits of the most susceptible and resistant genotypes were analyzed further. Physical analyses of Eucalyptus leaves by thickness measurements and leaf surface observations by SEM did not reveal significant differences between susceptible and resistant genotypes. On the contrary, chemical analyses concerning chemical fingerprints by NIRS and leaf volatiles by GC-MS revealed significant differences.