Possible windborne transmission of giant willow aphid Tuberolachnus salignus (Gmelin) (Hemiptera: Aphididae: Lachninae) westward from New Zealand to Australia

Abstract

ABSTRACTThe first records of Tuberolachnus salignus (Gmelin), the giant willow aphid, were reported from New Zealand and Australia in December 2013 and March 2014 respectively. The host plants are various members of Salix and Populus. The pathway used by the aphid to enter Australasia remains unknown, but natural aerial dispersal across the Tasman Sea is proposed to explain its first appearance within 3 months in Australia and New Zealand. Previous examples of aphids crossing the Tasman Sea are summarised. Windborne transmission due to the predominantly westerly winds from Australia to New Zealand is more likely based on past experience. However, we demonstrate using the HYSPLIT air trajectory model that it is possible that the aphid was carried on a reverse trajectory from New Zealand to southern Tasmania. Without more regular and systematic surveillance of New Zealand and Australian insect biota, it will continue to be difficult to ascertain the timing, origin and dispersal pathways of introduced insects.