Response of white-fringed weevil (Naupactus leucoloma) larvae to host plant roots and tubers

Response of white-fringed weevil (Naupactus leucoloma) larvae to host plant roots and tubers White-fringed weevils (WFW) are a major pest of several crops in Australia. Larvae cause severe damage to the roots of pasture and forage plants, particularly lucerne, sometimes reducing the life of crops to only a few years. In several States, particularly Tasmania, they have become a primary pest of potatoes. Recent research has shown that many soil dwelling organisms (insects, nematodes and earthworms) do not find their hosts in the soil through random searching. Rather, they detect and orient towards specific compounds released by their hosts. This poster presents the preliminary results from on-going bioassays to establish the mechanisms used by WFW larvae to find host plant roots or tubers (potatoes, carrots and lucerne). Two types of 2-choice bioassay chambers were used to test the response of larvae to roots and tubers. To date, no significant orientation by 1st instar larvae (non-feeding stage) to host plants has been detected but further bioassays using older, feeding instars are in progress.