Tussock moth species arriving on imported used vehicles determined by DNA analysis

Egg masses of tussock moths are frequently intercepted at the border, most commonly on imported used vehicles. These have been assumed to be of the gypsy moth, Lymantria dispar (Lepidoptera: Lymantriidae). However, there are six other Lymantriid pest species with similar indiscriminate oviposition and overwintering behaviour that are considered to have the potential to reach New Zealand. Unfortunately there is no accurate record of what arrives, as early immature life stages of tussock moths cannot be reliably identified morphologically to the species level. A molecular diagnostic system was therefore adopted for the identification of all interceptions. During the period 2000-2002, 151 specimens were intercepted on used vehicles from Japan and one on a vehicle from the USA. Of these 82% were identified as gypsy moth, 2% were other high-risk species (nun moth, L. monacha, and white spotted tussock moth, Orgyia thyellina), 6% were unknown species and 10% had no detectable DNA. This information is interpreted with respect to the quarantine systems in place and the practical role of molecular tools for biosecurity.