Multiple incursions and putative species revealed using a mitochondrial and nuclear phylogenetic approach to the Trogoderma variabile (Coleoptera: Dermestidae) trapping program in Australia

The Warehouse beetle, Trogoderma variabile (Coleoptera: Dermestidae), is an internationally significant invasive pest of packed goods and stored grain. When it was first documented in Australia at Griffith, New South Wales, in 1977, an eradication campaign was initiated. After several years and considerable effort, the eradication campaign was abandoned. To monitor the presence and spread of T. variabile, surveys were carried out by government agencies in 1992 and 2002. When survey data was compared, it was concluded that the distribution of morphologically identified T. variabile had doubled in most Australian states. Here, we used samples from the 2002 survey to conduct a phylogenetic study using partial sequences of mitochondrial genes Cytochrome oxidase I and Cytochrome B, and the nuclear gene 18S, to examine the distribution and dispersal of T. variabile and detect the presence of misidentified species. Based on our molecular results, we show that only 47% of the samples analysed were T. variabile, and the remaining were a mixture of six putative species. In addition, T. variabile was found in only 78% of the trapping sites. We discuss the importance of correct diagnosis in relation to the eradication campaign.