National Trapping program for Trogoderma and related Dermestids

The Khapra beetle, Trogoderma granarium Everts (Coleoptera: Dermestidae) is recognised as one of the world’s most destructive pests of grain products and is the subject of strict quarantine measures in many countries. Khapra beetle is listed in the 100 ‘World's Worst Invasive Alien Species’ by the Global Invasive Species Programme. Plant Health Australia has identified Khapra beetle as one of the top 5 biosecurity threats to the Australian Grains Industry. Australia is free of Khapra beetle, with records of intercepts only and one incursion that was swiftly eradicated in WA in 2007. If Khapra beetle became established in Australia there would be large trade and production impacts.

There are over 120 described Trogoderma species worldwide and many have yet to be discovered. Apart from the Khapra beetle, there is the less significant pest the Warehouse beetle, Trogoderma variabile Ballion, which is already established in Australia. There are another four minor pest species, 52 described native Australian species and many native Australian species remain undescribed, any of which could accidentally get into grain stores - as they have done so on a number of occasions, and be misidentified.

The Khapra beetle can only be reliably identified by a limited number of highly skilled taxonomists. Expert morphological determination requires keying-out specimens, dissection and slide mounting of diagnostic features. Suspected Trogoderma specimens found in grain products are usually the larvae or larval skins which are very difficult, sometimes impossible to diagnose morphologically. Adult specimens are usually scarce and damaged. Due to their similarity, warehouse beetle, or native Trogoderma spp. could be mistakenly identified as T. granarium, or could mask the early detection of Khapra beetle. Their misidentification has the potential to seriously compromise the Australian grain exports.

The national trapping program for Trogoderma has been designed as a “targeted” baseline survey of the distribution of Trogoderma variabile and related native Trogoderma spp. in Australia. Trapping sites were selected from locations in which T. variabile and related Dermestids were previously collected in CSIRO trapping surveys conducted in 1991/92 and 2001/2003, as well as in previous surveillance catches in WA. The trapping in the 2009/10 season included 64 sites across WA, SA, VIC, NSW and QLD using participating CRC-affiliated grain companies (CBH, GCO and Viterra).

More than 600 trap sample catches are providing material for diagnostic capacity building. Trap catch data was collected using the Urban Surveillance Database application developed in CRCNPB30014 (PDA-Assisted Surveillance). The trapping program plays an important role in supplying the National Trogoderma Reference Laboratory with specimens for taxonomic studies, diagnostic imaging, biogeographical diversity studies and validation of diagnostic DNA markers for exotic and native Trogoderma species.

This research supports the National Reference Laboratory for Trogoderma in its capacity to becoming an accredited facility for rapid diagnosis of suspect specimens of Trogoderma species detected in Quarantine and Biosecurity surveillance, and demonstrates to international markets Australia’s pest-free status. This work addresses the ‘International importance of accredited diagnostic laboratories using accepted diagnostic procedures’ as written in the International Standards for Phytosanitary Measures (ISPM 27).