What was it all about?

From 2020 to 2023, this investment developed the use of environmental DNA (eDNA) technology to assist the rapid and sensitive detection of brown marmorated stink bug.

Environmental DNA (eDNA) is an innovative species detection tool being used in Australia and overseas for a range of activities in the fields of biosecurity, biodiversity conservation and environmental impact assessments.  All organisms leave traces of their DNA in their surrounding environment and this technology now makes it possible to take environmental samples to determine what species were present in real-time. These molecular techniques detect trace amounts of DNA and are therefore an exciting prospect for integration into biosecurity activities to prevent incursions and also delimit outbreak areas.

Interceptions of the brown marmorated stink bug at Australian ports have been increasing in number for several years. The increased risk of transmission has arisen from establishment of the bug in countries that actively trade with Australia, such as the US and Italy.

An accurate, fast, and cost-effective diagnostic is necessary to improve surveillance power and direct activities towards high risk pathways at the national border. Such a diagnostic tool would also increase capabilities of biosecurity personnel to quickly delimit the extent of a post-border outbreak.

A single species test for brown marmorated stink bug was developed and tested to ensure it was highly sensitive and specific, meaning that it only detects brown marmorated stink bug and not other closely related insects at acceptable thresholds.

In order to assess how well eDNA methods worked in the field, a test was also developed for a surrogate species common in New Zealand and Australia, the green vegetable bug. Simple methods for collecting green vegetable bug eDNA were developed and evaluated. The most practical and effective of these was sampling of leaves into a sealed bag, collection of eDNA by agitation in water, with eDNA then concentrated by filtration, extracted, and tested. The effects of green vegetable bug density and the window of detection were investigated, over a time course from 1 - 72 hours. The test is able to robustly detect a single green vegetable bug when present on a leaf for at least 16 hours in dry conditions. Multiple species (including brown marmorated stink bug) can also be identified using these techniques, as well as other in-field collections, allowing for broader surveillance and monitoring.

The project also:

• Delivered a workshop with international eDNA experts, where the latest ideas and technologies were shared
• Developed a Pest Bites video, which details the ways to survey and identify brown marmorated stink bug
• Reviewed the literature for the wine and horticulture industries on the impact and management of brown marmorated stink bug.

The materials for a guide and workshop to train industry staff in the use of eDNA diagnostics are currently being produced.