Crop thieves caught red-handed

When you see feeding symptoms on your emerging crops are you sure you know the true culprit? The evidence is often clear: plants going missing, leaves are nibbled on or show silvery patches. However, knowing which pest is causing these issues can be difficult as many pests are active during the night and hide during the day. It is easy to blame the first critter you see…but is that slater really the culprit or might there be others?

A new SAGIT funded research project called ‘CAUGHT RED HANDED’ is trying to clarify these culprits using night-vision (infrared) time lapse cameras. In three South Australian paddocks, we have installed modified cameras focused on small plantings of seedlings (wheat, barley, faba bean, canola, vetch and lentils) replaced fortnightly. The images below were taken at Riverton at the end of April and you can clearly see earwigs munching into cereal seedlings causing lopping and even eating beans before they fully emerge. The paddock is bare and would appear to be lifeless but at night it comes alive with earwigs, weevils, millipedes, beetles and other invertebrates.

Initial test runs pre-sowing have shown an amazingly high variety of organisms, and we also regularly observed vertebrate pests (such as mice) enjoying an evening snack in an otherwise bare paddock. Between the mice and the earwigs, the seedlings were completely gone within three days, however, that was when the seedlings were the only sprigs of juicy green present this autumn. Currently, we are now collecting data from these cameras while the crops are emerging.

In addition to the camera monitoring, pitfall traps are also deployed to help us understand invertebrate movement from edges into crops. Understanding the conditions that cause some resident (generally harmless) invertebrates to switch to eating crop plants will help to predict risk.

We will soon review the latest footage taken after field sowing at the three sites in Riverton, Rhynie and Finniss and will keep you informed of our observations.

For more details, contact:

Maarten van Helden
Phone: 0481 544 429  
Email: maarten.vanhelden@sa.gov.au