Beneficial beetles not responsible for crop damage
Key points:
- Black beetles in canola crops identified as beneficials
- Correct identification of beetles critical for selection of best management and control methods.
Growers are reminded that not all invertebrates found in crops are pests, and some may actually be helping to reduce pest pressure.
The National Invertebrate Pest Initiative (NIPI) PestFacts South Australia and Western Victoria email advisory service has received several reports of small black beetles from growers and agronomists in the Naracoorte (South-East of South Australia), Harrow and Vasey (Western Victoria) areas.
The beetles were found in emerging canola crops that were showing evidence of feeding damage.
However, the beetles sent to the Pest Facts identification service, which is supported by growers and the Australian Government through the Grains Research and Development Corporation (GRDC), were not responsible for the crop damage as they were identified as beneficial beetles (Hypharpax sp.) belonging to the family Carabidae.
Researcher and PestFacts SA and Western Victoria co-ordinator, Kym Perry (South Australian Research and Development Institute Entomology), says both the adults and larvae are highly active ground-dwelling predators that feed on a wide range of crop and pasture pests such as caterpillars, wireworms, earwigs and slugs.
“Adult carabids are generally shiny black in colour, have a characteristic flattened ‘hot-water-bottle’ shaped body and large bulging eyes on the sides of the head,” Mr Perry said.
“They can be confused with some pest species in the tenebrionid family (such as vegetable beetles and bronzed field beetles) but can usually be distinguished by the prominent eyes and forward-protruding mouthparts.
“Carabid larvae have a hardened (sclerotised) head capsule and a relatively long cylindrical-shaped body.
“They are often confused with true and false wireworm larvae, but can be distinguished by prominent mouthparts that are directed forward and the presence of well-developed legs. They also have two very long processes projecting from the end of the body (last abdominal segment).”
Mr Perry said correct identification of crop insects was critical to avoid unnecessary treatment and disruption of beneficial insects such as carabid beetles.
A free identification service is available to those growers and advisers who subscribe to PestFacts.
To subscribe to the free service, contact SARDI Entomology researchers Kym Perry on (08) 8303 9370 or 0439 822 134 or Ken Henry on (08) 8303 9540 or visit www.grdc.com.au/pestlinks
For identification of invertebrates, growers and advisers are asked to send at least two undamaged specimens in a non-crushable container along with some food (host material). Details regarding collection date, location, host-plant, description of damage caused and contact details should also be included.
Specimens can be forwarded to: Kym Perry, Entomology Unit SARDI, GPO Box 397, Adelaide 5001.
For more information contact Kym Perry on (08) 8303 9370 or 0439 822 134.