Entomologists at the Tasmanian Institute of Agriculture (TIA) are urging berry growers to be vigilant about the Bronze Leaf Beetle (Diachus auratus), an emerging pest that is becoming an increasing concern in Tasmania.
The beetle feeds on leaves, flowers, and fruits, causing reduced fruit quality and lower yields. According to TIA entomologist Dr Lynne Forster, the beetle can inflict significant damage to berry crops within just a few weeks. Although first sighted in Australia in 1986, the beetle is now becoming a more persistent issue in the state.
Dr Forster explained that outbreaks in recent years have led to considerable damage in berry crops. The beetle, native to Central America, is small—about two millimetres in size—shiny, bullet-shaped, and flat-headed. Monitoring for its presence is particularly important in polytunnel systems, where the warmer microclimate can favour its development.
One challenge in identifying the pest is that its eggs and larvae are concealed in dark protective cases, often mistaken for caterpillar waste. Additionally, the beetle's feeding damage closely resembles that caused by caterpillars, making misidentification easy. Dr Forster noted that there are currently no registered sprays or biological control agents for the Bronze Leaf Beetle, which heightens the importance of early detection and regular monitoring.
She emphasised the need for growers to inspect crops carefully, particularly the young leaves at growing tips, as well as flowers, fruit, and nearby boundary plants. Damage can appear as chewed holes or shredded petals. Maintaining weed control and checking for signs of the beetle, both inside and outside polytunnels, is also recommended.
While berry growers are currently most affected, the beetle poses a broader threat. Internationally, it has been observed on various fruiting plants, and there are concerns it could spread to crops such as grapes, avocados, apples, and plums. Dr Forster stressed that all fruit growers should remain watchful.
TIA researchers are actively exploring management strategies to control the pest. Their work is supported by the Raspberry and Blackberry Research and Development Levy through a Hort Innovation-funded project focused on integrated pest management for raspberries and blackberries. Dr Forster encouraged growers to consult agronomists if they suspect Bronze Leaf Beetle infestations, noting that ongoing research is key to developing sustainable, practical solutions for the industry.
For more information:
Lynne Forster
University of Tasmania
Tel: +61 3 6226 6200
Email: [email protected]
www.utas.edu.au
