sustainability through science & innovation

African black beetle in pastures

Some paddocks have been resown because of severe African black beetle infestations.


The African black beetle (Heteronychus arator, ABB) is an introduced scarab pest found throughout south-eastern Australia. The larvae are soil dwelling, favouring pastures, particularly newly sown ryegrass and summer-dormant perennial grasses. Cereal crops (including wheat, barley, triticale, maize and sorghum) are also vulnerable to ABB attack.

ABB is most prominent in higher rainfall areas where there has been an abundance of summer grasses. However, adult beetles can fly into paddocks in late summer from nearby breeding areas dominated by perennial grasses. This year has seen considerable feeding damage caused by ABB in dairy pastures around Gippsland, Victoria. In several cases, entire paddocks have been completely resown (and many others over-sown) due to the severity of damage. We have previously received reports of ABB attacking pastures and broadacre crops in most other districts of Victoria and high rainfall areas of southern NSW.

Adult ABB lay their eggs in the soil in spring. The larvae hatch in 2-5 weeks depending on temperature, and typically reach the most damaging 3rd instar larval stage between mid-January to March. They then pupate in the soil and emerge as adults, which go on to feed on pastures and crops throughout autumn, winter and spring. This differs to other scarab species (e.g. blackheaded cockchafers), where the larvae are commonly associated with feeding damage in autumn and winter.

African black beetle adult (Source: Trevor James, AgResearch, NZ)

 

While there are limited chemical options available for controlling ABB, several agronomic practices can be implemented to renew damaged paddocks. As ABB is often mistaken for other scarabs in pastures and cereals, best practice management begins with correct species identification. Once confirmed, management options include sowing endophyte grass varieties which offer ABB protection and using effective insecticide seed treatments prior to sowing.

In problem paddocks, longer-term strategies should be considered. These include non-host rotations (e.g. planting a legume, chicory or brassica in spring which is likely to disrupt ABB at the larval stage of development), removing alternative food sources before establishing new pastures and keeping soil pH at around 6.

Click here for more information on ABB, including their occurrence, behaviour and damage symptoms, and click here for a useful guide on identification of common scarabs.

 

Field reports

Jackson Davis – MG Trading (North East, VIC)

Karen Romano – GippsDairy (Gippsland, VIC)

PestFacts is supported by