More Mandalotus weevils

There have been more reports of Mandalotus weevils (Mandalotus spp.) damaging several emerging crops in various locations across southern New South Wales. Agronomist, Nigel Clarke (JJS Glass & Co) reports Mandalotus weevils causing significant damage to canola crops around Junee, in the South West Slopes of New South Wales. Due to the level of the damage the weevils were sprayed with bifenthrin, which reportedly achieved adequate control.  Entomologist, Joanne Holloway (NSW DPI), has reported Mandalotus weevils in an early stage canola crop near Junee. Joanne says the crop has been sown into a paddock with sandy loam soil. Consultant, Tim Condon (Delta Agribusiness), has observed Mandalotus weevils in a 2-4 leaf canola paddock north west of Cootamundra, also in the South West Slopes of New South Wales. Tim reports finding 10-20 weevils/m² in patches across the paddock, which has been long-term pasture prior to this year. 

Agronomist, Phil Bowden (NSW DPI), reported that Mandalotus weevils have wiped out large patches of canola around Cootamundra and Junee. The weevils have eaten the stems at the base of plants, with several paddocks requiring large areas to be re-sown. Mark Harris (Rural Management Strategies) reports Mandalotus weevils causing damage to some canola crops around Lockhart, in the South West Slopes of New South Wales. Agronomist, Roger Garnsey (Roger Garnsey Agronomy), reports weevils attacking an oats crop near Yass, in the Southern Tablelands of New South Wales. Many of the plants have been chewed off at the ground level, resulting in several bare-patches within the paddock. The weevils are more prominent on lighter soil types. Roger says they have also been found attacking some paddocks of rye grass.

These recent reports suggest Mandalotus weevils may be increasing in pest importance across many regions. Mandalotus weevils are known as a sporadic pest of canola, cereals and beans. The adults are mostly active at night. During the day they can be found hiding under dirt and trash. It is commonly found on rubbly sandy loam soil; hence it is often referred to as the ‘rubble bug’. Mandalotus weevil can be mistaken for sitona weevil, however it is more rounded in appearance, 3-5 mm long and dull brown in colour.

Click here for images of Mandalotus weevils and refer to PestFacts Issue No. 4 for more information.