During winter, the native budworm (Helicoverpa punctigera) breeds on flowering plants in inland Australia.
When this inland vegetation dies off in late winter/spring, the larvae pupate, and moths emerge and migrate vast distances to agricultural regions. They then lay eggs in crops, and it is the ensuing larval population that cause damage, feeding on the fruiting parts and seeds of plants, particularly in pulses and canola.
Here we provide an update on native budworm activity for 2022.
Moth activity this season
With the help of volunteers, we have established a limited number of native budworm moth traps in some grain growing regions of south-eastern Australia (see table below).
These moth traps use the female moth’s pheromone to attract male moths.
Please keep in mind that the number of moths caught doesn’t reflect the risk to crops, however they do provide an indication of the timing of native budworm flights and activity in south-eastern Australia.
|Mallee VIC||Mallee VIC||Northern VIC||Northern VIC||Central VIC||Riverina NSW||Riverina NSW||Central West NSW||Central West NSW|
|19-Aug||40||Trap set-up||Trap set-up|
|9-Sep||5||3||0||Trap set-up||Trap set-up||Trap set-up||0||0|
Monitor for larval activity
Monitoring is the best way to get an indication of larvae numbers in crops.
Monitor pulse and canola crops regularly using sweep nets; it is important to sample representative parts of the entire paddock prior before making a control decision.
Taking multiples of 10 sweeps within at least five locations in a paddock is recommended.
For information on the economic thresholds for this pest, please see the native budworm Pestnote.
So far, we haven’t had any reports of larval activity to the PestFacts south-eastern team, but if you have seen otherwise let us know!
What to expect in a wet year
The Bureau of Meteorology has declared a La Niña in 2022 for the third year in a row. With much of eastern Australia expected to receive above average rainfall this spring you may be wondering how this may impact native budworm.
Helicoverpa moth species lay their eggs singly or in groups of twos or threes near the growing points of plants, but not all eggs will make it to the damaging caterpillar stage. There are several factors that can impact egg survival, including rain.
A study by Kyi et al. (1991) demonstrated clear effects of rain on egg mortality of the closely related Helicoverpa armigera in cotton.In this field trial study, the effect of simulated and actual rain was assessed. Rainfall was deemed an important factor in causing egg loss due to dislodgment from the plants.
However, while rain events help to suppress native budworm larvae in crops, wet conditions can also mean that some crops will continue to remain attractive to budworm for longer. The continued migration of moths through spring is probable and as long as crops are green, they are at risk and will need to be monitored.
Thanks to our network of native budworm trappers: Shayn Healey, Damien Jones, Bruce Larcombe, Ben Cameron, Adam Dellwo, David White, Andrew Rice, Laing Whinfield and Tim Condon.