Making the long flight from the arid inland of Australia, the native budworm, Helicoverpa punctigera, is set to arrive in south-eastern agricultural areas in late winter or spring.
As the timing of these flights can vary between years, traps are useful in providing an early warning of moth arrival.
Curious about native budworm moth trapping? Here we answer all your questions on how to set up moth traps in your winter grain crops in the south-east.
Why should I trap?
The primary purpose of native budworm moth monitoring is to provide a forewarning of moths immigrating into agricultural areas and susceptible crops, therefore providing an indication of when egg-laying will begin. (If you are unfamiliar with the biology, behavior and pest profile of the native budworm, please see our comprehensive PestNote.)
Larvae generally hatch 7-14 days after eggs are laid. So the detection of moths in a trap helps to plan the timing of more intensive, in field monitoring for larvae with a sweep net and/or beat sheet.
It’s important to note that native budworm moth trapping is not a substitute for infield monitoring of larvae. Our experience has been that the number of moths trapped does not necessarily reflect the size of larval populations in crops (eg. a large number of trapped moths may not result in crop damage).
What type of trap should I use?
Bucket traps and pheromones lures can be used to monitor for the arrival of native budworm moths in crops.
A bucket trap is constructed of a lid holding a small cage above a funnel that has a bucket attached underneath. A pheromone lure, which mimics the scent of the female native budworm moth, is placed in the small cage. This lure attracts male native budworm moths down the funnel into the bucket.
The pheromones lures must be kept in the fridge prior to their use. Ensure that the lures have not expired prior to their use, and be aware that their field life is around 4 weeks, so replacement lures may be needed throughout the season.
Some twisted wire or rigid fence wire can be used to suspend the trap off a star picket or similar stable stake in the crop.
Where do I place the trap?
Place the native budworm trap in a pulse crop or canola crop that is approaching flowering.
If possible, place the trap 50 m into the crop and suspend it at the height of the crop.
The trap should also be placed at least 100 m from buildings and light sources.
When should I start trapping?
It’s best to set-up native budworm moth traps by August 1st if possible. This is particularly important for growers in the northern mallee which are the first to receive moth flights from the arid inland.
Should I monitor for corn earworm, Helicoverpa armigera, too?
The cosmopolitan corn earworm is another agricultural pest that is related to the native budworm. The two species overlap in their host range to an extent (e.g. pulses and canola), and are both spring/summer pests.
While telling these two species apart is tricky and not always possible, knowing which species is present in a crop is important as corn earworm has developed resistance to insecticides and native budworm has not.
Like native budworm, the corn earworm can also be monitored with bucket traps and their own species specific pheromone lures formulated to attract corn earworm male moths.
However, it’s important to note that during the winter cropping season in the south-east, not all regions will be at risk from both species
Native budworm moths are long distance fliers, arriving in Victoria and southern NSW during August and September. Corn earworm moths on the other hand, are generally thought to arise from local populations that survive overwinter as pupae in winter crops, emerging with warmer spring temperatures.
Hence corn earworm damage is generally a problem in warmer regions such as northern to central New South Wales and southern Queensland during the winter cropping season.
Unless your crops are still flowering and podding in late November and December, corn earworm trapping is likely not necessary for the south-eastern winter crops in Victoria and southern NSW.
In the south-east, corn earworm moth traps are predominantly used for monitoring the emergence of moths in susceptible summer crops like maize and tomatoes.
For more information on the corn earworm, visit our comprehensive PestNote.
Cover image: Photo by Andrew Weeks, Cesar Australia
