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Native budworm and lesser budworm caterpillars are causing damage to crops

Caterpillar activity reports

  • Northampton
  • Yuna
Native budworm caterpillar
Native budworm caterpillar. Photo courtesy of: DPIRD.

An agronomist has reported native budworm caterpillars causing severe damage to flowering lupin crops near Northampton. The high number of caterpillars are stripping the lupin plants of their leaves and flowers. The agronomist also reported native budworm caterpillars causing extensive damage to cereal crops in the area.

A lesser budworm caterpillar
A lesser budworm caterpillar. Photo courtesy of: Nick McKenna (Planfarm).

Nick McKenna (Planfarm) has reported finding what has been confirmed as lesser budworm damaging a wheat crop near Yuna.

Native budworm thresholds are based on avoiding damage to seed in maturing crops, which is usually when the caterpillars are at their most damaging. This year there has been the unusual situation in some areas of very high numbers of native budworm moths arriving earlier than usual coinciding with late developing crops. This has resulted in severe damage to the developing buds, flowers and leaves of some lupin and canola crops in the northern agricultural region. High numbers of what appears to be native budworm caterpillars, but could be lesser budworm, have also been reported causing extensive damage to cereal crops in the same area. As thresholds are based on maturing crops, growers must decide for themselves whether spraying for budworm is worthwhile to protect the buds, flowers and leaves of pulse and canola crops.

Given the high number of moths having migrated into crops early, it may be that spraying for budworm is required more than once this season given the length of season remaining and moths likely to continue to lay eggs into crops. This activity is reflected in cesar’s MothTrapVis map below.

A screenshot of cesar's MothTrapVis map showing native budworm moth trapping numbers from 23 July to 16 August 2019.
Screenshot of cesar's MothTrapVis map showing native budworm moth trapping numbers from 23 July to 16 August 2019.

Caterpillars of both species (native budworm and lesser budworm) will eat increasing quantities of plant material and seed as they grow. They will grow through six or seven stages or instars until reaching maturity (up to 40 mm long). The last two growth stages account for over 90% of their total plant material and seed consumption.

Native budworm (Helicoverpa puntigera) will attack a wide range of crops and pastures (field peas, lupins, canola, serradella and medics etc) and is a frequently occurring pest each year in WA, especially in eastern, northern and southern agricultural areas adjoining pastoral areas. 

Another less frequent and closely related pest is the lesser budworm (Heliothis punctifera), also a native species, that will attack the same crops but is also known to additionally feed on cereal crops.

There has been a number of reports this year of what appears to be native budworm caterpillars damaging cereal crops. However it is possible that there is a much higher occurrence than usual of the lesser budworm this year.

The feeding habits of the lesser budworm may be different to the native budworm. In the past the lesser budworm has been observed commencing to chew into newly formed lupin pods on the flowering crop. It is not characteristic of native budworm to chew into lupin pods until caterpillars are greater than 15 mm long and the crop is much closer to maturity, around leaf drop and pod maturation. When native budworm caterpillars (of any size) feed on canola crops they only cause damage to pods late in the season when leaf drop has occurred and pods are maturing and changing colour. It is uncertain as to the timing when lesser budworm may start to chew on canola pods.

Pulse, cereal and canola growers in north and central areas are encouraged to monitor their crops for plant feeding damage and check caterpillar numbers using a sweep net or bashing plants into a container if they are too short to sweep. Serradella, lucerne, clover and annual medic seed crops should also be regularly checked for budworm caterpillars.

If you have found caterpillars that appear to be native budworm feeding on cereals, and would like confirmation of the species please send samples to:

Department of Primary Industries and Regional Development
75 York Road, Northam WA 6401, attention to Dusty Severtson.

For more information on distinguishing native budworm caterpillars from lesser budworm caterpillars refer to the 2019 PestFax Issue 14 article Native budworm moth numbers are high.

Native budworm moth trapping surveillance

  • Usual automated and manual trapping locations
Native budworm moth
Native budworm moth. Photo courtesy of: Alan Lord (DPIRD).

This week has seen the numbers of native budworm moth flights slowing in many areas.

The higher captures this week include; Cunderdin (109 moths), Kirwan (97), Kellerberrin (92), Southern Cross (87), Maya (83), Bindi Bindi (57), Walkaway (53) and Dowerin (47).

Results of this week's automated and manual trappings are available at the department’s Native budworm moth numbers 2019.

A mapped view of the native budworm trap captures is available at cesar’s MothTrapVisWA page. Viewers need to select the desired trapping date range.

 

Pesticide options for the control of native budworm can be found in the department’s Winter/Spring Insecticide Spray Chart 2019.

Detailed information on this pest can be found at DPIRD’s:

For more information contact Alan Lord, Technical Officer, South Perth on +61 (0)8 9368 3758 or +61 (0)409 689 468.

 

Article authors: Alan Lord (DPIRD South Perth) and Dustin Severtson (DPIRD Northam).