Etiella moths have been detected during sweep netting in a lentil crop at Sandilands, Yorke Peninsula, and caught in pheromone traps at Kadina and Port Broughton. The onset of peak flight activity for Etiella moths is still predicted to be a couple of weeks away for most districts (see model predictions below), however moth activity may occur either side of these dates. Given these sightings, it is recommended to begin checking susceptible lentil crops for moths and consider spraying if moths exceed threshold levels (> 1-2 moths per 20 sweeps). Lentils are susceptible to Etiella damage from late flowering onwards, as soon as the first pods appear.
Etiella or Lucerne seed web moths (Etiella behrii) have a protruding beak and a distinctive white stripe along the edge of the forewing. Larvae have pinkish-red stripes and are particularly damaging to lentils and lucerne. The risk period is when pods are green, while dry pods are not at risk. Etiella can have up to three generations per year from spring to autumn, with larvae from the previous autumn overwintering in the soil and adults emerging in September. Adult females are capable of laying approximately 200 eggs that are laid on the surface of leaves, stems and flowers and hatch in 1-14 days depending on temperature. Shortly after larvae hatch (i.e. within 24 hours), they bore directly into seedpods where they feed and develop. In summer pulses larvae complete development in a single pod before boring out through a pin-sized hole. Several insecticides are registered against Etiella, and these should be considered when moth activity is first observed in crops. Once larvae have entered seed pods, they are protected from contact sprays.
The Etiella degree-day model is able to predict the timing of initial spring Etiella moth flights for the various lentil-growing districts. The model uses maximum and minimum daily temperatures from June 21 onwards to forecast the flight activity of Etiella moths. The date when the cumulative total of degree-days first reaches 351 is the date to commence in-crop monitoring. No further temperatures need to be recorded after this value has been reached.Current model values at 14th September 2015 are:
- Kadina - 255
- Minlaton - 244
- Roseworthy - 246
- Horsham - 194
We will continue to provide updated model predictions in each issue of PestFacts.
To run the model yourself, download the Etiella degree-day model (). Temperature data for your local region can be obtained from the Bureau of Metereology website and must be entered into the model from 21st June onwards. Detailed instructions for running the model yourself can be obtained by emailing Bill Kimber (email@example.com).
Source of reports: Michael Brougham (Elders), Chris Davey (YPAG, Kadina)