A new tool in the battle against Sunn Pest

FIGS was applied in the ICARDA genebank to find sources of resistance to Sunn pest (Eurygaster integriceps), the major pest of wheat in West and Central Asia and eastern Europe. Sunn Pest can cause 100 per cent losses, but most importantly affects the bread quality even at very low infestation rates . It is reckoned to affect up to 15 million hectares of wheat annually and in excess of US$150 million is spent each year on pesticide treatments in the pest-prone regions.

A FIGS search identified 534 likely accessions. Initial field screening reduced these to 57, and advanced screening resulted in nine candidates with resistance to Sunn pest at the vegetative stage. The resistant varieties developed using the resistance genes found through the application of FIGS form an important part of integrated pest management development, designed to reduce populations of adult insects.

These nine entries are the first wheat sources found with good levels of resistance to Sunn pest at the vegetative stage. They are being used in the ICARDA wheat breeding program to develop wheat varieties resistant to Sunn pest feeding at the vegetative stage.

The 534 accessions identified by the FIGS filtering process were field screened at the ICARDA research station at Tel Hadya during 2007. In the initial evaluation, 10 seeds per hill were planted, in an augmented design, with bread wheat cultivar ‹Cham 6› as a susceptible check every 10 test entries.

Plants were covered by mesh screen cages and infested with three adult Sunn pests per hill in mid-March, the time when they usually migrate to wheat fields. The nine key accessions identified through FIGS are being used in ICARDA wheat breeding programs to develop resistant varieties against overwintered Sunn pest adults, which damage wheat at the vegetative stage (shoot and leaves).

Resistance at this stage could be important in reducing overwintered Sunn pest adult populations, as well as nymphal and new generation adult populations, which reduce wheat quality by feeding on spikes (grains). The introduction of wheat varieties carrying resistance at the vegetative stage should be one component of a total integrated pest management program against Sunn pest.

Since all the accessions resistant to Sunn pest came from the same geographical area, either from Afghanistan or from neighboring Tajikistan, it would be advisable to concentrate on these countries when screening other accessions for Sunn pest resistance in the future, and to return for additional sampling.