Antixenosis resistance to Oulema melanopus (Coleoptera: Chrysomelidae) in central Asian wheat germplasm.

Abstract

The cereal leaf beetle, Oulema melanopus (L.) (Coleoptera: Chrysomelidae), which is Eurasian in origin, is an emerging pest of agriculturally important cereal crops in western Canada, including wheat, oat, and barley. Among these crops, wheat (Triticum aestivum L.) has the highest number of resistant genotypes to O. melanopus infestation. Here we explored six genotypes from central Asia with putative resistance to the beetle in comparison with a widely grown Canadian wheat variety. We noted the highest oviposition on the susceptible control genotype, CDC GO, and the lowest on one of the central Asian genotypes (NN-100) in both choice and no-choice tests. Two of the other Asian genotypes (NN-78 and NN-105) were also less attractive for oviposition than the CDC GO check. Feeding trials also indicated less damage on some of the Asian genotypes (NN- 100, NN-105, and NN-78) relative to CDC GO, but other Asian genotypes (NN-41, NN-45, and NN-27) were highly attractive for feeding and oviposition and did not exhibit stronger resistance to O. melanopus infestation than moderately resistant central Asian genotypes (NN-103, NN-78, or NN-105). There were no significant differences in the amount of feeding by overwintered and teneral adults. The results indicated that some wheat genotypes developed in central Asia have categories of nonpreference for feeding and oviposition worth considering in further development of host-plant resistance and integrated management of this pest.