Breeding chickpea (Cicer arietinum [Fabaceae]) for better seed quality inadvertently increased susceptibility to adzuki bean beetle (Callosobruchus chinensis [Coleoptera: Bruchidae])

Continuous breeding efforts in Ethiopia resulted in the release of 15 improved chickpea (Cicer arietinum L.) varieties with improved yield, seed quality, disease resistance and better adaptation to different production zones within Ethiopia. This study was conducted to examine whether breeding for increased yield and other important agronomic traits without direct selection for resistance to the adzuki bean beetle (Callosobruchus chinensis L.) has inadvertently resulted in a significant level of susceptibility to this seed pest within the new cultivars. Field and laboratory studies were conducted to see whether breeding for better seed quality has increased susceptibility to infestation by the adzuki bean beetle. Seeds of 130 accessions/genotypes were infested with the beetle in 2009 under ambient temperature and relative humidity at Holetta, Ambo and Debre Zeit, Ethiopia. Data were recorded on attributes of infestation level and seed damage. Data on seed size, proportion of seed coat and grain yield were collected from a replicated field trial conducted with the same accessions/genotypes grown under the same conditions in 2009/10 at Ginchi and Ambo, Ethiopia. Differences among the genotypes were significant for most traits with the exception of the number of uninfested seeds. Accessions with partial resistance include 41320, 41289, 41291, 41134, 41315, 207658, 41103, 41168, 41142, 41174, 41029, 41207, 209087, 231327, 41161 and 41008. The improved varieties were more susceptible than germplasm accessions. The results indicate that genetic progress was achieved both in grain yield and seed size, but breeding efforts for these traits had also inadvertently increased seed susceptibility to C. chinensis. Improvements in seed size resulted in higher infestation levels and seed damage. Future breeding to improve seed quality should simultaneously consider corrective measures to incorporate resistance to the adzuki bean beetle. © 2011 ICIPE.