First sources of resistance in faba bean (Vicia faba L.) to the stem borer weevil, Lixus algirus L. (Coleoptera: Curculionidae)

Abstract

Faba bean (Vicia faba L.) is a grain legume widely cultivated in many countries for food and animal feed. The faba bean stem borer (Lixus algirus L.) (Coleoptera: Curculionidae) is considered one of the major biotic stresses of faba bean in some Mediterranean areas, including Morocco. The use of genetic resistance is the most economical and environmentally friendly control method of insect pests. Therefore, a set of 233 faba bean genotypes from two ICARDA sets (GCP Ref.Set-2015 and AYT-2015) was evaluated for resistance to L. algirus under open field and net cage conditions at Douyet and Marchouch Stations in Morocco. Twelve genotypes (11 from the GCP Ref.Set-2015 and one from AYT-2015) showed a low level of infestation by the stem borer in the field and under cages. The results of free-choice screening showed a significant egg-laying preference of stem borer for the susceptible cultivars Defes and Alfia, compared with the two germplasm accessions IG 11561 and IG 72498. The accession IG 72498 expressed the highest level of antibiosis; with 100% mortality of first or second instars, with no adult exit holes on any of the plants checked. These two accessions are being used in the ICARDA crossing program to develop recombinant inbred lines to study the genetics of resistance to faba bean stem borer. This is the first report of resistance to stem borer in faba bean with antixenotic and antibiotic categories of resistance.