Resistance of dried chips of yam (Dioscorea cayenensis-D. rotundata complex) landraces to Dinoderus porcellus Lesne (Coleoptera: Bostrichidae)

Yams (Dioscorea spp.) are one of the food crops that contribute to food security and poverty alleviation in Benin and, like several other products, the post-harvest phase is threatened by the rotting of fresh tubers. To overcome this constraint, yam tubers are traditionally processed into dried chips which unfortunately are severely attacked by Dinoderus porcellus Lesne (Coleoptera: Bostrichidae). Research studies on relative resistance of dried chips of 24 yam landraces to the attack of D. porcellus during storage were carried out using free-choice tests (antixenosis) and non-choice tests under laboratory conditions. Attractiveness of yam chips, mortality of initial pest populations, weight loss, and also the Dobie's index of susceptibility were considered as indicators of resistance. The results revealed that the landraces Boniwouré and Wonmangou were significantly less attractive and consumed by D. porcellus. The highest mortality rate of D. porcellus was observed on the landrace Boniwouré followed by Alahina. Based on the Dobie index of susceptibility five yam landraces (Gaboubaba, Boniwouré, Alahina, Yakanougo, and Wonmangou) were scored as resistant to D. porcellus. All the remaining landraces were categorized as moderately resistant. Based on the present study, these five resistant landraces deserve special consideration and may be recommended for relatively longer storage to achieve the goal of sustainable management of D. porcellus.