First report on the susceptibility of certain dry Egyptian common bean (Phaseolus vulgaris L.) (Fabaceae) varieties to infestation by Acanthoscelides obtectus (Say, 1831) (Coleoptera: Chrysomelidae: Bruchinae)

Abstract

Abstract Stored dry common bean seeds are subject to infestation by Acanthoscelides obtectus, which reduces the quality of the infested seeds and depletes their nutritional value, making them unfit for human consumption. The susceptibility of three Egyptian varieties to infestation by A. obtectus was investigated. The Nebraska variety was the most susceptible, with 34.5 and 62% infestation at artificial infestation levels that included 5 and 10 pairs of insects for every fifty seeds, respectively, followed by the Karnak and Giza 6 varieties. The maximum weight losses as a result of insect infestation were observed for Nebraska seeds, and as expected, the maximum numbers of emerged adults after 50 days of storage were also observed for this variety. Maximum means of infested seeds were recorded in the Nebraska and Karnak varieties at the 10- pair infestation level. According to the infestation index, the Giza 6 and Karnak varieties were moderately resistant, while the Nebraska variety was susceptible at the 10-pair infestation level. Moreover, changes in the chemical composition of infested dry common bean seeds were inconsistent, with increases in some nutritional properties (protein and fibre contents) and decreases in others (moisture, carbohydrate and fat contents).