Susceptibility of Some Dry Date Cultivars to Infestation by Oryzaephilus surinamensis (L.) (Coleoptera: Silvanidae)

Susceptibility of eight date cultivars (namely Barhi, Barni Al Madina, Deglet Noor, Rushodia, Sukari, Ajwa, Mabroom and Nabtat Ali) to an attack by saw-toothed grain beetle Oryzaephilus surinamensis (L.), was estimated under laboratory conditions. Physical characteristics (texture, shapes and colour) and chemical constituents (total amount soluble solid, sugar, moisture, nitrogen, lipids, and fatty acid and percentage of ash) of the tested date cultivars were recorded. The laboratory evaluation indicated that the most preferable cultivar to eggs deposition and attack adults of the saw- toothed grain beetle was Sukari while the most resistance cultivars were Deglet Noor and Ajwa. The growth index of immature stages increased in the most susceptible cultivars (Sukari) but decreased in the resistance one (Deglet Noor and Ajwa). On the other hand the susceptible index indicated that three cultivars as Sukari, Barhi, and Rushodia were the most susceptible cultivars compared to others. There was a positive and significant correlation between moisture contents and the susceptible index while ash content elicited negative and highly significant correlation with susceptible index. During six months of storage, the highest rate of weight loss of tested date cultivars, that caused by infestation of saw-toothed grain beetle, was for Barhi followed by Barni Al Madina, Rushodia, and Sukari.