Screening date cultivars for resistance against the saw-toothed grain beetle, Oryzaephilus surinamensis L. (Coleoptera: Silvanidae)

The saw-toothed grain beetle, Oryzaephilus surinamensis L. (Coleoptera: Silvanidae) is an important insect pest of stored dates. This study aims to assess the susceptibility of ten date cultivars to the infestation by O. surinamensis. The tested cultivars were Rushodia, Segae, Shaishee, Nabtat Ali, Sari, Khalas, Ruzeiz, Sukkari, Ajwa Al Madina, and Deglet Noor. The response of the beetle to the ten cultivars was studied using a ten-arm olfactometer choice test. The nature of injury incurred by the beetle on the cultivars and the number of individuals produced per gram of consumed dates were determined. Additionally, the F1 progeny produced on each cultivar and the median developmental time were identified and used to calculate the susceptibility index (SI) for each cultivar. The cultivars Rushodia, Segae, and Shaishee were highly susceptible to the infestation by the saw-toothed beetle according to their high SI of 12.05, 12.02, and 11.11, respectively. However, the cultivar Deglet Noor was resistant to the infestation showing the smallest SI of 4.15. The ten cultivars were classified as highly susceptible, susceptible, moderately resistant, and resistant to attack by the saw-toothed grain beetle. The degree of susceptibility or resistance of the tested cultivars to the beetle also coincided with the beetle's mode of damage as well as the total number of progeny developed upon feeding on each date cultivar. The findings of the study can be used in the management strategies of O. surinamensis in stored dates.