Document Type : Original Article


Plant Prot. Dept., Fac. Agric., Zagazig Univ., Zagazig, Egypt


The saw-toothed grain beetle, Oryzaephilus surinamensis (L.) is an important pest of many stored product foods. The effect of insect infestation on four various of whole food kinds as semi-dry date, dry date fruits, white sesame and reddish yellow sesame seeds as well as four food kinds of crushed seeds (chickpea, corn, rice and groundnut) as compared with standard diet (wheat flour, crushed wheat and dry yeast powder at 5:5:1, respectively) was investigated in the laboratory of Plant Protection Department, Faculty of Agriculture, Zagazig University, Egypt. Insect parameters on the tested food kinds as regards to resistance were duration of developmental stages, number of F1 progeny, growth index and weight loss (%) after one month of storage. All tested parameters were significantly affected by food kinds except the duration of pupal stage in whole foods. The shortest mean insect complete developmental period was 19.85 days on standard diet, while the longest one was 29.18 days on whole reddish yellow sesame seeds and 35.05 days on crushed groundnut. Values of the growth index (GI) increased from 3.22 to 3.76 on whole reddish yellow sesame seeds and crushed chickpea, respectively compared to 4.64 on standard diet. The wet weight loss (%) ranged from 0.50 and 0.67% in whole sesame seeds (white and reddish yellow) and crushed groundnut, suscessively compared to11.17% in standard diet. The relative wet weight loss (%) in whole seeds reached its minimum (1.94%) in each of whole white and reddish yellow sesame seeds and reached its maximum (43.23%) in standard diet, while in crushed foods, the lowest value was 3.16% in crushed groundnut as compared with the standard diet which recorded the highest percent 52.76%. All tested foods either whole or crushed were infested with O. surinamensis and no completely immune food was found free from the insect infestation but the insect preferred crushed foods and some foods than another.


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