الفهرس 
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Abstract
The present study was carried out to investigate the life history of the saw-toothed grain beetle, Oryzaephilus surinamensis (L.) reared on different date varieties. The experiments were conducted under different temperatures at the Plant Protection Department, Faculty of Agriculture, Minia University, Egypt.
Investigations included recognizing the role of this pest in date fruits decay at different temperatures, effect of temperature on the duration of different developmental stages and the thermal requirements of O. surinamensis, host range of different dried fruits, and the relative susceptibility of different date cultivars to infestation by this pest under laboratory conditions and 25ºC in incubators. Also, the relationship between the average fruit weight and the chemical components of the tested date varieties and the infestation by this pest was recorded. Moreover, the penetration ability of this pest in different packing materials, and the toxicity and repellency effect of some essential oils against this pest were carried out. Finally, using low temperature to control this pest was also taken into consideration.
The obtained results could be summarized as follows:
• The length of storing period increased the rate of decay because of the increase in number of the insect individuals and their activity, which led to the growth of microorganisms that caused decay. Results showed that lab condition and 25ºC were the degrees of temperature where decay and prevailing of the saw-toothed grain beetle occurred.
• The results showed significant differences among the incubation periods for all constant temperatures. The average thermal units required for eggs development till hatching was 99.71 D. D’s (degree-days) when determined by thermal summation equation k= y (T- 12.23).
• The results revealed that Apricot completely prevented the emergence of O. Surinamensis adults. The least number of adult emergence was also recorded on Raisin (7.50) under lab condition, while the highest number of adult emergence was observed on Scotty date (23.50) at 25ºC.
• Highly susceptible date varieties to infestation with O. surinamensis were Scotty and Barmatoda, while a moderately susceptible date variety was Malkabi, and the lower susceptible date varieties were Gondaila and Siwei.
• Jute material showed the maximum mean penetration by this beetle with highly significant difference as compared with all different tested packaging materials.
• Mint and Ginger oils induced 100% mortality with 100 ppm after 7 days of exposure.
• The repellency percentage increased with increasing concentrations and hours after treatment of the different tested plant oils.
• According to the percentages of mortality recorded after 15, 20, 30, 40, 60, 90 and 120 min exposure and estimated values of LT50, the mortality rate at 2ºC was very low as compared with the other two tested temperatures of -7 ºC and -10ºC. At 2, -7 and -10ºC no adults of O. surinamensis survived after 180, 120, 90 min, respectively. The LT50 values estimated for the effect of low temperature on O. surinamensis adults were found to be 133.4, 55.5 and 16.4 min for the temperature degrees of 2, -7 and -10, respectively.