Population fluctuation and Life history strategies of the Sawtoothed beetle (Oryzaephilus surinamensis L.) fed on Date palm cultivars

ABSTRACT: this study was conducted to investigating O. surinamensis elucidates dynamics of vital rates in response to changes in population density and date palm cultivars as food depletion. Experiments were conducted by preparing five glasses insectariums that looks like a Date palm stock held in the warehouse and filled by five Date cultivars and treated by 500 adults for six month. They had been sampled once every week by wet funnel. The Life history strategies of O. surinamensis were satisfied by KNM method analysis. There were four active period in the population fluctuation curves of all stages. The first population density peaks of egg, Larvae, pupa and adult occurred about on third, fifth or sixth, eighth and eighth or ninth weeks respectively. The second peak of them occurred about on thirteenth or fourteenth, thirteen, fourteen and twelfth or thirteenth week respectively. The third peaks of them occurred about on eighteenth or nineteenth, seventeenth to nineteenth, eighteen and twenty-first or twenty-second week respectively. The fourth peak of was happened about on twenty-third or twenty-fourth, twenty-third, twenty-second or twenty-third weeks respectively. The fourth period of adult showed an increasing trend until end of the storage period. Based on rate of population survival (Wj), the highest mortality of population in all studied date cultivars occurred on the transition from larval stage to pupa. The highest value of this parameter was recorded in population that rearing of Sayer cultivar. Based on developmental stage during (aj), the highest developmental stage during was recorded on adult. The highest value of this parameter was recorded in population of Zahedi cultivar. Based on indicates the number of individuals entering the next stage of growth (Mj), from egg to adult was observed a gradually decline in the number of individual entering to next developmental stage in all studied date cultivar. The highest value of this parameter was recorded in population of Zahedi cultivar.