Effect of temperature and different pulses species on biological traits of cowpea weevil, Callosobruchus maculatus F. (Coleoptera: Bruchidae)

The cowpea weevil, Callosobruchus maculatus is an important pest of pulses seed, with ample distribution in tropical and subtropical regions. In this research, the effect of temperature and host plants on population growth of this pest was investigated. Effect of five host pulse including pea, cowpea, lentil, vetch and broad bean on development time of cowpea weevil was studied at seven constant temperatures: 18, 21, 24, 27, 30, 33 and 36 (±1 °C). Population growth parameters of C. maculatus were measured on five host species at 27 °C and at seven constant temperatures on cowpea. Some physical and biochemical characteristics of pulse seeds were measured and the correlation between them and some life history parameters of C. maculatus was examined. Our research showed that the shortest development time was on cowpea at 33 °C and the longest one was on broad bean at 18 °C. The highest and lowest rm values were observed on cowpea and broad bean, respectively at 27 °C. A significant difference was observed in grain humidity, hardiness index, protein and starch content of various pulse seeds. The life cycle of C. maculatus was greatly affected by quality of host plant. Differences over the development time may be due to nutritional content in pulses seeds. The grain humidity was another factor affecting seed quality and feeding of this pest. The highest longevity at low temperatures could be associated with lower metabolic processes. The thermal characteristics of C. maculatus were relatively influenced by different host plant seeds