Abstract

Efficiency of most pesticides is monitored by many factors such as the method of application, the concentrations and the temperature. The study was aimed to investigate the optimal conditions for using Insect Growth Regulator (IGR), cyromazine to control the Southern cowpea weevil Callosobruchus muculatus Fab. (Bruchidae: Coleoptera). Interactions of the method of application and concentrations of cyromazine together with temperatures significantly affected the reproductive rate of C. muculatus. Accordingly, when seeds were completely embedded (dipping method) in 5% cyromazine at 30°C, the insect reproductive rate was significantly decreased to 1.37%. In addition, results revealed that the increase in cyromazine concentration simultaneously with the seed-dipping method clearly decreased the consumption of food storage by the insect population. However, the generation lifespan of the insect was increased. No significant change was observed in the percentage of the sexual ratio, while a clear significant difference was recorded in the weights of the males and females. In conclusion, the seed-embedding method with a high concentration (5%) of cyromazine at 30°C resulted in the most significant food consumption with a clear reduction in the generation reproductive rate. 

Key words: Food consumption, IGR, increasing rate, sex ratio.