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The effect of different temperatures on some biological properties of Nephus includens Kirsch (Coleoptera: Coccinellidae) was investigated. This species is one of the most important predators of Planococcus citri Risso (Homoptera: Pseudococcidae). The development time, mortality and fecundity were determined at constant temperatures of 15, 20, 25, 30, and 35°C and at the variable temperatures, 25-35°C (12 hours 25°C, 12 hours 35°C). Life tables were also constructed for 25, 30, 35, and 25-35°C. The mortality was lower and the mean generation time was shorter at 30°C than at all other temperatures except 35°C. The intrinsic rate of increase was the highest at 30°C (0.081), followed by 0.076 at 25-35°C. The net reproductive rate was higher at 25-35°C than at 30°C. From biological data and population growth parameters calculated from the life tables, 30°C and 25-35°C were determined to be the most suitable temperatures for mass rearing of Nephus includens. However, mass rearing at a temperature as high as 35°C could cause deterioration of sprouted potatoes on which the citrus mealybug is reared. Therefore, 30°C would be better than 25-35°C. |
