Effect of Temperature on the Development and Longevity ofPlanococcus ficus(Hemiptera: Pseudococcidae)

Abstract

AbstractThe developmental biology of Planococcus ficus (Signoret) (Hemiptera: Pseudococcidae) on table grape (Vitis spp.) leaves (‘Soultanina’) was studied at seven constant temperatures—15, 17.5, 20, 25, 30, 32.5, and 35°C—under laboratory conditions. Developmental time and adult longevity were inversely related to temperature. No nymphs hatched from eggs when incubated at 15 and 35°C, whereas no nymphs survived at 32.5°C. The highest egg-to-adult survival (72.09%) was found at 30°C and the lowest (48.80%) at 25°C. The mean total developmental time from egg to adults for females ranged from 39.87 d at 30°C to 112.62 d at 17.5°C. The recorded sex ratio of the offspring was strongly female biased. Adult females lived from 27.64 d at 30°C to 63.70 d at 20°C, whereas males lived 1.66–7.55 d, respectively. Both linear and nonlinear models adequately described the relationship between temperature and developmental rates for immature stages of P. ficus. Thus, P. ficus required 555.56 degree-days to complete development from egg to adult stage, above a minimum threshold of 11.11°C as estimated by linear regression. The temperature thresholds for all nymph instars of P. ficus, estimated by the linear model, were lower than values that were estimated by the non linear model. The predicted upper lethal temperature was 32.5°C, with a minimum threshold for total development occurring at 14.20°C, as estimated by a nonlinear model. These results may lead to better management of P. ficus by improving predictions of its seasonal appearance.