Comparative temperature-dependent development of Nephus includens (Kirsch) and Nephus bisignatus (Boheman) (Coleoptera: Coccinellidae) preying on Planococcus citri (Risso) (Homoptera: Pseudococcidae):: Evaluation of a linear and various nonlinear models using specific criteria

The effect of temperature on the development of the predators Nephus includens (Kirsch) and Nephus bisignatus (Boheman) (Coleoptera: Coccinellidae) was studied. The duration of the development of immature stages and the pre-oviposition period of the two predators, reared on Plancicoccus citri (Risso) (Homoptera: Pseudococcidae) at eight constant temperatures (10, 15, 20, 25, 30, 2.5,35, and 37.5 +/- 1degreesC), have been recorded. The developmental zero (lower temperature threshold) was estimated to be 10.9 and 9.4degreesC, and the thermal constant was 490.5 and 614.3 DD for N. includens and N. bisignatus, respectively, using the linear model. Data were fitted to various nonlinear temperature-dependent models, and the thermal developmental thresholds (lower and upper), as well as the optimum temperature for development, have been estimated. Evaluation of the models took-place, based on the following criteria: fit to data (residual sum of squares and coefficient of determination, or coefficient of nonlinear regression), number and biological value of the fitted coefficients, number of measurable parameters, and accuracy on the estimation of the thresholds. Conclusively,. linear and Lactin models are highly recommended for the description of temperature-dependent development of these two predators and possibly of other coccinellids.