Evaluation of different models to describe egg and pupal development of Xyleborus fornicatus Eichh. (Coleoptera: Scolytidae), the shot-hole borer of tea in Sri Lanka

Abstract Development data of eggs and pupae of Xyleborus fornicatus Eichh. (Coleoptera: Scolytidae), the shot-hole borer of tea in Sri Lanka, at constant temperatures were used to evaluate a linear and seven nonlinear models for insect development. Model evaluation was based on fit to data (residual sum of squares and coefficient of determination or coefficient of nonlinear regression), number of measurable parameters, the biological value of the fitted coefficients and accuracy in the estimation of thresholds. Of the nonlinear models, the Lactin model fitted experimental data well and along with the linear model, can be used to describe the temperature-dependent development of this species

Temperature-dependent development of Xyleborus fornicatus (Coleoptera : Scolytidae), the shot-hole borer of tea in Sri Lanka: Implications for distribution and abundance

The effect of temperature on the rate of development of Xyleborus fornicatus (Eichh.) was determined by rearing individuals under a range of constant temperatures (15 -32 degrees C). Rates of development changed in a linear fashion over a wide range of temperatures. Estimates of lower development thresholds were obtained for eggs (15.7 +/- 0.50 degrees C), larvae (15.8 +/- 0.8 degrees C) and pupae (14.3 +/- 1.4 degrees C) and the degree days (DD) for development were 70 +/- 4.4, 95 +/- 8.5 and 72 +/- 5.1 DD, respectively. Optimum temperature for development was around 30 degrees C for all stages. Temperature fluctuation in cooler High Country areas (above 1400 m) with a mean temperature around 15 degrees C seems to be critical for the development of the pest, which may be responsible for the near absence of pest in those areas. Temperature fluctuations (18-30 degrees C) in the Mid Country region (600-1200 m) favor the development of the pest compared to development under constant conditions. The altitudinal distribution of the shot-hole borer across tea growing areas in Sri Lanka is, therefore, mainly governed by temperature