Effects of Variable and Constant Temperatures on the Embryonic Development and Survival of a New Grape Pest, Xylotrechus arvicola (Coleoptera: Cerambycidae)

Abstract

Xylotrechus arvicola Olivier (Coleoptera: Cerambycidae) has become a new expanding pest in grape (Vitis spp.) crops. To better improve control tactics, the consequences of 11 constant (12, 15, 18, 21, 24, 27, 30, 32, 34, 35 and 36°C) and nine variable temperatures (with equal mean temperatures at each of the nine constant rates ranging from 15 to 35°C) on survival and embryonic development were studied. The eggs were able to complete development at constant temperatures between 15 and 35°C, with mortality rates at the extremes of the range of two and 81.5%, respectively. Using variable temperatures a mortality rate of 38.9% at a mean temperature of 15°C and 99% at 35°C was observed. The range of time for embryonic development was 29.5 d at 15°C to 6 d at 32°C at constant temperatures, and from 29.6 d at 15°C to 7.2 d at 32°C at variable temperatures. The goodness-of-fit of different development models was evaluated for the relationship between the development rate and temperature. The models that gave the best fit were the Logan type III for constant temperatures and the Brière for variable temperatures. Optimum temperatures were estimated to be from 31.7 to 32.9°C. The models that best described embryo development under natural field conditions were the Logan type III model for constant temperatures (98.7% adjustment) and the Lactin model for variable temperatures (99.2% adjustment). Nonlinear models predicted faster development at constant temperatures and slower development at variable ones when compared with real field development, whereas the linear model always predicted faster development than what actually took place.