Unraveling the effect of temperature and humidity on the life cycle of Diatraea saccharalis (Lepidoptera: Crambidae) and the impact on pest outbreaks.

Abstract

Temperature and humidity are considered the main abiotic factors that affect both the development and survival of ectothermic organisms. In this study, we estimated the development time as well as the thermal requirements of the sugarcane borer, Diatraea saccharalis (Fabricius, 1794; Lepidoptera: Crambidae), a key insect pest of sugarcane and discussed the influence of temperature and relative humidity and its infestation intensity in a scenario of climate change. The models Brière-1 and Ikemoto-Takai provided the best fit to the data of development rate versus temperature. The average life cycle (from egg to adult) ranged from 39.21 ± 4.84 at 32 °C to 137.10 ± 7.47 at 18 °C days. The thermal constant and average base temperature were 547.69 degree-days and 13.64 °C, respectively. The number of larval instars varied from 4 to 7 depending on the temperature, being higher at lower temperatures. The thermal range comprised the interval from 16.7 °C to 33.9 °C and the optimum temperature was estimated as 27.4 °C. Locations with elevated temperature (≥25 °C) and high relative humidity (≥70%) presented larger populations of D. saccharalis. Our findings show that the infestation pressure of this species is highly influenced by both temperature and humidity, and the studied models allow to forecast pest outbreaks. In the context of climate change, information about the thermal range and the optimum temperature contributes to predicting the spatial-temporal distribution of D. saccharalis and, consequently, aids decision making in pest management.