Biological characteristics of Anticarsia gemmatalis (Lepidoptera: Noctuidae) for three consecutive generations under different temperatures: understanding the possible impact of global warming on a soybean pest

Climate changes can affect the distribution and intensity of insect infestations through direct effects on their life cycles. Experiments were carried out during three consecutive generations to evaluate the effect of different temperatures (25°C, 28°C, 31°C, 34°C and 37±1°C) on biological traits of the velvetbean caterpillar Anticarsia gemmatalis Hübner, 1818 (Lepidoptera: Noctuidae). The insects were fed on artificial diet and reared in environmental chambers set at 14 h photophase. The developmental cycle slowed with the increase in the temperature, within the 25°C to 34°C range. Male and female longevities were reduced with an increase in temperature from 25°C to 28°C. Egg viability was highest at 25°C, and the sex ratio was not influenced by temperature, in the three generations. There was no interactive effect between development time and temperature on pupal weight. The results suggested that the increase in the temperature negatively impacted A. gemmatalis development inside the studied temperature range, indicating a possible future reduction of its occurrence on soybean crops, as a consequence of global warming, mainly considering its impact on tropical countries where this plant is cropped. A. gemmatalis was not able to adapt to higher temperatures in a three-generation interval for the studied temperature range. However, a gradual increase and a longer adaptation period may favor insect selection and consequently adaptation, and must be considered in future studies in this area. Moreover, it is important to consider that global warming might turn cold areas more suitable to A. gemmatalis outbreaks. Therefore, more than a future reduction of A. gemmatalis occurrence due to global warming, we might expect changes regarding its area of occurrence on a global perspective.