Morphological phenotypic plasticity of Monochamus saltuarius (Coleoptera: Cerambycidae) during post-diapause development in response to temperature

Temperature is one of the most important factors to determine many biological traits for exothermic animals. Overwintering populations adapt to maximize their biological fitness according to temperature experience after diapauses. This study was conducted to assess morphological phenotypic plasticity of Monochamus saltuarius, one of major vector of pine wood nematode, Bursaphelenchus xylophilus in Korea, after overwintering in response to temperature. In 2010, over 500 adult was introduced to 66 logs (1 m in length × 10 – 15 cm in diameter) of Korean pine, Pinus koraiensis and then overwintered in field conditions. After overwintering, the logs were cut into small piece (30 cm in length) and then were moved to the incubator with the constant temperature conditions of 16, 20, 23, 25, 27, 30 and 34 °C. At each temperature, five morphological traits of emerged adults, liveweight, body length, body width, head width, and antenna length were measured. Morphological phenotypic plasticity was observed in response to the temperature. For the female adults, liveweight and body length was highest at 23 °C whereas body width and head width was highest at 28 °C. In contrast, liveweight and body length of male adults were no significant differences between different temperatures. Antenna length of both sexes decreased linearly with increase in temperature. These results show that temperature experience after diapauses affected asymmetrically phenotypic plasticity of M. saltuarius between sexes.