Prediction of change in the occurrence of Chilo suppressalis (Lepidoptera: Pyralidae) in paddy fields in the context of new climate change scenario

The rice stem borer, Chilo suppressalis (Walker) is a serious insect pest of rice in Asia, Northern Africa and Southern Europe. In Korea, the rice stem borer overwinters as a larva and has 2 generations a year. Climate change would affect the phenologies of C. suppressalis and rice, differently. In this study, we estimate occurrence of 1st generation of C. suppressalis and transplanting time of rice in the context of new climate change scenario (RCP 8.5) for assessment of phonological synchrony. The occurrence of 1st generation was monitored by pheromone traps in paddy fields, in Gunsan-si, Jeollabuk-do from 2011 to 2012. These data were fitted to the two-parameter Weibull function. In rice, leaf appearance rate and final leaf number model were used to estimate the transplanting times of 3 types of rice cultivars (Odae, Hwaseong, Ilpum). Daily mean temperatures of 3 periods (2001~2010, 2051~2060, 2091~2100) were used for the models. As a result, the occurrence of C. suppressalis moves forward 8~14 days during each period. However, rice transplanting time is delayed 10~53 days during each period. In 2050s, the spring occurrence of C. suppressalis would be earlier than the transplanting time in southern coastal and central lowland areas. In 2090s, except for the north eastern mountainous area C. suppressalis occurs earlier than the transplanting time. In the future, asynchrony of the occurrence and the transplanting time leads to change the pest status of C. suppressalis in rice.