D3300: 50 years of rice pest records in Japan revealed dynamical changes of pest composition

In 2021, IPCC reported that the global warming is scientifically conscious and will become worse in future. It is said that the global warming will provide favourable environments and/or enlarge the window of the growing seasons for many pests. Consequently, crop productions in the world may face the growing risks of pest insects but is it really true? It is, however, difficult to quantify growing trends of pests since the severity of pest damages must be dependent on localities and be dependent on species. In our study, we specifically picked up the records of eight major pests, Sogatella furcifera, Nilaparvata lugens, Laodelphax striatella, Nephotettix cincticeps, Chilo suppressalis, Naranga aenescens, Tipula aino, in rice paddies having more than 50 years length with 5-day survey intervals. We employed redundancy analysis (RDA) to detect dynamical changes of these rice pest composition and found that there was a strong time-trend, i.e., all the pest species are generally decreasing year by year. Convergent cross-mapping (CCM) was tentatively employed to see the causal effects of possible factors on pest community. We found that the temperature increase and the fluctuations in precipitations causes the decreasing trends in the rice-pests in Japan. Rice pest insects in Japan may be still maladapted to the climate change and decrease their population sizes.