Relationship of Oedaleus decorus asiaticus Densities with Soil Moisture and Land Surface Temperature in Inner Mongolia, China

Oedaleus decorus asiaticus (O. decorus) is a significant pest in the grasslands of Inner Mongolia, posing considerable challenges to the development of animal husbandry. To understand the key factors influencing the population distribution of O. decorus, field surveys were conducted from 2018 to 2020, during which the population count, growth stage, and location information of O. decorus were recorded. Daily soil moisture (SM) data and daily land surface temperature (LST) data were obtained from the National Tibetan Plateau Data Center, and a Generalized Additive Model (GAM) was constructed. Our findings indicate that the SM (S8) in August of the previous year is the most critical factor, with an F-value of 27.422, followed by the LST (L10) in October of the previous year, the LST (L6) in June of the survey year, the SM (S9) in September of the previous year, the LST (L3) in March of the survey year, and the LST (L5) in May of the survey year, with F-values of 7.848, 7.223, 5.823, 4.919, and 3.547, respectively. S8 and S9 can be regarded as vital indicators for predicting and monitoring the occurrence of O. decorus. However, the contributions of S8 and S9 to O. decorus density differ considerably. S8 is negatively correlated with O. decorus density, while S9 values below 0.29 m3/m3 can promote the growth of O. decorus. A higher LST during early overwintering correlates with increased O. decorus density. During the survey year, LST emerged as the primary factor affecting grasshopper density. Additionally, it plays a more complex role during incubation periods. This study clearly identifies SM and LST as the major factors influencing the occurrence of O. decorus, which will aid in predicting and monitoring its density.