Abstract: 【Aim】 This study aims to reveal the impacts of the key ecological factors on the larvae of the large black chafer Holotrichia parallela so as to provide the theoretical basis for forecasting its occurrence. 【Methods】 By automatically controlling the temperature and manually adjusting the moisture, the effects of temperature, soil water content and food on the survival rates and developmental duration of H. parallela larvae were observed in the laboratory. 【Results】 The results showed that the optimum temperature range for the survival of H. parallela larvae was between 20℃ and 28℃, and the highest survival rate (74.9%±3.1%) was obtained at 24℃. The developmental duration was the longest at 12℃,the shortest at 32℃, and moderate at 20℃ and 24℃. Both the 1st and 2nd instar larvae could survive when the soil water content was between 7% and 19%. The highest survival rate (76.4%±2.5%) was observed when the soil water content was 16%. However, the survival rates were less than 50% when the soil water contents were 7% and 19%, but none survived when the soil water content was 25%. When H. parallela larvae were fed on the six tested foods including wheat root, maize root, cotton root, peanut root, soybean root and potato slices, respectively, the survival rate of the larvae fed on peanut roots was the highest (68.7%±3.2%). The larvae fed on different diets showed significant differences in the developmental duration, the developmental duration of the larvae fed on peanut roots was the shortest (only 259 d, including 227 d of the 3rd instar larval duration), while that of the larvae fed on cotton roots was the longest (346 d, including about 303 d of the 3rd instar larval duration). 【Conclusion】 Temperature, soil water content and food all have significant influences on the survival and development of H. parallela larvae. Controlling temperature and humidity and changing host plant structure during its larval stage can effectively control the occurrence and harmfulness of this pest.

Key words: Holotrichia parallela, larva, temperature, soil water content, food, survival rate, developmental duration