Study on Biological Characteristics of Stilphotia candida, in Nyingchi, Tibet

Stilphotia candida Staudinger, as an invasive species introduced into Tibet in recent years, harms the growth of local willow trees. The biological characteristics of the insect pests were systematically studied, which laid a theoretical foundation for the prevention and control of Stilphotia candida Staudinger in this area and the further research. Through the methods of field investigation, regular observation and indoor breeding, from April 2021 to July 2022, a fixed field observation base was set up in Jiemai village, Nyingchi city, and samples were collected for indoor rearing. The morphological characteristics, living habits and annual life history of Stilphotia candida Staudinger in Nyingchi, Tibet were systematically studied. The results showed that Stilphotia candida Staudinger occurred once a year in nyingchi Tibet, and began to overwinter with 2-3 instar larvae in mid-September. The overwintering sites were mainly inside the bark seams of willow branches or in the ground litter layer, and the overwintering larvae began to harm the newly developed leaves of poplar and willow in the middle and late April of the following year. During the feeding process, it was found that host volatiles were one of the necessary conditions for the normal hatching of Stilphotia candida Staudinger eggs, and the eggs could develop normally without the stimulation of host volatiles, but the larvae could not be hatched. Through the separate feeding of willow leaves, it was found that the larval stage of Beijing poplar leaves was significantly shorter than that of white willow leaves, and the survival rate of larvae was higher. Most of the Stilphotia candida Staudinger adults emerged at night and mate in the early morning of the next day, and the mating time was as long as 11-17 hours. At natural temperature conditions, the measured egg stage, larval stage and pupal stage, male/female adult period were 20.17±2.34 d, 44.03±4.00 d, 9.67±1.81 d and 5.7 ±0.84 /4.9±0.94 d, respectively.