Abstract: 【Aim】 The litchi fruit borer, Conopomorpha sinensis Bradley, is the most serious pest of litchi and logan in China. The objective of this study is to determine the number of larval instars of C. sinensis and the developmental duration of each stage at different temperatures. 【Methods】 The head capsule width of C. sinensis larvae was measured to determine the number of larval instars. The developmental duration of each stage at 17-38℃ was determined in the laboratory via artificial rearing, and the correlation between developmental rate and temperature was analyzed through the linear regression model. 【Results】The results in the frequency histogram of the head capsule width showed that the frequency istribution could be obviously divided into 5 areas, suggesting that C. sinensis has five larval instars, which follows the Dyar’s law. The average head capsule width of the 1st-5th instar larvae was 0.105, 0.170, 0.265, 0.435 and 0.652 mm, respectively. Temperature had significant effects on the developmental duration of egg, larva and pupa, and their durations all reduced with increasing temperatures, while the correlation between the developmental rate and temperature fitted with the linear regression model. C. sinensis could complete a whole generation from 20 to 32℃, but the larvae only developed to the 3rd instar at 17℃, few pupae could complete eclosion at 35℃ and few eggs could hatch at 38℃. The duration of one life cycle, pupa and preoviposition was 41.16-19.34, 12.74-5.35 and 4.75-4.22 d, respectively. However, temperature had no effect on the preoviposition period. Appropriate living temperature for C. sinensis larvae was from 20 to 35℃. The duration of the 1st, 2nd, 3rd, 4th and 5th instar larva and prepupa at 20-32℃ was 4.50-1.17, 2.09-1.40, 2.84-1.00, 3.41-1.18, 3.00-1.37 and 2.41-0.69 d, respectively. The egg could normally hatch at temperatures from 17-35℃, and its duration was 7.73-2.09 d. 【Conclusion】 C. sinensis has five larval instars instead of four instars reported in the previous research. Within the temperature range of 20-32℃, the durations of egg, each instar larva and pupa reduce with increasing temperatures. These results will provide data support for the forecast of C. sinensis.

Key words: Conopomorpha sinensis, larvae, instars, temperature, developmental duration