Abstract: 【Aim】 The jackfruit borer, Diaphania caesalis, is an important boring pest for tropical woody grain crop, Artocarpus heterophyllus, and seriously threats the development of jackfruit industry in hotspot. This study aims to clarify the biological characteristics and field population dynamics of D. caesalis and to provide a theoretical basis for the accurate prediction and efficient management of this pest. 【Methods】 The morphological characteristics, developmental duration and fecundity of various developmental stages of D. caesalis feeding on jackfruit leaves were observed under the room conditions of 26±1℃, RH 70％±5% and a photoperiod of 14L∶10D. The annual life cycle of D. caesalis was observed in the natural netting room. The host diversity of D. caesalis was assessed by selective and non-selective tests. The population dynamics of D. caesalis in Qiongzhong County, Hainan Province were measured during January-December, 2018 by systematic field investigation. 【Results】 The durations of egg, larval, pupal, prepupal and adult stages of D. caesalis were 4.58±0.50, 21.00±1.36, 2.50±0.51, 10.20±0.53 and 12.31±3.16 d, respectively. The average generation duration was 50.50±3.54 d. The main morphological characteristics of each stage were as follows: egg, elliptic with a reticulate surface; larva, yellowish-brown and becoming white before pupation, ecdysial suture shown as inverted “Y” shape; pupa, reddish brown, the legs and wings reaching to the 5th abdominal segment; adult, wheat yellow, fore wing with melon seed- and tower-shaped spots. The female adult laid eggs multiple times, and the egg-laying amount of a female was 147.25±84.24. The larvae showed a significant preference for A. heterophyllus, A. champeden and A. altilis. Observation results in the laboratory and natural netting room revealed that D. caesalis occur 8 generations per year in Hainan province. The results of field investigation during January-December, 2018 revealed that the population increased from March to July, reached the peak from late July to September, began to decline after October and remained at a low level until February of the following year. 【Conclusion】 D. caesalis is an oligophagous insect and can reproduce fertile offspring on jackfruit leaves. The 5th generation appears from July to September, during which the population of this insect reaches the peak in Hainan. So the key period for precise management is the adult stage of the 4th generation, i.e., from July to August.

Key words: Diaphania caesalis, morphological characteristics, developmental duration, life cycle, fecundity, population dynamics