Morphological indicators of the larval instars and developmental duration of Phenolia picta
Author of the article:LI Li-Li1** TIAN Su-Su2 CHI Bao-Jie2 SU Fang-Hui1,3 MEN Xing-Yuan1 WANG Yan-Shu4 GUO Wen-Xiu1 SONG Ying-Ying1 CUI Hong-Ying1 Lü Su-Hong1
Author's Workplace：1. Shandong Branch of the National Center for Agricultural Biosafety Sciences, Shandong Key Laboratory for Green Prevention and Control of Agricultural Pests, Institute of Plant Protection, Shandong Academy of Agricultural Sciences, Jinan 250100, China; 2. Shandong College of Agriculture and Engineering, Jinan 250100, China; 3. College of Plant Protection, Shandong Agricultural University, Tai'an 271018, China; 4. Linyi Agricultural Technology Service and Extension Center, Linyi 276000, China
Key Words：Phenolia picta; larval instar; head capsule width; developmental period
Abstract：[Aim] To identify morphological indicators of the larval instars and developmental duration of Phenolia picta, a new pest of fruit trees in China, and thereby provide a basis for the prediction, forecast and control of this pest. [Methods] The head capsule width, body length and body width of each larval instar of P. picta were measured in a laboratory. Based on the frequency distribution results for each index, Crosby’s growth rule and linear regression analysis were used to identify instar classification criteria. The developmental durations of different insect life-stages were determined simultaneously. [Results] The head capsule width of P. picta was trimodal with three distinct ranges: 414.42-513.79 μm, 746.81-876.60 μm and 1 106.38-1 270.21 μm. No overlap was observed between adjacent instars, and there was a significant linear relationship between head capsule width and instar. At room temperature, the complete development of P. picta from egg to adult required 42.32±10.14 days, including an egg stage of 4.53±0.99 days, a larval stage of (18.20±5.02) d [1st instar: (3.44 ± 0.75) d, 2nd instar: (2.86 ± 0.45) d, 3rd instar: (11.90 ± 3.82) d), prepupal and pupal stages of (8.88 ± 2.27) d and (10.71 ± 1.86) d, respectively, and an adult stage of (62.80 ± 3.81) d. [Conclusion] The larval instars of P. picta can be identified on the basis of head capsule width. The complete development of P. picta from egg to adult requires 42.32 d, and the adult lifespan is 62.80 d. These results provide a basis for the identification of the larval instars of P. picta in the field, and forecasting outbreaks of this pest.