title: Relationships between body weight of overwintering larvae and supercooling capacity; diapause intensity and post-diapause reproductive potential in Chilo suppressalis Walker.
abstract: The rice stem borer, Chilo suppressalis Walker, overwinters in China as a larva in facultative diapause. The instars and body weights of overwintering larvae vary widely. In this paper, the relationships between body weight and supercooling capacity, diapause intensity and post-diapause reproductive potential of overwintering larvae collected in late-stage rice field were examined. There was a significant positive correlation between body weight, instar, and head capsule width, thus the overwintering larvae were divided into five groups based on body weight (I, up to 35.0mg; II, 35.1-57.0mg; III, 57.1-79.0mg; IV, 79.1-101.0mg; and V, over 101.1mg) for further analysis. The body water content of the lighter group (I) was significantly higher than that of the heavier groups (IV-V). However, the mean supercooling point decreased with an increase of the mean larval body weight in five groups; mean supercooling point of group I was significantly lower than that of group V, except in January 2009. After transfer of overwintering larvae to 15, 20 and 25°C on different dates, smaller individuals pupated slightly faster than larger ones at the same temperature, suggesting that diapause was less intense in smaller overwintering larvae. On 19 March 2009 there was a strong positive correlation between larval body weight and the weight of 3 day-old pupae, and the number of eggs carried by 2 day-old adult females at 15, 20 and 25°C. The average number of eggs carried by 2 day-old adult females differed significantly among different groups. The average number of eggs carried by 2 day-old adult females in group V was significantly greater than those of other groups, and that of group I was significantly lower than those of other groups, suggesting that post-diapause reproductive potential was determined, to a certain extent, by body weight of the overwintering larvae.
authors.affiliation: Hubei Insect Resources Utilization and Sustainable Pest Management Key Laboratory, College of Plant Science and Technology, Huazhong Agricultural University, Wuhan 430070, PR China.
authors.forename: Shu
authors.initials: S
authors.lastname: Xu
authors.forename: Ming-Liang
authors.initials: ML
authors.lastname: Wang
authors.forename: Nan
authors.initials: N
authors.lastname: Ding
authors.forename: Wei-Hua
authors.initials: WH
authors.lastname: Ma
authors.forename: Yan-Ning
authors.initials: YN
authors.lastname: Li
authors.forename: Chao-Liang
authors.initials: CL
authors.lastname: Lei
authors.forename: Xiao-Ping
authors.initials: XP
authors.lastname: Wang
mesh_terms: D000064:Acclimatization; D000818:Animals; D001834:Body Water / Q000737:chemistry; D001835:Body Weight; D002681:China; D003080:Cold Temperature; D007814:Larva; D008675:Metamorphosis, Biological; D009036:Moths / Q000502:physiology*; D012098:Reproduction