Phenology Synchronization Between Carduus Crispus And Tephritis Hendeliana In Hongyuan And Songpan Sites: A Comparative Study

Phenological match is necessary for species interactions in natural ecosystems.Interacting species involving in predation,mutualism,parasitism,and competition ensure phenological match usually via similar responses to physical environments and/or eco-physiological signals among species.Thus,the change in physical environments(e.g.climate change)may change the phenological synchronization of interacting species.In northwestern Sichuan Province of China,the Tephritid fly Tephritis hendeliana infest the flowerheads of the curled thistle Carduus crispus.In the early growing season,the female flies lay eggs into the flowerheads,and the larvae hatched from the eggs consume the developing seeds and then pupate and emerge from the flowerheads.The flies have to lay the eggs before full flowering and have to fully developed before fruit dehiscence in order to successfully complete life histories.This study compared the phenological synchronization between the flies and plant flowering and fruiting in Hongyuan and Songpan sites.The mean annual temperature is 3.0? and annual precipitation is 753 mm in Hongyuan,while they are 6.4? and730 mm,respectively,in Songpan.I investigated the flowering and fruiting phenology for both the thistle population and individual plants,the growth and development rate for the flies,and the infestation rate of the plants by the flies.The investigation frequency was once per 3-7 days.Subsequently,we compared the difference in the phenological synchronization between the flies and plant flowering and fruiting in Hongyuan and Songpan.The major results are shown as follows.The beginning time of flowering was later for 6.0 days in Hongyuan than Songpan population.The flowering stage and fruiting stage of a single capitulum last for 5.1 days and 16.2 days in Hongyuan,whereas they were 4.3 days and 12.8 days,respectively,in Songpan,such that the duration of flowering and fruiting was longer for 4.2 days for a single capitulum in Hongyuan than Songpan.The body size of fly adults was indistinguishable between two sites,but the growth rate differed.Specifically,the time when plant capitula were first found to have pupae was later for 10 days in Hongyuan than Songpan.The pupae collected from Hongyuan plant capitula took 6.4 days longer to emerge in Hongyuan than Songpan,and similarly the pupae collected from Songpan plant capitula took 4.8 days longer to emerge in Hongyuan than Songpan,i.e.,the flies took4 days longer for the larvae to develop into the pupae in Hongyuan than that in Songpan.During the larval length was positively and linearly associated with seed length in the capitula,and also the larval length was positively and linearly associated capitulum flowering stage as reflected by the proportion of pistils protruding above capitulum surface.Our results show that there is a high phenological synchronization between the fly growth and plant flowering and fruiting time in both sites,despite the large difference in plant phenology and larval growth and development rate between sites.This synchronization may result from responses of phenotypic plasticity of the plants and flies to environmental changes and/or long-term coevolution between the plant and fly species.Our results imply that the parasitic relationship between the plants and flies can be maintained for the high-altitude population under the climate warming conditions.Future research may further explore the acclimation and adaptation of the plant-fly parasitic relationship by means of reciprocal transplanting of the plants-flies systems.