LB 25-265 - Reduction in operative strength of staminodes maintains the neutral effect of nectar robbing on reproductive success of Delphinium caeruleum (Ranunculaceae)

Thursday, August 18, 2022

5:00 PM – 6:30 PM EDT

Located in: ESA Exhibit Hall

Presenting Author(s)

QH

Qin-Zheng Hou

College of Life Sciences, Northwest Normal University, China (People's Republic)

Coauthor(s)

TW

Tai-hong Wang

College of Life Sciences, Northwest Normal University, China (People's Republic)
GY

Guang Yang

College of Life Sciences, Northwest Normal University, China (People's Republic)
WS

Wen-juan Shao

College of Life Sciences, Northwest Normal University, China (People's Republic)

Background/Question/Methods:

Nectar robbers, who are frequently described as cheaters in plant-pollinator mutualism, obtain nectar reward without providing pollination service, which affects plant reproductive fitness. The negative effects of nectar robbing on plant reproductive success have been widely reported, but the reasons for neutral effects remain needing further investigation. The target of our study was to evaluate the effects of nectar robbing on the reproductive success of Delphinium caeruleum. Two staminodes cover the stamens and pistils in D. caeruleum forming a “double door” type of structure which compels pollinators to open the “double door” to visit flowers. In order to explore whether the operative strength required to open staminodes is affected by nectar robbing, we used a sensor to measure and compare the operative strength required to open staminodes in both robbed flowers and non-robbed flowers. Furthermore, we assessed the effect of nectar robbing on flower visiting behavior, flower handling time and flower visiting rate of visitors in the field. Finally, we detect the effect of nectar robbing on pollen export, pollen deposition and seed set rate to estimate the effect of nectar robbing on reproduction success.

Results/Conclusions:

The results showed that the operative strength needed to open staminodes in robbed flowers was significantly lower than that in non-robbed flowers. The flower visiting behaviors and flower handling time of visitors were not significantly affected by nectar robbing, but we found a clue that the flower visiting rate of visitors decreased which was affected by nectar robbing. Both the pollen export and pollen deposition in robbed flowers were significantly higher than non-robbed flowers, however the seed set rate had no significant differences between robber flowers and non-robbed flowers. Our results demonstrate that nectar robbing did not affect reproductive success because the reduction in operative strength required to open staminodes maintained the neutral effect of nectar robbing on reproductive success by increasing male reproductive fitness. The reduction in operative strength required to open staminodes might be a defense mechanism which responds to nectar robbing.