Florivory and pollinator visitation: a cautionary tale.

Area of Science:

• Ecology
• Plant-pollinator interactions
• Behavioral ecology

Background:

• Florivory, the consumption of flowers by herbivores, can negatively impact plant reproductive success by reducing pollinator attraction.
• The direct causal link between florivory and pollination success is not well-established, as few studies integrate observational and experimental approaches.
• Understanding this relationship is crucial for plant fitness and ecosystem dynamics.

Purpose of the Study:

• To investigate the causal relationship between florivory and pollinator visitation in the hummingbird-pollinated sticky monkeyflower (Mimulus aurantiacus).
• To assess whether artificial floral damage affects indicators of pollinator activity, specifically stigma closure and microbial presence in nectar.
• To determine the relative importance of florivory versus flower location in influencing pollinator visitation.

Main Methods:

• Conducted field observations across eight sites in northern California.
• Performed field experiments involving artificial damage to Mimulus aurantiacus flowers.
• Utilized stigma closure and microbial detection in floral nectar as proxies for pollinator visitation.

Main Results:

• Field observations indicated a lower frequency of stigma closure in naturally damaged flowers compared to intact flowers.
• Experimental floral damage did not significantly alter stigma closure rates or microbial presence in nectar.
• Both damaged and intact flowers, as well as neighboring flowers, showed similar levels for the measured indicators.

Conclusions:

• The negative association observed between florivory and pollination in field observations is likely not causal.
• Floral damage does not appear to be a primary driver of reduced pollinator visitation in this system.
• Flower spatial arrangement and location are more significant factors than florivory in determining pollinator visitation for Mimulus aurantiacus.