Pollinator-mediated interactions

What determines whether plants will help or harm each other’s pollination?


Holocarpha virgata, the species used in Prof. Essenberg’s studies of effects of flower density on flower visitation

A wealth of studies on the effects of plants on one another’s pollination, both within and between plant species, shows that these effects are often strong but vary greatly, making it difficult to predict whether plants will help or harm one another.  Prof. Essenberg’s work prior to coming to Bates focused on how flower visitors respond to flower density and helps to explain the variation in how plants influence pollination success of other members of their own species.  You can read about that work in the following publications:

Essenberg, C. J. 2012. Explaining variation in the effect of floral density on pollinator visitation. American Naturalist 180(2): 153-166.

Essenberg, C. J. 2013. Scale-dependent shifts in the species composition of flower visitors with changing floral density. Oecologia 171(1): 187-196.

Essenberg, C. J. 2013. Explaining the effects of floral density on flower visitor species composition. American Naturalist 181(3): 344-356.

Students in Prof. Essenberg’s lab at Bates have explored how plants influence the pollination of other species growing near them.  Bates student Emma Katz used a lab experiment to investigate how the spatial dispersion of two plant species, one of them with rewardless flowers (a deceptive strategy seen in many wild plants, particularly in the orchid family), would influence the rewardless species’ interactions with bumblebee pollinators.  She found that the rewardless species received the most visits when its flowers were intermingled with those of a rewarding species.  However, these higher visitation rates came at a cost: bees switched between species frequently when they were intermingled, which could be detrimental to both plant species.  You can read about her work here:

Katz, E. J. and C. J. Essenberg. 2018.  The effect of the dispersion of rewarding and rewardless flowers on visitation and constancy by bumblebees.  Journal of Pollination Ecology 23(13): 119-126.

We are also interested in how the cues presented by flowers influence how plant species interact and have ongoing work in that area.  If you are a Bates student and find these questions interesting, Prof. Essenberg would love to talk with you about them!

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Bee entering an artificial flower during an experiment exploring how floral cues influence the effects flowers of different species could have on each other’s pollination