Open Collections

Modelling the effects of landscape, behaviour, and population on bumble bee crop pollination services

University of British Columbia

Experimental and observational studies have shown that wildflower enhancements near crops can, but may not always, increase the pollination services that wild bees provide to the crops. However, the effects of spatial landscape structure, behavioural mechanisms, and wild bee population growth on pollination services are not well understood. Bee behaviours and crop pollination services are generally studied in isolation from one another. The majority of field studies that study pollination services have focused on counting pollinator populations rather than quantifying the number of flowers visited or providing other measures of crop specific pollination services, while behavioural studies focus on the behaviours of bees and do not consider their effects in pollinating flowers. Most modelling-based studies focus on how the wildflower plantings affect bee populations or provide very general indicators of pollination services, such a bee densities. In this thesis, I take an individual based modelling approach, developing a model that uses wild bumble bee flight patterns and foraging behaviour, incorporates memory, and allows for flower type preference, to measure bumble bee visits to flowers. I additionally use the Bee-Steward model to introduce the effect of population dynamics, and develop a Markov chain model to explore parameter estimation and the pitfalls that arise when attempting to fit models when data are scant. With these models, I simulate and analyze bumble bee movement and flower visits across simple landscapes with a single crop field and a single wildflower enhancement, as well as larger more complex landscapes with randomly generated crop fields and areas of wild flowers. I find that the spatial structure of the landscape has a significant effect on the pollination services delivered to the crops, that the mechanism by which bees select foraging sites can have a significant effect on crop pollination services, and that population growth can be responsible for increased pollination services, even in the absence of any changes in individual bee foraging behaviour.

Text

2020-08-12

Attribution-NonCommercial-NoDerivatives 4.0 International

http://hdl.handle.net/2429/75499

Mathematics

University of British Columbia

UBCO

http://creativecommons.org/licenses/by-nc-nd/4.0/