Behavioural mechanisms underlying food-deceptive pollination and neonicotinoid exposure of bumblebees

Thesis event information

Date and time of the thesis defence

Place of the thesis defence

Oulanka Research Station, lecture hall. Remote access: https://oulu.zoom.us/j/66273802252

Topic of the dissertation

Behavioural mechanisms underlying food-deceptive pollination and neonicotinoid exposure of bumblebees

Doctoral candidate

Master of Science Juho Lämsä

Faculty and unit

University of Oulu Graduate School, Faculty of Science, Ecology and Genetics Research Unit

Subject of study

Ecology

Opponent

Professor Jeff Ollerton, University of Northampton

Custos

Docent Olli Loukola, University of Oulu

Add event to calendar

Plant - pollinator interactions: how bumblebees help deceptive plants and respond to neonicotinoids

Pollination is often used as a classic example of mutualism. However, not all plants produce any food reward for their pollinators. Such non-rewarding pollination strategies are called pollinator deception, as plants take advantage of innate and learned sensory traits that interest their pollinators. Pollinator deception has evolved several times in different plant lineages but reduces the seed production in relation to rewarding plant species. In this thesis I aimed to find out possible advantages of pollinator deception for plants.

My results show that on natural populations of deceptive plant Calypso bulbosa, pollination success is best when local populations are small and distances between individual plants are long - opposite to rewarding plants. I also studied bumblebee behaviour by developing a computer controlled robotic flower system with automatic data collection via motion detectors. Studying bumblebee foraging patterns in an indoors flight arena using the robotic flower system, I found out that pollinator deception increases outcrossing especially when plants are scattered on isolated patches. Due to bumblebee foraging behaviour, inbreeding depression is a serious risk for regular rewarding plants on such patchy habitats.

During my experiments, I became interested in a timely question related to pollination, the inadvertent effects of neonicotinoid pesticides on pollinator behaviour. My results show that bumblebee’s foraging motivation reduces before any effects on physical performance or learning abilities appear. Such reduction in foraging motivation could partly explain bee pollinator decline, as similar concentrations of neonicotinoids as were used in the study are commonly measured from plant nectar and pollen in agriculturally intensive regions. My results also show that when evaluating the effects of neonicotinoids on non-target species, a lack of detectable effects on physical performance cannot be viewed as evidence that the current practices have little or no impact on bee foraging.
Last updated: 29.6.2021