Dr Nigel Raine

Research interests

Overview of current research

Research in my group has three main themes: (i) the impacts of pesticides on bees, (ii) cognitive ecology of insects and (iii) pollination ecology. Whilst current research is focused on bees, I have also worked on ant-plant interactions in the neotropics. My googlescholar page can be found here.

Impacts of pesticides on bees

Understanding, and ameliorating, the causes of global bee declines has important consequences for the pollination of food crops and wild flowers. Our reliance on agricultural chemicals (e.g. pesticides) to boost crop quality and yield is one environmental stressor that could have a significant detrimental impact on both wild and managed bees. Pesticides act on insects by disrupting the normal flow of information through the nervous system, so even when applied at levels that are not fatal it is likely that they could affect behaviour. Such sublethal behavioural effects will happen in beneficial insects (e.g. pollinators) as well as insect pests. Furthermore, widespread agricultural intensification means that bees are exposed to numerous pesticides when foraging, leading to a key question that my research aims to answer: how is field relevant exposure to multiple pesticides affecting the behaviour of individual bees and therefore (in social species) colony function?

In a recent high profile study my lab showed that chronic exposure of bumblebees to two pesticides impairs natural foraging behaviour and increases worker mortality leading to significant reductions in brood development and colony success (Gill et al. 2012 Nature 491:105-108). Using radio frequency identification (RFID) tagging technology to track the behaviour of over 1000 individuals we showed that the foraging performance of pesticide exposed bees was significantly reduced, with important knock-on effects for forager recruitment, worker losses and overall worker productivity. A short video outlining the wider significance of these results can be seen here.

Cognitive Ecology

I am interested in how (or indeed if) the cognitive abilities of animals are adapted to their environment. The fact that individuals within a population can differ widely in their cognitive capacities despite apparently operating in the same environment has lead me to examine the costs and benefits of this behavioural variation. I use bumblebees as my model system as they face complex cognitive tasks everyday when making foraging decisions about which flowers to visit in nature’s dynamic pollination market.

Foraging bees use a variety of cues, including floral colour, pattern and scent, to recognize, discriminate and learn the flowers from which they collect food. As bees naturally forage in an environment in which the most rewarding flower type often changes, it seems likely that bees which learn quickly have the flexibility to keep track of the most rewarding flowers. Bees also need to learn the locations of their nest, flower patches they visit, and major landmarks in their environment. Therefore they must continually update the routes they follow as the flowers in bloom change over time.

Bumblebee (Bombus terrestris) queen collecting pollen from Galega officinalis flowers

Over more than a decade dedicated to working with bees, I have had a rare opportunity to develop my understanding of their behaviour, ecology and natural history. My approach to investigating the adaptive significance of behavioural traits is to link laboratory experiments quantifying trait variation under controlled conditions with the variation in task performance shown by the same bee colonies under field conditions. Such detailed observation of bee behaviour involves marking bees so we can recognise each individual. This can be done using individually numbered bee tags (see photo right), or with Radio Frequency Identification (RFID) tags (like London Transport Oyster cards). Once we can identify individual animals we can reliably observe how their behaviour changes with experience (as a result of learning).

Individually marked bumblebee (Bombus terrestris) worker visiting a gorse flower

Pollination Ecology

I am fascinated by the complex evolutionary ecology of plant-pollinator interactions, specifically how pollination systems have evolved to reduce the incidence of ‘unproductive’ pollen flow between species. During my DPhil I used pollination as a model system to investigate how competitive interactions might facilitate niche partitioning at the community level. I examined how Acacia trees modify both spatial and temporal patterns of floral reward presentation with an emphasis on what impact such patterning might have both on pollinator behaviour and the overlap of shared pollinator guilds amongst tree species.

Bumblebees (Bombus terrestris) visiting Salvia nemorosa flowers

Ant-plant Interactions

Ants regularly form associations with plants which vary from opportunistic short-term interactions to life-long obligate mutualistic relationships. I am interested in the conflict and co-operation that occur in ant-plant systems. Particularly how ant-acacias resolve potential ant-pollinator conflicts with repellents, and how some ant species appear to cheat their host plant by not guarding it against herbivores.

Pseudomyrmex flavicornis ants guarding their host plant Acacia collinsii against herbivore damage.

 

Research Group

Current

Dr Dara Stanley (Postdoctoral Research Associate, Insect Pollinator Initiative)

Oscar Ramos-Rodriguez (Research Technician, Insect Pollinator Initiative)

Gemma Baron (PhD Student)

Lisa Evans (PhD Student)

Karen Smith (PhD Student)

Dylan Smith (MSc Student)

 

Alumni

Dr Richard Gill (now Lecturer in Ecology at Imperial College)

Robert Mitton (MSc Student)

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