A practitioner’s perspective on what we know about safeguarding pollinators on farmland

By Chris Hartfield

Flowering margin with sprayer

Farmers understand the general importance of pollinators, and through their management of cropped land and non-cropped areas on the farm they have the potential to do more than any other group in the UK to help provide habitat and food for pollinating insects.

Pollinators are a continually topical issue for the media and policymakers, and against this challenging background it is not always clear what the best approaches are for farmers or land managers to take to protect and increase pollinators. What do we know about the state of pollinator populations on farmland in the UK? To what extent can the use of agri-environment measures, the maintenance and creation of other habitats, and the management of pesticide use, help protect and increase pollinator populations?

In 2014, I produced a ‘Farming for bees’ leaflet as a simple introduction to pollinators and what farmers could do to help them. It focused on providing wild pollinators with habitat and food. It also discussed taking particular care when using insecticides, and how to provide good apiary sites for managed honeybees. I want to update this guidance and so started to reflect on ‘what has changed?’. While a huge volume of research has been published in the last eight years, what do we know now that we can advise UK farmers about, beyond top-line messages about providing more habitat and food, and taking care with pesticide use? What actions can they take that are supported by a weight of evidence and are relevant to the UK farming context, and will have a clear measurable impact benefitting pollinators in and around farmed fields?

I explore these questions by providing a farming perspective on the evidence in these areas; reflecting on what the knowns and unknowns are, and identifying where there are still gaps in the evidence that need to be plugged to better conserve and manage pollinators on farmland. I also invite researchers and other stakeholders to input to this process, as it needs to be based on all the important evidence.

Farming can offer solutions to protect and increase UK pollinator populations, but to do this effectively we need clarity on the problem to solve, and confidence the solution will deliver benefits.

Read the scientific publication in JPE here!

 

Crop and landscape factors affecting variation in composition and behaviour of the pollinator community in field bean crops

 by Capstick et al.

A large proportion of crops are reliant, to some extent, on insects to pollinate them and produce seeds and/or fruit. The global decline in pollinators has implications for crop yield and quality, and it is important to understand how the number and species of pollinators present relates to crop yield.

Previous work has shown that field bean yield can be affected by the level of insect pollination, but yield is not always positively related to number or visitation of pollinators. We wanted to explore what factors affected insect pollination of field beans and how this related to yield. This could inform management to increase pollinators and pollination of field beans.

In this study we observed pollinators foraging in 13 field bean fields and measured the crop yield in these fields. We explored how these pollinators were affected by infield factors (sowing time and plant density) and the wider landscape (area of flower-rich habitat or area of field beans surrounding the focal field).

The pollinators we saw in the fields were mainly bumblebees and honeybees. The bees were either legitimately foraging or robbing nectar from the bean flowers. Foraging bees entered from the front of the flower taking both pollen and nectar, robbing bees made or found a hole in the back of flower and only took nectar. The former behaviour is much more effective at pollinating the field beans and can facilitate cross-pollination.

We found that bees differed in their behaviour depending on the type of bee. Long-tongued bumblebees were more likely to legitimately forage from the deep bell-shaped bean flowers whereas short-tongued bumblebees were more likely to rob nectar. Short-tongued bumblebees were also more likely to rob in winter sown crops.

The number of bees in the field bean fields was higher in the spring sown crops and in fields where there was a smaller area of field beans in the surrounding landscape. We didn’t find a relationship between the number of bees and the yield of the field beans. Contrary to our expectations we did find that when more bees were robbing in the field bean fields the yield was higher. 

Our results indicate that the effect of pollinators on field beans are variable and depend on wider context. Further research is needed to see how we can manage habitat and bean crops to increase the overall number of pollinators and the number legitimately foraging specifically. 

Read the scientific publication in JPE