Pesticides Wiping The Memories of Our Bees

by Lucy Hagger

This year, evidence has mounted supporting the idea that neonicotinoid pesticides are contributing to the dramatic falls in bee populations over the last few decades. I have already written two posts regarding this matter. If you are interested feel free to give them a quick read as I won’t be going over too much of the stuff I included. The first can be f0und here and delves into what effects neonicotinoids are having on bees and other pollinating insects. The second summarises the results of the EU vote against the ban of these pesticides and can be found here.

The proposed ban of neonicotinoids was rejected when put forward to the European Commission on the 15th March this year. One of the main arguments presented by opposers of the ban, including the UK environmental secretary, Owen Paterson, was that more data and research was required supporting the idea that neonicotinoids are negatively impacting bees, before a ban could be properly considered.

There has been a lot of response to this, including  a recent evaluation by Department for Environment, Food and Rural Affairs (DEFRA). This report has suggested that neonicotinoids do not pose a serious threat to bees in a natural, real life setting. One of their main arguments is that the majority of the research that has been carried out has been done so in a lab based environment. They believe that the levels of neonicotinoids that most bees are exposed to in the wild are not comparable to those used in the lab based research and that the results are therefore over estimations.

This is a major punch in the face for supporters of the ban and researchers trying to investigate into this topic. With DEFRA being such a big name, it is likely that many people will be swayed due to this report. However, I have not.

This is a little irritating to me. Yes, a lot of the research was carried out in lab based environments, but I do not feel that this fact alone is enough to render these findings invalid. The huge majority of scientific work takes place in the most part in labs. Does this mean that all lab based work should be dismissed? NO.

The neonicotinoids are affecting bees and other pollinating insects in detrimental ways, whether that be in the lab or the field. It is likely that the lab setting may intensify these effects, but bees are being affected in the real world. Numbers are falling and something is causing that.

I found this very recent study published yesterday in Nature. This study is something different, it has lab AND field based experimentation. The researchers have shown that neonicotinoids actually impair the memory of bees which is impacting their ability to successfully forage and therefore pollinate the world’s plants. The study was led by Mary Palmer and her team and they state that it is known that neonicotinoids do impact bees, but that there is little empirical evidence to explain how and this needs to improve.

They successfully demonstrate how 2 neonicotinoids (imidacloprid and clothianidin) directly affect neuronal transmission within the nicotinic receptors in the brains of honey bees. They looked at the effects of neonicotinoids in bee Kenyon cells (KCs). KCs are neurons found in the brains of arthropods, including incsects. These KCs play an important role in learning and memory, particularly when it comes to smells.

The research team looked at the effects of sublethal levels of neonicotinoids on honeybees in the field and in the lab. They found in the lab group that the exposure led to a significant impairment of the bees’ abilities to learn and remember smells. This is particularly important as bees rely in part on the specific scents of certain flowers in their foraging and pollination behaviours. In the field, the neonicotinoids impair bees’ abilities to forage efficiently and navigate to and from the nest. Effects are being seen in the field.

These findings are worrying as they show that the levels of neonicotinoids that many bees are exposed to are impacting learning and foraging abilities. If bees cannot forage efficiently, then they cannot pollinate efficiently. This does not bode well for our already suffering global food security.

Another concerning finding is that these impacts are being exacerbated by other pesticides. This is very important as there is a lot of overlap in pesticide use and also regular switching of pesticides. This means that the majority of bees will be affected as they find themselves in ever increasingly common regions of extensive pesticide usage.

This study is great in showing an actual physiological change that results in the cells of bees in response to exposure to neonicotinoids. The use of research in a lab and field environment also helps with securing the accuracy and representativeness of their findings and reducing the opportunity to dismiss this important work. However, Mary Palmer and her team do state in the paper that improvements could be made. They explain that the cultured KCs do show marginally different levels of response to actual KCs and that future work could look into this disparity.

Regardless of the potential flaws, this study empirically shows neonicotinoids directly impacting bee learning and memory. I’m sure that this study will be just one of many similar studies appearing in the near future. The research is likely to be faced by a lot of opposition, with papers like the above being in the firing line of organisations who intend to undermine as much as possible.

This area is a hot topic and the demand for this type of research is ever increasing. Let’s hope that the methodology is a stringent as possible giving opposition very little excuse to dig their claws in and undermine very important work.