Pollinator decline debate Part 2- Is there a crisis?

Image: Pixabay

In Part 1 of this topic, we discussed a 2016 paper highlighting that non-bee pollinators have a significant role to play in pollination, as opposed to the conventional view that bees pollinate flowers and that’s largely it. However, as I’m going to discuss this time, there are some in the scientific community who think that labelling a ‘bee decline’ is premature. One example of this would be Jaboury Ghazoul- then a professor of Ecosystem Management at ETH Zurich- who published a review paper on the subject in ‘Trends in Ecology and Evolution’ back in 2005. There’s a link to the abstract of the paper here.

Ghazoul noted that many of the world’s staple crops, such as cereals or potatoes, do not rely on animal pollination at all, instead being wind pollinated or not requiring pollination in the first place. Instead, most of the crops that needed to be pollinated were high value-per-unit commodities, which would shift the apparent economic importance of bee declines and distort our picture.

Second of all, he argued that reports of a pollination crisis were mainly driven by reports of honeybees declining in North America, or the decline of bumblebees/butterflies in Europe. By contrast, he argued that the response of native pollinators to climate change has been mixed rather than a universal decline as is often portrayed.

This does not mean, Ghazoul’s reasoning goes, that there isn’t a real threat. However, his argument was that labelling a pollination crisis was premature and that research efforts should instead focus on preventing such a decline rather than panicking about one.

Now, I am not a professional pollination ecologist, so it’s very difficult for me to say what the exact nature and extent of the pollination crisis is. However, in a media which is usually dominated by the narrative of bee declines, it’s interesting to note that there are voices of dissention within the scientific community. The question, it seems, has not been settled yet in the minds of some.

Pollinator decline debate Part 1- Non-bee pollinators

Image: Pixabay

Bee declines are prevalent in the modern news and it is an issue which many people feel strongly about. The worry is that pollination services and thus the economy will suffer if bees are not able to carry out their job- as was highlighted to me as a child in the Bee Movie. However, how real is the threat? In this first part of a series, I’m going to discuss a 2016 paper by Rader et al., which argues that we might be overlooking something crucial- namely, non-bee pollinators.

This review paper synthesised 39 individual studies across five continents. Rader et al. found that, on the whole, non-bee pollinators make a pretty sizeable contribution; non-bees provided about 38% of visits to all crops. In addition, non-bees seemed to be more robust when it came to landscape change. The number of bee visits declined sharply, while this decrease was not as marked for non-bees.

Although non-bee species were found to deposit less pollen per visit and were thereby less efficient, they compensated for this by having a high proportion of visits than bees did, meaning that on the whole this limitation was cancelled out.

However, the study does have its limitations. For example, it specifically focuses on non-bee insects and does not consider other pollinators such as hummingbirds or bats at all.

So, what do these findings mean? The authors emphasise that the reliance of the modern world on one or a few pollinators is an inherently fragile situation. This makes logical sense; if you hypothetically rely on one species, your prospects don’t look great if that species becomes threatened in any way. This warning is likely to become increasingly relevant as the threat of climate change advances.