The following essay is reprinted with permission from The Conversation, an online publication covering the latest research.
Are we facing insect Armageddon? A recent study found that German nature reserves have seen a 75% reduction in flying insects over the last 27 years. The researchers involved made stark warnings that this indicated a wider collapse of the general insect population that would bring about an ecological catastrophe if left unchecked.
But is this an over-dramatisation of a single study in one country, or is there some real cause for concern? Here we answer five questions about how important this result is and whether we should be worried.
Does it matter if insect populations decrease?
The idea of going out on a beautiful afternoon for a picnic and not having any wasps buzzing around might sound actually quite appealing, so why worry about insect decline? Well, besides annoying us, insects are a key link in many food chains. They are the main resources for many birds, small mammals, reptiles and other creatures.
They are also key for human food production, since many of our crops depend on insects for the pollination that leads to fruit and seed production. And insects play a very important role in decomposing organic matter, which allows nutrients to return to the soil and support the next year’s crops. So, in terms of insect’s ecological importance, a sharp decline in their abundance should be of great concern.
Can we trust the methods of this study?
Different from previous studies, this study monitored insect biomass. What this means is that we do not know what specific kinds of insects are declining (although the data collected will allow this analysis in the future). Nor do we know if all kinds of insects are declining equally. We also do not know if the problem is that insects are getting smaller or whether there are fewer of them.
But this approach provides a better estimate of the scale of the problem, even if it doesn’t show the specific details. For example, whether the insects are getting smaller or fewer in number, the decline would have just as big an impact on bird diets. Previous studies looked mostly at one particular group of insects, and an argument about why a particular group was at risk overshadows the bigger question of whether this is a general problem. The new study suggests there is a very large, general problem.
Are the results reliable?
The study is the result of a collaboration with the Entomological Society of Krefeld – essentially made up of members of the public. This is a perfect demonstration of how we can collect much more data by involving interested members of the public, also known as “citizen science”.
Under current research funding models that usually only consider projects between one and five years in length, it’s not possible to run a university-based study for a project on this scale (64 locations over 27 years). So without the dedication of insect enthusiasts, we would not even know about this problem.
The data analysis was supported by a very good team of university scientists, so there should be no concern about the results. Instead we should consider whether the current funding models for research and the focus this creates can miss some crucial aspects of ecological science that have potentially very detrimental effects.
What does a study in Germany mean to the rest of the world?
There are no comparable studies in other countries so any discussion of whether the results are applicable elsewhere would be purely speculative. This is especially true because we don’t know the cause of the decline.
But there is plenty of evidence that supports the idea that insect populations are under threat globally. For example a 2014 study indicated a 45% decline in insect abundance on the majority of the worldwide monitored locations.
What is the reason for the decline?
The main problem with this study is that it does not help us find possible causes for such drastic decline. The researchers considered some aspects of vegetation and some climate variables, and neither seemed to be the main cause.
The fact that the decline was observed in nature reserves is particularly worrying, since it suggests that the decline might be even worse elsewhere. And the fact that we can detect the decline over a number of different reserves suggests that the cause isn’t just a localised event.
Possible answers include the industrial scale use of pesticides (which might not be as safe as previously thought, or the increase in farms dedicated to a single crop and deforestation that is associated with this (which may not sustain as many insect species). The next step is to work out exactly what’s going on so we can attempt to reverse this worrying trend.