Insect populations falling at dramatic rate ****************************************************************************************** * Insect populations falling at alarming rate ****************************************************************************************** More and more analysis is pointing to a dramatic drop in insect populations in Europe and A long-term study in neighbouring Germany, for example, suggests that flying insect popula alarmingly by more than 75 percent over the last three decades. Are we on the cusp of extinction of various insect species? And, if so, what can be done t downward trend? Those were questions I put to Dr. Petr Šípek a specialist at the Department of Zoology at University’s Faculty of Science. There is something like 10 quintillion insects on the planet and about one million species (10 followed by 18 zeroes)! “Ordinarily people don’t think about insects or realize that there are so many and that th diverse group of multi-cellular organisms. But we find insects in most ecosystems with the marine and saltwater systems; otherwise they are present almost everywhere and usually in Despite the numbers, various scientific studies around the world are seeing evidence that populations are largely on the decline. And the drop according to many indicators is not t significant to alarming, depending on who you ask. “It is very difficult to map insect populations in general; you mentioned one million spec estimated that another 5 – 7 million which have not been described and catalogued before n may never be or may disappear before we have a chance, with land conversion going extinct. enormous. “For a long time entomologists had a sense that things were changing but exact numbers are You can count the number of butterflies on a meadow but it is very hard to estimate popula there is evidence now of big changes: there has been a huge decrease in insect populations longer possible to ignore]. “In daily life, you can notice that there are fewer insects around than in the 1980s and 1 fewer of them flying around and you have to wipe the windshield of your car far less often the case…” Not as many are ending up splattered against the glass! “There are also indirect indicators of the change, specifically of populations of insect f ecosystems. If their primary food sources drop, their own population numbers suffer. There in the Czech Republic conducted by the Czech Society for Ornithology and scientists from C such as Jiří Reif and colleagues. They discovered that since 2004 there was around a 40 pe common species among common agricultural farmland birds. And that is quite a lot.” We will talk more about the aspects of the negative impact but before we do, I would like study in Germany from 2017, which surveyed developments for 30 years. It measured flying i three decades and is now referenced in report after report. “The funny thing about that is that scientists did not set out to estimate the biomass of and that was a side-product of their work. They monitored the situation over 30 years and afterwards what they had in terms of data. The samples were unsorted and nobody really kne at first but after all that time they realised they could count the average biomass of fly caught per day and according to that they could estimate how many flying insects there wer “What they uncovered was remarkable: that there was a decrease of 2.5 percent per year. Th term trend and this was not a situation with peaks and valleys but a continuous decrease. took place at small scale nature reservations so I think it reflected changes to the broad countryside and the impact of that.” What are some of factors that are likely to have contributed to the population decrease? “The German scientists were not able to point to a single factor but said it could be the several, including what is known as extinction depth, which means it could be related to c landscape that took place 10 or 20 years before. That makes it trickier to make clear conn be difficult to link extinction to the changes but it can reflect things that happened 20 before.” The visible effect was staggered… “Yes. That is correct. And for that reason, in this study, scientists were not able to see had had an influence. “That said, progress has been made: very recently there was analysis published in Biologic in which the authors (having surveyed or studied some 600 long-term studies monitoring ins focussing most on around 80 or 90 of those) outlined four major causes. The first is the i of agriculture and the conversion of land for agricultural use; the second was pollution ( everyday pollution or from agricultural pollution in the form of pesticides and fertiliser was biological reasons (such as the impact of new incoming invasive species), and the four change. “Members of the public often think climate change is a greater culprit, and it can be, but cases where it paradoxically help some species to survive. At least in Central Europe. War have seen some insects rebound or return after being driven off by land conversion. Some a an acceptable habitat again. The same is not true for mountainous areas. Animals there are habitats because vegetation is shifting: insects that have been hard hit include bumblebee is also having an impact in tropical areas but that is still not yet fully understood.” Extinction, we should perhaps also point out, is also part of the natural cycle, isn’t it? “That is certainly true but that is not the case here: this is not about natural extinctio falling too fast. Common species are vanishing and this is not really a natural process. S course go extinct but usually this is a very slow process. and what we see there is an evo old species Sso we cannot say that what is happening is due to natural extinction. In fact opposite.” You mentioned the fewer bugs splattered on the windshield: many people on their picnic or don’t mind if there are fewer wasps or certain bugs but that doesn’t do justice to the ser situation. The role insects play in the food chain that can have a much broader effect… “Insects may seem marginal in our eyes but you have to take into consideration the enormou Their role in the evolution of flowers and flowering plants, blossoms, was a joint work. I that 80 percent of plant species are pollinated by insects so their role is massively impo lose the pollinators then clearly there will be an impact on the ecosystem. “Then you have insects that prey on other species so if you lose the natural threat, pests unchecked. It is about maintaining a balance: if you lose predators new pests arrive easil they are among the most adaptable. “The degradation of organic matter is another area where insects play a crucial role: with students we did tests in the field where we left dead mice. In the spring, these mice are percent of case by burying beetles. If they are not, they are decomposed by flies; as each grams, can host around 70 larvae of Calliphoridae flies, which – in the next generation – produce 400 eggs each. “If you lose the control element of the burying beetles, you risk in the summer and next s higher fly population. These are links that we can now uncover bit by bit. The general rol by insects is difficult to gauge, because each have their place or have a different role w habitat.” Will we humans feel the bite, for example, in food production, when a key insect species d “I think so. We see it already, with the problems faced by honeybee producers. This has an and we have seen large turmoil about colony collapse disorder which has affected bees in N also in Europe and the costs can be tabulated. You cannot have production without pollinat grow apples in your orchards without them. So the impact is being felt. When a natural pre it has an effect and producers then have to use more chemicals against destructive insects Generally-speaking, does it mean in the future that there will be less variety in species “There may be less variety and there will be a greater evenness of biodiversity around the fewer insects that will be endemic to only some areas. But we will lose local assemblages diversity. The make-up of insects from ecosystem to ecosystem will be much more alike, whe talking about insects here, the US, or France.” I guess that the big “If” now is what we can actually do to change the trend. I suppose th a big difference between government or internationally-funded projects which might provide between small things each of us or citizen scientists can do… “Certainly we can start with ourselves and there are small things each of us can do to hel can help create microhabitats if you have a garden or country cottage, not just insect hot ponds without fish and generally looking after our countryside in ways that create diversi you have across Europe is huge agricultural areas and areas that are neglected – land no o And that’s bad, especially if you consider that all of the landscape and forestland and me careful created and tended to for centuries. “So the management of deserted areas can help insects too. We recreated nature around us a abandon parts now that is a prime setting for invasive species. We need to tend to areas a them be overrun. We have to create good conditions. Grass can be cut in a way that helps i promotes biodiversity and heterogeneity. “Then, agricultural firms, forestry companies and aquaculture, need to realise they have a too: they too are landscape engineers. They carry responsibility not only for food product an impact on how landscape functions. They need to accept that and help look for solutions “Each of us can also exert pressure that we want the problem to be taken seriously. A lot going on now, people are signing petitions and various organisations are focussing on the need to find a balance between economic and ecological concerns, namely a healthy environm support us and other living creatures. Education of course helps and a biennial exhibition proven enormously popular among schoolchildren – who are fascinated by insects the more th