The extinction of insect species threatens all ecosystems on which humans depend
Scientists constantly emphasize that there is a great extinction crisis going on today. The current extinction, called the sixth mass extinction, is claimed to be as extensive and rapid as the five mass extinctions in the last 600 million years. In particular, the loss of tropical forest biodiversity affects the future regeneration of some important tropical forest plant species. Correspondingly, we are currently witnessing a major shift in the composition of flowers and the dynamics of many tropical forests around the world. Gross domestic product, which is created by the increasing human population and the consumption of more resources and energy, has increased by 460% in the last century and is expected to increase by another 240% by 2050. It is estimated that 109 hectares of the natural ecosystem will be converted into agricultural land by 2050. With pollution, habitat fragmentation, the impact of invasive alien organisms and global warming, the loss of biodiversity will continue to increase.
Among the lost biodiversity, insects are perhaps the least that comes to mind. Because, when people hear anything about insects, annoying insects such as cockroaches or mosquitoes come to their mind. The great difficulty in drawing attention to the extinction of insect species is this problem of perception. However, the presence of insects in ecosystems is too important to ignore. The extinction of insect species is not just the loss of a piece of the complex puzzle in ecosystems. It also means losing the biomass needed to feed other animals in the food chain. The break in the food pyramid will create a chain effect on the feeding of living things that are dependent on each other. In addition, the survival of plants in the ecosystem depends on pollination by insects. Apart from the destruction of ecosystems on which humans depend, we also lose unique genes or components that may one day contribute to curing diseases.
Insects are important for biodiversity
Insects are extremely successful organisms in terms of both species number and abundance. Insects develop important functional roles in terrestrial ecosystems as herbivores, pollinators, decomposers, predators and parasites. It is estimated that 50% of insects are herbivores. These insects accelerate the carbon and nitrogen cycles and contribute greatly to the transfer of energy within ecosystems. Although some insect species are agriculturally pest and disease vectors, the vast majority contribute positively to the world economy by serving the ecosystem and providing crops. Despite the ecological and evolutionary importance of insects for the last 300 million years, little attention has been paid to insect extinction.
Human activities are causing the collapse of many ecosystems. As ecosystems collapse, immeasurable insect extinctions occur. The biggest concern is probably the loss of tropical forests, where more than half of all insects live. Deforestation encourages weeds, invasive species and pathogens, which further fragment populations, reducing their chances of acting to survive climate change. As a result, problems such as intensive agriculture, climate change, urbanization, habitat loss, disease and the emergence of invasive species have triggered insect genocide by acting synergistically on insects. As can be seen, threats to insect fauna are often synergistic. If the loss of insect species is not stopped, this will have disastrous consequences for both the planet’s ecosystems and the survival of humanity.
Several studies have been published in the past years showing dramatic decreases in insect numbers over time. Significant declines in flying insect biomass have been suggested in nature reserves in West Germany (>75% reduction in 27 years), striking that we are in a ‘bug apocalypse’. Following this study, different studies were conducted in different parts of the world, and most pointed to strong declines in insects. This is the largest data collection to date, combining available data on trends in insect abundance around the world to explore how widespread and severe insect reductions are.
Here, trends in insect abundance were investigated by considering the number of individuals, not the insect species. For this, data from 166 long-term surveys conducted at 1,676 sites around the world between 1925 and 2018 were compiled. By combining all the trends around the world after complex analysis, the researchers were able to estimate how the total insect abundance changed on average over time.
The silent extinction of insects
The results of the analysis found an average of 0.92% reduction per year for terrestrial insects (insects that spend their entire lives on lands, such as butterflies, grasshoppers, and ants). You may think that the rate of 0.92% is not much. However, if we consider this small ratio for long periods such as 30 and 75 years, we can predict that the number of insects will decrease by 24% in 30 years and 50% in 75 years. As you can see, we are not aware of the silent decline of insects from year to year.
Data analysis with insects shows that the average of flying insects is decreasing. In addition, the numbers of insects living in soil, trees and water were also analyzed. On average, it was found that insects living in the grass and on the ground were less than in the past. In contrast, the number of insects living in tree canopies remained largely unchanged on average.
Studies of insects such as sandflies and mayflies that live part of their lives underwater showed an average annual increase of 1.08%. This corresponds to a 38% increase in 30 years. This positive trend was particularly strong in Northern Europe, the Western United States and, since the early 1990s, in Russia. This increase indicates that the negative trends in insect numbers can be reversed. In the last 50 years, polluted rivers and lakes in many parts of the world have been cleaned, allowing much freshwater to be recovered. This recovery has allowed increasing the richness of biodiversity.
What can be done to alleviate the insect apocalypse?
There has been a drastic decline in insect numbers, including in many protected habitats. Since the success or failure of insects in reproduction varies according to species or regions, it is necessary to conduct a large number of studies. Habitat destruction is most likely the biggest cause of insect decline. The best example of this is the findings showing that the destruction of the natural habitats of insects (especially through urbanization) is associated with the reduction of terrestrial insects. Land use and habitat destruction by humans is the main cause of all global biodiversity change, not just insects.
Researchers suggest possible practical solutions to help prevent species extinction. These include actions such as reserving high-quality and manageable portions of land for conservation, transforming global farming practices to promote species coexistence, and mitigating climate change. Above all, communicating and engaging with civil society and policymakers is essential to the future and mutual well-being of both humans and insects.
We need to be more aware of tiny creatures. Every time we see these tiny creatures, we should think of them as tiny workers who keep ecosystems alive. Our most important responsibility towards them is to stay away from all unsustainable practices.
References and Further Reading
Stork, N.E. Re-assessing current extinction rates. Biodivers Conserv 19, 357–371 (2010).
Samways, M. J. (2007). Insect Conservation: A Synthetic Management Approach. Annual Review of Entomology, 52(1), 465–487.
The University of Helsinki. “Scientists warn humanity about worldwide insect decline: They also suggest ways to recognize and avert its consequences.” ScienceDaily. ScienceDaily, 10 February 2020.
Roel van Klink, et al. Meta-analysis reveals declines in terrestrial but increases in freshwater insect abundances. Science, 2020; 368 (6489): 417–420