Don’t let the buzz die
The sharp fall in insect population can be catastrophic
Anew entomological study suggests that an ecological catastrophe may have been developing unnoticed over the past three decades. While plenty of attention has been devoted to the loss of large species, the insect population may actually have suffered the biggest decline. The study was led by Caspar Hallmann from Radboud University in The Netherlands and published recently in the open access journal Plos One. It focused on aerial insect populations across nature preserves in Germany and estimated that the insect biomass had declined by 75 per cent in these protected areas.
The researchers took biomass data from malaise traps (netting tents designed to trap flying insects) in 96 locations across 63 German nature preserves over a period of 27 years (1989-2016) to estimate changes in aerial insect populations. It compared the annual weight of all insects trapped — this biomass- oriented approach provides a broad overall picture. The study estimates that there has been a midsummer decline of 82 per cent in flying insect biomass and a seasonally adjusted decline of 76 per cent. It shows that this decline is apparent regardless of specific habitats. It also claims that changes in weather, land use and habitat characteristics cannot easily explain this massive decline.
This is an alarming trend and it has catastrophic implications. Around 70 per cent of the world’s species are insects and they all occupy vital ecological niches. For example, 80 per cent of wild plants depend on insects for pollination and 60 per cent of birds rely on insects as a food source. Quite apart from bees and butterflies, even cockroaches and ants perform vital services in taking care of bio-waste and breaking it down. If insect populations have declined to this extent, it must already have had an enormous negative impact on plant, bird, fish and animal populations. It has been estimated that insects contribute as much as $57 billion annually to the US due to their virtuous impact on the ecosystem.
It is not clear yet whether this decline is specific to Germany or is more globalised, and it is also not known whether non-aerial insects have suffered to quite the same extent. Rigorous studies on insect trends have hitherto been limited and have tended to focus on specific species. But data from other studies gel with the trend of decline seen in Germany. For example, populations of European grassland butterflies have declined by 50 per cent between 1990 and 2011. Data for species such as bees and moths also suggest similar declining trends.
The preservation of insect species and their abundance should be a high priority concern but it has not really been on the public radar. No one is even sure about the causes of the decline in Germany. Climate change, habitat loss and fragmentation, and deterioration of habitat quality are all possible factors that contributed to this situation. It is also notable that this study was conducted specifically in preserves — havens designed for conservation. Declines in less protected areas could well be much worse.
The bottom line: the world cannot survive without insects and their contribution to biodiversity and the services, for want of a better word, that they provide to the ecosystem. If insect decline reaches an irreversible tipping point, it would result in a catastrophe by disrupting the global ecosystem quickly and completely. This study serves as a wake-up call. It is likely to trigger research funding into this vital area, and concerted efforts will now be made to identify the causes. Devising solutions to halt and reverse the trend could perhaps be as simple as planting more wildflowers. The solutions and remedies might also be extremely complex. It is impossible to tell until the causes are identified. Whatever the remedies may be, these need to be found and implemented as soon as possible.