Earth’s insects in danger of disappearing because of this

By Mark Waghorn via SWNS

Insects are being wiped out by urbanization, according to new research.

Numbers have been almost halved by replacing wild habitats with towns and cities.

The crisis facing Earth's most abundant animals is even more complicated than feared.

They can benefit from climate change but are killed off by land change.

Scientists have carried out a count in different settings ranging from semi-natural to agricultural and built-up areas.

First author Johannes Uhler, a Ph.D. student at the Julius Maximilian University of Wurzburg, in Germnany said: "We observed the largest difference in insect biomass between semi-natural and urban environments.

"In the city, the biomass was 42 percent lower. Insect diversity was 29 percent lower in agricultural environments compared to semi-natural habitats.

"There were even 56 percent fewer endangered species in agricultural areas."

The planet is at the start of the sixth mass extinction in its history, with huge losses already reported in larger animals that are easier to quantify.

But despite their size, insects' biomass is 17 times greater than that of humans.

They are essential for all ecosystems, providing food for other creatures, pollinating plants and recycling nutrients.

More than 40 percent of species are declining and a third are endangered.

Insect extinction is eight times faster than that of mammals, birds and reptiles.

Changes in land use, such as intensive farming of maize and rape, and global warming with increasing droughts have been blamed.

But previous analyses have weaknesses and fail to represent the diversity or only consider short periods of time and small regions.

Co-author Professor Jorg Muller, an animal ecologist, explained: "In this study, we were able for the first time to disentangle the impact of climate and land use on insects in a Central European landscape.

"Interestingly, temperature at the local site as well as annual temperature have only positive effects on the biomass and diversity of insect populations.

"The form of land use, on the other hand, has different effects on biomass and diversity."

The results in Nature Communications identify urban sprawl as a key factor for the overall reduction.

They were based on 179 sites in Germany from Lower Franconia to the Bavarian Forest and the Alps over 200 miles away.

The researchers placed large, tent-like nets called Malaise-traps to collect flying, crawling and jumping insects in spring 2019.

The study spanned lowlands to elevations above 1,100 meters and included forests, meadows, fields as well as semi-natural, agricultural and urban landscapes.

Traps were emptied every 14 days, an entire vegetation period. Biomass was calculated and individual species were identified using DNA sequencing.

Mr. Uhler said: "These contrasting patterns of biomass and species diversity are an important warning sign for researchers.

"For insect monitoring, one should not conclude that a decline in biomass also means a decline in species diversity and vice versa."

The researchers recommend creating more green spaces in urban environments to increase insect biomass.

They also advise further expansion of agri-environmental schemes to improve biodiversity and the promotion of forest habitats.

Insect population collapses have recently been reported in Germany and Puerto Rico, but the crisis is global.

In Britain, for instance, a third of wild bees and are in decline. If current trends continue, certain species will be lost altogether.

Earlier studies have found losses of butterflies, moths, beetles, bees and hoverflies across the UK other crucial species globally.