The Guardian reports:

Reports of falling insect numbers around the world are not new. International reviews have estimated annual losses globally of between 1% and 2.5% of total biomass every year.

Widespread use of pesticides and fertilisers, light and chemical pollution, loss of habitat and the growth of industrial agriculture have all carved into their numbers. Often, these were deaths of proximity: insects are sensitive creatures, and any nearby source of pollution can send their populations crumbling.

But what [Daniel] Janzen and [Winnie] Hallwachs are witnessing is a part of a newer phenomenon: the catastrophic collapse of insect populations in supposedly protected regions of forest. “In the parts of Costa Rica that are heavily hit by pesticides, the insects are completely wiped out,” Hallwachs says.

“But what we see here in the preserved areas – that as far as we can tell, are free of even these destructive insecticides and pesticides – even here, the insect numbers are going down horrifyingly dramatically,” she says.

Long-term data for insect populations – particularly less charismatic species – is still patchy, but Janzen and Hallwachs join a number of scientists that have recorded huge die-offs of insects in nature reserves around the world.

They include in Germany, where flying insects across 63 insect reserves dropped 75% in less than 30 years; the US, where beetle numbers dropped 83% in 45 years; and Puerto Rico, where insect biomass dropped up to 60-fold since the 1970s. These declines are occurring in ecosystems that are otherwise protected from direct human influence. [Continue reading…]