The UK Guardian reports on the collapse of insect populations in Puerto Rico’s Luquillo rainforest. Plummeting insect populations, in Puerto Rico and other parts of the world, have been attributed to climate change, and could have effects that ripple through entire ecosystems and food webs:

“We knew that something was amiss in the first couple days,” said Brad Lister. “We were driving into the forest and at the same time both Andres and I said: ‘Where are all the birds?’ There was nothing.”

His return to the Luquillo rainforest in Puerto Rico after 35 years was to reveal an appalling discovery. The insect population that once provided plentiful food for birds throughout the mountainous national park had collapsed. On the ground, 98% had gone. Up in the leafy canopy, 80% had vanished. The most likely culprit by far is global warming.

“It was just astonishing,” Lister said. “Before, both the sticky ground plates and canopy plates would be covered with insects. You’d be there for hours picking them off the plates at night. But now the plates would come down after 12 hours in the tropical forest with a couple of lonely insects trapped or none at all.”

“It was a true collapse of the insect populations in that rainforest,” he said. “We began to realise this is terrible – a very, very disturbing result.”

Earth’s bugs outweigh humans 17 times over and are such a fundamental foundation of the food chain that scientists say a crash in insect numbers risks “ecological Armageddon”. When Lister’s study was published in October, one expert called the findings “hyper-alarming”.

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Lister calls these impacts a “bottom-up trophic cascade”, in which the knock-on effects of the insect collapse surge up through the food chain.
“I don’t think most people have a systems view of the natural world,” he said. “But it’s all connected and when the invertebrates are declining the entire food web is going to suffer and degrade. It is a system-wide effect.”

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“We are essentially destroying the very life support systems that allow us to sustain our existence on the planet, along with all the other life on the planet,” Lister said. “It is just horrifying to watch us decimate the natural world like this.”

Visit the Guardian website to read the full article. The research paper on Lister’s findings is available online: Climate-driven declines in arthropod abundance restructure a rainforest food web.

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