Environment-Biodiversity-Effects
Long-term predator–prey cycles finally achieved in the lab
A key question in ecology is what allows species to persist over time — particularly when there are pairs of species in which one is an exploiter and the other its victim. A long-standing theory attempts to answer this question by explaining how relative numbers of predators and their prey can cycle continuously1. First, prey numbers would increase, giving the predator more food. The subsequent increase in predators would lead to a decline in prey. Predator numbers would then decline owing to a lack of food, restarting the cycle. However, it has proved unexpectedly challenging to demonstrate this type of persistent predator–prey cycle in simple controlled systems in the laboratory. Writing in Nature, Blasius et al.2 report just such a demonstration, succeeding where almost 90 years of experimental work has failed.
The challenge posed by such a demonstration was exemplified in 1934 by the ecologist Georgii Gause4, who studied the dynamics of two unicellular organisms — the predator Didinium nasutum and its prey, Paramecium caudatum. Gause found that, on the one hand, if the predator was efficient, it ate up all the prey and then starved. On the other hand, if part of the environment helped to conceal the prey, the predator was less efficient — and so starved (Fig. 1a). Coexistence and long-term cycles could be achieved only through artificial means — namely, by adding prey at regular intervals.
Light pollution is key 'bringer of insect apocalypse'
Artificial light at night can affect every aspect of insects’ lives, the researchers said, from luring moths to their deaths around bulbs, to spotlighting insect prey for rats and toads, to obscuring the mating signals of fireflies.
Brett Seymoure, a behavioural ecologist at Washington University in St Louis and senior author of the review, said: “Artificial light at night is human-caused lighting – ranging from streetlights to gas flares from oil extraction. It can affect insects in pretty much every imaginable part of their lives.”
‘Insect apocalypse’ poses risk to all life on Earth, conservationists warn
A new report suggested half of all insects may have been lost since 1970 as a result of the destruction of nature and heavy use of pesticides. The report said 40% of the 1million known species of insect are facing extinction. The analysis, written by one of the UK’s leading ecologists, has a particular focus on the UK, whose insects are the most studied in the world. It said 23 bee and wasp species have become extinct in the last century, while the number of pesticide applications has approximately doubled in the last 25 years.
Worldwide decline of the entomofauna: A review of its drivers
• Over 40% of insect species are threatened with extinction.
• Lepidoptera, Hymenoptera and dung beetles (Coleoptera) are the taxa most affected.
• Four aquatic taxa are imperiled and have already lost a large proportion of species.
• Habitat loss by conversion to intensive agriculture is the main driver of the declines.
• Agro-chemical pollutants, invasive species and climate change are additional causes.
The Bugs We Can’t Live Without
Insect populations are in dramatic decline, and the consequences could be serious for everything from waste management to agriculture
"Nearly half of all insect species worldwide are in rapid decline and a third could disappear altogether, according to a study warning of dire consequences for crop pollination and natural food chains. The recent decline in bugs that fly, crawl, burrow and skitter across still water is part of a gathering "mass extinction," only the sixth in the last half-billion years. "We are witnessing the largest extinction event on Earth since the late Permian and Cretaceous periods," the authors noted.
Biodiversity crisis is about to put humanity at risk, UN scientists to warn
The Guardian Biodiversity Crisis UN report 503 2019
The world’s leading scientists will warn the planet’s life-support systems are approaching a danger zone for humanity when they release the results of the most comprehensive study of life on Earth ever undertaken.
Up to 1m species are at risk of annihilation, many within decades, according to a leaked draft of the global assessment report, which has been compiled over three years by the UN’s leading research body on nature.
The 1,800-page study will show people living today, as well as wildlife and future generations, are at risk unless urgent action is taken to reverse the loss of plants, insects and other creatures on which humanity depends for food, pollination, clean water and a stable climate.
The final wording of the summary for policymakers is being finalised in Paris by a gathering of experts and government representatives before the launch on Monday, but the overall message is already clear, according to Robert Watson, the chair of the Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services (IPBES).
