March 15, 2017
by Brett Smith
It is a long-held belief that spiders are one of the most essential categories of predators of insects, and a recent study has revealed that spiders kill 400 to 800 million tons of insects around the world each year.
With over 45,000 species and a population density up to 1,000 individuals per square meter, spiders are among the world’s most species-rich and wide-ranging groups of predators. As a result of most spiders’ clandestine lifestyle, it has been challenging to show their ecological role.
Published in The Science of Nature journal, the study is based on two calculations derived from various models that reliably showed the global spider population wipes out about 20 times its weight in prey each year. Greater than 90 percent of that prey is insects and springtails (Collembola). In addition to eating insects, big, tropical spiders will also prey on small vertebrates like frogs and fish from time to time, or eat plants. The massive range of the global prey killed shows that rates of predation can vary widely inside of certain ecosystems, and these variants must be considered for ecological projections, the researchers said.
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