Spiders across the world devour a whopping 400-800 million tonnes of insects annually, a new study has claimed suggesting that these crawlies could very well be the top-most eaters in the world.
The spider community has been well recognized as a large predator species, but it is the first time that such a quantification of its prey has been done. Researchers at the University of Basel led by Martin Nyfeller carried out a study, which has been published in the journal The Science of Nature, estimate that spiders around the world weigh 25 million tonnes and they collectively consume 400-800 million tonnes of insects each year. This makes spiders one of the biggest groups of predators with 45,000 recognised species. Spiders have a widespread existence with high population density of around 1000 spiders per square metre.
Scientists used two different methods to determine how much food these crawlies eat. First method was a simple one involving determining the food needs of a spider per the spider’s mass. Second one was extrapolating from data taken from the field in which scientists actually counted the number of insects spiders ate. Both the methods yielded results in just about the same range at 400-800 million tonnes of insects.
More than 90 per cent of its spiders’ consumption includes insects and collembolans. The study also shows that the major contribution comes from the predators in the forests and grasslands areas, compared to the spiders in the desert regions and in the Arctic tundra region. Spiders existence in the agricultural areas is lesser since they are usually intervened by human activities and thus the conditions are lesser favorable for the spider community.
However spiders are the ones whose spread is as extensive as humans and their presence is observed in the most extreme conditions also ranging from the mountain ranges at very high altitudes to the hot deserted regions, from the ocean shores to the wide food plains.
According to Dr. Nyfeller, spiders thus help maintain the ecological balance and the food chain and by killing the herbivorous insects which are their main prey, they facilitate the prevention of herbivorous plant damage, proving their essential contribution to the nature as a species.