By Sharon Oosthoek and Nature magazine
Pesticide use has sharply reduced the regional biodiversity of stream invertebrates, such as mayflies and dragonflies, in Europe and Australia, finds astudy published today in the Proceedings of the National Academy of Sciences.
Previous research has shown similar decreases in individual streams, but the study by Mikhail Beketov, an aquatic ecologist at the Helmholtz Center for Environmental Research in Leipzig, Germany, and his colleagues analyzed the effects of pesticides over broad regions.
The team examined 23 streams in the central plains of Germany, 16 in the western plains of France and 24 in southern Victoria, Australia. They classified streams according to three different levels of pesticide contamination: uncontaminated, slightly contaminated and highly contaminated.
The researchers found that there were up to 42% fewer species in highly contaminated than in uncontaminated streams in Europe. Highly contaminated streams in Australia showed a decrease in the number of invertebrate families by up to 27% when contrasted with uncontaminated streams.
Moreover, the authors say that diversity decreased at pesticide concentrations that European regulations deem environmentally protective. "It shows our risk assessments don't work," says Beketov. "I think we should care about this because invertebrates are an important part of the food web."
Emma Rosi-Marshall, an aquatic ecologist at the Cary Institute of Ecosystem Studies in Millbrook, New York, says that she finds the results compelling. "We are at a crisis point, with species loss on a global scale, especially in freshwater ecosystems. Considering pesticides along with other known threats to biodiversity may be crucial for halting species declines," she says.
But toxicologist Keith Solomon of the University of Guelph in Ontario, Canada, says he has concerns about the study's sample size. "It begs the question as to what is happening in all the other streams out there," he says. "If these streams are representative of the worst case, then the effects may only be confined to these types of scenarios and not apply to the entire environment."
Insecticide threat
The second paper, from biologist Dave Goulson of the University of Sussex, UK, reviews the environmental risk posed by neonicotinoid insecticides. Its publication on 14 June in The Journal of Applied Ecology comes soon after the European Commission's April announcement of a two-year ban on three commonly used neonicotinoids over concerns that they are killing bees.
Comment by Anumakonda Jagadeesh
During sowing of Groundnut(Peanut) in the fields Crows were a menace as they take away the seeds. To avoid this, local people put the latex of "Euphorbia Anti Quorm" and mix it with cooked rice and place it on the nearby tree. The crow after eating it dies instantly. The farmers tie a dead crow in the middle of the field on a stick. The crows circle in air but won't descend. Perhaps one studies scientifically the properties of the latex which may lead to natural rat killer. Also there is Red Hairy Cater Pillar which comes out in the night and digs a hole and goes under ground during day. Local people put the latex of "Calotropis" in the Groundnut Fields. The Red hairy cater pillar after eating the Calotropis leaves further regeneration is stopped. Perhaps the latex in the leaves plays the trick. If the pigment in the calotropis leaves is isolated and remedy for Red hairy caterpillar can be found.
Modernise the Traditional - Traditionalise the Modern.
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