Pollinators make the world go ’round, but according to a recent report by the National Academy of Sciences, their populations are in rapid decline. Shrinking numbers of insects, bats, birds, and other animals that pollinate the world’s 240,000 species of flowering plants, the report warns, could affect plant survival everywhere, including that of many agricultural crops.
The report states that “there is direct evidence for the decline of some pollinator species in North America” and emphasizes that there has not been enough monitoring over time to assess the level of population decline of most species. One species with a long history of monitoring, the honeybee – studied by the USDA since 1947 – has clearly begun to decline, and scientists think that wild pollinator populations are close behind.
Honeybees, which are leased by some farmers to help pollinate their crops, had to be imported in 2005 for the first time since 1922 due to the decline in their populations. Honeybees began to decline following the introduction of the varroa mite, an external parasite of both adult and larval honeybees, which was first reported in the U.S. in 1987.
Populations of the few wild pollinator species that are monitored, including some other bee species, butterflies, bats, and hummingbirds, are falling “demonstrably downward,” according to the report. The extent of the decline is hard to pinpoint, due in part to the lack of long-term population data. In order to successfully track wild pollinator population trends, researchers need to be able to identify pollinators quickly in the field, which can be difficult. They also need to figure out what makes wild pollinator populations decline. It may be that parasites imported from other countries are causing pollinator numbers to drop, but other factors, such as competition with exotic pollinators or global climate change, could also be significant causes, the committee suggests.
It’s not just the pollinators that are at risk, because their decline could in turn cause “an increased vulnerability of some plant species to extinction,” says the committee, though they point out that the consequences for plants – as well as for the pollinators – are difficult to define without better data.
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