Beleid en debat

New research has identified the world’s most widely used insecticides as the key factor in the recent reduction in numbers of farmland birds. The finding represents a significant escalation of the known dangers of the insecticides and follows an assessment in June that warned that pervasive pollution by these nerve agents was now threatening all food production. The neonicotinoid insecticides are believed to seriously harm bees and other pollinating insects, and a two-year EU suspension on three of the poisons began at the end of 2013. Peer-reviewed research, published in the leading journal Nature this Wednesday, has revealed data from the Netherlands showing that bird populations fell most sharply in those areas where neonicotinoid pollution was highest. Starlings, tree sparrows and swallows were among the most affected. At least 95% of neonicotinoids applied to crops ends up in the wider environment, killing the insects the birds rely on for food, particularly when raising chicks.

This is the time of the year when night life has a new meaning. The city's fireflies, with their alluring, blinking magical displays, offer a fascinating contrast to the city's techno-colored street and shop lighting, and many Shanghai people are setting out to spend time watching and enjoying this natural spectacle. The hunt for the fireflies has also been given a public push recently by the publication of recommended viewing spots for the tiny nocturnal creatures by the Shanghai Municipal Tourism Administration. The list of six destinations includes the highly recommended Cenbu village, a village beside Shanghai's largest freshwater lake Dianshan Lake in Qingpu district. Other spots listed are the Shanghai Botanical Garden, the Chenshan Botanical Garden and the Shanghai Zoo.

Imidacloprid, one of the most commonly used insecticides, is highly toxic to bees and other beneficial insects. The regulatory challenge to determine safe levels of residual pesticides can benefit from information about the time-dependent toxicity of this chemical. Using published toxicity data for imidacloprid for several insect species, we construct time-to-lethal-effect toxicity plots and fit temporal power-law scaling curves to the data. The level of toxic exposure that results in 50% mortality after time t is found to scale as t1.7 for ants, from t1.6 to t5 for honeybees, and from t1.46 to t2.9 for termites. We present a simple toxicological model that can explain t2 scaling. Extrapolating the toxicity scaling for honeybees to the lifespan of winter bees suggests that imidacloprid in honey at 0.25 μg/kg would be lethal to a large proportion of bees nearing the end of their life.

Since the end of World War II there has been a decline in forest songbird populations over much of the eastern United States. For example, in Rock Creek Park in the middle of Washington, D.C., populations of Red-eyed Vireos (Vireo olivaceus) have dropped by 79 percent and Ovenbirds (Seiurus aurocapilla) by 94 percent. Acadian Flycatchers, Yellow-throated Vireos (Vireo flavifrons), Black-and-white Warblers (Mniotilta varia), and Hooded Warblers (Setophaga citrina) have disappeared entirely. The decline has not been uniform for all species; the Acadian Flycatcher (Empidonax virescens) and others that migrate long distances to tropical America have suffered more than residents or those like robins and towhees that can overwinter in the southern United States. Nor has the decline been equal in all types of forest; the loss of species from woodlots and small forest tracts exceeds the loss from large stretches of forest such as those of the Great Smoky Mountains National Park.