Daily News Archive
From October 20, 2006                                                                                                        

National Academy of Sciences Says Pollinator Populations Are Declining
(Beyond Pesticides, October 20, 2006) Long-term population trends for some North American pollinators -- bees, birds, bats, and other animals and insects that spread pollen so plant fertilization can occur -- are "demonstrably downward," says a new report from the National Research Council. However, there is little or no population data for many pollinators, which prompted the committee that wrote the report to call for stepped-up efforts to monitor these creatures and improve understanding of their basic ecology. According to Ohio State University, over 75 commonly used pesticides are highly or moderately toxic to bees. The major contributors to this are considered to be habitat fragmentation, agricultural and industrial chemicals, parasites and diseases, and the introduction of alien species.

In order to bear fruit, three-quarters of all flowering plants -- including most food crops and some that provide fiber, drugs, and fuel -- rely on pollinators for fertilization, and farmers often lease thousands of colonies of bees to ensure pollination. Research indicates that shortages of pollinators for agriculture already exist and that decreases in wild pollinator populations could disrupt ecosystems in the future. "Despite its apparent lack of marquee appeal, a decline in pollinator populations is one form of global change that actually has credible potential to alter the shape and structure of terrestrial ecosystems," said committee chair May R. Berenbaum, Swanlund Chair, entomology department, University of Illinois, Urbana-Champaign.

The report notes that much more data have been gathered on pollinators in Europe, where researchers have definitively documented declines and even extinctions. Nevertheless, there was sufficient evidence for the committee to conclude that some North American species are in decline, especially the honeybee. Honeybees are crucial to agriculture, pollinating more than 90 commercially grown crops; for example, it takes about 1.4 million colonies of honeybees to pollinate 550,000 acres of almond trees in California. Studies show that U.S. honeybee populations have dropped since the 1980s, when a non-native parasitic mite was introduced, although the full extent of the decline is unclear because of problems with the way the federal government collects statistics on the beekeeping industry. The U.S. Department of Agriculture's National Agricultural Statistics Service should improve its methods for surveying honeybee populations, and do so on a yearly basis, the committee said.

The shortage is significant enough, however, that honeybees had to be imported from outside North America last year for the first time since 1922, when the Honeybee Act banned such imports for fear they would introduce non-native pests.

Long-term trends for several wild bee species -- especially bumblebees -- as well as some butterflies, bats, and hummingbirds also show population drops, the committee found. However, it emphasizes that a paucity of data on most wild pollinators, together with incomplete knowledge of their taxonomy and ecology, make authoritative assessments exceedingly difficult.

The causes of decline in wild pollinators vary by species and are difficult to determine, the report says. Like the honeybee, the bumblebee has been hurt by the introduction of a non-native parasite. Many pollinator declines are associated with habitat loss, although U.S. data often are inadequate to link the two definitively; one exception is the drop in the bat population, which can be attributed to destruction of cave roosts.

To better track wild pollinators in North America, the United States should collaborate with Canada and Mexico to form a network of long-term monitoring projects, the committee recommends. A rapid, one-time survey should be conducted as soon as possible to establish baseline data to which future assessments can be compared. USDA also should support research to improve the quick identification of pollinator species, which is very difficult in the field.

Although the consequences of wild pollinator declines for nonagricultural settings are more difficult to define, one result could be a greater vulnerability of some plant species to extinction, the report adds. Few plants rely on a single pollinator, but certain species could be at increased risk.

The issue of protecting pollinators from pesticides and other environmental hazards has been heating up recently. In a landmark decision, the Minnesota Supreme Court ruled that landowners who spray pesticides on the tree groves can be held liable for damages to beekeepers' neighboring apiaries. (Anderson, et al. v. International Paper, March 2005) The case was brought by three beekeepers who raise bees for honey and sale. This ruling sets a standard that could have dramatic ramifications for pesticide use across the country. For more information on this issue, see “The Minnesota Honey Bee Battle” printed in the Spring 2006 issue of Pesticides and You.

According to Ohio State University, the following pesticides are highly toxic to bees: 2,4-D (Weed-B-Gone), abamectin (Zephyr), acephate (Orthene), azinphos-methyl (Guthion), bifenthrin (Capture), carbaryl (Sevin), carbosulfan (Advantage), chlormephos (Dotan), chlorpyrifos (Lorsban, Dursban), cyfluthrin (Baythroid), d-phenothrin (Sumithrin), demeton-s-methyl (Metasystox (i), (50-% Premix), diazinon (Spectracide), dichlorvos (DDVP), dicrotophos (Bibrin), dimethoate (Cygon, De-Fend), esfenvalerate (Asana XL), ethion (tech), (Ethanox), etrimfos (Ekamet), fenitrothion (Sumithion), fenpropathrin (Farmatox), fensulfothion (Dasanit), fenthion (Baytex), fenvalerate (DMSO), (Belmark), flucythrinate (Pay-Off), fonofos (Dyfonate), heptachlor (Fennotox), lindane (Lindane), malathion (Malathion 50, Malathion ULV), methamidophos (Monitor, Tamaron), methidathion (Supracide), methiocarb (Mesurol), methyl parathion (Penncap-M), mevinphos (Phosdrin), monocrotophos (Azodrin), naled (Dibrom), omethoate (Folimat), oxydemethon-methyl (Metasystox-R), oxydisulfoton (Disyston S), parathion (Bladan), permethrin (Ambush, Pounce), phosmet (Imidan), phosphamidon (Dimecron), propoxur (Baygon), pyrazophos (Afugan), resmethrin (Chrysron), tetrachlorvinphos (Gardona), and tralomethrin (Scout X-TRA). The following are moderately toxic: Acetochlor (Acenit), Aclonifen (Challenge), allethrin (Pynamin), alphacypermethrin (Fastac), ametryn(Evik), bromopropylate (Acarol), cinmethylin (Argold), crotoxyphos (Ciodrin, Decrotox), DCPA (Dacthal), diphenamid (Dymid), disulfoton (DiSyston, Ekanon), endosulfan (Thiodan), endrin (Hexadrin), ethoprop (Mocap), flufenoxuron (Cascade), fluvalinate (tau-fluvalinate), (Mavrik, Spur), formetanate hydrochloride (Carzol), mancozeb (Manzate, Dithane, Fore), methanearsonic acid (MAA), neburon (Granurex, Propuron), pebulate (Tillam), phorate (Geomet, Thimet), pirimiphos-methyl (Acetellic), sethoxydim (Poast), sulfosate (Touchdown), terbufos (Counter), thiocyclam hydrogen oxalate (Evisect), thiodicarb (Larvin, Nivral), and triforine (Denarin, Funginex).

Copies of Status of Pollinators in North America (summary) are available from the National Academies Press; 202-334-3313 or 1-800-624-6242 or http://www.nap.edu/catalog/11761.html.