". . .These hardworking heroes of nature are not well understood but are clearly in peril . . . Loss of habitat, poisonings, and fragmentation of plant life on which they depend is reducing the number of pollinators alarmingly."

United States Secretary of the Interior Bruce Babbitt,
September 30, 1998 speech, Austin, Texas

WHY POLLINATORS ARE IMPORTANT

Pollinators, such as honey bees, birds, bats and insects, play a crucial role in flowering plant reproduction and in the production of most fruits and vegetables. Without the assistance of pollinators, most plants cannot reproduce. In fact, over 90% of all flowering plants and over three-quarters of the staple crop plants that feed humankind rely on animal pollinators (Buchmann and Naban, 1996; Free, 1970 In Tependino, 1979; McGregor, 1976 In Tepedino 1979). According to the U.S. Department of Agriculture, we are facing an "impending pollination crisis," in which both wild and managed pollinators are disappearing at alarming rates (USDA In Ingram, et al., 1996). These dramatic declines are believed to be the result of PESTICIDES, such as insecticides and herbicides, reduced availability of nectar, parasites, destruction of habitat along migratory corridors, modern agricultural practices, grazing, and invasive species (Nabhan, 1996 and Kearns et al., 1998).

At the request of the Environmental Protection Agency, Fish and Wildlife Service (Service) contaminants specialists consult on certain pesticide registrations and re-registrations to ensure that potential impacts to fish and wildlife, including wild pollinators, are considered. In addition, Service contaminants specialists review pesticide use on Service lands to ensure that nonchemical alternatives for managing pests are fully considered and that risks to non-target plants and animals are reduced by selecting the least hazardous, yet effective, pesticides and application methods. [MORE AT THE PESTICIDE HOME PAGE]

Recommendations for Minimizing Pesticide Impacts to Pollinators

Arizona-Sonora Desert Museum: Forgotten Pollinators

Wanted! Pollinators: Alarming Declines in Insect, Bird, and Mammal Populations Jeopardize Cash Crops, Forests, and Wild Plants (Articles from the Sept/Oct 1999 issue of the US Department of Interior's monthly newsletter People, Land & Water) (pdf format available 3083K)

MORE FACTS ABOUT POLLINATORS:

• Honey bees pollinate approximately $10 billion worth of crops in the United States each year (Watanabe, 1994). However, of the hundred or so crops that make up most of the world's food supply, only 15% are pollinated by domestic bees, while at least 80% are pollinated by wild bees and other wildlife (Prescott-Allen and Prescott-Allen, 1990; Ingram et al., 1996a; See also Buchmann and Nabhan, 1996).



• More than 100,000 different animal species - and perhaps as many as 200,000 - play roles in pollinating the 250,000 kinds of flowering plants on this planet. In addition to countless bees, wasps, moths, butterflies, flies, beetles and other invertebrates, as many as 1,500 species of vertebrates such as birds and mammals serve as pollinators, including hummingbirds, perching birds, flying foxes, fruit bats, possums, lemurs and even a lizard (gecko) (Ingram et al., 1996).

• Domesticated honey bees, which are commonly used to pollinate crops, have declined dramatically in recent years. The number of commercially managed colonies has declined from 5.9 million in the 1940s to 4.3 million in 1985 and 2.7 million in 1995 (Ingram et al., 1996b In Kearns et al., 1998). Feral (wild) bees are essentially gone (Watanabe, 1994).



• Exotic parasitic mites, economic factors, pesticide misuse, bad weather, and threats from Africanized honey bees are believed to be responsible for the decline of honey bees (Watanabe, 1994; and Matheson et al., 1996 In Allen-Wardell et al., 1998).



• It is estimated that 20 percent of all losses of honey-bee colonies involve some degree of pesticide exposure (Ingram et al., 1996).



• Honey bee poisonings result in annual losses of $13.3 million (Pimentel et al., 1992 In Ingram et al., 1996a).

• Bees recover slowly from insecticide spraying and other disturbances because of their low fecundity (they are unable to reproduce rapidly or in great numbers) which also makes them more susceptible to local extinction (Tepedino, 1979). It may take 3 to 4 years for bumble bee populations to return to pre-pesticide application levels (Plowright et al., 1978 In Tepedino, 1979).



• There are no documented cases of bees becoming resistant to insecticides (Tepedino, 1979).



• Many crops that would benefit in quality and quantity from more thorough pollination are not sufficiently pollinated because of heavy pesticide applications (Ingram et al., 1996). Income from harvests could increase by an estimated $400 million per year if pollinators were available in sufficient numbers (Pimentel et al., 1992 In Ingram et al., 1996a).



• Pollinators support biodiversity: There is a correlation between plant diversity and pollinator diversity (Heithaus, 1974 In Tepedino, 1979; Moldenke, 1975 In Tepedino, 1979; del Moral and Standley, 1979 In Tepedino, 1979).



• Declines of hummingbirds, flying foxes, and other wild crop pollinators have been documented (Buchman and Nabhan, 1996). Declines of native bees have been attributed to habitat destruction and insecticide and herbicide use (Tepedino, 1979).



• For migratory pollinators, such as bats, hummingbirds, and the monarch butterfly, the identification and protection of nectar corridors is important (Allen-Wardell et al., 1998). If nectar is unavailable anywhere along their migratory route at the time of migration, it could result in the death of part of the population (Buchmann and Nabhan, 1996). Nectar sources near areas where pesticides are sprayed may be tainted or, where herbicides are used, eliminated.



• At least 2 bat and 13 birds species in the United States that are federally listed as endangered under the Endangered Species Act of 1973, as amended, are pollinators. It is unknown how many of the listed insects are pollinators or how many listed plants require pollinators. See Table 1.

Pollinators that are federally listed as endangered species.

Source: Pollinator list from Nabhan, 1996, cross-checked with current Endangered Species list (US Fish and Wildlife Service, 1999).

RECOMMENDATIONS FOR MINIMIZING PESTICIDE IMPACTS TO POLLINATORS
(developed in part from USEPA, 1998c; Florida Agricultural Information Retrieval System, 1999; and Tew, 1997).

• Apply pesticides only when needed, using pest scouting (routine field checks for the presence/absence of pests) to minimize the need for application.



• Leave buffer zones between areas of pesticide application and sensitive species, sensitive habitats, water, and potential nectar sources.
  

• Use the least toxic pesticide recommended for control of the target pest at the lowest effective rate.
  

• Avoid applying pesticides while crops or wildflowers adjacent to or near fields are in bloom.
  

• If pesticides must be applied while crops are in bloom, apply in late afternoon or at night when pollinators are least likely to be working the blooms. However, note the "Caution" below.
  

• Always target pesticide applications to avoid contaminating water, habitat of rare species, and adjacent wildflowers.
  

• Reduce the amount of drift by using ground equipment instead of aerial spraying to apply pesticides. (Note: When pesticides are applied by aircraft, as much as 50% to 75% of the chemicals sprayed can miss their target (Pimentel et al., 1992 In Ingram 1996), leading to inadvertent exposure of non-target organisms such as pollinators (Ingram 1996).
  

• Avoid drift of pesticides onto plants that are attractive to bees by not spraying under windy conditions.
• Rinse pesticide tanks thoroughly between pesticide applications to avoid cross-contamination of pesticides.

• Use the pesticide formulation least hazardous to bees that will control the pest involved (See "Caution" below).

• Use liquid sprays or granules instead of dusts.
  

• Avoid use of microencapsulated pesticides, as they are similar in size to pollen, and may cause severe poisonings as has been documented with microencapsulated methyl parathion (Free et al., 1967 In Johansen, 1977 and Johansen and Eves, 1967 In Johansen, 1977).
  

• Notify beekeepers several days before applying any pesticide that is hazardous to honey bees.
  

• Develop and implement training programs to increase awareness and knowledge of pollinators and their activity patterns among pesticide applicators.
  
  
• Develop public outreach information to heighten awareness of the potential role that pesticides may play in the decline of pollinators.

CAUTIONS

• While timing application to avoid flowering periods or diurnal activity periods may reduce the impacts of pesticides to many pollinators, some pollinators, such as Normia bees that rest in crop fields overnight, may be harmed by nighttime application of pesticides (Natural Resource Council Canada, 1981 In Kearns et al., 1998). Similarly, moths that are active at night may be harmed by nighttime application of pesticides.



• Regardless of application time, if toxins remain on plant parts, pollinators such as leafcutter bees still may be harmed if they bring contaminated leaves back to their nest (Kearns et al., 1998). Likewise, the larvae of butterflies that pollinate plants may be harmed by ingesting toxins remaining on plant parts.

The University of Nebraska's Institute of Agricultural Resources: Protecting Bees When Using Insecticides provides information on Steps Beekeepers Can Take to Protect Their Colonies, Relative Toxicities of Selected Insecticides and Miticides to Honey Bees, and Honey Bee Activity in Field Crops and Rangeland developed in cooperation with the US Department of Agriculture.

Literature cited:

Allen-Wardell, G., P. Bernhardt, R. Bitner, A. Burquez, S. Buchmann, J. Cane, P.A. Cox, V. Dalton, P. Feinsinger, M. Ingram, D. Inouye, C.E Jones, K. Kennedy, P. Kevan, H. Koopowitz, R. Medellin, S. Medellin-Morales, and G. P. Nabhan. 1998. The potential consequences of pollinator declines on the conservation of biodiversity and stability of food crop yields. Conserv. Biol. 12 (1): 8-17.

Buchmann, S.L. and G.P. Nabhan. 1996. The Forgotten Pollinators. Island Press, Washington, DC.

del Moral, R. and L. A. Standley. 1979. Pollination of angiosperms in contrasting coniferous forests. Amer. J. Bot. 66: 26-35.

Florida Agricultural Information Retrieval System. 1999. Protecting Bees from Pesticides. http://hammock.ifas.ufl.edu/txt/fairs/1264.

Free, J.B. 1970. Insect pollination of crops. Academic Press, NY.

Free, J.B., P.H. Needham, P.A. Racey, J.H. Stevenson. 1967. The effect on honey bee mortality of applying insecticides as sprays or granules to flowering field beans. J. Sci. Food Agric. 18: 133-38.

Heithaus, E.R. 1974. The role of plant-pollinator interactions in determining community structure. Ann. Missouri Bot. Gard. 61:675-691.

Ingram, M., G.P. Nabhan, and S.L Buchmann. Our Forgotten Pollinators: Protecting the Birds and Bees. Global Pesticide Campaigner, Volume 6, Number 4, December 1996, PANNA, San Francisco, CA, http://www.pmac.net/birdbee.htm.

Ingram, M., G.P. Nabhan, and S.L. Buchmann (with assistance from the Board of Advisors of the Forgotten Pollinators). 1996a. Ten essential reasons to protect the birds and the bees. Arizona-Sonora Desert Museum, Tuscon, AZ, http://www.desertmuseum.org/conservation/fp/ten_reasons.html.

Ingram, M. G.P. Nabhan, S. Buchmann. 1996b. Impending pollination crisis threatens biodiversity and agriculture. Tropinet 7:1.

Johansen, C.A. 1977. Pesticides and pollinators. Ann. Rev. Entomol. 22: 177-192.

Johansen, C.A. and J.D. Eves. 1972. Development of a pest management program on alfalfa grown for seed. Environ. Entomol. 2:515-17.

Kearns, C.A., D.W. Inouye, and N.M. Waser. 1998. Endangered mutualisms: the conservation of plant-pollinator interactions. Annu. Rev. Ecol. Syst. 29: 83-112.

Matheson, A., S. L. Buchmann, C. O'Toole, P. Westrich, and I.H. Williams (eds.). 1996. The conservation of bees. Academic Press, Harcourt Brace, London.

McGregor, S.E. 1976. Insect pollination of cultivated crop plants. U.S. Dept. Agric., Agric. Handbook No. 496. U.S. Govt. Printing Office, Washington, DC.

Moldenke, A.R. 1975. Niche specialization and species diversity along a California transect. Oecologia 21: 219-242.

Nabhan, G.P. 1996. Pollinator Redbook, Volume one: Global list of threatened vertebrate Wildlife. Wildlife species serving as pollinators for crops and wild plants, http://www.desertmuseum.org/conservation/fp/redbook.html.

Natural Resource Council Canada. 1981. Pesticide-Pollinator Interactions. NRC Assoc. Comm. Sci. Criteria Environ. Qual. Publ. NRCC No. 18471. Ottawa, Canada: Natl. Res. Counc. Can. Environ. Secr.

Pimentel, D., H. Acquay, M. Biltonen, P. Rice, M. Silva, J. Nelson, V. Lipner, S. Giordano, A. Horowitz, and M. D'Amore. 1992. Environmental and economic cost of pesticide use. BioScience 42(10): 750-760.

Plowright, R.C., B.A. Pendrel and I.A. McLaren. 1978. The impact of aerial fenitrothion spraying upon the population biology of bumble bees (Bombus Latr.: Hym.) in southwestern New Brunswick. Can. Entomol. 110: 1145-1156.

Prescott-Allen, R. and C. Prescott-Allen. 1990. How many plants feed the world? Conserv. Biol. 4(4): 365-374.

Tepedino, V.J. 1979. The importance of bees and other insect pollinators in maintaining floral species composition. Great Basin Naturalist Memoirs 3: 139-150.

Tew, J.E. Protecting Honey Bees from Pesticides. The Ohio State University, Horticulture and Crop Science, Factsheet HYG-2161-97. Wooster, OH.

USDA-ARS, 1991, Pollination Workshop Proceedings, unpublished, Denver, CO.

U.S. Environmental Protection Agency. 1998c. Environmental Fate and Effects Division's Reregistration Eligibility Decision Chapter for Methyl Parathion: Case 2345. October 1998. Washington, DC. 92 pp. http://www.epa.gov/oppsrrd1/op/methyl_parathion.htm.

Watanabe, M.E. 1994. Pollination worries rise as honey bees decline. Science 265:1170.

Updated: June 27, 2001