![]() Williams (1994) provided coefficients for the dependence of European crops on animal pollination and estimated the proportion of insect pollinators that are honeybees, using information from Crane & Walker (1984) and Free (1993). 1989 a, b Morse & Calderone 2000), but despite their continuing acceptance, most of these reports do not cite data sources, and so it is impossible to assess the reported level of dependence. Some authors provide coefficients of dependence on animal-mediated pollination for several crops ( Borneck & Merle 1989 Robinson et al. The major caloric inputs in the human diet come from a few staple foods with large world production for which animal pollination is irrelevant ( Richards 2001 Ghazoul 2005), or come indirectly via animals fed with these same staple crops. These rough estimates can be deceptive as they often neither consider variation in the level of dependence on animal pollination nor take into account the importance of the crop to consumers. Previous estimates have used mostly secondary data and relied on crude guesses of the proportional contribution of pollinators to crop production. From this list, ca 70% of tropical crops seem to have at least one variety for which production is improved by animal pollination.įor European crops, Williams (1994) assessed the pollinator needs for 264 crop species and concluded that the production of 84% of these depends at least to some extent upon animal pollination. 2006).įor tropical crops, Roubik (1995) provided a detailed list for 1330 species and compiled a list of potential breeding systems and pollinating taxa. Furthermore, the decline of pollinating species can lead to a parallel decline of plant species ( Biesmeijer et al. 2004), which can also be important for providing calories and micronutrients for humans ( Sundriyal & Sundriyal 2004). Animal pollination is important to the sexual reproduction of many crops ( McGregor 1976 Crane & Walker 1984 Free 1993 Williams 1994 Nabhan & Buchmann 1997 Westerkamp & Gottsberger 2000) and the majority of wild plants ( Burd 1994 Kearns et al. 2005, but see Ghazoul 2005), detailed studies of the crop pollination systems are incomplete or out of date. 1998 Kevan & Phillips 2001 Steffan-Dewenter et al. ![]() Although crop pollination is commonly cited as an example of an endangered ecosystem service ( Corbet 1991 Williams 1994 Ingram et al. Pollination by wild animals is a key ecosystem service. Case studies for nine crops on four continents revealed that agricultural intensification jeopardizes wild bee communities and their stabilizing effect on pollination services at the landscape scale.Įcosystem services, defined as the benefits to human welfare provided by organisms interacting in ecosystems, are considered to be at risk ( Daily 1997 Palmer et al. ![]() We further evaluated whether local and landscape-wide management for natural pollination services could help to sustain crop diversity and production. We found that pollinators are essential for 13 crops, production is highly pollinator dependent for 30, moderately for 27, slightly for 21, unimportant for 7, and is of unknown significance for the remaining 9. Using all crops traded on the world market and setting aside crops that are solely passively self-pollinated, wind-pollinated or parthenocarpic, we then evaluated the level of dependence on animal-mediated pollination for crops that are directly consumed by humans. ![]() However, global production volumes give a contrasting perspective, since 60% of global production comes from crops that do not depend on animal pollination, 35% from crops that depend on pollinators, and 5% are unevaluated. In this review, we expand the previous estimates using novel primary data from 200 countries and found that fruit, vegetable or seed production from 87 of the leading global food crops is dependent upon animal pollination, while 28 crops do not rely upon animal pollination. The extent of our reliance on animal pollination for world crop production for human food has not previously been evaluated and the previous estimates for countries or continents have seldom used primary data.
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