Assessing the impact of declining pollinators on world agriculture

Abstract – Bernard Vassiére - texte en français pas disponible

The decline of pollinator populations,especially bees including honey bees,has now clearly documented in several areas of the world.Yet the actual and the potential impact of this decline on crop production and farming economy is only starting to be assessed in quantiative terms.Based on a weight output,a third of our food supply is dependent on the pollination service provided by animals,mainly insects and particularly bees.To go beyond this first estimate is difficult for several reasons.First of all,many of the past and current methods used to assess the dependence of crop yield and quality on pollinator activity give heavily biased results so that valid measurments of this dependence remain actually unknown for the majority of crops grown in the world.Also the link between the density and diversity of pollinators,on one hand,and the pollination service they perfom,on the other hand,remains poorly known so that the impact of pollinator decline remains very difficult to assess unlessone takes their completed isappearance as a working hypothesis.Indeed,this is what we did to calculate the monetary value of the pollination service provided by insects to the world crop production used for human food and found that it amounted to 135 billion in 2005.This figure represented 9,5% of the value of the world agricultural production.Vegetables and fruits were the leading crop categories in value of insect pollination followd by edible oil crops,stimulants,nuts and spices.Also the greater the dependency of a crop category on pollinators,the higher its unit production value.