A number of recent studies have examined the decline in pollinating insects and particularly in wild bees and honey bees – the most commonly found and the most diverse. Few studies, however, look at the consequences that a pollination shortage has on agriculture and, by extension, on food security. Excluding modelling, certain empirical studies conducted in recent years have focused on the effects of pollination levels on crops, but most study individual flowers, branches, or individual potted plants, making it very difficult to extrapolate information on farmers’ yields.
A 35-member international team involving INRA applied the same field protocol1 in 344 plots for the study of 33 types of crops in 12 different countries (primarily in Africa, Asia and South America) over a five-year period. The team was able to quantify at a global level the links between agricultural yields (in kilos per hectare) and the abundance and diversity of the pollinating insect population present. In particular, researchers focused on small farms in developing countries since these were excluded from previous studies despite their significant role in ensuring food security for the world’s population.
Scientists were able to show that shortages in pollinating insects were responsible for a significant proportion of yield shortages in these crops, independently of other major environmental and agronomic factors (e.g. intensification levels, importance of pollination for a certain crop). This means that the size of a pollinating insect population alone causes 31% of all yield deficit on average in plots of less than 2 hectares. In bigger plots, where pollinator populations are more homogeneous and largely made up of honey bees, scientists observed a similar increase in productivity (30% on average) when the pollinator population is diversified. When diversity is weak, however, productivity is not improved, demonstrating that an increase in both the number and variety of pollinating insects raises crop yields by over 20% on average at the global level. These results underscore the effects of pollinating insect shortages at the international level.
Humanity is facing a twofold challenge: first, it must produce enough food to meet the growing needs of an expanding population, and second, it must produce this food in an environmentally and socially acceptable way. Ecological intensification – the use of biodiversity to increase yields – is one (sustainable) way to meet these challenges. With this in mind, the results of this study show that ecological intensification that increases the size and diversity of pollinating insect populations creates mutually beneficial outcomes for biodiversity and crop yields. This type of production contributes to the development of sustainable farming systems, including small farms in developing countries.
1. Vaissière BE, Freitas BM, Gemmill-Herren B. 2011. Protocol to detect and assess pollination deficits in crops: a handbook for its use. FAO, United Nations, Rome, 81 p. http://www.fao.org/docrep/013/i1929e/i1929e00.pdf
|Lucas A. Garibaldi et al. (2016). Mutually beneficial pollinator diversity and crop yield outcomes in small and large farms. Science 351: 388.