Economic gain, stability of pollination and bee diversity decrease from southern to northern Europe

Bees are in decline potentially leading to reduced pollination and hence production of insect-pollinated crops in many countries. It is however still unclear whether the consequences of pollinator shortages differ among countries with different climatic and social conditions. Here, we calculated economic gains attributed to insect (particularly bee) pollination (EVIP) as well as their contribution to the total value of crop production (vulnerability), and analyzed their temporal trends and inter-annual variability from 1991 to 2009 for each country of the European Union (EU). To understand which factors drive country specific differences in pollinator dependency and stability of crop yields in Europe, we further asked whether EVIP, vulnerability and stability of yields were influenced by a country's latitude, the number of wild bee species and/or managed honeybee hives per country, and their gross domestic products (GDP). Across Europe, crop pollination by insects accounted for 14.6 [± 3.3] billion EUR annually (EVIP), which equals 12 (± 0.8) % of the total economic value of annual crop production. Gains strongly varied among countries. Both EVIP and vulnerability increased (and their inter-annual variation decreased) significantly from northern to southern Europe, concomitantly with increases in the number of wild bee species and managed honeybee hives. Across years, economic importance of pollination increased in all but three EU countries. Apples were the most important insect-pollinated crop in the EU, accounting for 16% of the EU's total EVIP. Our results show that whereas dependency on insect pollination increased from north to south, variation in economic gain from insect pollination decreased, indicating that, compared to northern countries, southern countries had more stable yields of pollinator-dependent crops across years and hence more reliable gains from pollination services. Hence, future policies should promote even greater investments in biodiversity conservation of central and northern than southern European countries.