POLLINATORS POLLINATION AND FOOD PRODUCTION

THE ASSESSMENT REPORT ON POLLINATORS, POLLINATION AND FOOD PRODUCTION
166
3. THE STATUS AND TRENDS IN POLLINATORS
AND POLLINATION
number of colonies at any one point in time) and annual
rates of colony mortality (the proportion of colonies that
die in one year). Indeed, rates of colony mortality have
recently been reported to be much higher than the usual
rate of ca. 10%, and up to 30% or more since the winter
of 2006-to-2007 in some parts of the temperate Northern
Hemisphere (Oldroyd, 2007; see Chapter 2, sections 2.5
and 2.6), and may be equally high in South Africa (Pirk et
al., 2014). Information from the FAO database nevertheless
suggests an increasing world number of managed colonies
of honey bees (Figure 3.2B), a trend driven by Asia (Aizen
and Harder, 2009b, Barron, 2015, see Chapter 2, Figure
3.3), with a current world stock of greater than 81 million
hives, each comprising 10,000-40,000 or more worker
honey bees (Figure 3.2B). Within this global increase in
stock, some countries have suffered declines whereas
others have seen growths (Figure 3.3, Aizen and Harder,
2009b, Potts et al., 2010a, b, Smith et al., 2013). Even
neighbouring countries (e.g., the USA and Canada) may
exhibit contrasting growth rates in the stock of honey-bee
hives (Figure 3.4).
This overall pattern of increasing numbers of honey bee
colonies worldwide is rather robust and may reflect an
increasing market value of honey and of honey bee colonies
as pollination ‘units’, though not withstanding regional
trends global honey production has consequently increased
with the number of colonies to ca. 1.6 million tonnes
annually in 2013, though the risk of a drop in production
varies widely across the world (Chapter 6, Table 6.2.2).
FIGURE 3.3
Some developed countries in the temperate Northern
Hemisphere have witnessed an on-going decrease in colony
numbers since the 2 nd World War (Figure 3.3, Aizen and
Harder, 2009a), possibly a consequence of societal changes
(e.g. increasing wealth, collapse of communism; see Moritz
et al., 2010, vanEngelsdorp and Meixner, 2010, Smith et
al., 2013), intensification of land use, and emerging pests
and diseases (see Chapter 2, sections 2.5.1 and 2.6).
Indeed, wild (where they are native) and feral (where they
are introduced) A. mellifera have almost disappeared from
the temperate Northern Hemisphere (Jaffé et al., 2010).
However, socioeconomic factors affecting the honey market
seem to be the primary cause for long-term trends in the
growth in the number of honey-bee hives (Aizen and Harder,
2009b). For instance, countries exhibiting negative growth
rates in the number of hives can exhibit positive rates in
honey production (e.g., Germany, France; Figure 3.4),
which is inconsistent with a scenario of declines in the stock
of honey-bee hives being driven by disease. Furthermore,
there has been an increasing global trend in honey
production per hive over the last five decades, so that today
an average hive produces approximately 50% more honey
than 50 years ago (Aizen and Harder, 2009a).
Genomic analyses indicate that managed honey bees have
not suffered from a reduction in genetic diversity, either
where they are native in Europe (Wallberg et al., 2014) or
where they have been introduced to North America (Harpur
et al., 2012). These introductions have also affected other
honey bee species; for example, in South Korea, A. cerana
Number of managed colonies of Apis mellifera in selected countries, showing overall losses in some countries and gains in others
(from Aizen and Harder, 2009a, Suppl. Materials).
∆ number of hives (%)
20
0
-20
-40
-60
USSR
20
USA
Germany
y 1961
= 10,250,000 hives y 1961
= 5,514,000 hives y 1961
= 1,997,000 hives
0
0
-20
-40
-60
20
-20
-40
-60
-80
-80
-80
1960 1970 1980 1990 2000 2010 1960 1970 1980 1990 2000 2010 1960 1970 1980 1990 2000 2010
400
China
400
Argentina
400
Spain
∆ number of hives (%)
300
200
100
0
y 1961
= 3,356,000 hives
300
200
100
0
y 1961
= 650,000 hives
300
200
100
0
y 1961
= 728,100 hives
-100
-100
-100
1960 1970 1980 1990 2000 2010 1960 1970 1980 1990 2000 2010 1960 1970 1980 1990 2000 2010