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ANALYSIS
Economic valuation of the vulnerability of world agriculture
confronted with pollinator decline
Nicola Gallai
a,b,
⁎, Jean-Michel Salles
c
, Josef Settele
d
, Bernard E. Vaissière
a
a
INRA, Laboratoire Pollinisation & Ecologie des Abeilles, UMR406 Abeilles & Environnement, 84914 Avignon Cedex 9, France
b
INRA, UMR LAMETA, 2 place Viala, 34060 Montpellier Cedex 1, France
c
CNRS, UMR LAMETA, 2 place Viala, 34060 Montpellier Cedex 1, France
d
UFZ, Helmholtz-Centre for Environmental Research, Department of Community Ecology, Theodor-Lieser-Str. 4, 06120 Halle, Germany
ARTICLE INFO ABSTRACT
Article history:
Received 8 November 2007
Received in revised form 6 May 2008
Accepted 24 June 2008
Available online 3 August 2008
There is mounting evidence of pollinator decline all over the world and consequences in
many agricultural areas could be significant. We assessed these consequences by
measuring 1) the contribution of insect pollination to the world agricultural output
economic value, and 2) the vulnerability of world agriculture in the face of pollinator
decline. We used a bioeconomic approach, which integrated the production dependence
ratio on pollinators, for the 100 crops used directly for human food worldwide as listed by
FAO. The total economic value of pollination worldwide amounted to €153 billion, which
represented 9.5% of the value of the world agricultural production used for human food in
2005. In terms of welfare, the consumer surplus loss was estimated between €190 and
€310 billion based upon average price elasticities of −1.5 to −0.8, respectively. Vegetables
and fruits were the leading crop categories in value of insect pollination with about
€50 billion each, followed by edible oil crops, stimulants, nuts and spices. The production
value of a ton of the crop categories that do not depend on insect pollination averaged €151
while that of those that are pollinator-dependent averaged €761. The vulnerability ratio was
calculated for each crop category at the regional and world scales as the ratio between the
economic value of pollination and the current total crop value. This ratio varied
considerably among crop categories and there was a positive correlation between the rate
of vulnerability to pollinators decline of a crop category and its value per production unit.
Looking at the capacity to nourish the world population after pollinator loss, the production
of 3 crop categories –namely fruits, vegetables, and stimulants - will clearly be below the
current consumption level at the world scale and even more so for certain regions like
Europe. Yet, although our valuation clearly demonstrates the economic importance of
insect pollinators, it cannot be considered as a scenario since it does not take into account
the strategic responses of the markets.
© 2008 Elsevier B.V. All rights reserved.
Keywords:
Pollination
Valuation
Vulnerability
Agriculture
Ecosystem service
Crop
ECOLOGICAL ECONOMICS 68 (2009) 810–821
⁎Corresponding author. INRA, UMR LAMETA, 2 place Viala, 34060 Montpellier Cedex 1, France. Tel.: +33 4 99 61 29 67; fax: +33 4 67 54 58 05.
E-mail address: gallai@supagro.inra.fr (N. Gallai).
0921-8009/$ –see front matter © 2008 Elsevier B.V. All rights reserved.
doi:10.1016/j.ecolecon.2008.06.014
available at www.sciencedirect.com
www.elsevier.com/locate/ecolecon
Author's personal copy
1. Introduction
The production of 84% of crop species cultivated in Europe
depends directly on insect pollinators, especially bees (Wil-
liams, 1994). And Klein et al. (2007) found that 87 crops, that is
70% of the 124 main crops used directly for human consump-
tion in the world, are dependent on pollinators. Insect
pollination is both an ecosystem service and a production
practice used extensively by farmers all over the world for crop
production. It is an ecosystem service in that wild pollinators,
in particular wild bees, contribute significantly to the pollina-
tion of a large array of crops (Kremen et al., 2002; Morandin
and Winston, 2005; Greenleaf and Kremen, 2006; Winfree
et al., 2007, 2008). And it is also a management tool in that
honeybees, bumblebees and a few other bee species are
purchasedorrentedbyfarmersinmanycountriesto
supplement the local pollinator fauna (McGregor, 1976;
Olmstead and Wooten, 1987; Robinson et al., 1989; Free,
1993; Dag et al., 2006). Thus the economic benefit of insect
pollination is clear for farmers and the market of colony rental
is now well developed and organized for honey bees in the
United States of America (Sumner, and Boriss, 2006) and
Europe (Carreck et al., 1997) as well as for bumble bees all over
the world (Velthuis and van Doorn, 2006). This practice also
suggests that there is already not enough wild pollinators to
insure adequate pollination of all crops throughout the year in
these countries. Yet the abundance and diversity of wild bees
as well as the abundance of honeybees are now declining and
some species are clearly at risk (Biesmeijer et al., 2006;
National Research Council, 2007; Olroyd, 2007; Stokstad
2007). The current decline of insect pollinator populations
emphasizes the need to better assess the potential loss in
terms of economic value that may result from this trend and
the possible ultimate disappearance of pollinators, and to
estimate the level of vulnerability of the world agriculture to
insect pollinators.
Two main ways have been used to date to assess the
monetary value of pollinators. The first one consists in simply
assessing the total value of insect-pollinated crops. This
approach has been used at a national scale in the USA (Martin,
1975; Levin, 1984; Metcalf and Metcalf, 1992) as well as on a
world scale (Costanza et al., 1997; Pimentel et al., 1997). Since
the production of most crops is only partially reduced in the
absence of insect pollinators, a second more refined approach
to improve the previous estimate has been to introduce a
dependence ratio that takes into account the real impact of
insect pollinators on crop production. This dependence ratio
enables the calculation of the production loss in case of a
complete disappearance of pollinators, and the economic
value of insect pollination service is assimilated with the
corresponding loss of crop value. Thus the monetary assess-
ment is directly related to reported values of the dependence
of crop production on the level of insect pollination and, in this
paper, it will be called a bioeconomic approach. This type of
assessment has also been done at national and larger scales
(France —Borneck and Bricout, 1984; Hungary —Benedek,
1983; Switzerland —Fluri and Frick, 2005; United Kingdom —
Carreck and Williams, 1998; USA —Robinson et al., 1989,
Morse and Calderone, 2000, Losey and Vaughan, 2006; 12-
member-states European Community —Borneck and Merle,
1989). Unfortunately, these studies have used a wide range of
dependence ratios for the same crops (Table 1). Indeed, these
ratios were estimated based largely on personal communica-
tions and interpretation of review material, such as McGregor
(1976) and Free (1993), which do not provide dependence
ratios. None of the bioeconomic studies to date have evaluated
the impact of insect pollinators at the world scale, nor did they
make a geographical analysis of the impact of pollinators in
terms of the possible vulnerability of agriculture or examined
the potential impact of pollinator loss on production com-
pared with the consumption structure.
Our first objective was to quantify the economic loss that
could result from the total disappearance of insect pollinators
on world agricultural output and we based our calculations on
the dependence ratios recently published for the crops used
directly for human food (Klein et al., 2007). Due to the many
crop species and the heterogeneity of the structure of the
agricultural production, the vulnerability to pollinator decline
is likely to vary widely among the different continents and
regions. Our second objective was therefore to provide a
measure of the vulnerability of the regional and world
agriculture when confronted to the decline, or even the total
disappearance, of insect pollinators. Finally our third objective
Table 1 –Heterogeneity of the dependence ratios reported for the production of some selected crops in regards to insect
pollination (extrema are underlined)
Crop species Common name Borneck and
Bricout (1984)
Robinson
et al. (1989)
Southwick and
Southwick
(1992)
Morse and
Calderone
(2000)
Klein et al. (2007)
Min Max Mean Min Max Mean
Fruits
Fragaria ×ananassa Strawberry 0.100 0.200 0.150 0.4 0.30 0.2 0.1 0.4 0.25
Malus domestica Apple 0.100 0.200 0.150 1.0 0.80 1.0 0.4 0.9 0.65
Vitis vinifera Grape 0.001 0.010 0.006 0.1 0.15 0.1 0.0 0.0 0.00
Nuts
Amygdalus communis Almond 0.100 0.200 0.150 1.0 0.90 1.0 0.4 0.9 0.65
Vegetables
Cucumis melo Melon (incl. cantaloupe) 0.100 0.200 0.150 0.8 0.70 0.9 0.9 1.0 0.95
Mean 0.120 0.66 0.57 0.64 0.50
811ECOLOGICAL ECONOMICS 68 (2009) 810–821
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was to compare the production and consumption of insect-
pollinated crop categories at the regional and world scale in
the face of pollinator loss in order to draw some insight on
potential local shortages and impacts on trade. Our calcula-
tions were based on the assumption of a total pollinator loss,
but our results can be extended to any level of pollinator
decline as there is empirical evidence that the yield of
entomophilous crops –that is crops that are pollinated by
insects solely or in a dominant way –responds linearly to
pollinator density (Dedej and Delaplane, 2003; Steffan-Dewen-
ter, 2003; Clement et al., 2007).
2. Methods
2.1. Principles
Among the main crops that contribute to human food, some,
such as most cereals, do not depend on insects for their
pollination, while others can be highly or totally dependent on
insect pollination, such as many fruits, vegetables and stimu-
lant crops (Klein et al., 2007). Our study is based on the
hypothesis that the economic impact of pollinators on agricul-
tural outputis measurable throughthe use of dependence ratios
quantifying the impact of a lack of insect pollinators on crop
production value. This decrease in the production value could
result from a reduction in yield as well as in quality (Free, 1993).
Unfortunately, this impact on production value is unknown for
most crops as what is usually reported is solely the degree of
dependence of the production on insect pollinators (Borneck
and Bricout, 1984; Robinson et al., 1989; Southwick and South-
wick, 1992; Morse and Calderone, 2000; Klein et al., 2007). It is this
dependence ratio that we used again in our study to calculate
the economic impact of pollinators and the vulnerability of the
agricultural output at various scales.
Because of the lack of substitution among agricultural
produce, the economic impact and the vulnerability of the
agricultural output is not enough to assess the full value of
insect pollinators as, indeed, one ton of rice is not an
appropriate substitute for one ton of coffee or of cantaloupe.
Thus, in addition to looking at individual crops, we examined
the vulnerability to pollinator decline of the FAO crop
categories to which each crop belonged based upon the
assumption that crops within a category could be considered
as potential appropriate substitute for one another while this
would not be the case for crops in different categories. We
used the following 10 categories based on FAO: cereals, edible
oilseed crops, fruits, nuts, pulses, roots and tubers, spices,
stimulant crops, sugar crops, vegetables.
2.2. Indicators and formulae
We used a bioeconomic approach to calculate the economic value
of the impact of pollinator loss as well as the overall vulnerability
of the agricultural output to such a loss. The variables used for
each crop i,wherei2[1;I], in each world region x,wherex2[1;X],
were the quantity produced (Q
ix
), the quantity consumed (C
ix
), the
dependence ratio of the crop ion insect pollinators (D
i
)andthe
price of crop iper unit produced in region x(P
ix
). We used the price
of each crop in each of the 5 regions of the world (sensu FAO; see
supplementary data —Appendix A) because, despite the growing
interdependence of agricultural markets, producer prices for the
same crop may vary widely from one region to another and
therefore cannot be appropriately summarized by a single
average world price. Indeed, we found that neither the FAO
database nor that of any other world organization provided these
prices on a worldwide basis for all our study crops. The total
economic value of insect pollination (IPEV) was then calculated as
follows:
IPEV ¼X
I
i¼1X
X
x¼1
Pix Qix Di
ðÞ ð1Þ
Following White (1974), a precise definition of vulnerability
was given by Turner et al. (2003) and used by Schröter et al.
(2005) to assess the vulnerability of Europe faced with global
change. Vulnerability is a function of three elements: expo-
sure, sensitivity and adaptive capacity. In this context, we
used the ratio of the economic value of insect pollination to
the economic value of the crop (EV) to calculate a level of
vulnerability since it provides a measure of the potential
relative production loss attributable solely to the lack of insect
pollination. The ratio of vulnerability (RV) for the world output
used for human food was thus calculated as follow:
RV ¼IPEV
EV ¼P
I
i¼1P
X
x¼1
Pix Qix Di
ðÞ
P
I
i¼1P
X
x¼1
Pix Qix
ðÞ
kðÞ ð2Þ
So defined, the agricultural vulnerability to pollinator
decline depends upon crop dependence to pollinators, and
farmers' capacity to adapt to pollinator decline. We used part
of the overall matrix to calculate the vulnerability of a crop, of
a crop category, and of the agricultural industry in a given
region when faced with pollinator decline.
To compare production with consumption per region and per
crop category, we calculated the 2005 relative overproduction as:
P
I
i¼1P
X
x¼1
Qix Cix
ðÞ
P
I
i¼1P
X
x¼1
Cix
ðÞ
ð3Þ
The corresponding matrix after total pollinator loss was:
P
I
i¼1P
X
x¼1
Qix 1Di
ðÞCix
ðÞ
P
I
i¼1P
X
x¼1
Cix
ðÞ
ð4Þ
2.3. Data collection
The geographical scale of our study was the world based upon
the 2005 data from the FAO database (http://www.fao.org) and
thus restricted to the 162 countries that are members of this
international organization. Following FAO definitions, we
gathered these countries into 5 main regions (Africa, Asia
and Oceania, Europe, North America and Caribbean, South
and Central America), and, within each region, into sub-
regions (see supplementary data —Appendix A).
812 ECOLOGICAL ECONOMICS 68 (2009) 810–821
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We limited the scope of our study to the direct crops and
commodity crops used directly for human food as reported by
FAO (see supplementary data —Appendix B). Direct crops are
those listed individually with their production by the FAO
while a commodity is an aggregation of different crops for
which the production figures are pooled together and most are
reported as Not Elsewhere Classified. Commodity production
figures are based on a questionnaire that countries fill out to
include important crops for the world market that are not
listed individually by the FAO. We included the commodity
crops in the study because they represent a significant part of
the agricultural world output.
For Q
ix
and C
ix,
we used the 2005 FAO production and
consumption data, respectively (http://www.fao.org). For P
ix
,
we needed the mean 2005 producer price per unit weight for
each crop or commodity and each region as we opted to take
into account regional specialization, geographical context, and
socio-economic factors. We chose this approach because
producer prices vary with many factors such as crop manage-
ment, climate, varieties and market in such a way that a
regional approach should provide more accurate price esti-
mates than a worldwide approach. To fit complex geographical
patterns as well as to be able to concentrate on large producing
regions without having to go to the level of individual countries
for which many price data are not available either, we used the
five main world regions defined previously (see supplemen-
tary data —Appendix A). Major world field crops, like most
cereals and sugar crops, are produced on a large scale and have
a large-enough commercial value to be traded on financial
markets. For these crops, we used the “free on board”(FOB)
prices, which are future contracts for 2005. These prices are
available on the websites of financial market places specialized
in commodities such as the Chicago Board of Trade (CBOT) and
the New York Board of Trade (NYBOT). For most other crops,
prices are not available on the financial market place because
of lower interest in their international trading on a large scale.
For these crops, we used the 2005 producer prices for each
world region that were provided by the European database
Eurostat (http://epp.eurostat.ec.europa.eu) and by the United
States Department of Agriculture (http://www.fas.usda.gov).
For minor crops, defined as those for which the 2005 producer
price was not available in either of these two large databases,
as well as for all the commodities, we used the average
producer price listed on the FAOSTAT website for the period
1991–2002 for the most important producing country of each
world region. We used this method to reduce the effect of year-
to-year price variation as well as the biases on prices that
might take place in small producing countries. Furthermore,
when a country or a world region largely exceeded its expected
share of world production for a given crop based on its sole size,
we considered it to be specialized in this crop. For example,
Asia produced 90% of the rice, so we assumed that the world
demand for rice, and thus its world price, would be influenced
by the Asian supply. In this example, we took the producer
price of Asia rice and applied it on a worldwide basis. In all
cases, we used the local currency and the exchange rate of the
years of the data collected to calculate the prices and
production values in 2005 euros.
We calculated the dependence ratios D
i
based upon the five
levels of the extensive recent review of Klein et al. (2007;see
supplementary data —Appendix B). Starting with the complete
set of direct and commodity crops used for human food, we
selected the ones for which we had production and price data. For
the individual crops among the 11 commodities, neither the
production nor the producer price was available and the crops
that composed each of these commodities were not all dependent
on insect pollination at a similar level for their production.
Consequently we could not calculate the economic value of
pollinators for these commodity crops and they were not
considered further. For the direct crops, we focused on those
reviewed in Appendices 1 and 2 of Klein et al. (2007) for which we
calculated the average dependence ratio based on the reported
range of dependence to animal-mediated pollination in this work
(See supplementary data —Appendix B).
3. Results
We found 89 direct crops and 11 commodities used for human
food (100 lines in Appendix B). Among these, 46 direct crops in
7 categories are dependent on insect pollinators for their
production and pollinators are essential for 6 of these crops.
The contribution of insect pollinators is also reported as great
for 13 direct crops, modest for 13 and little for 14 (See
supplementary data —Appendix B). It is noteworthy that
within each crop category, there was considerable variation
among the crops as to their level of dependence on pollinators.
The 2005 world production value for crops used for human
food was €1618 trillion, and the total value of the 46 insect-
pollinated direct crops was €625 billion, that is 39% of the
world production value (Table 2 and supplementary data in
Appendix C). The economic value of insect pollination was
€153 billion (Table 2). The most pollinator-dependent crop
categories ranked by decreasing economic value of insect
pollination were vegetables, fruits, and edible oil crops
(Table 2). It is noteworthy that the production value of a ton of
the crop categories that do not depend on insect pollination –
namely cereals, sugar crops, and roots and tubers –averaged
151 €while that of those that are pollinator-dependent
averaged 761 €, or five times more, and these values were
significantly different (t=4.851;n= 3 and 7, respectively; P=
0.0013; ttest on the Log-transformed values to have similar
variance among the two groups).
The rate of vulnerability of the world agricultural produc-
tion used for human food in the face of total pollinator loss
was 9.5% (Table 2). This overall value may seem small, but it
does not reveal the large range of values among the different
crop categories. The stimulant crops with a total production
value of only €19 billion had the highest vulnerability ratio
(39%). And vegetables, the category with the highest crop
production value (€418 billion) still had a vulnerability ratio of
12%. Interestingly, there was a positive correlation between
the rate of vulnerability of a crop category to pollinators and its
value per production unit (r= 0.729, n= 10, P= 0.017).
Looking at the economic vulnerability ratios of the different
crop categories among the regions of the world indicates that,
in each region, there is a category that is highly vulnerable to
pollinator loss with vulnerability ratios ranging from 22% to
94% (Table 4). Interestingly, nuts were the most vulnerable
crop category over the largest area (7 sub-regions), followed by
813ECOLOGICAL ECONOMICS 68 (2009) 810–821
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fruits and stimulant crops (5 sub-regions each). Furthermore,
because some regions are specialized in the production of
some pollinator-dependent crop category, the vulnerability of
the world production for these categories is much higher than
the overall worldwide value indicated on Table 3. For example,
East Asia produced nearly 52% of the world vegetables with a
vulnerability ratio of 15% while the worldwide value was 12%
(Tables 2 and 4). Also North and South Americas produced 36%
of the edible oil crops with a vulnerability ratio greater than
22%, while the worldwide value was 16% (Tables 2 and 4). And
West Africa, South East Asia and North America together
produced 36% of the nuts in the world with a vulnerability
ratio ≥44% in all three regions. The situation appeared
particularly critical for stimulant crops as West Africa
produced 56% of the world production with a vulnerability
ratio of 90% (Table 4). This region produced a lot of coffee and/
or cocoa, both of which are dependent of insect pollinators for
their production, and the consequences of a total pollinator
loss on these crops could be considerable not only for the
revenues that West Africa derives from these crops, but also
Table 3 –Geographical distribution of crop production value, economic impact of pollinators and vulnerability ratio among
the 16 sub-regions of the world defined following FAO (http://faostat.fao.org); the economic value of insect pollination was
calculated following (1); sub-regions with high vulnerability ratios (≥10%) are in bold
Geographical region
and sub-region
Total production
economic value (EV)
Insect pollination
economic value (IPEV)
Rate of vulnerability
for the region (IPEV/EV)
10
9
€10
9
€%
Africa
Central Africa 10.1 0.7 7
East Africa 19.6 0.9 5
North Africa 39.7 4.2 11
South Africa 19.2 1.1 6
West Africa 48.9 5.0 10
Asia
Central Asia 11.8 1.7 14
East Asia 418.4 51.5 12
Middle East Asia 63.5 9.3 15
Oceania 18.8 1.3 7
South Asia 219.4 14.0 6
South East Asia 167.9 11.6 7
Europe
European Union (25 members) 148.9 14.2 10
Non EU25 67.8 7.8 12
North America
Bermuda, Canada and USA 125.7 14.4 11
South and Central America
Central America and Caribbean 51.1 3.5 7
South America 187.7 11.6 6
Table 2 –Economic impact of insect pollination of the world agricultural production used directly for human food and listed
by the main categories ranked by their rate of vulnerability to pollinator loss; the economic value of insect pollination was
calculated following (1)
Crop category Average value of a
production unit
Total production
economic value (EV)
Insect pollination
economic value (IPEV)
Rate of vulnerability
(IPEV/EV)
€per metric ton 10
9
€10
9
€%
Stimulant crops 1225 19 7.0 39.0
Nuts 1269 13 4.2 31.0
Fruits 452 219 50.6 23.1
Edible oil crops 385 240 39.0 16.3
Vegetables 468 418 50.9 12.2
Pulse 515 24 1.0 4.3
Spices 1003 7 0.2 2.7
Cereals 139 312 0.0 0.0
Sugar crops 177 268 0.0 0.0
Roots and tubers 137 98 0.0 0.0
All categories pooled together 1618 152.9 9.5
814 ECOLOGICAL ECONOMICS 68 (2009) 810–821
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on a global scale for the world production and resulting price
structure of these stimulants.
On a global scale, the difference between production and
consumption in 2005 was positive for all crop categories that
are pollinator-dependent.
1
Looking at these same differences
after total pollinator loss, the overall world food supply would
not be in jeopardy, but the production drop would create a
deficit in three crop categories including fruits and vegetables,
two pollinator-dependent categories with a high economic
value and low ability for storage from one year to the next
(Table 5). Looking at these three categories for which the
overall production would no longer meet consumption
patterns after total pollinator loss, we examined their change
in availability in each geographical region. The deficit result-
ing from the loss of pollinators appears important in many
region and crop category combinations, and it could have
some serious consequences in two types of situations. First, in
some regions where production was clearly exceeding con-
sumption, the loss of pollinators would result in a deficit such
that production would no longer be able to meet consumption.
This is the case for fruits in North Africa as well as in Central,
East and South Asia (Table 6). A case in point is East Asia
where fruit production exceeded consumption by 19% in 2005
and where total pollinator loss would result in a deficit with
consumption exceeding production by 26%, which is con-
siderable since this region produces nearly 20% of the world
fruit output. Other examples of a similar situation of
consumption exceeding production as a consequence of
pollinator loss are found (i) for vegetables in North and
South Africa, East and Middle East Asia, and South America,
and (ii) for stimulant crops in South Africa. A second type of
situation where pollinator loss could have serious conse-
quences arises for regions which are already barely meeting
their consumption patterns or which are net importers for a
given crop category and could therefore be severely impacted
by the drop of production following pollinator loss. This is the
case for example with fruits in the European Union where
consumption exceeded production by 20% in 2005 and this
deficit would double following total pollinator loss in Europe.
Other examples include fruits in West Africa and North
America, vegetables in Central Africa, Oceania, the European
Table 4 –Economic vulnerability ratio (in bold) and 2005 production figures in 10
6
metric tons (in italics) for the pollinator-
dependent crop categories among the 16 sub-regions of the world defined following FAO (http://faostat.fao.org). highest
value of the economic vulnerability ratio for the sub-region
1
This global statement is not in contradiction with the fact that,
according with the World Health Organization (WHO) some
3.7 billion people were malnourished in 2005 or, following the
Food and Agricultural Organization (FAO) estimates, 850 million,
as FAO recorded only the people that are protein/calories
malnourished, rather than nutrient deficient.
815ECOLOGICAL ECONOMICS 68 (2009) 810–821
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Union and North America, and stimulant crops in the
European Union and North America.
4. Discussion
We found a value of about €153 billion as an assessment of the
economic value of insect pollination for the worldagriculture in
2005. This is the direct result of the calculations based on Eq. (1)
using the dependence ratios towards pollinators given by a
recent review (Klein et al., 2007) and the production value of the
most important crops directlyused for human food.It measures
the part of the gross value of the world food production
attributable to insect pollination and can therefore be consid-
ered as a conservative assessment of the gross value of the
insect pollination service. Indeed, in an early valuation of the
service provided by bees on US agriculture, Martin (1975) stated
that the value of beef and dairy products that result from the
seed production of forage legumes such as alfalfa accounts for
about 80% of the economic value of insect pollinators. At the
world scale, such a high value is most unlikely, at least because
forage legume are not as important worldwide as in the USA. But
this statement nevertheless underlines the fact that the indirect
impact of pollinator decline on forage production, though quite
difficult to assess, may not be anecdotal. Similarly, our
assessment did not take into account the value of pollinators
for the seed production necessaryto grow the vegetative parts of
many species which are consumed by humans (such as many
vegetables; see Appendix 1 of Klein et al., 2007, and our
supplementary data —Appendix B), nor the seed production
for ornamental flowers and other uses not devoted to human
food such as biofuels. Soybean and other pollinator-dependent
edible oil crops contribute to the supply of biofuels, but current
relative prices limit their use and biofuels are mainly produced
from non-pollinator dependent crops such as sugar cane and
corn (Schubert, 2006; see supplementary data —Appendix B).
In the literature, we found only two studies giving an
economic valuation of the pollination service at the world
scale (Costanza et al., 1997; Pimentel et al., 1997). Yet the
comparison of our results with those of these two studies is
Table 5 –Effect of pollinator loss on the capacity to provide
food at the world scale for the pollinator-dependent crop
categories
Crop
categories
Relative production
surplus before
pollinator loss
Relative production
surplus after
pollinator loss
% of consumption
Stimulant crops 18 −24
Fruits 12 −12
Vegetables 19 −6
Spices 11 8
Nuts 29 16
Edible oil crops 75 40
Pulses 60 54
The differences between 2005 production and consumption figures
are expressed in relative terms as % of the 2005 consumption
figures following FAO (http://faostat.fao.org).
Table 6 –Regional effect of pollinator loss on the capacity to meet consumption before and after (in bold) total pollinator loss
for the three crop categories for which the 2005 overall balance was negative following pollinator loss
Geographical region
(FAO classification)
Fruits Stimulant crops Vegetables
% of consumption
Africa
Central Africa 22 16 633 102 −4−16
East Africa −51 −54 369 297 95
North Africa 15 −4−100 −100 16 −13
South Africa 56 29 10 −52−11
West Africa −22 −28 2982 169 21 16
Asia
Central Asia 31 −22 −100 −100 40 5
East Asia 1 −26 −30 −30 28 −4
Middle East Asia 31 2−43 −43 31 −12
Oceania 60 21 −93 −100 −4−22
South Asia 20 −323 45 90
South East Asia 30 20 289 140 15 6
Europe
European Union (25 members) −20 −40 −100 −100 −3−16
Non EU25 −30 −61 −98 −98 −2−23
North America
Bermuda. Canada and USA −30 −46 −100 −100 −3−16
South and Central America
Central America and Caribbean 54 35 183 99 63 27
South America 83 65 176 103 17 −4
The differences between 2005 production and consumption figures are expressed in relative terms as % of the 2005 consumption figures
following FAO (http://faostat.fao.org).
816 ECOLOGICAL ECONOMICS 68 (2009) 810–821
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difficult because their methods are so different. Costanza et al.
used the findings of Levin (1984) to determine a lower limit of the
value of insect pollination service of US$140 million, corre-
sponding to the value of honey and beeswax in 1980, and an
upper limit of US$18.9 billion, which was the value of 1980 U.S
crops that they considered dependent on insect pollinators
(fruits, nuts, vegetables, seeds, fibers, cattle, calve and liquid
milk production). Conservatively and without further justifica-
tion, they chose a value of US$2 billion from this interval and
assumed that the U.S. agriculture represented 10% of the world
crop value. In this way, they found a value of the insect
pollination service to crops worldwide of US$20 billion for 1996
which amounts to about €20 billion when adjusted for inflation
(http://data.bls.gov) and 2005 exchange rate (http://fxtop.com).
Pimentel et al. (1997) started with the figure of US$8 billion
reported by Martin (1975) and quoted in Robinsonet al. (1989) for
the 1970 valueof USA crops dependent on insect pollinators and
used for human food. Martin increased this figure to US$
40 billion when adding the value of beef and dairy products that
are derived from insect-pollinated legume forage to the value of
crops used directly for humans. Then, Pimentel et al. extra-
polated this value to the entire world by assuming that the
economic value of insect pollination worldwide was at least five
times that of the USA. With appropriate exchange rate and
inflation correction, the figures of Pimentel et al. (1997) give an
economic value of insect pollination to the world agriculture of
US$200 billion in 1996, and gives a 2005 economic value of
€200 billion, which takes into account the value of beef and
dairy products that are derived from insect-pollinated forage
legumes. Interestingly, if we start with the original figure of US$
8 billion for the crops used for human foods only, the economic
value of insect pollination worldwide amounts to US$40 billion
(€40 billion in 2005 economic value).
Even after appropriate corrections, the 2005 estimated
values from these two studies (€20 billion and €40 billion for
Costanza et al., 1997 and Pimentel et al., 1997, respectively)
remain considerably smaller than our result (€153 billion;
Table 2). Such a difference raises many questions. Since these
authors give little explanations on their methods, we might
assume that they have integrated in their calculations some
more sophisticated –though unformulated –considerations,
especially in relation to the behavior of economic actors that
will adapt to a pollinator-free context.
These €153 billion stand for about 9.5% of the world value
of the crops used directly for human food. This ratio of
vulnerability can be interpreted as an indicator of the value of
pollination service relative to the other factors that contribute
to agricultural production worldwide. The value of the
vulnerability ratio is of course contingent upon the relative
prices of crops and, especially, the prices of pollinator-
dependent crops relative those which are not.
2
It must be clearly stated that this economicvaluation is not a
scenario assessment, since all economic agents can change
their behavior in order to adapt to a pollinator decline. These
changes will have some costs, namely opportunity costs. But
one can assume that producers will make efficient trade-offs
between the costs of changing crop species, or varieties, or
production technologies –namely pollination techniques –and
the losses resulting from keeping less profitable practices.
3
It appears difficult to gauge the real significance of a
vulnerability of about 10% on the agricultural industry. In
some cases, a small variation may induce large consequences,
especially through the impact it might have on the financial
equilibrium of farms. The transmission of the price change
can have variable effects within the food supply chain (Wu,
2004; Tang, 2005) and the capacity of the food supply chain
operators to adapt to new situations and limit the conse-
quences, either through technical change or because of the
existence of market power, is poorly known (Hassan and
Simioni, 2001).
Furthermore, the decline of pollinators will certainly be
heterogeneous among different regions of the world due to
differences in land and crop management as well as the
abundance and diversity of wild and managed bees. For
example, in a reverse scenario Roubik and Wolda (2001) found
that the arrival of Africanized honey bees in South and Central
America resulted in much higher population densities of bees,
and this translated into increased coffee production (Roubik,
2002). On a smaller scale, landscape management is also likely
to affect pollinator density (Kremen et al., 2002; Klein et al.,
2007).
A first step towards a better understanding of the meaning
of a 10% vulnerability ratio could consist in introducing an
economic measure of this vulnerability in terms of consumer
surplus. Southwick and Southwick (1992) estimated the
economic value of honeybees as agricultural pollinators in
the USA based upon a measure of the surplus gain resulting
from their pollination service. They considered a price
reaction to quantity limitation related to the dependence
ratio that leads to the following expression of the consumer
monetary surplus gain for each crop:
Gain ¼Q1P1P0
ðÞþ
ZQ0
Q1
PQðÞP0
½dQ ð5Þ
where P
0
and Q
0
are the price and quantity with honeybee
pollination, the price Pwas estimated as a function of the
quantity Qand the income of American households from
temporal series, P
1
and Q
1
are the price and quantity without
honeybee pollination.
Our assessment is based upon the calculation of the loss in
terms of agricultural production for each crop i, that is P
i0
(Q
i0
−
Q
i1
) (see Fig. 1). This result must be transformed into economic
surplus loss for consumers to obtain an assessment of the
social cost of pollinator decline. Since there are no appropriate
data to find econometrically for each crop at the world scale
2
It must be mentioned that crops vary in the manner in which
their prices behave. Tropical fruits and spices also suffer from
price volatility, which produce losses or windfall gains. There are
high price regimes and low price regimes as in the case of coffee
and spices (also bee-pollinated crops) coinciding with crop
failures in major producing countries such as Brazil (for coffee)
and Guatemala (for cardamom). This might implicitly mean high
elasticity of demand in high price regimes and low elasticity in
low price regimes.
3
For orchard crops that are perennial in nature, elasticity of
adaptation measures such as shifting to other crops is low.
Supply elasticity for perennial crops tends to be low as compared
to demand elasticity. As a result, the opportunity costs of taking
up new crops would likely be very high.
817ECOLOGICAL ECONOMICS 68 (2009) 810–821
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the price elasticities, assumptions must be made on the shape
and value of P(Q). A simple idea is to assume that for all crops
the price elasticities (E) are constant. Inverse demand func-
tions can then easily be expressed and consumer surplus
variations analytically calculated.
The choice of a constant elasticity price is acceptable for
mostcropsaslongasthepricerangeremainsinthe
neighborhood of current prices. The neighborhood wideness
is variable with the crop and its economic status as primary
good or luxury good. It is probably unacceptable when the
ratio of dependence is very high, since the price should then
rise considerably (e.g. for the 6 crops with a dependence ratio
of 95%, which means that for a price elasticity value of −1, the
price following total pollinator loss would be multiplied by 20).
Given a constant elasticity price, the mathematical repre-
sentation of the demand function comes from the definition of
the price-elasticity E¼dQ=Q
dP=P, which leads to P(Q)−EQP′(Q)=0
and, assuming E≠0, gives the inverse demand function:
PQðÞ¼P0Q
Q0
1
E
ð6Þ
We will also assume, following Southwick and Southwick
(1992), that the long-term supply curve is perfectly elastic,
which means that farmers can switch from one crop to
another without increasing production cost and without
constraint of arable land availability. It means that there is
no producer surplus variation and then the consumer surplus
variation is actually the social surplus variation.
We used the large matrix that was built to measure the
economic value of insect pollination (Appendices B and C) to
calculate what would be the consumer surplus loss according
to several price elasticity values. For each value, we applied
our hypotheses to each crop with its specific dependence ratio
to pollinators.
The choice of a unique value for E may seem like an
oversimplification. But choosing different values of E for each
crop in each region would be equally arbitrary since these
values could not be determined from appropriate econometric
data. Some crops, like cereals, are generally associated with
low price elasticities, usually estimated to be |E|b0.5 in the
literature. Other crops, such as fruits, appear to have higher
price-elasticities, |E|N1 and possibly much more in some cases
(Southwick and Southwick, 1992).
The choice of the unique value of Efor all crops must take into
account the relative importance of crops with high and low
elasticities, which are used to calculate the total consumer
surplus loss. Fruits, vegetables, nuts, edible oil crops, stimulant
crops, and spices are the most pollinator-dependent crop
categories and they are also those that will make the largest
part of the total loss. Yet they are also those that appear most
likely to have the highest elasticities in absolute terms. So the
overall appropriate figure for Eis likely to be in the neighborhood
of −1. Furthermore, a distinction must be made between short-
term and long-term elasticities, the latter being traditionally
higher (|E|N1). Since we consider a hypothetical situation of total
pollinator loss, long-term elasticities appear more appropriate.
Fig. 1 –Estimates of the consumer surplus loss for different values of price elasticity.
818 ECOLOGICAL ECONOMICS 68 (2009) 810–821
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We have to assess now what will happen to the food
production and markets after insect pollinators decline to a
complete loss. The first consequence is a loss in production
from Q
0
to Q
0
(1 −D) for a similar production effort (i.e. without
change in the total production costs). If a smaller production is
obtained for the same total cost, we can assume that the
unitary production cost will grow from P
0
to P
0
/(1 −D)=P
1
.We
will then consider that P
i1
is the new price of the crop i on the
market of our pollinator-free economy. At this price, the
effective demand will be Q
i
(P
i1
)=Q
i1
. This assumption allowed
us to calculate the consequent surplus loss (CSloss; Fig. 1)
according to the value of E.
CSlossi¼Qi1Pi1Pi0
ðÞþ
ZQi0
Qi1
PiQi
ðÞPi0
½dQ ð7Þ
For the value E=−1, it comes from Eq. (6) that P(Q)=P
0
×
Q
0
/Q, and Q
1
(P
1
−P
0
)=P
0
(Q
0
−Q
1
). The consumer surplus loss
is then:
CSloss ¼ZQ0
Q1
PQ
ðÞ½
dQ ¼ZQ1
Q0
P0Q0
QdQ¼P0Q0log Q1
Q0ð8Þ
where P
1
and Q
1
are the price and quantity without insect
pollination, P
0
and Q
0
are the price and quantity with insect
pollination. If we apply this expression to a quantity reduction
related to a total pollinator loss for a crop with a ratio
of dependence D,Q
1
=Q
0
(1 −D) and it comes: CSloss = P
0
⋅Q
0
⋅log
(1 −D). This value is easy to calculate using the matrix of prices
and quantities in Appendices B and C. Applying this formula to all
crops used directly for human food on a worldwide basis gives a
total loss of consumer surplus of about €260 billion for 2005.
For any price-elasticity E≠−1, it comes:
CSloss ¼P0Q0
1þE
1
1D
1þE
1
!
:ð9Þ
This value can be calculated for any value of Eusing the
database of all crops in each world region (See supplementary
data —Appendices B and C):
X
I
i¼1X
X
x¼1
Pix0Qix0
1þE
1
1Di
1þE
1
!
:ð10Þ
For E=−0.8, we find €310 billions; and for E=−1.5, about
€191 billion (see Table 7).
Though a more refined analysis remains to be done, it is
possible to suggest some changes that are likely to take place
in the behavior of producers, agro food supply chains, and
consumers, if the decline in insect pollination services is
further confirmed. Farmers would at least to some extent
switch from pollinator-dependent crops to less dependent
species or, when available, varieties. But a first reaction would
probably be in many cases, as it is widely done for fruit
production in the USA, to try to improve insect pollination
through the management of selected species and the devel-
opment of artificial pollination techniques.
For the rare pollinator-dependent crops with low price
elasticity (|E|b1; i.e. apples with E=−0.59, (Southwick and
Southwick, 1992) the farmers' income will increase when
yields decrease since prices will rise faster (‘King effect’). This
effect should nevertheless be limited by competition among
farmers and resulting production enhancing investment.
Following the agro food supply chains, it can be assumed
that optimization tuning will aim at reducing the impact of
pollinator decline onto consumers, through substitution both
in the nature of the good and the processing formula. Finally,
consumers would modify their choices according to the
relative prices of food items and, in the case of strong changes;
the food budget might compete with other parts of the
consumption patterns.
4
The potential loss in some food production may not have
measurable consequences in economic terms only, as it might
also have serious consequences on human health. In parti-
cular, the decrease of fruit and vegetable availability could
impact the health of consumers worldwide. The World Health
Organisation (WHO) has set a lower limit of 400 grams per
capita and per day for fruit and vegetable consumption (WHO
Report, 1990). Naska et al. (2000) studied fruit and vegetable
consumption among ten European countries and found that
more than 50% of the households were below this recom-
mendation. In the case of a total disappearance of pollinators,
this situation is very likely to worsen.
5. Conclusions
The aim of our work was to assess the vulnerability of the food
production worldwide faced to the decline of insect pollinators.
Non-food agricultural production, cattle raising, and natural
vegetation will also be impacted but are not studied in this paper.
Using a bioeconomic approach, we calculated a world value for
the contribution of pollinators to the production of crops used
directly for human food of €153 billion, which is about 9.5% of the
total value of the production of human food worldwide.
Table 7 –Consumer surplus loss at the world scale for
2005 in relation with price elasticity
Price elasticity parameter Consumer surplus loss (10
9
€)
−0.50 422
−0.60 378
−0.70 341
−0.80 310
−0.90 285
−1.00 263
−1.10 244
−1.20 228
−1.30 214
−1.40 202
−1.50 191
−1.60 182
−1.70 173
−1.80 166
−1.90 159
−2.00 153
4
The emergence of organic foods and widespread concerns
about GM foods has reduced elasticity of substitution for health
foods (organic and non GM traditional foods) despite health foods
carrying higher prices. Finally, the loss in output of conventional
pollinated crops due to inadequate pollination forms a dead-
weight loss, net loss to producer and consumers and hence to
society.
819ECOLOGICAL ECONOMICS 68 (2009) 810–821
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Since this first result was obtained through multiples sums,
we extracted partial results such as the most vulnerable crop
categories (stimulant crops, nuts and fruits) or the categories
that stood for the largest part of the economic vulnerability
(fruits, edible oil crops, vegetables). Related to their agricul-
tural orientations, some regions appeared more vulnerable
like Middle East Asia (15%), Central Asia (14%), East Asia (12%)
and non European Union countries (12%). At the global scale,
the vulnerability of the Northern countries appeared higher
than the southern ones, which suggests that the decline of
insect pollinators might have heavy consequences for the
North–South agro-food trade. To complete these data, we
calculated the capacity to nourish world population after
pollinator loss and found that the production of 3 crop
categories will be clearly below the current consumption at
the world scale and even more so for certain regions like
Europe.
Although we created a complete database of prices and
production quantities for each crop in each region of the world
and we used a very recent review to get the dependence ratio of
each crop on insect pollination, the uncertainties are probably
large but difficult to assess, especially since ecological
responses to pollinator decline on large scales remain poorly
known (National Research Council, 2007). More specifically,
there is an ongoing debate on the existence of a “pollinator
paradox”meaning that though crops depend on pollinators,
the overall crop yield may not necessarily be as dependent
because farmers will take into account pollinator decline in
their production management and strategies (Ghazoul, 2007).
Despite these uncertainties, we discussed these results in
terms of consumer surplus loss, which is a more appropriate
indicator of the economic valuation of these vulnerabilities.
Since it was not possible to rely on econometrically estimated
price elasticities for each crop in each region, our calculations
relied on the assumption of an average sensitivity of prices to
quantity shortage. Stating that the most vulnerable crops
appear to be more sensitive to price variation, the more
realistic elasticity parameter is likely to be |E|N1. Furthermore,
since we considered the evolution over the long term, we can
make the optimistic assumption that farmers would adapt
without significant cost, and the social surplus losses would
be in the range of €310–191 billions for elasticity parameters
ranging from −0.8 down to −1.5.
Although our results demonstrate the economic impor-
tance of insect pollinators, it cannot be considered as a
scenario since it does not take into account the strategic
response of the market. Producers might have several levels of
response strategies in interaction with the intermediate
demands of the food supply chain. Moreover, the response
of consumers faced to dramatic changes of relative prices
would probably be more elaborate than the simple price-
elasticity can summarize. Short and long term reaction for
each crop and in each region would probably be quite different
and should be studied specifically in further work.
Acknowledgements
This research was funded by the EC within the FP6 Integrated
Project “ALARM”(AssessingLArge scale environmental Risks for
biodiversity with tested Methods; GOCE-CT-2003-506675; http://
www.alarmproject.net;Settele et al., 2005). The authors thank
Joshua Bishop, Jean-Marie Boisson, Gabriel Carré, Charles
Figuières, Ghislain Géniaux, Mabel Tidball and three anon-
ymous referees for valuable comments on an early version of
this text.
Appendix A. Supplementary data
Supplementary data associated with this article can be found,
in the online version, at doi:10.1016/j.ecolecon.2008.06.014.
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