Case Study 12
Cotton
Pollination Aware
This case study is the primary source of information on potential pollination services for the industry. It is based on data provided
by industry, the ABS and other relevant sources. Therefore, information in this case study on potential hive requirements may differ
to the tables in the Pollination Aware report (RIRDC Pub. No. 10/081) which are based on ABS (2008) Agricultural Commodities Small
Area Data, Australia 2005-06.
Introduction
Cotton (Gossypium hirsutum) is grown worldwide for its soft,
staple fibre that develops around the seeds of the plant into
a form known as a boll. The shrub is native to tropical and
subtropical regions around the world, including the Americas,
India and Africa. The fibre is most often spun into yarn or thread
and used to make a soft, breathable textile which gives it the
status of the most widely used natural-fibre cloth in the world
(Rhodes 2002). Additionally, cotton seeds can be crushed for oil
or animal feed and the leaves may be used as mulch (CA 2009).
Cotton was first brought to Australia in the late-seventeenth
century by the first fleet and since then has grown into a
significant industry. Today, not only is cotton an important part
of many regional communities, it also contributes $1.7 billion to
the national economy each year, despite competition from large
subsidised cotton producers such as the USA and China (CA
2009). In Australia, most on-farm cotton activities occur from
September/October/November (planting) to March/April/
May (harvest).
Cotton production in Australia
All Australian cotton is grown in New South Wales and Queensland (see Table 1 and Figure 1) on about 800 farms, the majority
of which are run by families (CA 2009). The major production
areas in New South Wales stretch from the Macintyre River
on the Queensland boarder and cover the Gwydir, Namoi and
Macquarie valleys as well as along the Barwon and Darling Rivers
in the west and the Lachlan and Murrumbidgee rivers in the
south. In Queensland, cotton is grown mostly in the south, in
the Darling Downs, St George, Dirranbandi and Macintyre Valley
regions. The remainder is grown near Emerald, Theodore and
Biloela in central Queensland.
Although a relatively small producer on the world scale, Australia
is the world’s third-largest cotton exporter, producing sustaina-
ble, high-quality, low-contaminant cottons that attract a premium
on the world market. Up to 98% of cotton grown in Australia is
exported, mainly to Asian spinning mill customers (ICAC 2007)
and in 2005/06 China, Indonesia, Thailand, South Korea and
Japan were the main markets for Australian cotton (ABS 2008).
In 2006/07 a total of 487,000 tonnes of raw cotton, valued at
around $832 million, was exported; however, output in this
year was severely drought affected and was only about 64% of
‘normal’ production (ICAC 2007). The enormous growth in
Australia’s cotton production in recent years has coincided with
growth in the textiles markets of some of Australia’s nearest
trading neighbours in Asia (CA 2009).
Case Study 12
weight) (tonnes)
44,712
0
44,712
Total area (ha)
197,465
129,729
327,194
Total cotton lint production (tonnes)
345,328
0
345,328
Total seed cotton production (tonnes)
916,178
0
916,178
Pollination Aware
Figure 1 Production regions
within Australia (ABS
2008)
F igure 1
Table 1
P roduc tion regions within Aus tralia (AB S 2008)
Cotton production in Australia
(ABS 2008)
Pollination in cotton
Cotton is commonly regarded as being a partially cross-pollinated crop, and largely self-fertile and
self-pollinating (McGregor 1976), although introducing insect pollinators into
the crop during QLD
NSW
flowering has resulted in increased quantity and quality of cotton lint and seed (McGregor 1976;
pollination on the
one day
Irrigated – area (h) Rhodes 2002; Moffett et al. 1975). Each cotton flower is only available for
168,863
100,844
the flower opens, with the corolla and stiminal column falling off on the second day (Rhodes 2002).
is secreted(tonnes)
by floral nectaries inside the flower and by extra floral329,347
nectaries on the outer
or
Irrigated – cotton lintNectar
production
192,328
sub-bracteal, foliar, and unipapillate (microscopic) areas on the flower peduncles and young leaf
petioles
(McGregor(total
1976),module
with all nectar
secreting
sites shown to be attractive
to foraging honey
bees
Irrigated – seed cotton
production
weight)
(tonnes)
871,467
490,335
(Rhodes 2002).
Irrigated – area (h)
Total
269,707
521,675
1,361,802
Non-irrigated – area (ha)
28,602
28,885
57,487
Non-irrigated – cotton lint production (tonnes)
15,981
0
15,981
119 (tonnes)
Non-irrigated – seed cotton production (total module weight)
44,712
0
44,712
Total area (ha)
197,465
129,729
327,194
Total cotton lint production (tonnes)
345,328
0
345,328
Total seed cotton production (tonnes)
916,178
0
916,178
Pollination in cotton
Cotton is commonly regarded as being a partially cross-pollinated crop, and largely self-fertile and self-pollinating (McGregor
1976), although introducing insect pollinators into the crop
during flowering has resulted in increased quantity and quality
of cotton lint and seed (McGregor 1976; Rhodes 2002; Moffett
et al. 1975). Each cotton flower is only available for pollination
on the one day the flower opens, with the corolla and stiminal
column falling off on the second day (Rhodes 2002). Nectar is
secreted by floral nectaries inside the flower and by extra floral
Page 2
nectaries on the outer or sub-bracteal, foliar, and unipapillate
(microscopic) areas on the flower peduncles and young leaf
petioles (McGregor 1976), with all nectar secreting sites shown
to be attractive to foraging honey bees (Rhodes 2002).
About 50 ovules must be fertilised if a full complement of seeds
is to be produced; therefore, at least 50 viable pollen grains
must contact the stigma (McGregor 1976). Insect pollination,
in particular honey bee pollination, can aid in this process and result in higher yields and better quality lint (Rhodes 2002; Kaziev
Cotton
1960). Several authors have shown that honey bees are effective and total number of seeds per sample (16.5%) for plots receivpollinators of cotton (Rhodes 2002; Moffett et al. 1975; Kaziev ing the highest number of bee visits compared to plots receiving
1960). Benefits of honey bee pollination include increases in
the lowest number of bee visits (Table 2).
the percentage of bolls per 100 flowers,
more seeds per boll, more seed cotton
Table 2
Values for variable measure for the three
per boll and more seed cotton per flower
cage treatments (Rhodes 2002)
(Rhodes 2002). Improvements in lint
Variable
Control
Cage with
Cage withquality characteristics such as fibre strength
(open
plots)
bees
out bees
and length have also been demonstrated
(McGregor 1976).
Total boll mass (g)
29.5
19.4
9.8
Rhodes (2002) found significant increases
in the total number of bolls harvested
(11.1%), total mass of bolls (16.5%), total
lint mass (15.8%), total seed mass (19.7%)
Total seed mass (g)
16.3
10.0
4.9
Total lint mass (g)
14.2
7.8
4.1
Total number of
seeds per sample
246
117
76
Pollination management for cotton
in Australia
There are a number of factors within the field which have a
direct bearing on the pollination efficiency of honey bees:
Crop layout
• Row spacing and blossom density: Cotton seeds are most
•
commonly planted in spring, in long rows using specialised
farm machinery. Seed capsules (bolls) can grow as big as
an egg whereby after a further 35–55 days, the bolls burst
open and expose the cotton. The point at which most of the
bolls are open indicates that the crop is ready to pick (Ward
and Ward 2001).
Access: From a beekeeper’s point of view, all-weather truck
access is highly desirable. Limited access may lead to an
increased workload for the beekeeper, uneven placement of
hives and thus inefficient pollination.
Density of bees
There is little in the way of recommendations as to honey bee
management on cotton crops apart from recommendations of
one hive per hectare by Ward and Ward (2001). Rhodes (2002)
and Moffet et al. (1975) both recommend the use of honey bees
on cotton crops but give no indication as to the density of hives
required for adequate pollination. Rhodes (2002) used an apiary
of 30 hives on a 47ha plot of irrigated cotton (0.6 hives/ha)
which showed significant improvements in quality and quantity
of cotton lint and seeds.
Arrangement of hives
Most seed is set within a 100m radius of a colony. Research has
suggested colonies should be deposited in groups of 12–18 per
location, with about 150m between locations(Somerville 2005).
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Case Study 12
Pollination Aware
The distribution of honey bees within the crop suggest that bees
tend to forage around the edges of the crop. Use of a greater
number of bee hives may improve the result by increasing honey
bee activity in the centre of the crop.
Whatever the distribution, pattern hives should be placed in
shady areas to avoid extreme temperatures. Honey bees collect
significant amounts of water for use in the hive and as temperatures rise, the need for water increases, diverting many field bees
into water gathering duties. Ensuring hives are located relatively
close to water and in shady areas will significantly reduce stress
levels of colonies, aiding in optimal pollination of the target
crops (Somerville 2005).
Timing
Australia’s cotton growing season lasts approximately six
months, starting in September/October/November (planting)
and ending in March/April/May (picking) – depending on
the region. Each cotton flower is only available for pollination
on the one day the flower opens, with the corolla and stiminal
column falling off on the second day (Rhodes 2002). Thus to
ensure sufficient pollination, bee hives must be available after
around 5% of the cotton crop has begun flowering and stay until
flowering has ceased (Robertson and Rhodes 1992).
Bee husbandry in the paddock
Moving hives into a crop during the night is less stressful on
the bees, because they are not flying and the representatives are
generally cooler.
Attractiveness, nutritional value of
pollen and nectar
In cotton, honey bees collect nectar from extra-floral nectaries
as well as floral nectaries and may be foraging in a cotton crop
before, during and for a short time after the crop has flowers
present. Honey bees require nectar and pollen to satisfy their
nutritional requirements. The quality of pollen collected by
honey bees directly affects the welfare of a colony. Poor quality
or low volumes of pollen can equate to shorter lived bees and
a colony that has a greater susceptibility to disease. The sugar
Page 4
content of one sample of nectar collected from the sub-bracteal
nectar produced a reading of 17% sugar content, which is an
acceptable level for foraging bees (Robertson and Rhodes 1992).
Cotton honey is light in colour and flavour and like all flower
honeys, has a tendency to crystallise fairly rapidly. This is
because tree honeys generally granulate more slowly and some
of the sugars are stable as a crystal, not as a liquid (Rhodes 2002;
Robertson and Rhodes 1992).
Availability of honey bees for pollination
While cotton may be a significant crop for the grower, it is not
seen as a primary resource by apiarists. The nutritional value
of cotton has been said to be acceptable for honey bee foraging,
having a sugar content of 17% (Robertson and Rhodes 1992),
although research describing pollen and nectar characteristics is
lacking. Use of honey bees in cotton is not common in Australia
thus little information exists on pollination contracts and
associated costs.
Feral bees
The majority of recent research in Australia identifies significant
production benefits when introducing honey bees into cotton
crops. Cotton growers relying on feral bees for part or all of
their pollination services should be similarly aware first, that
feral colonies are unlikely to be at full strength at the time that
cotton flowers bloom and, second, that even if they were, foraging by these bees is unlikely to be sufficiently intense to achieve
the level of pollination required for optimal seed production.
Risks
Pesticides: Placing hives well back from the crop also may help
the grower. If a crop needs spraying with pesticide the location
of the hives is crucial. The further the beehives are placed away
from the crop the better. If spraying is necessary, then this
should be conducted in late afternoon or evening when foraging
bees have ceased their foraging activities. One of the biggest
dangers of placing bees near any agricultural crop is the possibility of colonies or field bees being sprayed by pesticides.
Cotton
It is strongly recommended that growers take the following steps
to prevent or reduce bee losses:
• Apiarists should always inform cotton growers where hives
•
•
•
are located
Cotton growers should always inform beekeepers when they
are likely to spray and with what insecticides, so that the
beekeepers may take precautionary measures. Due to the
logistics involved in moving an apiary, beekeepers require
as much warning time as possible and, where practical, 24
hours warning is required.
Apiarists should position their hives deep within tree stands
where practicable to minimise possible spray drift impacts.
Apiarists should avoid locating hives on the prevailing
downwind side of cotton fields.
Where possible and practical, cotton growers should restrict
spray activities (within flight range of apiaries) until after
4.00pm by which time the numbers of honey bees present
in a cotton crop would be at low levels. Growers and
applicators need to be aware, though, that it is in the early
mornings and late afternoons that inversion layers are either
present or forming and this can increase the likelihood of
spray drift.
activity tends to remain at a relatively high level. Decreases in
both numbers of bees visiting blossoms and the distance from the
hive at which bees forage occur with a decrease in temperature.
Under rainy conditions bees fly between showers but only
usually for very short distances. Wind, particularly strong wind,
tends to reduce the ground speed of bees and hence reduces the
number of flights per day.
Colony strength will also have a direct bearing on the temperature at which honey bees will leave the hive. Only strong
colonies will fly at lower temperatures. Bees need to keep their
brood nests within their hives at a constant temperature of 37oC.
The cooler the external temperature, the more the bees are
required within the hive to maintain that temperature. Hence if
the colony is strong in numbers the surplus bees not required for
maintaining hive temperature are available for foraging duties.
Environmental factors have a direct bearing on the amount
of nectar secreted. It has also been found that nectar is the
most concentrated in old flowers about to wither, but nectar
concentration fluctuates widely in accordance with the relative
humidity throughout the day. The number of honey bees that
visit the blossom has been directly correlated with the amount
and concentration of nectar produced.
Weather
Temperature and rainfall have a marked effect on honey bee
activity. Bee activity is very limited below temperatures of
13oC with activity increasing up to around 19oC, above which
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Case Study 12
Pollination Aware
Potential pollination service requirement
for cotton in Australia
Optimal use of managed pollination services in all cotton plantations in Australia would require a service capacity as indicated in
Table 3 below.
Table 3
Potential pollination service requirement for cotton in Australia
State
Month
(flowering)
NSW
September
197,465
0.6
118,479
QLD
October
129,729
0.6
77,837
Total
Area (ha)
Average hive
density (h/ha)*
327,194
Estimated Number of
hives required
196,316
Notes: * Area sourced from ABS (2008) Agricultural Commodities Small Area Data, Australia 2005-06,
flowering times and average hive density estimated from McGregor (1976)
References
AUSTRALIAN BUREAU OF STATISTICS (ABS) 2008. Agricultural Commodities: Small Area Data, Australia, 2005–06
(Reissue), ABS No 7125.0.
COTTON AUSTRALIA (CA) 2009. 2008/2009 Annual Report
– Advancing Australian Cotton. Cotton Australia.
INTERNATIONAL COTTON ADVISORY COMMITTEE
(ICAC) 2007. The International Cotton Advisory Committee. The International Cotton Advisory Committee.
KAZIEV, T. 1960. ‘The influence of bee pollination on cotton
quality’. Pchelovodstvo, 37: 33–35.
MCGREGOR, S.E. 1976. Insect pollination of cultivated crop
plants. USDA, Tucson, Arizona.
MOFFETT, J.O., STITH, L.S., BURKHART, C.C. & SHIPMAN, C.W. 1975. ‘Honey bee visits to cotton flowers’.
Environmental Entomology, 4: 203–206.
Page 6
RHODES, J. 2002. ‘Cotton pollination by honey bees’. Australian Journal of Experimental Agriculture, 42: 513–518.
ROBERTSON, L.N. & RHODES, J.W. 1992. ‘Honey bee
(Apis mellifera L.) deaths near sprayed cotton and
observations on bee foraging behaviour in flowering
cotton (Hymenoptera: Apidae)’. Australian Journal of
Entomology, 31: 243–246.
SOMERVILLE, D. 2005. ‘Best practise in a honeybee pollination service’. Agnote. NSW Department of Primary
Industry, Goulburn.
WARD, R.N. & WARD, K.E. 2001. ‘Impact of honeybee pollination activities on Bt cotton production in northern
Alabama’. In: Annual meeting of the Entomological
Society of America, South Eastern Branch, 2001,
Augusta, GA.
Cotton
Notes
This case study was prepared as part of Pollination Aware – The
RealValue of Pollination in Australia, by RC Keogh, APW
Robinson and IJ Mullins, which consolidates the available
information on pollination in Australia at a number of different levels: commodity/industry; regional/state; and national.
Pollination Aware and the accompanying case studies provide
a base for more detailed decision making on the management
of pollination across a broad range of commodities.
The full report and 35 individual case studies are available at
www.rirdc.gov.au.
Page 7
This project is part of the Pollination Program – a jointly
funded partnership with the Rural Industries Research
and Development Corporation (RIRDC), Horticulture
Australia Limited (HAL) and the Australian Government
Department of Agriculture, Fisheries and Forestry. The
Pollination Program is managed by RIRDC and aims to
secure the pollination of Australia’s horticultural and agricultural crops into the future on a sustainable and profitable basis. Research and development in this program
is conducted to raise awareness that will help protect
pollination in Australia.
RIRDC funds for the program are provided by the
Honeybee Research and Development Program, with
industry levies matched by funds provided by the Australian Government. Funding from HAL for the program
is from the apple and pear, almond, avocado, cherry,
vegetable and summerfruit levies and voluntary contributions from the dried prune and melon industries, with
matched funds from the Australian Government.
RIRDC Publication No 10/119
ISBN 978-1-74254-089-4