Bee pollination benefits for field crops

Nectar production:

T. resupinatum (Persian clover): Nectar per floret was 0.006 microL. Did not require insect pollination for seed production, but caged plots that included honeybees yielded about twice as much seed as caged plots without bees. 500 ha grown in WA in irrigation areas.

T. nigrescens (Ball clover): Nectar per floret was 0.09 microL.

T. xerocephalum : Nectar per floret was 0.06 microL.

T. michelianum : Nectar per floret was 0.12 microL.

T. isthmocarpum : Nectar per floret was 0.14 microL.

All species had a sugar concentration of slightly more than 50 per cent.

T. repens var. latum (Ladino clover): Plots without bees produced 2.7 seeds per head and plots with bees produced 90 seeds per head. T. fragiferum (Strawberry clover): Predominantly self-incompatible.

T. alexandrinum (Egyptian clover): Honeybees constituted 85 to 97 per cent of pollinating insects. Average number of seeds per head was 22 in open plots, 1.2 when screened from insects and 44 in cages with honeybees.

T. purpureum (Purple clover): Potential for seed export from Western Australia.

^top

Linseed (flax) (Linum usitatissimum var.)

Nectar production:

0.79 mg per flower per day. Sucrose content: 26, 33 and 49 per cent.

Honey production:

2 kg/hive (Russia), 10 kg/hive (Rumania) and 12 kg/hive (Bulgaria). Honey grade is light.

Review of bee pollination benefits:

• Honeybees collected pollen.
• 23 to 93 per cent of the insect visitors are honeybees.
• In the USA and Germany, open plots compared to bee-excluded plots showed no difference in yield.
• 9 to 24 per cent increase in seeds per capsule (Russia).
• 22 to 24 per cent increase in seed weight.
• 21 per cent increase in the number of seeds per capsule; 28 per cent increase in seed weight (Egypt).
• 90 per cent of the flowers are visited by honeybees.
• 29 per cent increase in seed production.
• Honeybee pollination not required.

^top

Lucerne (also luzerne, alfalfa) (Medicago sativa)

Area of production:

4900 ha (pure); 3 to 4000 ha for hay.

Flowering:

February.

99.9 per cent of 2389 bees in one experiment extracted nectar from the flowers with the so-called 'side work' movement without opening the flowers. When using honeybees, management is aimed at 'forcing' the bees to work the crop. The bees rapidly learn not to trip the flowers (in 10 to 14 days) and it is necessary to renew a supply of bees to the crop after this period. The crop needs to be 10 per cent in bloom before the bees are brought into the crop.

Hives per hectare:

3 to 6 bees per sq m (USA); 50 to 80/10 ha (Qld); 3 to 8; five in groups of 12; maximum yields obtained with ten (NSW). Recommended that bees pollinating M. sativa remain on the crop for a minimum period of six weeks.

Nectar production:

Sucrose levels vary significantly from 4.9 to 17.9 per cent depending upon cultivar. Yields vary with cultivar (see table below).

Pollen, a light cream colour, has similar protein levels as capeweed. Flowers will remain open for at least one week without pollination. Good flows of nectar have been recorded at about 21 degrees C. The nectar contains significantly more glucose than sucrose or fructose (Czechoslovakia).

Honey production:

200 to 500 kg/ha. Light, very mild in flavour, fine in granulation, which is rapid. Heavy crops of honey can be obtained. Honey production in South Australia per hive was 27.2 kg every five days with a maximum crop of 136.1 kg honey per hive.

Average nectar yield of 24 varieties of lucerne
Average nectar yield of 24 varieties of lucerne, Medicago sativa (Morthorpe and Jones (1988) Proc. 2nd Aust. Internl. Bee Congress, pp 144-49)

Review of bee pollination benefits -- lucerne

One of the classic misconceptions of the benefits of honeybee pollination occurred with alfalfa (lucerne) in USA in 1929. It is an interesting story to read. It took a beekeeper offering to bear all the costs associated with pollinating an alfalfa crop and his subsequent success to create the massive four to five times increase in alfalfa seed production the USA now experiences; see Olmstead and Wooten (1987) 'Bee pollination and productivity growth: The case of alfalfa', American Journal of Agricultural Economics, 67(1).

Native bees as effective pollinators of lucerne

Native bees are highly effective pollinators. Percentages of tripped flowers have been 30 per cent, 95 per cent, 97.5 per cent and 98 per cent of the crop. In the United States, the importance of native bees was realized and farmers encouraged their survival. Within a short space of time, spectacular increases in yield occurred with increased production of 332 kg/ha The technology of managing and rearing these leaf-cutter bees is well developed in Western Canada.

Another common problem with this crop is the lure of other nearby plant species that also may be in flower which the bees may prefer.

"Lucerne growers will be interested in knowing that where plants are grown from seed, bees have been proved to have been the best means of conveying the pollen from one flower to the pistil of another. In districts where bees are absent, the crop, as a seed one, is often a failure, while in districts where bees are kept, seed is obtained in abundance." -- Journal of Agriculture, Western Australia 14(2) 1906.

• Increased seed yields by 2.6 times; 1.6 times.
• Percentage flowers tripped: 1.2, 0.4, 0.83, 4, less than 1, 1 to 2, 13, 2.
• Crop saturation with honeybees increased seed production by 39 per cent in variety Siriver (NSW).
• In South Australia over a ten-year period, average yields from irrigated areas were 313 kg per ha (1972-82). From 1983, a crop which previously yielded no more than 450 kg/ha used honeybees and subsequently produced 1400 kg/ha.
• In Victoria, two growers experienced increased yields of 3.3 times and 4.8 times using honeybees at 2.6 hives per hectare.
• Seed yields with and without pollinators - Australia: see table below

Seed yields with and without pollinators - Australia
Lucerne Medicago sativa (Morthorpe and Jones (1988) Proc. 2nd Aust and Intnl Bee Congress, pp 144-49)
Averages in the same column followed by the same letter are not statistically different, P>0.05, Duncan's multiple range test.

	Seed yield (kg/ha)	Pollination efficiency* (%)
Caged excluding bees and insects	32c	12.4c
Caged with bees	1113a	62.6a
Caged open to field insects	566b	43.6b
Uncaged open to field insects	674b	46.7b

* Pollination efficiency = per cent of flowers which set seed.

Lucerne Medicago sativa The figures are the average of samples of 200 racemes of flowers (Doull, K. The Australasian Beekeeper 1961)

^top

Lupin Lupinus spp. (mainly L. angustifolius)

Area of production:

Production per hectare has ranged from 0.83 to 1.11 tonnes per ha (1987-1992 ABS).

Hives per hectare:

Possibly similar to lucerne.

Pollination caution:

Crops need to be sprayed for winged aphids which transmit cucumber mosaic virus (CMV) from Geraldton, Moora and Three Springs.

Nectar production:

L. albus: abundant pollen, no nectar. Anecdotal evidence in Western Australia suggests that albus variety Kiev Mutant does produce nectar and honeybees will work the flowers.

Honey production:

Said to provide an excellent build up for bees. In one instance an average of 14 kg of honey was stored and 1 kg of pollen was obtained per colony.

Review of bee pollination benefits:

• L. albus var. Hamburg with honeybees increased the yield over that of caged (bee-excluded) plot by 31.5 per cent (Victoria).
• L. angustifolius var. Uniwhite with honeybees increased the yield over that of caged (bee-excluded) plot by 22.7 per cent (Victoria).
• Honeybees represented 83 per cent of the pollinators.
• 13 to 15 per cent increase in cross-pollination in L. luteus, yellow lupins (Portugal).
• Visits by insects (including honeybees) are unlikely to benefit yield of L. albus from glasshouse results. Honeybees extract nectar from the 'side-work' movement without opening the flowers.

^top

Safflower (Carthamus tinctorius)

Hives per hectare:

25 to 50/10 ha (Qld).

Pollination fee:

$37 per hive.

Nectar production:

Honeybees collect nectar and pollen. Sucrose content: 25 per cent, 12.7 to 29.5 per cent.

Honey production:

Dark, strong and unpleasant flavour and aroma.

Review of bee pollination benefits:

• 50 to 90 per cent of visitors to flowers were honeybees.
• Seed production was 46.7 per cent higher with honeybees and insects over that of insect excluded plots.

^top

Soybean (Glycine max)

Flowering:

Crops produce 400,000 to 600,000 florets/acre. A single plant may bear up to 800 florets.

Hives per hectare:

3 to 5.

Nectar production:

35 to 53 per cent sucrose content (average 43.6 per cent). Water white nectar with a mild to unpleasant taste. Pollen grey-brown. For G. wightii, total sugar per flower was 50 per cent, and nectar production was 0.048 microL/flower/24 hour period.

Review of bee pollination benefits:

• 71 per cent of honeybees collected pollen.
• It is unlikely that yields could be increased by bee visits.
• >For G. wightii, honeybees were the most abundant visitor. Other pollinators were butterflies, wasps and flies (Brazil).
• For G. wightii, honeybees increased bean pod production by 56 per cent and seeds per pod by 45 per cent. Total seed production more than doubled to 125 per cent (Brazil).
• In the presence of bees, the number of pods set was 24 per cent higher than with bees excluded from the crop and 4 per cent higher when compared to an open field plot (Brazil).

^top

Sunflower (Helianthus annuus (Other species: Helianthus debilis, Helianthus argophyllus, Helianthus petiolaris))

General:

Sunflower oil and birdseed planted at a rate of 44 460 plants/ha, from 20 kg seed/ha with 76.2 cm between rows (Ref. 19). Yields in Illinois (USA) range from 316 to 2726 kg/ha (Ref. 11). Yields in Australia are generally 0.5 t/ha from dryland crops and less than 2 t/ha under irrigation (Ref. 10). In Victoria (Australia), trials showed plant density at 277 425 plants/ha (produced 5.5 cm flowerheads) which was in excess of the average 61 775 plants/ha (Ref. 112). Weather conditions are important in pollination efficiency (Ref. 27).

COMMON PROBLEM:

Growers that have crops with swollen flowerheads (also known as capitula) often find that very little oil is produced. Examination shows phantom seed set - that is, no kernel inside seed coat. This problem is caused by inadequate pollination - that is, not enough honey bees.

Honey bees increased yields when crop conditions for growth are good. When crop growth was poor, honey bees had no effect.

Flowering:

Flowers on the outer rim (known as ray flowers) of the flower are sterile and only serve to attract insects the flowers beyond this are flowers known as disc florets. Disc florets are male and female and upon pollination develop into oil bearing seeds. There are about 19.4 florets/cm² of flowerhead (Ref. 12).

Flowering period ranges from 34 to 40 days; 64 to 81 million florets per hectare. Non-irrigated sunflower crop may carry up to 50 000 plants/ha, which is equivalent to 75 million florets (Ref. 10). Most rain-fed crops carry less flowers.

Hybrid sunflowers have been developed which are more self-compatible (60% to 90%) than older varieties that required cross-pollination (usually by honey bees). Hybrid cultivars vary their dependence on insect pollination. Most hybrids benefit from cross-pollination (up to 50%, but a 20% benefit is an average) but some can achieve full seed set (92%) by self-pollination in some years (Ref. 10).

The effect of honey bees on some varieties can cause an incorrect assessment of sunflower varieties under test for yield in the field and may have a flow-on effect into plant breeding (Ref. 10).

F1 seed production:

For seed set to occur in hybrid sunflowers, pollen must be moved from male-fertile to male-sterile plants.

Creation of hybrid varieties that produce high yields is dependent upon their attractiveness to insects. Pollen is a major cue for insects and research showed significant differences between genotypes and possible selection of high and low pollen production from plants (Ref. 5).

The honey bee foraged on both male-sterile lines and restorer lines. The use of honey bees produced seed set similar to hand-pollination (22.5%) and seed weight were similar at 10.25 g/flowerhead (Ref. 2). Hand pollination set 45.5% seed whilst bee pollination set 45.6%. Weight of seed filled flowerhead was 22.1 g for hand pollination and 11.1 g for bee pollination.

The results of research showed that on an average day, when the population density of A. mellifera was 6 to 40 bees per 100 flowerheads, there was no correlation between the row spacing between the self-pollinated line 2607 and the male line in a 5:1 planting design and the density of honey bees on the rows (Ref. 13).

Over 94% of bees on male flowers carried pollen loads, and 3.7% on female flowers. Only 4.2% of flights were between male and female flowers. Only 54% of bees caught and examined were carrying a large number of pollen grains on their bodies (Ref. 25).

Kununurra: July to August.

South-West: December to January.

Nectar production:

Nectar production and quality are regarded as poor. The extra floral nectaries may attract bees. Significant differences in nectar secretion occurred among cultivars, and cultivars that had higher nectar production had more honey bee visits (Ref. 14).

An average of 18.1 mg/50 sugar per 50 flowers was secreted (Ref. 14). Sugar produced per flower ranges from 0.11 mg to 0.25 mg (Rumania).

About 27% of flowers in a flowerhead do not yield nectar. Average flower yield of nectar was 0.159 mg, which calculated to 16.8 to 17.7 kg sugar or 20.2 to 21.3 kg honey/ha.

During dry weather, sugar concentration of the nectar was high (40 to 70%, mean 66.1%) and the amount of nectar was only 0.6 µL/floret and 0.03 µL/floret. As a result, honey bee colonies lost, on average, 116 to 174 g/day.

Pollen production:

Low protein causes bees to lose condition. Pollen (rich yellow colour) has a crude protein level of 17.6%, which is 2.3% below optimum level for honey bees.

Pollen is too heavy for effective wind pollination, but with small insects it can account for 7% to 11% of seed set in a sunflower canopy (Ref. 10). The number of pollen grains per cubic metre of air was 117 over the open canopy (Ref. 12).

Temperatures greater than 30°C cause rapid decline in pollen viability (Ref. 10).

Beehives fitted with pollen traps can trap about 1.71 kg/hive/crop (Ref. 12).

Pollination:

Sunflower varieties will all show differences in yield when honey bee pollinated. For example, in India, three varieties showed yields of 2.66, 6.63 and 12.0 g seed/flower head when self-pollinated and 76.3, 66.1 and 53.2 g seed/flower head when honey bee pollinated (Ref. 1).

The seed weight was maximum (25.4 g/head) in honey bee pollinated plot followed by hand and bees pollinated (24.7 g/head); pollination by other pollinators (13.59 g/head) and exclusively hand pollinated (12.98 g/head) plots in case of female parent. However, it was recorded lowest (5.16 g/head) in control plots without hand or bee pollination (Ref. 4).

Honey bee foraging:

As a base line researchers have measured on average 6.5 honey bees/18.2 m of row of plants. This peaked at 20 honey bees/18.2 m (Ref. 11). If you observe less than 1 honey bee/four flowerheads on a bright sunny day - your crop is not reaching its full potential (Ref. 10). In a crop in Victoria, honey bee density was 1 bee/3.4 flowerheads when 40 hives were within 1000 m of the crop and another 26 hives were within 100 m of the crop (Ref. 12). In India, Apis mellifera visit to flowers was 22.8 bees/30 flowers (Ref. 17).

Sunflower is one of the few crops that the behaviour of honey bees differs in that nectar gathering honey bees are better pollinators than pollen gathering bees. Only 2.7% of all foragers were pollen gatherers but they still collected significant quantities of pure sunflower pollen (Ref. 12).

The average time a honey bee spends on each flower was 36 seconds (range: 3 to 187 secs) and the average number of florets/flowerhead visited was 15.3 (range: 1 to 93) - Ref. 12. Other research showed honey bee visits to flowers lasted 5.1 to 6.2 seconds (Ref. 9).

Honey bees made up 96.9% of visits to sunflower crops, foraging from 6 am to 6 pm with a peak from 9 am to 11 am (Ref. 6). Analysis of pollen showed 96.2% was from sunflower, bees visited the crop from 6 am to 7 pm with a peak from 7 am to 1 pm (Ref. 8). In Turkey, honey bees constituted 80% to 88% of total insect visitors to flowers (Ref. 20).

There was no significant relationship between the size of a colony's foraging population on male-fertile sunflowers and the amount of sunflower pollen on the bodies of nest mates within the hive or honey bees departing the hive. Honey bees obtained much of the sunflower pollen on their bodies from previously visited male-sterile flowers. Most foragers do not need to visit male-fertile flowers first or acquire sunflower pollen in the hive from nestmate contacts in order to pollinate male-sterile sunflowers (Ref. 16).

When honey bees forage on male-fertile flowers and then move to male-sterile flowers they transfer thousands of pollen grains. Most honey bees foraging in male-sterile rows obtain pollen that has been transferred from male-fertile flowers. Bees in male-sterile rows were mostly honey bees (Ref. 22).

Pollinator density was 49.8 and 34.8 insects/flower head, respectively, with honey bees constituting 66.6% and 13.4% of the total.

Effect of isolation cages on experiments:

Reduced light intensity in the cages seemed to reduce the bee activity: bees tended to collect in corners of the cages and did not start to visit flowers until noon, whereas bees visited flowers in the open fields from 7 am. Relative humidity was also higher (Ref. 26).

Effect of distance of crop from apiary on yield:

When beehives were placed at varying distances from 100 m² sunflower crops, the increase in distance from 500 m to 1250 m caused the number of honey bee foragers to decline from 100 to 61/plot, the weight of seed to decline from 6 kg to 3.7 kg/100m² and the weight of empty seeds to rise from 110 to 200 g/plot (Ref. 7).

No differences in seed set were measured in relation to distance from apiary (probably due to small sample size and all distances being less than 500 m). Distances sampled were 15.2 m, 61 m, 122 m and 183 m from apiary, consisting of 15 two-story hives in a 18.2 ha sunflower crop. Seed set ranged from 47.1% to 93.1% with the average at 73%. Yield was 1453  kg/ha (Ref. 11).

The greatest visitation to sunflowers was within 250 to 270 m of an apiary (Ref. 8).

Density of honey bees was 0.35 bees/flower near stands of 100 colonies, 0.56 bees/flower at 500 m away and 0.40 bees/flower at 1500 m. Densities were comparable on male and female inflorescences (0.095 and 0.078 bees/inflorescence, respectively) - Ref. 25.

Hives per hectare:

Even distribution of hives is very important.

0.8 hives/ha (Ref. 11); 1 to 2 hives/ha (Ref. 10); 2 to 3 hive/ha. 25 bees/100 flowers (USA); 20 to 40 hives/ha (Qld); 7.5 to 10 hives/ha; 2 hives/ha, but if other bee attractive crops are close by, then up the rate to 3 or 4 hives/ha (Ref. 24).

Caged honey bee colonies have a lower population, fewer pollen stores and a lower rate of honey storage. Brood rearing ceased when the queen stopped laying after 60 days inside the isolation cage. Colonies used in cages for pollination should be regularly supplied with frames of pollen (Ref. 23).

Pollination fee:

More than $2/hive/day (Kununurra), which can include hive servicing by the beekeeper, that is, checking, feeding and extraction. $330/hive/season Kununurra (ex Perth).

Cost/benefit:

The benefit of using honey bees as vectors of Bacillus thuringiensis was estimated at US$111/ha whilst just spraying the crop with Bacillus thuringiensis was US$74/ha. So the honey bee value alone was worth $37/ha (1999) - Ref. 19.

Honey production:

Pronounced characteristic flavour and amber colour (Ref. 11). 26 to 50 kg/ha. Average 57 kg/ha in Rumania; 20 to 21 kg/ha (Russia). One hive gained 47 kg in 15 days (USA).

Honey bees as the vector for biological control agents:

Honey bees are being used to carry bacterial, fungal or viral pathogens onto flowers they visit which kills pest insect larvae. These larvae feed on seed causing severe yield losses. The pathogens the honey bees carry are harmless to bees.

Bacillus thuringiensis var kurstaki (DIPEL - 50 g/hive) has been used in sunflower crops for the control of the banded sunflower moth using honey bees. Pathogen applicators deposited enough Bacillus thuringiensis on the flower to cause moth larval mortality. Using honey bees as vectors gave better or equivalent control of the banded sunflower moth than manual sprays (Ref. 19).

Other pollinators:

A myriad of other insects pollinate sunflower such from Diptera (for example, Syrphus sp), Hemiptera (for example, Rutherglen bug) - see Ref. 12.

Apis cerana (close relative of Apis mellifera - the European honey bee) was 26% of visitors in Indian crops. Foraged from 6 am to 5.45 pm. Visited 1.28 flowerheads/minute (Ref. 4).

Xylocopa aestuans (carpenter bees) 8% of visitors in Indian crops. Visited 1.74 flowerheads/minute.

Halictus sp 6% of visitors in Indian crops.

Syrphus sp 16% of visitors in Indian crops.

Trigona iridipennis (Ref. 3, Ref. 4).

Apis florea (Ref. 3, Ref. 4).

Apis dorsata started to forage at 7.30 am and peaked one hour later (Ref. 3, Ref. 4). Flower visit rates were 9.9 bees/30 flowerheads (Ref. 17).

Insects in general were most abundant between 8 am and 11 am (Ref. 17).

Review of bee pollination benefits:

• Honey bee activity resulted in a significantly higher seed set (4%) and seed oil content (1%). Overall, there was an increase in seed yield of 10 g/plant (444.6 kg/ha) in bee-visited plants compared with control plants. Four beehives were placed in a 1.77 ha block of sunflowers (North Dakota, USA Ref. 19).

• Yields were increased by 20% (83.3 g seed/head versus 69.4 g seed/head - not honey bee pollinated) and 33% (132.6 g seed/head versus 99.7 g seed/head - not honey bee pollinated), with one cultivar showing an increased quantity of harvested seed up by 101%. Oil content was increased by about 2% when honey bee pollinated. The experiment used 60 beehives located 200 m from the sunflower crop (Czech Republic Ref. 14).

• Seed set from sunflowers pollinated by honey bees was 77.7 to 85.9% whilst for self-pollinated plants the seed set was 25% to 25.7% (Ref. 7).

• Sunflower cv Pole Star showed yields of 1.2% when insect-excluded and 64.9% when exposed to insects, a 54-fold improvement in yield (Ref. 28).

• Heavy yield losses in open-pollinated varieties (for example, Sunfola 68) without honey bees (Ref. 10).

• Cross-pollination by honey bees results in faster germination of pollen on the stigma and enhances heterosis (hybrid vigour) in the developing seed embryo (Ref. 10).

• Crops pollinated by honey bees often flower more quickly and set more uniformly and up to two weeks earlier with greater increases in yield and oil content/seed. Quicker setting crops reduce the risk from pest and diseases and weather (heat and moisture stress) (Ref. 10).

• In the variety VNIIMK, increase in seed production was 61.2% with honeybees over bee-excluded plot. (Ref. 12 - Victoria).

• Sunflower variety VNIIMK showed about 5% seed set without insect pollinators (Ref. 12).

• In Victoria, 98.7% of pollinators were honeybees, with 97.3% collecting nectar and 2.3% collecting pollen (Ref. 14).

• Seed set were higher on plots caged with honey bees.

• The grain filling (93%) and oil content (53.1%) were highest in the plots pollinated with bees (Ref. 4).

• The number of seed (408) was also highest with bees and other insects pollinated plot followed by hand pollinated (395.3 seeds) and control plots (238.7 seeds) - Ref. 4.

• The number of seeds/flowerhead and seed weight were much higher on open-pollinated flowerheads than on those bagged to exclude insects (Ref. 6).

• Sunflowers pollinated by honey bees had 8.5% empty seeds whereas it was higher at 21.6% when no honey bees were used (Ref. 8).

• Research indicates that both the amount of pollen on the bodies of honey bees foraging on male-sterile flowers and seed set increase with greater numbers of honey bees and non-Apis species of bee foraging together (Ref. 15).

• Seed yield and oil contents of seed from two cultivars, EC-68415 and MSFH-8 were significantly higher on insect-pollinated flowers than on those bagged to exclude insects (Ref. 18).

• Seed yields were 34.7% higher than on plots caged to exclude insects; on plots caged with honey bees.

• Percentage seed set was 86.8% on open-pollinated flowers, 67.8% on flowers in cages with some bees and 31.5% in cages with no bees. Open-pollinated flowers had an average of 1151 filled seeds/flower head (wt 67.2 g) compared with 373/head (16.4 g) in caged plots without bees; the oil content of seeds was 39.2% and 32.4%, respectively (Ref. 20).

• Although differences were not significant, numbers and weight of flowers formed and flowerhead were 47.4% and 67.4% higher, respectively, in plots freely visited than in plots where insects were excluded (Ref. 21).

• Number of seeds/head was greater on open-pollinated plants than on hand-pollinated plants.

• Fruit set on flowers caged to exclude insects averaged 22% and on open-pollinated flowers 80% to 95%; number of seeds/cm² of flower head were 2.4 and 6.4 to 7.8, respectively (Ref. 25).

• Seed set and number of filled seeds/head were similar on plants inside and outside cages, but lower on hand-pollinated plants. However, the weight of seeds/head was significantly lower on caged plants than on open-pollinated plants (Ref. 26).

Yield increases when beehives are introduced into various sunflower crop types

Estimates of yield increase when beehives are introduced into crops with various sunflowers (Rural Research, CSIRO, 126, Autumn 1985)

Sunflower: % increase in seed yield with pollination (Jones (1988) Pro. 2nd Aust. Internl. Bee Congress, pp 131­34)
Each figure is an average of 30 heads expressed as grams of seed/head.
% increase = (unbagged - bagged) / bagged x 100.

References:

1. TITLE: Design of experiments for estimation of increased crop yields due to their bee pollination
   AUTHOR: Deodikar, G. B.
   JOURNAL: Journal of the Indian Society of Agricultural Statistics 27(1): 25-36 (1975).

2. TITLE: Studies on production of F1 seed of sunflower cv. LDMRSH-3 using honey bees
   ABSTRACT: Bee visits to flowers were observed on plots of a male-sterile line (MS) and a restorer line (R) of Helianthus annuus; 5 colonies of Apis mellifera and three of A cerana were placed on the crop. Honey bees (A. mellifera, A. dorsata and A. florea) and Trigona iridipennis constituted 97% of insect visitors; only a few A. cerana visited the flowers. All species foraged on R plants, but only A mellifera and Trigona on MS plants. The percentage of seeds filled compared well with that obtained by hand-pollination (22.5%) and was on average higher in some planting ratios, especially MS:R at 1:6. The weight of seeds/head obtained by bee pollination was slightly less than that obtained by hand-pollination (10.25 g) and varied from 3.25 g to 14.45 g.
   AUTHOR: Rao, G. M.; Suryanarayana, M. C.; Nadre, K. R.
   JOURNAL: Indian Bee Journal 58 (2) 68-70 (1996)

3. TITLE: Effect of honey bee pollination on foundation seed production of sunflower cv. LDMRSH-3
   ABSTRACT: Seed of this sunflower cultivar is normally produced by hand-pollination. In trials on plots of A and B lines, bee pollination (BP) was compared with hand- + insect-pollination (HP). Although Apis cerana colonies were kept nearby, few bees visited the flowers. However, A. dorsata, A. florea and Trigona iridipennis foraged on them. A. dorsata was the main pollinator; these bees started foraging at 07.30 h and were most active an hour later. They collected pollen and nectar from the B-line plants and only nectar from the A- line plants. Although some bees foraged on one line, others moved between lines. HP gave 45.5% seed set, and BP gave 45.6% for an A:B ratio of 2:1; values were lower for ratios of 4:1 to 8:1. The weight of filled seed/head was 22.1 g (HP) and 11.1 g (BP, 2:1 ratio); it was 11.5 g for BP with an A:B 6:1 ratio.
   AUTHOR: Nadre, K. R.; Suryanarayana, M.C.; Rao, G. M.
   JOURNAL: Indian Bee Journal 58 (1) 17-18 (1996).

4. TITLE: Potentiality of honey bees in hybrid seed production of sunflower (Helianthus annuus).
   ABSTRACT: A field experiment was conducted during summer 1995 on honey bee pollination at Bangalore using CMS 234A and 234B (female parent and maintainer) parents of sunflower (Helianthus annuus L.). Observations revealed that all the five species of honey bees, viz. Apis dorsata, Apis mellifera, Apis cerana, Apis florea and Trigona irridipennis participated in foraging in sunflower throughout the day. Two peak foraging periods were encountered in all the species. The filled seed weight, grain filling (%) and oil content were considerably increased in the plots pollinated only by the honey bees. The seed weight was maximum (25.4 g/head) in honey bee pollinated plot followed by hand and bees pollinated (24.7 g/head); pollination by other pollinators (13.59 g/head) and exclusively hand pollinated (12.98 g/head) plots in case of female parent. However, it was recorded lowest (5.16 g/head) in control plots without hand or bees pollination. The grain filling (%) (92.95) and oil content (%) (53.10) were also maximum in the plots pollinated with bees. In case of maintainer (234B), the seed weight was maximum 14.49 g/head) in the plots pollinated by bees and other pollinators followed by exclusively hand pollinated (12.66 g/head) and control plot without hand or bees pollination (9.75 g/head). The number of seed was also maximum (407.95) with bees and other insects pollinated plot followed by exclusively hand pollinated (395.31) and control plots (238.70).
   AUTHOR: Rajogopal, D.; Veeres, G. K.; Chikkadevaiah, N; Nagaraja and Kencharaddi R. N.
   JOURNAL: Indian Journal of Agricultural Sciences 69(1): 40-43 (1999).

5. TITLE: The pollen as an attraction parameter for pollinators to sunflower (Helianthus annuus L.)
   ABSTRACT: In the sunflower crop, the creation of hybrid varieties requires to take into account attraction parameters for pollinating insects; in this regard, pollen is a major cue. An attempt to characterise genotypes according to their pollen production and the biochemistry of the pollenkitt is described herein.
   Pollen production: an automatic method for counting pollen grains using a Coulter Counter apparatus is set to quantify the pollen production of fertile male inbreds and their hybrids. The results show an important variability, differences between genotypes and parental effect, with however high interaction for parental inbreds. The significant differences between genotypes allow to expect a possible selection of varieties upon a higher or lower pollen production.
   Pollenkitt characterisation: the biochemical composition of the lipid outer coat is analysed quantitatively and qualitatively. The quantitative analysis is carried out from the splitting on a silicic acid column Sep Pak into different classes (hydrocarbons, triacylglycerols, sterols, monoacylglycerols, diacylglycerols), and the separation by thin layer chromatography on silica gel G in a single dimension. In a first step, we focus the qualitative analysis of the free fatty acids using a gas chromatography method. This set of data is to be considered together with other plant parameters, such as aromas and nectar, in order to better define the pattern of chemical cues underlying the pollinators' foraging behaviour.
   AUTHOR: Loublier, Y.; Dugruet, V.; Pham-Delegue, M.-H.; Douault, P.; Vear, F.; Degas, C.; Masson, C.
   JOURNAL: 6^th Pollination Symposium, Acta Horticulturae 288: 394- (1991)

6. TITLE: Studies on the foraging behaviour of honey bees and their role as pollinators of sunflower (Helianthus annuus L.).
   ABSTRACT: Observations were carried out on an 8 ha crop of sunflowers cv. Mahico-8, growing at Latur, Maharashtra, India. Honey bees made 96.9% of insect visits to the flowers, with Apis mellifera (38%) making slightly more than A. dorsata (35.2%) and A. florea (20.3%). There were 71 A. mellifera colonies in the area, but only one A. cerana colony, and visits by A. cerana were insignificant. Bees foraged from 6 am to 6 pm with a peak from 9 am to 11 am. The foraging periods of pollen collectors and nectar collectors of each species are reported. The number of seeds/head and seed weight were much higher on open-pollinated flower heads than on those bagged to exclude insects.
   AUTHOR: Kumar, R.; Chaudhary, O. P.; Lenin, J. K.
   JOURNAL: Indian Bee Journal 56(3/4): 207-210 (1994).

7. TITLE: The effect of pollination by bees of yield of sunflower seeds
   ABSTRACT: Fields tests with sunflower plants, which were either completely or partially covered with gauze to prevent pollination by the bees, indicated that percentage of settings was 77.7 to 85.9 in the insect-pollinated and 25.0 to 25.7 in the self-pollinated flowers. Trials in field conditions (when a number of bee hives was placed at varying distances from several observation plots 100 m² each in a large sunflower plantation) showed that, with the increase from 500 to 1250 m of the distance of a bee hive from the plantation, the number of bees visiting each plot daily fell from 100 to 61, the weight of ripe seeds dropped from 6000 to 3700 g, and the weight of empty seeds rose from 110 to 200 g.
   AUTHOR: Rundev, V. Z.
   JOURNAL: Imp. Pur. Pastures and Forage Crops, Herbage Abs. 14: 55-56 (1994).

8. TITLE: Sunflower and bees
   ABSTRACT: Bees visited sunflower heads most actively between 7 am and 4 pm, collecting mostly nectar. In warm weather they started about 6 am; maximum visitation was at 7 am to 1 pm; at 7 pm visitation was minimal. The greatest visitation was within 250 to 270 m of the apiary. Analysis of the pollen brought into the hive showed that 96.2% was from sunflowers; that is, the bees preferred sunflower to other sources of pollen present in abundance. There were 8.5% empty seeds in sunflower heads pollinated by bees, and 21.6% where there were no bees. About 27% of the flowers in sunflower heads do not secrete nectar. One flower yields an average of 0.159 mg nectar, and from 1 hectare 16.8 to 17.7 kg sugar (20.2 to 21.3 kg honey) can be obtained.
   AUTHOR: Bitkolov, R.
   JOURNAL: Pchelovodstvo (1961) 38(5): 20-21.

9. TITLE: An experiment in increasing effectiveness of bee pollination of sunflowers
   ABSTRACT: The number of visiting bees at certain distances from apiaries was counted, and the resulting seed crops were ascertained. At 400 m there were 5590 bees per hectare; the seed crop was 1.81 t and the number of visits per flower 5.1; 89.0% flowers produced seeds, and the weight of seeds per hectare was 66.3 g (an error!). The corresponding figures for 2000 m distance were 3109 bees per hectare, 1.77 t, 2.9, 79.0%, 64.0 g. A visit to one flower lasted 5.1 to 6.2 sec. Training bees increased the number of visitors.
   AUTHOR: Kurennio, N. M.
   JOURNAL: Pchelovodsrvo (1957) 34(9): 42-48.

10. TITLE: Sunflower pollination - to bee or not to bee
    AUTHOR: Davidson, S.
    JOURNAL: Rural Research 126 Autumn 1985 CSIRO AUSTRALIA pp. 4-7.

11. TITLE: Observations of sunflower pollination in Illinois
    AUTHOR: Guynn, G. and Jaycox, E. R.
    JOURNAL: American Bee Journal 113(5): 168-169 (1973).

12. TITLE: A study on pollination of sunflowers (Helianthus annuus)
    ABSTRACT: In a trial on an irrigated sunflower (Helianthus annuus) crop in northern Victoria, plots to which bees had access produced in excess of 60% more seed than plots from which bees were excluded. The number of seeds set per cm² of flower head, the percentage germination and the oil content of seed from plots serviced by bees were significantly greater than from plots without bees. Individual seeds were heavier in plots without bees than in those serviced by bees.
    AUTHOR: Langridge, D. F. and Goodman, R. D.
    JOURNAL: Aust. J. Exp. Agric and Animal Husb. (14 April 1974)

13. TITLE: Density of honey bees (Apis mellifera L.) on rows of the self-pollinated sunflower line 2607 in seed production of Albena hybrid
    ABSTRACT: Studies on the production of hybrid sunflower seed were carried out in 1989-91 I Dobroudja, Bulgaria, in order to determine the effects of the spacing of the female line rows (line 2607) from the male line row on the density of Apis mellifera on the female line rows.
    The results of the investigation showed that on an average day, when the population density of A. mellifera was from 6 to 40 bees per 100 heads, there was no correlation between the traits studies; that is, the row spacing between the self-pollinated line 2607 and the male line in a 5:1 planting design and the density of honey bees on the rows.
    AUTHOR: Dimitrov, P.; Dimitrova, Z.; Piskov, A.
    JOURNAL: Helia 17(21): 53-56 (1994).

14. TITLE: Sunflower pollination in Czech Republic.
    ABSTRACT: The study was conducted in Central Bohemia from 1993 to 1995. Nectar secretion from 15 cultivars (hybrids) was determined and on the average 18.1 mg sugar in the nectar per 50 flowers was secreted. Significant differences in nectar secretion occurred among the cultivars. Cultivars with higher nectar production had more bee visits. Special attention was also given to gumming on flowers. The gumming intensity was influenced more by cultivar than by site. The limitation of bee foraging by gumming was not confirmed. Pollination by honey bees, increased the quantity of harvested seed up to 101% with an average of 26%. The main component in the increased yield was a larger number of harvested seeds. Honey bees foraging on sunflower did not die, and colonies moved to sunflower offered a honey harvest and had better colony development the following year.
    AUTHOR: F. Kamler.
    JOURNAL: Proc. Int’l Symp. on Pollination. Acta Hort. 437 (1997).

15. TITLE: The foraging activity of honey bees (Apis mellifera L.) and non-Apis bees on hybrid sunflowers (Helianthus annuus L.) and its influence on cross-pollination and seed set
    ABSTRACT: For seed set to occur in hybrid sunflowers, pollen must be moved from male-fertile to male sterile plants. Honey bees and other bees (non-Apis bees) forage concurrently in male sterile rows and move pollen between male-fertile and male sterile flower heads by various behaviour. Our study indicates that both the amount of pollen on the bodies of honey bees foraging on male sterile flowers and seed set increase with greater numbers of honey bees and non-Apis bees foraging together. This study is a departure from more commonly performed experiments with non-Apis and honey bees which usually focus on which bee is the best pollinator when foraging alone or whether competition is occurring between the two types of bees. Findings from this study might be applicable to other hybrid seed crops where honey bees and non-Apis bees forage together and suggest that the interactions between different bee populations are not confined simply to competition.
    AUTHOR: Hoffman, Gloria D. and Watkins, J. C.
    JOURNAL: Website: Tektran. United States Department of Agriculture. Agricultural Research Service.

16. TITLE: Does a honey bee (Apis mellifera) colony's foraging population on male-fertile sunflowers (Helianthus annuus) affect the amount of pollen on nestmates foraging on male-steriles?
    ABSTRACT: The relationship between a honey bee colony’s foraging population on male-fertile sunflowers and the amount of sunflower pollen on the bodies of nestmates both in the hive (free-running-bees), and departing the hive (departing bees) was determined. There was no significant relationship between the size of a colony’s foraging population on male-fertile sunflowers and the amount of sunflower pollen on the bodies of free-running or departing bees. Departing and free-running bees had considerably less pollen on their bodies than foragers in male-sterile rows.
    Pollen-free worker honey bees forced to forage on male-sterile capitula (forced foragers) in rows next to (MS-1) and 6 rows away from male-fertile plants (MS-7) obtained amounts of sunflower pollen on their bodies comparable to those counted on foragers randomly sampled in those rows. The distribution of pollen on the bodies of forced and random foragers in both male-sterile rows was similar. Honey bees (and perhaps other bees) that forage on male-sterile plants apparently obtain much of the sunflower pollen on their bodies from previously-visited male-sterile capitula (flower heads). Therefore, most foragers do not need to visit male-fertile capitula first or acquire sunflower pollen in the hive from nestmate contacts in order to pollinate male-sterile sunflowers.
    AUTHOR: DeGrandi-Hoffman, G.; Martin, J. H.
    JOURNAL: Journal of Apicultural Research 34(3): 109-114 (1995).

17. TITLE: Diversity, abundance and foraging activity of insect pollinators of sunflower (Helianthus annuus L.) at Hisar (India).
    ABSTRACT: In a survey on sunflower plots at Hisar, India, 20 insect species were observed visiting the floral heads. Of the 12 bee species observed, the honey bees Apis mellifera (22.8 bees per 30 heads) and A. dorsata (9.9 bees per 30 heads) were the most frequent visitors, foraging for both nectar and pollen. Five species of Diptera and three species of Lepidoptera also visited the flowers, but were much lower in abundance. Insects were more abundant on the hybrid MSFH-8 than on the other hybrid grown, EC-6815. In general, insects were most abundant between 08.00 and 11.00 h.
    AUTHOR: Arya, D. R.; Sihag, R. C.; Yadav, P. R.
    JOURNAL: Indian Bee Journal 56(3/4): 172-178 (1994).

18. TITLE: Role of insect pollination in seed yield of sunflower (Helianthus annuus L.)
    ABSTRACT: Seed yield and oil contents of seed from two cultivars, EC-68415 and MSFH-8 were significantly higher on insect-pollinated flowers than on those bagged to exclude insects. The main pollinators at the experimental site at Hisar, India, were honey bees (Apis mellifera). The effects of insect pollination were greater on EC-6815 than on MSFH-8.
    AUTHOR: Arya, D. R.; Sihag, R. C.; Yadav, P. R.
    JOURNAL: Indian Bee Journal 56(3/4): 179-182 (1994).

19. TITLE: Honey bees (Hymenoptera: Apidae) as Vectors of Bacillus thuringiensis for control of banded sunflower moth (Lepidoptera: Tortricidae).
    ABSTRACT: A study was conducted in 1996 and 1997 to determine of honey bees, Apis mellifera L., could vector Bacillus thuringiensis Berliner variety kurstaki from hives equipped with a pathogen applicator to sunflower capitula and if the amount of B. thuringiensis deposited on the capitula would be sufficient to control the banded sunflower moth, Cochylis hospes Walsingham. The study demonstrated that honey bees became contaminated with B. thuringiensis as they exited hives equipped with filled pathogen applicators and deposited enough B. thuringiensis on the capitula to cause banded sunflower moth larval mortality. When two methods of applying B. thuringiensis were compared, the honey bee vectoring method gave better or equivalent control of the banded sunflower moth larvae than manual sprays, resulting in higher seed yields than manual sprays. The presence of honey bees also increased seed set which contributed to greater yield.
    AUTHOR: Jawahar, L.; Jyoti and Brewer, Gary J.
    JOURNAL: Environ. Entomol. 28(6): 1172-1176 (1999).

20. TITLE: Pollinator bees (Hymenoptera, Apoidea) on sunflower (Helianthus annuus L.) and their effects on seed setting in the Erzurum region [Turkey].
    ABSTRACT: In 1995-96 a total of 42 bee species from five families were recorded visiting sunflowers. Apis mellifera constituted 80% to 88% of the total visitors. From 12% to 20% of flower visits were made by wild bees; the most abundant species are listed. Percentage seed set was 86.8% on open-pollinated flowers, 67.8% on flowers in cages with some bees and 31.5% in cages with no bees. Open-pollinated flowers had an average of 1151 filled seeds/flower head (wt 67.2 g) compared with 373/head (16.4 g) in caged plots without bees; the oil content of seeds was 39.2% and 32.4%, respectively.
    AUTHOR: Calmsur, Ö.; Özbek, H.
    JOURNAL: Turkish Journal of Biology (1999) 23: 73-89.

21. TITLE: Initial observations regarding the pollination of sunflower (Helianthus annuus L.) by Apis mellifera L., Pindamonhangaba, Sŕo Paulo.
    ABSTRACT: In field trials in Pindamonhangaba, Sâo Paulo, areas of a stand of sunflowers cv Anhardy were either freely visited by insects throughout development or enclosed at floral initiation in insect-proof cages containing or excluding a colony of Apis  mellifera. Although differences were not significant, numbers and weight of achenes formed/capitulum (flower head) were 47.4% and 67.4% higher, respectively, in plots freely visited than in plots where insects were excluded.
    AUTHOR: Moreti, A. C. De C. C.; Silva, E. C. E. D; Alves, M. L. T. M. F.; Silva, R. M. B.; Otsuk, I. P.
    JOURNAL: Boletim de Indústra Animal 50(1): 31-34 (1993).

22. TITLE: Some new perspectives on the pollination of hybrid sunflowers
    ABSTRACT: The following conclusions were drawn from a series of tests and observations on Helianthus annuus. When honey bees forage on male-fertile flowers and then move to male-sterile flowers, they transfer thousands of pollen grains. Most honey bees foraging in male-sterile rows obtain pollen that has been transferred from male-fertile flowers; they spread this pollen as they move along the male-sterile row.
    Wild bees also contribute to cross-pollination by transferring large amounts of pollen from male-fertile to male-sterile row. Bees in male-sterile rows were mostly honey bees; wild bees and honey bees thus appear to complement each other’s activities rather than competing for resources.
    AUTHOR: DeGrandi-Hoffman, G.; Buchmann, S.
    JOURNAL: American Bee Journal 135(9): 628-629 (1995).

23. TITLE: Use of honey bees for controlled interpollination of wild Helianthus annuus L. and Helianthus petiolaris ssp. petiolaris Nuttall.
    ABSTRACT: This study evaluated four methods of pollination: caged with honey bees; open pollination; hand pollination using mixed pollen and self-pollination. The test included eleven populations of wild Helianthus annuus and six populations of H. petiolaris petiolaris. The method of controlled pollination with bees produced significantly higher numbers of achenes than the other three methods in all but two H. annuus populations. With H. petiolaris, bee pollination produced a lower number of achenes than open-pollination. Compared with a colony kept outside, the caged honey bee colony had a lower population, fewer pollen stores, a lower rate of honey storage and brood rearing ceased when the queen stopped laying after 60 days inside the isolation cage. Colonies used in cages for pollination should be supplied with frames of pollen.
    AUTHOR: Dozet, B. M.; Mandelc, S.; ŠkoriC , D.; Farkaš, B.
    JOURNAL: Helia 16(19): 69-76 (1993).

24. TITLE: Pollination of sunflower
    ABSTRACT: Work carried out on sunflower (Helianthus annuus) seed-growing plots, of the firm Deklab is described. The preparation of colonies for pollination and the timing of their introduction are discussed, as well as the costs involved. The recommended density is 2 colonies/ha, or 3 or 4 if there are other flowers that bees may visit.
    AUTHOR: unknown
    JOURNAL: Espacio apicola 9(36): 4-11 (1999).

25. TITLE: Sunflowers: pollination by honey bees
    ABSTRACT: Fruit set on flowers caged to exclude insects averaged 22% and on open-pollinated flowers 80% to 95%; number of seeds/cm² of flower head were 2.4 and 6.4 to 7.8, respectively. Density of honey bees was 0.35/flower near stands of 100 colonies, 0.56/flower at 500 m away and 0.40/flower at 1500 m. Densities were comparable on male and female inflorescences (0.095 and 0.078 bees/inflorescence, respectively). Over 94% of bees on male flowers carried pollen loads, and 3.7% on female flowers. Only 4.2% of flights were between male and female flowers. Only 54% of bees caught and examined were carrying a large number of pollen grains on their bodies. Nectar volumes and sugar concentrations were determined in flowers at two sites (irrigated and dry) and results are presented graphically.
    AUTHOR: Munoz Rodríguez, A. F.
    JOURNAL: Vida apícola 84, 14-17 (1979).

26. TITLE: Pollination requirements in sunflower hybrid seed production: effect of caging on bee behaviour and pollination.
    ABSTRACT: On a field of Helianthus annuus in Haryana, the microclimate inside nylon mosquito-net cages (20x20x30 m) was determined during the flowering period. Relative Humidity was higher and light intensity was lower than on uncaged plots, but air temperatures were similar. Each cage contained a small Apis mellifera colony, but flowers in cages received fewer bee visits than other flowers. Seed set and number of filled seeds/head were similar on plants inside and outside cages, but lower on hand-pollinated plants. However, the weight of seeds/head was significantly lower on caged plants than on open-pollinated plants. Reduced light intensity in the cages seemed to reduce the bee activity: bees tended to collect in corners of the cages and did not start to visit flowers until noon, whereas bees visited flowers in the open from 07.00 h.
    AUTHOR: Sinha, S.N.; Vaishampayan, S., Jr.
    JOURNAL: Indian Bee Journal 57(2): 71-73 (1995).

27. TITLE: Evaluation of pollination methods of hybrid seed production in sunflower (Helianthus annuus L.)
    ABSTRACT: Three pollination methods, viz. Bee pollination under natural conditions, hand pollination under controlled (under muslin cloth bag) conditions and a combination of both (bee pollinations supplemented by hand pollination), were compared for hybrid seed production in three sunflower hybrids grown at Hisar in 1991 under spring and autumn sowings. Data are tabulated on seed set, seed size, number of seeds/head, 100-seed weight and seed yield/plant.
    Pollination efficiency was better during the spring than autumn sowing because of favourable weather conditions. Supplementary hand pollination increased percentage seed set in both seasons, but the increase was greater in the autumn. Hand pollination was the poorest method.
    AUTHOR: Yadava, D. K.; Sangwan, R. S.; Yadav, O. P.
    JOURNAL: Crop Research (Hisar) 8(3): 512-516. (1994)

28. TITLE: The pollination requirements of sunflowers (Helianthus annuus L.)
    AUTHOR: Free, J. B. and Simpson, J.
    JOURNAL: Empire J. Exp. Agr. 32: 340-342.

    Page reviewed: March 2006