Literature Review on Genetically Modified Plants and Bee Products
Executive Summary
Louise A. Malone June 2002
1. Bees collect pollen, nectar, resins and honeydew from plants and incorporate these into bee products such as honey, pollen and propolis.
2. GM material, i.e. transgene DNA or novel proteins encoded by transgenes, may be present in bee products if it occurs in the plant tissues and secretions collected by bees and if they incorporate it into those products.
3. GM plants have the potential to produce:
- pollen containing both transgene DNA and novel proteins
- nectar containing novel proteins, although probably only rarely
- resins containing novel proteins, although this is not at all certain
- sap containing both transgene DNA and novel proteins, but whether they would remain after passing through the gut of a sucking insect (to make honeydew) is not known.
4. Pollen, which commonly occurs in honey at concentrations ranging from 20,000 to 100,000 grains per 10 g (and rarely to a maximum of 5 million grains per 10 g), is thought to represent the most likely source of GM material in bee products. If we assume that an "average" pollen grain weighs 0.03 mg, these values are equivalent to honey containing 0.0006% to 0.03% w:w pollen, with a maximum value of 1.5% w:w.
5. GM material has been recorded in honey samples:
- transgene DNA was detected by PCR in shop-bought honey from regions where field trials of herbicide-resistant GM oilseed rape were grown (Friends of the Earth study)
- a novel protein (conferring kanamycin resistance) was detected by ELISA in a sample of honey taken from a hive near flowering herbicide-resistant GM oilseed rape in the United Kingdom (MAFF study)
6. GM food labelling legislation allows for a food to contain up to a certain percentage of GM material where its presence is unintentional. At present this percentage is:
- 1% w:w in New Zealand, Australia, the European Union and Saudi Arabia
- 3% w:w in South Korea
- 5% w:w in Japan
There is presently no requirement to label foods containing GM material in Canada or the United States.
7. Honey containing GM material cannot be certified as organic. Organic beekeeping rules in New Zealand do not specifically mention GM crops, but hives must be kept at least 3 km from conventionally-grown crops.
8. There are no GM plants being grown outdoors in New Zealand at present. Of the New Zealand crops for which GM varieties are available commercially overseas or are being developed in laboratories, clover, oilseed rape (canola) and eucalypts are the most likely to be important for honey production. Apple and kiwifruit pollen may be a component of bee-collected pollen and may occur in honey. Pollen from other crops, such as maize, grass, pine, tamarillo, potato, onion and leek, may occur in some honeys, but only as very minor components.
9. Bees have been reported to fly up to 13.7 km, although this was to a single food source in a desert where there was no other forage available. Most authors report 10 km as a maximum distance for a bee foraging flight, that most bees will be found within 6 km of their hive, and that most will have mean foraging distances of about 0.5 to 1.5 km.
10. Strategies to minimise the presence of GM material in bee products may include:
11. Honey containing GM material cannot be certified as organic. Organic beekeeping rules in New Zealand do not specifically mention GM crops, but hives must be kept at least 3 km from conventionally-grown crops.
12. There are no GM plants being grown outdoors in New Zealand at present. Of the New Zealand crops for which GM varieties are available commercially overseas or are being developed in laboratories, clover, oilseed rape (canola) and eucalypts are the most likely to be important for honey production. Apple and kiwifruit pollen may be a component of bee-collected pollen and may occur in honey. Pollen from other crops, such as maize, grass, pine, tamarillo, potato, onion and leek, may occur in some honeys, but only as very minor components.
13. Bees have been reported to fly up to 13.7 km, although this was to a single food source in a desert where there was no other forage available. Most authors report 10 km as a maximum distance for a bee foraging flight, that most bees will be found within 6 km of their hive, and that most will have mean foraging distances of about 0.5 to 1.5 km.
14. Strategies to minimise the presence of GM material in bee products may include:
- separating GM and non-GM crops (effectiveness will depend on bee flight distances)
- screening GM crops with bee-proof mesh (not practical except on a very small scale)
- using bee attractants such as a sugar syrup spray on non-GM crops
- using bee repellents such as some pesticides on GM crops
- using GM plants where the transgene is not expressed in pollen, or the transgene occurs only in chloroplasts, or where pollen or flower formation is blocked
- removing pollen grains from honey by filtering after harvest.
15. Although the low levels of pollen in most honeys should ensure that GM labelling would not usually be required for honey sold to New Zealand's main honey markets (even if the bees foraged solely on GM plants), there may be a market reaction to honey from a country where GM crops are grown.
16. Some shipments of honey from Canada, where bees can forage on GM canola and GM food labelling is not required, were rejected by Germany in 1999. This event has received considerable publicity, but the Canadian Honey Council reports that this market has now recovered. Reports of difficulties with honey exports from Argentina, the United States or Australia could not be found.
17. Potential impacts of GM plants on bee health are being actively researched in several countries, including New Zealand. The effects on honey bees of a number of novel proteins which might be expressed in pollen have been determined. No negative effects have been observed thus far for the types of GM plants currently commercially available. Slight negative effects for a small number of novel proteins from GM plants under experimental development have been observed.
For further information contact: Louise Malone
HortResearch
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Ph (09) 815 4200
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