1. Introduction
Genetically modified (GM) plants manifest new traits via the production (expression) of novel proteins encoded by inserted transgenes (DNA). For example, cotton modified to contain a Bt (Bacillus thuringiensis) gene and expressing Bt insecticidal protein in its leaves and buds will be protected from caterpillar attack. Both the transgene DNA and the novel protein in such plants could be considered "GM material".
Bees collect pollen and nectar from plants as food for their colonies. They may also collect honeydew (plant sap that has been ingested and then excreted by sucking insects such as aphids) for food and plant resin to make propolis with which to seal up cracks in the hive. With GM plants, there is a possibility that transgene DNA and/or novel proteins may be present in the plant parts and secretions collected by bees. Hive products intended for human consumption and derived from the plant parts collected by bees include honey (from nectar or honeydew, and containing traces of pollen), pollen and propolis. Other products, such as pure royal jelly, bee venom and beeswax, are secretions from the bees themselves and would not be expected to contain any plant matter. Section 2 examines the evidence for "GM material" from GM plants occurring in hive products.
The relevance of this to the production and marketing of bee products will depend on the tolerance limits for GM material in food. GM labelling requirements in countries to which New Zealand exports honey, and organic food standards, are described in Section 3.
GM plants are now being grown commercially in thirteen different countries. In 2000, the estimated global area planted with these crops was 44.2 million hectares (James, 2000). Ninety nine percent of these crops were grown in the USA, Canada, Argentina and China. Herbicide-tolerant soybean was the most common GM crop, occupying 59% of the global area, followed (in descending order) by Bt corn (maize), herbicide-tolerant canola (oilseed rape), herbicide-tolerant corn, herbicide-tolerant cotton, Bt/herbicide-tolerant cotton, Bt cotton and Bt/herbicide-tolerant corn. In addition to these commercially available varieties, many other plants can now be genetically modified. Field trials are under way overseas for field crops (e.g. wheat, rice, barley, tobacco), flowers (e.g. roses, carnations), trees (e.g. poplar, spruce, sweetgum), oil crops (e.g. sunflower, peanut), grasses, sugar crops (beet and cane), fruits (e.g. apple, cranberry, grape, melon, strawberry) and vegetables (e.g. tomato, potato, broccoli, carrot, eggplant, lettuce, pea) (Hagedorn, 1997). In New Zealand, there is sufficient scientific expertise to modify a number of locally important crop plants, experimentally at least (Christey and Woodfield, 2001).
New Zealand beekeepers rely on a wide range of plants to provide nectar and pollen for their bees (Matheson, 1997). Many of these plants are not commercially cultivated, but are native plants (e.g. manuka, rewarewa, pohutukawa, rata), garden plants (e.g. rosemary, flowering currant), or weeds (e.g. gorse, heather, thistles). Of the commercial crops, white clover is the most important for honey production. Trees grown for shelter (e.g. willow, hawthorn) and for fruit (e.g. apple, pear) and field crops (e.g. brassicas, sunflowers) can also be useful sources of forage for bees. Bees are also used to pollinate crops for fruit, vegetable and seed production (Appendix 1). There have also been reports of bees visiting plants such as corn, grasses and potatoes in the absence of better sources of forage and of the occurrence of traces of pine pollen in honey. Thus, if modified, some of these plants might represent sources of GM materials that could be collected by bees. Section 4 describes GM plants which could be visited by bees and might be grown in New Zealand. It also examines methods for separating GM and non-GM crops for the purposes of keeping separate the bee products derived from them.
Market reaction to the presence of GM materials in bee products will play an important role in determining the economic significance of any impact that GM plants may have on bee products from New Zealand. Section 5 describes the experiences of some beekeepers in countries where GM crops are grown.
Finally, current scientific knowledge of the potential for GM plants to have impacts on honey bee health is reviewed in Section 6.
Contact for Enquiries
Dr Sharon Adamson
Manager,
Innovation Policy
Ministry of Agriculture and Forestry
PO Box 2526
Wellington
NEW ZEALAND
Phone: +64 4 894 0618
Fax: +64 4 4 894 0741
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