Leonard Gianessi and Ashley Williams
Oilseed rape is an important crop in the European Union. Rapeseed oil is used in the production of cooking oils, margarines and salad dressings. After the oil has been pressed out, the solid remains of the rapeseed are used as animal feed. Oilseed rape is called “canola” in the U.S. and Canada. The name “rape” originated from the Latin word “rapum” meaning turnip. In Europe, oilseed rape is attacked by a wide range of insect pests. Insects attack the roots, stems, leaves, flowers, pods, and seeds of oilseed rape plants. In the years before development of chemical insecticides, yield losses due to insects in European rapeseed fields were significant. In Germany, a full yield of rapeseed was harvested only one year during the period from 1910 to 1939. Yield reductions from insect pests averaged 25% and amounted to as much as 50% in two years [1].
A recent survey determined that in 18 of 20 European countries, 50% or more of the rapeseed acres are sprayed with insecticides to control populations of blossom beetles (also called pollen beetles)[2]. In 8 of the countries, more than 90% of the rapeseed acres are sprayed for blossom beetles. Blossom beetles hibernate in the woods and migrate to rape fields attracted by the crop’s yellow flowers. The adults feed on pollen, and lay eggs in holes chewed in the base of the flower buds. An individual female lays up to 185 eggs. The eggs hatch and the larvae feed on the flower parts for up to three weeks [3]. Feeding by larvae results in buds falling from the plant, resulting in podless stalks and dramatically reduced yields [4].
European organic farmers are reluctant to grow oilseed rape because it is attacked by so many insects, which are difficult to control without chemical treatments [5].
References
1. Cramer, H.H. 1967. Plant protection and world crop production. Pflanzenschutz- Nachrichten. 20(1):5.
2. Richardson, D.M. 2008. Summary of findings from a participant country pollen beetle questionnaire. EPPO Bulletin. 38(1):68-72.
3. Winfield, A.L. 1992. Management of oilseed rape pests in Europe. Agricultural Zoology Reviews. 5:51.
4. Zimmer, C.T. and R. Nauen. 2011. Pyrethroid resistance and thiacloprid baseline susceptibility of European populations of Meligethes aeneus (Coleoptera: Nitidulidae) collected in winter oilseed rape. Pest Management Science. 67:599-608.
5. Valantin-Morison, M., J.-M. Meynard and T. Doré. 2007. Effects of crop management and surrounding field environment on insect incidence in organic winter oilseed rate (Brassica napus L.). Crop Protection. 26:1108-1120.
Crop Protection Research Institute
CropLife Foundation
1156 15th Street, NW #400 Washington, DC 20005
Phone: +1 202-296-1585
www.croplifefoundation.org
Fax: +1 202-463-0474