One Component of Sustainable Pest Control
Bacillus thurengiensis (BT) is a natural bacterium that is widely used as a safe and effective pesticide.
Current approaches used by farmers to control pests in cabbage crops are failing. More pests are emerging, pesticide abuse is rampant, and pesticide residues are often detected on cabbage at the market. In response, the Indian Council of Agricultural Research (ICAR) called a meeting to discuss innovative and sustainable approaches to cabbage pest control. Representatives from environmental, regulatory, research and consumer communities in India attended.
Dr. O.P. Dubey of ICAR presented the background to the issues faced. He reported that the number of pests attacking cabbage in India has increased from 10 to 38 since 1920. This is despite the use of pesticides, pheromone traps, trap crops, pest-resistant varieties, and other pest management strategies. Although the volume of pesticides used in India has declined from 75,000 MT in 1990-91 to 43,600 MT in 2001-01, pesticide abuse is rampant and pesticide residues persist as a major problem (12% of vegetables at the market have unacceptable levels of residues).
The development of pest-resistant varieties has always been the ultimate goal of researchers since varieties are the easiest of technologies for farmers to adopt. But scientists have yet to develop a marketable variety that can resist cabbage pests. Now researchers are turning their attention toward transgenic varieties as the solution.
“Major risks include the creation of new weeds or new pests when the transgenic varieties are released into the environment,” reported K.V. Prabhu of the Indian Agricultural Research Institute. Prabhu says that these risks can be managed through several mechanisms, including making the transgenic cabbage varieties sterile, or perhaps, making their pollen incompatible with other plants.
A great fear among consumers is that eating an unnatural food source will harm their health. But Bruce Chassy of the University of Illinois, USA stated that transgenic crops with Bacillus thurengiensis (BT) genes have been planted over large areas for the past 10 years without any confirmed human health problems. Itself is a natural bacterium that is widely used in agriculture (including organic agriculture) as a safe and effective pesticide.
Researcher debated on the durability of the BT resistance when it was incorporated into the plant. Cabbage pests, specifically diamondblack moth (Plutella xylostella) have developed resistance to nearly all chemical insecticides, rendering such pesticides worthless and forcing farmers to use more hazardous chemicals.
Dr. Anthony Shelton of Cornell University, USA provided encouraging news in this regard. He reported that insects are slower to develop resistance against Bt-transgenic plants as compared to chemical insecticides.
This durable resistance could be made even more sustainable if dual BT genes, rather than a standard single BT gene, were incorporated into cabbage.
Although extremely promising, the costs of developing such dual BT gene varieties could be prohibitive. Orlando de Ponti, Director of R&D for Nunhems Vegetable Seeds, emphasized the need to build a private-public partnership consortium for the development and registration of plants with this dual BT gene system. The private partners would develop the transgenic varieties, while the public partners would play the leading role in testing the safety and suitability of the materials for the environment and consumers.
At the end of the meeting, all persons expressed their continued support to this promising approach, in the hope of minimizing the abuse of chemical pesticides in cabbage production.
Source: Asian Vegetable Research and Development Center, Taiwan
Marid Agribusiness Digest
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