Author
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Henneberry, Thomas |
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Submitted to: Guest Editorial for Phytoparasitica
Publication Type: Peer Reviewed Journal Publication Acceptance Date: 12/1/2001 Publication Date: 4/1/2002 Citation: N/A Interpretive Summary: Technical Abstract: The introduction of genetically modified cottons into agroecosystems in the SW US has revolutionized pink bollworm (PBW). PBW was first noted in the US from Mexico in TX cotton in 1917. Eradication of early infestations was followed by reinfestation in the lower Rio Grande Valley in 1936 and spread to other states. Spread of PBW throughout AZ to the Imperial and Palo Verde Valleys of CA occurred by 1965. Insecticide use on cotton for PBW increased in the invaded areas from 1-2 applications to 10-15 applications. Resistance to DDT occurred in Mexico in the late 1950's and TX in 1962. By the mid-1970's, reports of reduced effectiveness of some organophosphate and carbamate insecticides occurred, but without documentation and tolerance to certain pyrethroid insecticides was later documented. Losses in the Imperial Valley, CA alone ranged from 8 to 79% of the crop value from 1966 to 1980. These losses and reduced cotton prices in the world market were major factors resulting in reduced cotton production from 57,871 ha in 1977 to 3,713 ha in 1994 in the Imperial Valley. A major breakthrough for managing PBW occurred with the development of cottons carrying the gene that mediates production of one of the insect toxic proteins from Bacillus thuringiensis kurstaki (Berliner). Grower acceptance occurred with 50% or more of the acreage from 1997 to 2000 planted to Bt cottons in AZ. Economic models suggest that pest control costs have been reduced 62 to 136 dollars per ha, with overall grower gains in excess of 10 million dollars per year. Bt cotton implementation and use of insect growth regulators for sweetpotato whitefly in AZ has resulted in a 65% drop in conventional insecticide use. There is concern that PBW will become resistant to the Bt cotton. The U.S. EPA required a resistance management plan as a part of Bt registration. After 6 years of commercial use, no failures in the field have been reported and high levels of efficacy have been maintained. Increased yields, reduced insecticide use and environmental compatibility have been documented. We need estimates of refugia effectiveness and a better understanding of the spatial, temporal and quantitative manipulation of refugias. Other needed information concerns PBW behavior, dispersal and reproductive biology within and between Bt and non-Bt cotton cultivars. A concerted effort to define the mechanism of resistance may be necessary to reveal strategies to cope with or circumvent resistance if it occurs. Information on the more subtle, long-term concerns such as transgene flow to native plant species, potential effects on behavior and behavioral interactions of natural enemies and their hosts, and other environmental and ecological impacts are also urgently needed and are at present in their infancy. |
