The suspicion that the exotic Mexican beetle (Zigogramma bicolorata) may be causing more harm than good has been confirmed by the Union agriculture ministry. The ministry's plant protection adviser, R L Rajak, has asked agricultural universities to stop immediately multiplication and distribution of the species. The beetle was introduced in India in 1983 to control biologically the rampant weed, parthenium.
The ministerial missive was prompted by definitive proof from field surveys that the beetle had a far greater appetite for sunflower, a vital oilseed crop, than the parthenium for which it was intended (See Down To Earth, March 31, 1993). Indeed, even though warnings had earlier been sounded by researchers at the University of Agricultural Sciences in Bangalore, it took laboratory tests conducted by the Hessarghata-based Indian Institute of Horticultural Research (IIHR) to convince the Union government.
The IIHR scientists reported that the beetle showed an inclination to attack all the 28 types of sunflower cultivated in the country. Though sunflower crops in only Hasan and Kolar districts have reportedly fallen prey to the beetle, ministry officials say they are ordering fresh surveys throughout the country.
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