THE CHRISTMAS INVASION

摘要

For many Americans, the festive season is hardly seasonal without a centrepiece of poinsettias. But for some entomologists the annual flood of red foliage is not such a welcome sight. When Timothy Den-nehy lifts up a potted plant in a store or a nursery to inspect it - as he will be doing more and more over the next couple of months - he's not admiring the shape or the colour with an eye to how it might look sitting in his home. He's looking for little greenish-white harbingers of agricultural chaos.Every autumn, Dennehy, an entomologist at the University of Arizona, Tucson, hits the states flower stalls searching for whitefly (Bemisia tabaci) on the poinsettias shipped in for the festive holidays. In December 2004, his horticultural gumshoe work paid off in a Tucson market with the first US identification of the whitefly variant in question - the pesticide-resistant Q-biotype1. The following year, the Q-biotype was found in stores across Arizona, spurring a nationwide survey that found the superfly in 22 states.