When a butterfly flaps its wings…

On 20 May, most UK newspapers carried large colour photographs of the monarch butterfly. Some were even bigger than the accompanying reports, with headlines typified by the Daily Mail’s “GM pollen that can mean a cloud of death for butterflies.” The implication was that genetically modified plants in general threaten butterflies in general — even the environment in general. The articles stemmed from the appearance in Nature (1999, 399:214) of work by John Losey and colleagues at Cornell University, USA. They had shown that monarch larvae, placed on milkweed leaves dusted with pollen from Bt corn (corn transformed with DNA from the bacterium Bacillus thuringiensis), ate less, grew more slowly and suffered higher mortality than those placed on leaves dusted with pollen from untransformed corn. Losey et al. said these effects were probably attributable to Bt toxin in the pollen, and argued that this could threaten monarch butterflies within range of pollen from the US corn belt. Although these concerns seem justified, media coverage of the story illustrated the relentless escalation of hysteria that has characterized reporting of GM foods in the UK over the past year. First, the work itself was significant yet incomplete. Crucially, the authors did not compare the effect of GM pollen with Bt toxin itself or with other widely used pesticides that transgenic plants are intended to replace. Then, the importance of the story was highlighted by a press release from Nature. Third, its photogenic quality and timing — in the midst of a nationwide frenzy over GM foods — ensured a prime place on the media agenda. It dominated the front page of the Independent, relegating the Kosovo conflict to a smaller item at the bottom of the page. Such antics will perplex many scientists outside the UK (and many inside). Yet there are wider messages here. One is the danger that national hysteria can not only jeopardise an entire industry in one country but create tidal waves elsewhere and indeed threaten international trade.