Boosting tomato's SOS gets pests killed.A field test has now shown that making a tomato scream louder brings a horde of bug-hunting parasitic wasps to trash the tomato's attackers. In the botanical version of "Help! They're eating me," plants release volatile chemicals when caterpillars bite their leaves. Creatures that prey on caterpillars home in on these distress signals. Like ambulance chasers, they rush to the scene. The recent test demonstrated that spraying a plant hormone on a tomato crop to boost the distress signals pays off, says Jennifer S. Thaler THALER. The name of a coin. The thaler of Prussia and of the northern states of Germany is deemed as money of account, at the custom-house, to be of the value of sixty-nine cents. Act of May 22, 1846. 2. of the University of California, Davis The University of California, Davis, commonly known as UC Davis, is one of the ten campuses of the University of California, and was established as the University Farm in 1905. . "This SOS SOS, code letters of the international distress signal. The signal is expressed in International Morse code as … — — — … (three dots, three dashes, three dots). actually results in more herbivores being killed--that's new," she notes. In a California field infested in·fest tr.v. in·fest·ed, in·fest·ing, in·fests 1. To inhabit or overrun in numbers or quantities large enough to be harmful, threatening, or obnoxious: with beet armyworms, Thaler sprayed jasmonic acid on half the young tomato plants. That hormone, found in plants as diverse as ferns and cotton, triggers the manufacture of insect toxins and SOS signals. Native parasitic wasps, Hyposoter exiguae, cruise the fields and inject eggs into armyworms. When the eggs hatch, larvae eat the armyworm armyworm, larva of a moth, Pseudaletia unipuncta, found in North America E of the Rocky Mts. When numerous, armyworms move in hordes, traveling by night and devouring grasses, young grains, and some leguminous crops. The full-grown larva is about 2 in. from inside. Three weeks after treating the field, Thaler looked for wasp larvae that had killed their armyworms and formed protective cases that look like bird droppings. She found such pupae on about half of the sprayed plants. The body armyworm count in sprayed plots was twice that in control areas, she reports in the June 17 NATURE. In another experiment, lab-reared caterpillars in cups beside sprayed plants suffered 37 percent more parasitism parasitism: see parasite. parasitism Relationship between two species in which one benefits at the expense of the other. Ectoparasites live on the body surface of the host; endoparasites live in their hosts' organs, tissues, or cells and often rely than those near controls. Thaler's research "is a very important next step," comments the Department of Agriculture's W. Joe Lewis of Tifton, Ga., who studies ways to incorporate SOS signals into pest control. He says that intriguing as the strategy sounds, he wants to know more about the big picture. For instance, does amplifying the signals crowd wasps into an area with no corresponding profusion of caterpillars, so that it reduces the next wasp generation? USDA USDA, n.pr See United States Department of Agriculture. chemist and plant-defense specialist James H. Tumlinson of Gainesville, Fla., notes, "The really interesting part of this is that it was done in the field." Remarking that the strategy holds promise, he says, "This is a really red-hot area." |
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