Unleash the Wasps 



Cuddly they're not, but trained wasps might 

 one day offer some stinging competition to 

 bloodhounds trained to sniff for corpses. In 

 as little as five minutes, parasitic wasps of 

 the species Microplitis croceipes can be con- 

 ditioned to recognize and respond to certain 

 odors. The training teaches the wasps to 

 associate an odor with food. But how could 

 forensic investigators exploit the talents of 

 trained wasps? 



Glen C. Rains, a biological engineer at 

 the University of Georgia in Tifton, and two 

 colleagues have devised a practical answer. 

 Their invention, aptly called the Wasp 



Hound, is a portable, eight-inch tube with 

 an interior chamber housing five wasps. 

 When air bearing the target chemical blows 

 through the chamber, the wasps cluster in- 

 quisitively near the odor's source. A camera 

 transmits a video image of the insects to a 

 computer, which is programmed to recog- 

 nize wasp behavior that indicates the 

 presence of the chemical — and then signal 

 accordingly. Rains and his team say the 

 wasps could be conditioned to detect not 

 only corpses but also drugs, plant diseases, 

 spoiled food, accelerants used in arson, and 

 even human diseases such as cancer. 

 {Biotechnology Progress, forthcoming) 



— Rebecca Kessler 



Sea otter snacks on abalone in California. 



Fossil By Proxy 



Kelps dominate the reefs of cool seas. They 

 represent most of the biomass in these richly 

 productive ecosystems, yet relatively little is 

 known about their origins. One theory holds 

 that kelps became widespread in the Northern 

 Hemisphere sometime between 5 and 10 mil- 

 lion years ago, when northern oceans cooled 

 off and became rich enough in nutrients for 

 kelps to flourish. But evidence supporting the 

 theory is hard to come by, because the fossil 

 record is bereft of kelps — their soft tissue sim- 

 ply does not mineralize well. 



So one must approach the question side- 

 ways. James A. Estes, a marine biologist at 

 the University of California, Santa Cruz, and 

 two colleagues noted a pattern among spe- 

 cies of abalone that grow to more than six 

 inches long. Throughout the world, those 

 larger species live only in cold seas that have 



plenty of kelp, their preferred food. Unlike 

 kelps, though, abalones leave fossils behind. 

 Examining the fossil record, Estes and his co- 

 workers found that small species of abalone 

 have been around for more than 60 million 

 years, but large ones only 5 million years. 

 That sharpens the time estimate for the 

 kelps' population surge in northern seas. 



The work also offers insight into another 

 question: How could large abalones evolve 

 in kelp forests that also harbor otters? Ot- 

 ters dine on abalones and prefer the big 

 ones. Estes and his colleagues think 

 abalones survive in protective crevices on 

 the rocky seafloor; meanwhile, otters prey 

 on other kelp eaters, such as sea urchins. 

 The reduction in predators enables the kelp 

 to grow so lush that the dead bits raining 

 from their rubbery fronds provide the shel- 

 tered abalones with food aplenty. {Paleo- 

 biology 31 :591-606, 2005) — S.R. 



Birth of the Spud 



For every hot, salted, deep-fried bite of 

 potato you've enjoyed, you have Andean 

 farmers to thank. They were first to cultivate 

 the spud {Solanum tuberosum), perhaps as 

 early as 7,000 years ago. Today, from west- 

 ern Venezuela to northern Argentina, many 

 primitive cultivars survive, some as weeds in 

 commercial potato fields, others naturalized 

 into the wild flora. The cultivars present a 

 rich variety of shapes, colors, and growth 

 habits. Such widespread distribution and 

 great diversity have long led botanists to 

 think the potato was independently domes- 

 ticated several times in various places, pos- 

 sibly from different wild Solanum species. 



Not so, say David M. Spooner, a taxono- 

 mist at the University of Wisconsin-Madi- 

 son, and his colleagues from the Scottish 

 Crop Research Institute in Dundee. After 

 comparing the DNA of 365 specimens of 

 Solanum from all over the Andes, including 

 the primitive cultivars and the wild species 

 from which they could have been derived, 

 the team unearthed a pattern that points to 

 a single origin in southern Peru, from the 

 wild plant Solanum bukasovii or a close rela- 

 tive. Local farmers along the Cordilleras 

 then presumably developed the profusion 

 of potatoes after the original cultivar was 

 exported from its native soil. {PNAS 

 102:14694-99, 2005) 



—S.R. 



South American farmer introduces the 

 potato to Spanish conquistadors. 



February 2006 naturai iiistou.\ 



