allow time to set up the complex orga­nization, headquartered at the Hague, that is required to put the treaty into effect and monitor compliance with it. The body responsible for establishing the new organization is the so-called Preparatory Commission, which itself will be set up once 50 nations sign.

Arms control specialist Michael Krepon, president of the Henry L. Stimson Center, a nonprofit organiza­tion concerned with arms control and international security issues, calls the treaty a "historic achievement." But he warns that there will be problems be­cause its scope is so vast.

Brookings Institution chemical weapons expert Elisa Harris agrees. She contends the treaty will not solve all chemical-weapons-related prob­lems, but is useful nonetheless. For one thing, the treaty will make it more dif­ficult for nonsignatory countries to ac­quire and use these weapons.

Lois Ember

U.S.-Japan spacelab to be launched this week Two major space missions that will rack up a number of "firsts" are sched­uled for launch by the National Aero­nautics & Space Administration during the next three weeks.

On Sept. 12, if all goes as planned, space shuttle Endeavour will blast off from Kennedy Space Center in Florida, launching the first joint U.S.-Japanese space-based science mission. Endeavour will spend seven days orbiting Earth, carrying in its cargo bay a laboratory, Spacelab-J, in which seven astronauts will carry out 43 experiments on the ef­fects of microgravity.

Moreover, on Sept. 25 a Titan III rocket is slated to lift off with the Mars Observer spacecraft. The flight was postponed from Sept. 16 after the spacecraft was contaminated during precautions taken against Hurricane Andrew. After the spacecraft achieves Earth orbit, it will be boosted on an 11-month journey toward Mars, where it will explore the Red Planet's surface, atmosphere, interior, and magnetic field from a series of different orbits for a Martian year (687 Earth days).

The Endeavour crew will include the first Japanese astronaut on a U.S. spaceflight, Ph.D. physicist Mamoru

Mohri, and the first African American woman astronaut, physician Mae C. Jemison. It also will include the first married couple on a shuttle flight, Air Force Lt. Col. Mark C. Lee and N. Jan Davis, who has a Ph.D. in mechanical engineering.

Of the experiments that the astro­nauts will perform in the 23-foot-long spacelab, Japanese scientists are pro­viding 34, U.S. scientists seven, and two are collaborations. Twenty-four ex­periments are devoted to materials sci­ence, and 19 to life sciences.

The materials science experiments will focus on the effects of weightless­ness in five areas: biotechnology, elec­tronic materials, fluid dynamics and transport phenomena, glasses and ce­ramics, and metals and alloys. For ex­ample, the astronauts will grow protein crystals by both vapor diffusion and liquid diffusion methods. In the elec­tronic materials experiments, they will grow five kinds of semiconductor crys­tals using four specialized furnaces—a gradient heating furnace, image fur­nace, crystal growth furnace, and con­tinuous heating furnace.

Crew members also will study de­velopment of new types of glasses and ceramics through containerless pro­cessing methods. For instance, they will use an acoustic lévitation fur­nace—employing sound waves for sus­pending, combining, and melting in-

Jemison (Hght) practices frog egg test in training for flight of spacelab, being

assembled (below) by NASA workers

gredients under microgravity—to try to prepare a non-silicon-based glass that has superior transmission proper­ties in the infrared region.

Life sciences experiments will cover cell separation, cell biology, develop­mental biology, animal and human physiology and behavior, space radia­tion, and biological rhythms. For exam­ple, three experiments will test the in­fluence of gravity on development and function of plant and animal cells. Studies also will be done on Japanese koi fish (carp) and fruit flies.

Of particular interest to the general public is an experiment on the effects of weightlessness on amphibian eggs fertilized in space, using female frogs that will be carried onboard. Half the eggs will be incubated under micro-gravity, and half (a control group) will be incubated in a centrifuge, spinning

SEPTEMBER 7, 1992 C&EN 7

NEWS OF THE WEEK

to simulate normal gravity. Growth of some eggs will be fixed with formalde­hyde at various points, and others will be allowed to develop into tadpoles.

The astronauts will carry out further experiments middeck on the shuttle, outside the spacelab. For example, add­ing to the orbiting menagerie, an Israeli Space Agency Investigation About Hornets (ISAIAH) will focus on the ef­fect of weightlessness on combs built by oriental hornets.

Mars Observer will continue the ex­ploration of Mars, carried out by U.S. and Soviet spacecraft between 1964 and 1982. The spacecraft's scientific ob­jectives are to determine which ele­ments and minerals are found in sur­face material; define the topography

Corn plants attacked by caterpillars can activate an extraordinary, sophisticated defense mechanism, according to work published last week by U.S. Depart­ment of Agriculture researchers.

The attacked plants release volatile chemicals from all their leaves—both undamaged ones and those munched on by the caterpillars. These chemicals serve as a kind of distress call, acting as beacons to attract wasps that then res­cue the plant by destroying the cater­pillars.

Chemical emissions by plants in re­sponse to insect attacks have been ob­served before. However, the new study is apparently the first to show that plants can mount a systemic chemical defense against predators that is not

and gravitational field; search for a planetary magnetic field; find the dis­tribution, abundance, sources, and des­tinations of carbon dioxide, water, and dust over a seasonal cycle; and mea­sure the temperature, water, and dust in the atmosphere. Of particular inter­est is the role water once played on Mars. Its surface has no liquid water now, but there is ample evidence the liquid flowed there long ago.

Mars Observer will carry seven in­struments. Among them will be a gam­ma-ray spectrometer to measure the abundance of elements on the surface, and a thermal-emission spectrometer to map surface rock mineral content, frosts, and cloud composition.

Richard Seltzer

limited to sites of damage, but that is activated throughout the plant.

The USDA team's findings could help improve the effectiveness of wasps for biological control of insect pests, and might make it possible to ge­netically engineer plants that require less insecticide protection. The study was conducted by entomologist Ted G J. Turlings and chemist James H. Tum­linson of USDA's Agricultural Re­search Service (ARS) laboratory in Gainesville, Fla., and published in the Proceedings of the National Academy of Sciences [89, 8399 (1992)].

What the corn plants release are vol­atile terpenoids used as a signal by a parasitic wasp, Cotesia marginiventris, to locate caterpillar hosts. The tiny wasps

are beneficial insects that are harmless to animals and humans, and that are already in use to control caterpillars and other crop pests.

After finding a caterpillar, the wasp injects an egg into it. This immediately slows feeding by the caterpillar. Later, the wasp egg develops into a larva that feeds internally on the caterpillar.

In their study, the Gainesville scien­tists scratched the surfaces of two leaves on corn plant seedlings and ex­posed them to caterpillar oral secretion, a combination of digestive fluids and saliva that is known to induce local ter­penoid release. They left two other leaves on each corn seedling undam­aged.

They found that terpenoids that at­tract wasps were emitted from the scratched, treated leaves of the corn plants, as expected. However, Turlings and Tumlinson also found significant amounts of terpenoids released from undamaged leaves.

"This indicated to us that the plant was releasing these chemicals through all the leaves to defend itself," says Tumlinson. "It was systemwide, not just in the leaves that were damaged."

Tumlinson adds, "There's a factor in the saliva or gut of the caterpillar that induces the damaged plant to begin producing these compounds." The ARS researchers and other groups are now seeking to identify this factor. The mechanism by which the plants r e ­spond to local injury by a systemwide response is also still unknown.

Corn plants may have originally de­veloped the volatile terpenoids for use as direct herbivore repellants. Tumlin­son believes that parasitic wasps later learned (in an evolutionary sense) to respond to the chemicals as a way to help them find the caterpillars they use as reproductive hosts.

One aim of the ARS work is to max­imize the wasps' effectiveness as bio­logical control organisms for various crops. Terpenoids and other volatile chemicals that attract wasps are known to be released—in response to injury and caterpillar oral secretions—from lima bean, eggplant, cotton, cowpea, and soybean plants, in addition to corn. So far, however, release of the volatile chemicals has been found only at at­tacked sites in these other plants. A systemic, plantwide reaction like that of corn has not yet been found.

Stu Borman Parasitic wasp approaches caterpillar on corn plant (left), and lays egg inside caterpillar

8 SEPTEMBER 7,1992 C&EN

Attacked corn plants call wasps to the rescue