Micro

“Of course not,” Peter answered, with a smile. “It’s because you’ve already killed the plant-heartlessly dispatched it for your own selfish meal. You just pretend the plant didn’t scream in agony when you killed it, because you don’t want to face the consequences of your cold-blooded plant murder.”

“Absurd.”

“Speciesism,” Peter said. “And you know it.” He was smiling, but there was truth to what he was saying. Peter was surprised to see that Erika was in the lab, and so was Jenny. Few of the graduate students worked at night. What was going on?

Erika Moll stood at a dissecting board, carefully cutting open a black beetle. Erika was a coleopterist, meaning an entomologist with a special interest in beetles. As she said, that was a conversation-stopper at cocktail parties. (“What do you do?” “I study beetles.”) But, in fact, beetles were very important to the ecosystem. A quarter of all known species were beetles. Years ago, a reporter had asked the famed biologist J. B. S. Haldane what could be deduced about the Creator from the creation, and Haldane had answered, “He has an inordinate fondness for beetles.”

“What have you got there?” Peter said to Erika.

“This is a bombardier beetle,” she said. “One of the Australian Pheropsophus that sprays so effectively.”

As she spoke, she returned to her dissection, shifting her body so she was touching his. It seemed to be an accidental contact; she gave no indication that she had even noticed. But she was a notorious flirt. “What’s special about this bombardier?” Peter said.

Bombardier beetles got their name from their ability to fire a hot, noxious spray in any direction from a rotating turret at the tip of their abdomen. The spray was sufficiently unpleasant that it stopped toads and birds from eating them, and it was toxic enough to kill smaller insects immediately. How bombardier beetles accomplished this had been studied since the early 1900s, and by now the mechanism was well understood.

“The beetles produce boiling-hot benzoquinone spray,” she explained, “which they make from precursors stored in the body. They have two sacs in the rear of the abdomen-I’m cutting them open now, there, you see them? The first sac contains the precursor hydroquinone along with the oxidant, hydrogen peroxide. The second sac is a rigid chamber, and contains enzymes, catalases, and peroxidases. When the beetle is attacked, it muscularly squeezes the contents of the first sac into the second, where all the ingredients combine to produce an explosive blast of benzoquinone spray.”

“And this particular beetle?”

“It adds something more to its armamentarium,” she said. “It also produces a ketone, 2-tridecanone. The ketone has repellent properties, but it also acts as a surfactant, a wetting agent that accelerates the spread of the benzoquinone. I want to know where the ketone is made.” She rested her hand lightly on his arm for a moment.

Peter said, “You don’t think the beetle makes it?”

“Not necessarily, no. It might have taken on bacteria, and let the bacteria make the ketone for it.” That was a fairly common event in nature. Making chemicals for defense consumed energy, and if an animal could incorporate bacteria to do the work on its behalf, so much the better.

“This ketone is found elsewhere?” Peter said. That would suggest it was of external bacterial origin.

“In several caterpillars, yes.”

“By the way,” he said, “why are you working so late?”

“We all are.”

“Because?”

“I don’t want to fall behind,” she said, “and I assume I’ll be gone next week. In Hawaii.”

Jenny Linn held a stopwatch while she watched a complex apparatus: leafy plants under one large flask were being eaten by caterpillars, while an air hose connected the first flask to three more flasks, each with more plants but no caterpillars. A small pump controlled air flow among the flasks.

“We already know the basic situation,” she said. “There are 300,000 known species of plants in the world, and 900,000 species of insects, and many of them eat plants. Why haven’t all the plants vanished, chewed down to the ground? Because all plants long ago evolved defenses against insects that attack them. Animals can run away from predators, but plants can’t. So they have evolved chemical warfare. Plants produce their own pesticides, or they generate toxins to make their leaves taste bad, or they release volatile chemicals that attract the insect’s predators. And sometimes they release chemicals that signal other plants to make their leaves more toxic, less edible. Inter-plant communications, that’s what we are measuring here.”