Entomology: Hot Wasp Nests

Near Oak Ridge National Laboratory in Tennessee is a green woodland dot with man-made pits and a steadily pond. Both pits and pond been used for the disposal of ra wastes, so an 8-ft. chain-link fringed with barbed wire keeps people away from the dangers. Unmanned monitor stations, looking like small refrigerators packed with instruments, keep for signs of trouble. Last sum some of the monitors began to give high readings. One reported than one roentgen per hour, and takes an accumulated dose of only roentgens to kill a man.

Mud in the Monitor. Somehow, radioactive mud seemed to be getting into instrument boxes. But how? Insect Ecologist Alvin Fleetwood Shinn was called in to investigate. Dressed in white coveralls, rubber boots and gloves, and carrying a radiation survey meter, he prowled the forbidden woods and soon identified the culprits. Hidden among the monitor instruments, sometimes even plastered on vacuum tubes, were dozens of mud nests built by wasps.

Other places in the fenced-off reservation were thick with “hot” nests; an abandoned house had so many that sleeping in its bedroom would have been dangerous. Actually, the yellow-and-black dauber wasps that built the nests were no threat to humans because they never fly far enough to carry radioactive material outside the high fence. To make sure that wasps would not confuse the instruments again, he had the monitors screened. Then he went to work studyings the wasps, which had handed him a readymade experiment on the biological effects of radiation.

Dauber’s Difference. Insects can stand more radiation than humans, but they are not immune. Shinn put dosimeters in the nests and found that young wasps sometimes got 25 times as much radiation as a human can stand. The dose apparently reduced by 40% the number of wasps that developed success fully into adults. Of the two kinds of wasps that built nests among the instruments, Shinn noticed that only the yellow-and-black daubers used radioactive mud. The nests of the closely related pipe-organ daubers were always as free of radioactivity as if nuclear phys ics had never come to Tennessee. How could the wasps tell the difference?

Shinn does not yet have the answer, but he is running elaborate tests to find out. It may be that the cautious pipe-organ wasps are repelled by the faint odor of ozone and other gases that rise from radioactive mud. More fascinating is the possibility that among the wasps of Oak Ridge, which have been exposed to radioactive wastes for a longer period than any others, the pipe-organ daub ers may have evolved a special sense that detects radioactivity and enables them to build nests that will not be lethal to their sensitive young.