These predatory worms have figured out meal delivery. Called entomopathogenic (for insect-killing) nematodes, they infect and feed on an insect, then multiply within its carcass. While feeding, the nematodes produce smells that attract their next insect feast, reports a study published October 13 at bioRxiv.org.
Farmers worldwide use this nematode to control insect pests, such as the western corn rootworm (Diabrotica virgifera). Because smells, or volatile chemicals, are known to drive many plant and animal interactions, scientists at the University of Bern, in Switzerland, examined whether the rootworm’s larvae, which eat maize roots, would avoid the smell of a nematode predator (Heterorhabditis bacteriophora). In the experiment, rootworms had to choose between two pots of maize plants. Surprisingly, up to two-thirds preferred maize roots containing nematode-infected rootworm carcasses over roots with uninfected carcasses or no carcass.