Bug parents have it easy. Instead of suffering the starving cries of their babies like bird and mammal mommies do, new research indicates that insects merely need a whiff of their kids to gauge what little ones need. The new findings reveal a novel way for offspring to communicate hunger.
Most larvae aren't blessed with a strong set of noisemakers. So it's a safe bet that they must get their parents' attention in some other way. Recognizing that bugs tend to use chemical signals to communicate with each other, evolutionary biologist Edmund Brodie III of Indiana University, Bloomington, wondered if baby insects speak by stinking.
To find out, Brodie and colleagues looked at parental feeding behavior in burrower bugs (Sehirus cinctus). Adults are about the size of a pencil eraser, and the youngest babes--there can be up to 100 per brood--look like bright red pinheads. The researchers separated the babies into two groups: One got plenty to eat, while the other was underfed. They then collected the volatile chemicals wafting from each clutch. Finally, using a "smell-o-tron," the researchers blew these odors toward mother bugs.
Moms receiving odors from ill-fed babies immediately set to finding more food. Mothers gassed with sated-baby odors, on the other hand, slowed their food search. When the team analyzed the chemical make-up of the odors, they found 8 distinct compounds: One was more prevalent in gas from starving babies; another was more prevalent in well fed ones. The mothers didn't respond to these individual compounds alone, however, suggesting a complex interplay between the odors is required. Figuring out exactly which combination of odors is needed to elicit a maternal response will take a lot of trial and error, says Brodie, whose team reports its findings online this week in the Proceedings of the Royal Society B: Biological Sciences.
"This may be the first example of animals communicating hunger by chemicals," says evolutionary biologist Allen Moore of the University of Exeter, Cornwall, U.K. Behavioral ecologist Marty Leonard of Dalhousie University, in Halifax, Canada, says the work is exciting because "it takes us off in another route we haven't traveled."