Studies on bean plant defense, mouse learning, and mosquito DEET behavior published
NPR’s Short Wave science podcast covered three new studies in its latest roundup. One study, published in Science Advances, found that when caterpillars eat bean plants, a compound in caterpillar spit causes the plants to release a chemical signal that attracts predatory wasps. A separate study in Science examined how reward size affects learning in mice, finding that bigger rewards given less frequently led to faster learning than smaller, more frequent rewards. A third study, published in the Journal of Experimental Biology, showed that mosquitoes can learn to associate the smell of DEET with a blood meal through training, though researchers emphasized that DEET remains effective in real-world situations.
What’s reported
Bean plants release a chemical distress signal only when caterpillars eat them, triggered by a compound in caterpillar spit.
The chemical attracts predatory wasps that eat caterpillars or lay eggs inside them.
In mice, larger rewards of artificially sweetened water given less frequently resulted in faster learning than smaller, more frequent rewards.
The faster learning is thought to be linked to a bigger dopamine burst that keeps mice engaged longer.
Mosquitoes can be trained via Pavlovian conditioning to associate the smell of DEET with a blood reward.
After training, mosquitoes approached DEET even without a reward, and preferred a hand sprayed with DEET over an untreated hand.
Researchers caution that this behavior may not occur in the wild because untrained mosquitoes avoid DEET.
Open questions
Exactly how DEET repels mosquitoes is not fully understood.
Whether mosquitoes can learn to associate DEET with food in natural conditions remains unclear, as the lab required extensive training.
The full mechanism behind why larger rewards speed learning in mice is not known; other factors beyond dopamine may be involved.
Key figures
Adam Steinbrenner (plant biologist, University of Washington, author of bean plant study)
Josh Dudman (author of mouse learning study)
Clement Vinauger (neuroethologist, Virginia Tech, author of mosquito DEET study)
Ali Afify (entomologist and neuroscientist, Drexel University, not involved in the mosquito study)
Sources: NPR
