For decades, scientists have understood that plants can release volatile organic compounds—essentially airborne chemical signals—to attract the natural enemies of the things that eat them, like caterpillars. What we didn’t know was exactly how a plant translates the physical act of being eaten into a specific, predator-summoning distress signal.

“[One] thing we didn’t know is how the plant detects the caterpillar in the first place,” says Adam Steinbrenner, a biologist at the University of Washington. Now, after years of experimenting with common bean plants in the lab and in the agricultural fields of Oaxaca, Mexico, Steinbrenner’s team pinpointed a single immune receptor that orchestrates its anti-caterpillar defense system.

Drooling caterpillars

When an herbivorous insect like a caterpillar feeds on a plant, it introduces its saliva straight into the plant's damaged tissues. This saliva contains biological clues called HAMPs: herbivore-associated molecular patterns. One of the HAMPs molecules is a peptide called inceptin, and there’s an 11-amino acid fragment of inceptin named In11, as well. Both of them turn out to be a fragment of the ATP synthase found in chloroplasts—basically a piece of one of the plant’s own proteins. As the caterpillar ingests the leaf, its gut enzymes chop up the plant's cellular engines and their pieces, including In11, are regurgitated back onto the leaf’s surface, albeit at extremely small concentrations.

Read full article

Comments

Male bowerbirds are notorious for their complex mating rituals. They build intricate tunnels out of twigs—the bowers from which they get their name—and then decorate them with random colorful items gleaned from the environment. When a female of the species shows up to check out a male's fancy digs, the male tosses his shiniest objects in her direction and shows off his plumage in hopes of impressing her.

According to a new paper published in the journal Royal Society Open Science by University of Exeter scientists, urbanization and the associated growing availability of brightly colored human-made items have had a significant impact on courtship display behavior in Australian male bowerbirds. There are marked differences in the choice of decorations for bowerbirds in urban versus rural environments. This might be because urban birds simply have greater access to the items than their rural counterparts, since birds in both environments show a marked preference for human items.

The University of Exeter researchers monitored the bowers of 61 male great bowerbirds in two sites in Australia's northern Queensland—the rural Dreghorn Cattle Station and the urban Townsville City—during the prime breeding season (September–December 2023). Then they photographed the bower decorations in situ from above in both visible and UV light (bowerbirds can see in the UV range), using an umbrella to create diffuse lighting.

Read full article

Comments