SciTech

Science Briefs: How a caterpillar fools defenses of corn plant

A caterpillar eats out the center of a leaf of a corn plant.
A caterpillar eats out the center of a leaf of a corn plant. Penn State

Caterpillar tricks corn leaves into lowering defenses

In a deception that likely has evolved over thousands of years, a caterpillar that feeds on corn leaves induces the plant to turn off its defenses against insect predators, allowing the caterpillar to eat more and grow faster, according to Penn State chemical ecologists.

Fall armyworm larvae are voracious feeders on leaves in the confined space of corn plants, and by necessity the insects defecate where the leaves meet the stalks. Copious amounts of frass – caterpillar feces – accumulate there and can remain for a long period.

Caterpillar frass is composed of molecules derived from the host plant, the insect itself and associated microbes. It provides abundant cues that may alter plant defense responses. The frass tricks the plant into sensing it is being attacked by fungal pathogens. The corn plant mounts a defense against them – and that suppresses the plant’s defenses against hungry insects.

The research was published in the Journal of Chemical Ecology.

psu.edu

# or @? What you use affects your Twitter language

Despite all the shortened words and slang seen on Twitter, it turns out people follow many of the same communication etiquette rules on social media as they do in speech. Research from the Georgia Institute of Technology shows that when tweeters use hashtags – a practice that can enable messages to reach more people –they tend to be more formal and drop the use of abbreviations and emoticons. But when they use the @ symbol to address smaller audiences, they're more likely to use non-standard words such as “nah,” “cuz” and “smh.” The study also found when people write to someone from the same city, they are even more likely to use non-standard language – often lingo that is specific to that geographical area.

The researchers sifted through three years of tweets – including 114 million geo-tagged messages from 2.77 million users.

gatech.edu

Where migrating birds want to look for fruit

Birds stopping for a break during their grueling migratory flights face a difficult tradeoff: They need to fuel up with food as efficiently as possible, but they need to avoid predators while they do it.

Research at the University of Maine, published in The Auk: Ornithological Advances, shows that fruit-eating birds prefer overall to stop in habitats with plenty of dense vegetation in which they can hide from predators such as hawks. However, the longer the migration a bird is facing, the more likely it is to take risks in order to fill up with high-energy fruit.

Habitat patches that maximize both food availability and vegetation to hide in are not the mature, intact forests many songbirds prefer to breed in. Instead, they tend to be in places such as brushy forest edges. The authors recommend that if wildlife managers want to support birds during migration as well as the breeding season, this sort of habitat cannot be overlooked, even if it appears less than pristine.

aoucospubs.org

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