In the first experimental test of a 112- year-old theory, the tails of luna moths have been seen to have helped save the insects from hunting bats by distracting the flying mammals’ sonar, researchers reported last week in PNAS.

The function of the North American moths’ two graceful nearly fourcentimetre long tails has long been a topic of scientific study. They are not required for flight and are unlikely to play a role in attracting mates, as the insects are nocturnal and do not appear to be selective about their sexual partners. In 1903, entomologist Archibald Weeks suggested that the tails might create air patterns similar to those generated by wings that could confuse bats using echolocation to hunt.

To test this idea, researchers from Boise State University, the University of Florida and Northeast Ohio Medical University affixed 162 luna moths to the ceiling with fishing line, then used high-speed infrared cameras and ultrasonic recorders to capture information on eight brown bats attacking the moths. Of the 87 moths with intact tails, 34.5 per cent were nabbed by bats. By contrast, 81 per cent of the 75 tailless luna moths in the study were eaten. The researchers also noted that the bats often aimed for the tails of intact moths, and in the vast majority of these attacks, the moths were able to escape.

The Scientist

Nibbled?

No problem You might expect that a plant would respond unfavourably to having its top bitten off by an herbivore. But as ecologist Ken Paige and colleagues at the University of Illinois at Urbana-Champaign first observed in the 1980s, some plants respond by making more seeds, ultimately benefiting from injury in a phenomenon called overcompensation. More recently, Paige and postdoc Daniel Scholes suspected a role for endoreduplication, in which a cell makes extra copies of its genome without dividing, multiplying its number of chromosome sets, or “ploidy”.

Undamaged plants tend to increase their ploidy over time, but after experimental clipping changes in ploidy diverge in different strains of Arabidopsis thaliana. To test the hypothesis that ramping up ploidy helps plants compensate for damage, the researchers overexpressed a gene called ILP1, known to cause endoreduplication, in a strain that ordinarily responds to clipping with undercompensation: decreasing seed yield and slowing of its normal rise in ploidy. They found that with the extra gene product, seed production and ploidy trends remained normal after clipping.

“The ploidy that the damaged plants are generating is directly influencing (their) ability to produce seeds when (they are) damaged,” says Scholes.

Ashley P Taylor/The Scientist

Creating database

Scientists conducting a global study of coral reefs are surveying the Chagos Archipelago in the Indian Ocean after selecting it as the latest destination to gather data to aid worldwide conservation efforts. A crew from the Catlin Seaview Survey is now exploring and mapping the archipelago&’s coral reefs. The area, about 500 nautical miles south of the Maldives and around twice the size of the UK, consists of hundreds of individual reefs. But the region remains mostly unexplored, with only patchy cartographic coverage dating from 1998.

The Catlin team is creating an extensive database of satellite-located, panoramic images of the reefs, along with scientific data on reef growth and environmental impacts. This material will be added to the Catlin Global Reef Record online database, which already hosts more than 217,000 panoramic images. This openaccess database is intended to enable scientists around the world to collaborate on research to understand coral reef and marine environments. It is also meant to provide insights for policy makers, especially in countries with limited capacity for coral conservation.