Alien wasps munch on large number of birds and bugs in Hawaii

Washington, July 25 (ANI): A new study has indicated that invasive western yellowjacket wasps in Hawaii are munching their way through an "astonishing diversity" of creatures, ranging from caterpillars to pheasants.

Adult yellowjackets consume only nectar. But they kill or scavenge prey to deliver needed protein to their growing broods.

"They basically just carry it in their mandibles-you see them flying with their balls of meat," said lead study author Erin Wilson told National Geographic News.

In their native habitat in the western US, the wasps die off in winter. But in Hawaii, the wasps survive the winter, possibly due to mild year-round temperatures or subtle genetic changes.

A longer life-span gives the insects more time to build up their nests.

So, what would normally be a basketball-size nest can become, at the extreme, several feet long-big enough to fill the back of a pickup truck, according to Wilson.

The extra room allows a colony of 50,000 workers to explode to 500,000 or more.

Larger colonies mean that the insects deplete more prey than in areas where the wasps die off in winter.

Western yellowjackets were accidentally introduced to Hawaii during the 1900s, with the last wave of arrivals, in the 1970s, coming from the US Pacific Northwest.

To learn more about the invaders' impact, Wilson and colleagues studied ten colonies in two national parks where the wasps are now widespread: Hawaii Volcanoes on the Big Island and Haleakala on Maui.

The team collected bits of food from the jaws of 50 wasps and ran DNA analyses to determine what the insects had eaten.

Wilson had guessed that the aggressive bugs mostly go after slow-moving caterpillars and other "big, gooey organisms" and don't bother with many other types of prey.

But, the introduced wasps' taste for flesh shocked Wilson.

The insects' prey spans 14 taxonomic groups of animals, including tree lice, spiders, rats, and geckos.

Although the wasps don't kill larger animals such as birds and lizards, they do scavenge them.

In addition, the adult wasps collect huge amounts of nectar, draining resources for native insects and birds such as the Hawaiian honeycreeper.

The wasps' hunger for nectar may even be disrupting pollination of native plants, according to the study authors.

Overall, the wasps have been filling in the role of top insect-eater, left open as Hawaii's bird populations dwindle. (ANI)