Hawaii threatened by meat-munching wasps
Updated
It is the stuff of Hollywood horror movies. A nest the size of a small truck, populated by more than half a million aggressive, meat devouring insects with a taste for everything from lice to lizards...and even the occasional bird. Western yellowjacket wasps were introduced to Hawaii by accident, and have found the mild Pacific temperatures much to their liking.
Presenter: Geraldine Coutts
Speaker: Dr Erin Wilson, of the University of California, San Diego
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DR ERIN WILSON, OF THE UNIVERSITY OF CALIFORNIA, SAN DIEGO: It's unclear exactly what has caused them to do extremely well. What we do know is that the Pacific Islands in general, those that don't have social insects, really don't have a native counterpart. So the environment is not adapted to having such a voracious social insect predator.
COUTTS: So that means that because they're alone they can go it alone and there's a population explosion because there's no competition?
DR ERIN WILSON, OF THE UNIVERSITY OF CALIFORNIA, SAN DIEGO: There's no competition. We're basically, when we introduce these wasps, usually accidentally through shipping, what we're doing is we're bringing in a totally new keystone predator, a top predator which native species, especially on these islands are just they're unable to defend themselves against these very numerous predators.
COUTTS: Where are they from originally?
DR ERIN WILSON, OF THE UNIVERSITY OF CALIFORNIA, SAN DIEGO: Well the species I've worked with is the Western Yellow Jacket. It's from the western North America from Canada and south to Baja, California.
COUTTS: Now they have massive nests apparently, can you describe one?
DR ERIN WILSON, OF THE UNIVERSITY OF CALIFORNIA, SAN DIEGO: Well, they tend to form these perennial colonies in Hawaii, about 20 per cent of their colonies are perennial. They will be anywhere the size of - well about a very large medicine ball to the size of basically a 57 Buick or would fill up the entire back end of a full size pick up.
COUTTS: But what do they look like? Are they made of leaves or branches and what shape are they?
DR ERIN WILSON, OF THE UNIVERSITY OF CALIFORNIA, SAN DIEGO: Well these nests are all subterranean so we don't know exactly what they look like in tact. We can only look at the pieces as we dig them up but they are a series of cones made up of chewed up pieces of wood and other plant material that the wasps will harvest and build cones in which the larvae - very much like honeycomb although there's no honey stored in the wasps' nest.
COUTTS: Well, what impact does having so many insects in one spot have?
DR ERIN WILSON, OF THE UNIVERSITY OF CALIFORNIA, SAN DIEGO: Well, you have a very large population and they're going to be all feeding all at the same time, so you're having a very strong point source predation pressure and it's not just that there are so many of them eating so many different types of animals but they're also foraging over a larger area so these perennial colonies have a much larger footprint in the environment than say a small annual colony which in our field site tends to be about the size of a basketball.
COUTTS: So they're capable of killing prey, quite large prey, lizards and birds, I mean do they actually kill them?
DR ERIN WILSON, OF THE UNIVERSITY OF CALIFORNIA, SAN DIEGO: With the vertebrates they're probably scavenging. We don't think they're killing much anything besides the arthropods. So when they're collecting the birds they're probably just scavenging carcasses.
COUTTS: Now they're living in two national parks in Hawaii, are they doing much damage to the park itself?
DR ERIN WILSON, OF THE UNIVERSITY OF CALIFORNIA, SAN DIEGO: Well, with the wildlife within the park, yes. Hawaii is known for its very diverse insect fauna. There are some amazing radiations of insects, the drosophilid flies which have been - their numbers have been drastically reduced by these Yellow Jackets. Other organisms like the Yellow-Face Bee, there are over 60 species native to Hawaii and these bees are also preyed upon by the Yellow Jacket.
COUTTS: I understand that the adult wasps don't eat meat, they survive purely on the nectar. So are the lizards and the birds they kill for their babies?
DR ERIN WILSON, OF THE UNIVERSITY OF CALIFORNIA, SAN DIEGO: That's right, they bring become all of these protein resources to feed the larvae which if they don't have the protein the larvae will not develop properly.
COUTTS: Are they all over Hawaii or are they restricted to a number of islands?
DR ERIN WILSON, OF THE UNIVERSITY OF CALIFORNIA, SAN DIEGO: Well they are on all the major islands including Oahu and Lahaina, Maui and Hawaii. The ones we've been working with, what's unique about these is they tend to do very well in natural areas. So other species of Yellow Jackets which have been quite successful in Australia and New Zealand like Vespula germanica and Vespula vulgaris, some of them do very well in urban environments and this Yellow Jacket, the Western Yellow Jacket, tends to do much better in natural areas which does mean, unfortunately, that the native species and biodiversity is more likely to be affected
