Posts Tagged: yellowjackets
They're here. They're there.
The Western yellowjacket (Vespula pensylvanica) likes to hang around bee hives.
If you're a beekeeper, you've probably seen them nesting in a rodent burrow or hollow log near your hives.
At the Harry H. Laidlaw Jr. Honey Bee Research Facility at the University of California, Davis, yellowjackets currently occupy two rodent holes a few feet from the hives. To mark the spot, beekeeper and research associate Elizabeth Frost placed a brick over each nest (see photo below).
The yellowjackets are not welcome.
Members of the Vespula genus are "the most abundant and troublesome wasps in California," according to scientists Jerry A. Powell and the late Charles L. Hogue in their book, California Insects, published by the University of California Press.
"The voracious workers attack everything in the vicinity, from resting insects to pieces of hamburgers on the picnic table," they noted, and "the colonies may become very large by late summer or fall."
Bee breeder-geneticist Susan Cobey, who divides her time between UC Davis and Washington State University, agrees that yellowjackets "can be a big problem. I've seen them kill hives."
Cobey says she's fighting them now in Island County, Washington. "I have only 10 colonies, but these are special--the imports (for bee research). The wasps are always hanging around the entrance harassing the bees."
"I've had to move hives at times because the invasion was decimating the bee population," she said. "They go for the thorax (meat). They especially like the drones being kicked out of the hives in the fall--big and juicy. This is an easy dinner so then they start going in the hives and taking workers."
One way to counter the yellowjacket invasions is to "reduce the size of the entrance so the bees can protect themselves." Also, beekeepers must "keep the hives strong and healthy--yellowjackets pick on the weak."
To decrease the yellowjacket population, beekeepers bait traps in the summer "as the reproductives come out," Cobey says.
Since yellowjackets are meat eaters and honey bees are not--you can use cat food with the bait.
"But the bait must be protected from other critters," Cobey cautions. "You can put in it an empty beehive with a very small entrance."
(Note: Postdoctoral scholar Erin Wilson of the Louie Yang lab, UC Davis Department of Entomology, will speak from 12:10 to 1 p.m., Wednesday, Dec. 1 in 122 Briggs on how yellowjackets are wreaking havoc in Hawaii. Listen live at http://uc-d.na4.acrobat.com/ucsn1/. The seminar later will be archived.)
Emerging from Hole
They probably annoy you when they invite themselves to your barbecue to partake of your hamburger and other protein-rich foods. They're persistent predators.
But, do you know that they often build their nests near bee hives? "It's one-stop shopping," says postdoctoral scholar Erin Wilson (right) of the Louie Yang lab, UC Davis Department of Entomology.
Yellowjackets prey on honey bees. They raid the hives (killing the adults and brood, and stealing honey) and take the food back to their young.
Wilson, who does research on the Western yellowjacket (Vespula pensylvanica), is the lead author of a research article published in the Nov. 11 edition of Ecology.
On Wednesday, Dec. 1, she'll discuss "Yellowjacket Life History Shifts Modify Invasion Impacts in Hawaiian Ecosystems" at a UC Davis Department of Entomology seminar, set from 12:10 to 1 p.m., in 122 Briggs Hall. The talk, open to the public, also will be webcast live at http://uc-d.na4.acrobat.com/ucsn1/ and then archived on the entomology website.
The Western yellowjacket is an introduced, invasive species in Hawaii. Native to the western United States, it was first discovered in Hawaii in 1977. It's like a "vaccuum cleaner," Wilson says, and is clearly a threat to native species in Hawaii.
“The introduction of non-native organisms is a leading cause of imperilment of native species,” says Wilson, who since 2004 has studied the social wasps at two sites: the Hawaii Volcanoes National Park on the island of Hawaii and the Haleakala National Park on Maui.
The yellowjacket “may seriously threaten endemic invertebrates that evolved in the absence of these social insects," she says. "Invasive predators affect native species directly and indirectly, and the magnitude of these effects is highly dependent on the history of the recipient community. Furthermore, the impact of this social wasp may be magnified by apparent shifts in colony structure in the introduced range."
Scientists have found that the incidence of perennial or overwintering colonies is higher in Hawaii than in the native range of V. pensylvanica.
Compared to annual colonies, overwintering perennial colonies can collect twice as many prey items and produce 10 times the worker force, Wilson says. Some perennial colonies were huge, the size linked to Hawaii’s mild climate and the ability of the yellowjackets to establish perennial colonies. One Maui colony included as many as 600,000 individuals.
Yes, that's 600,000 wasps! In its native range, the typical size is less than a few thousand wasps.
Check out Wilson's research article, yellowjacket photos and her website and then listen to her seminar on Dec. 1:
- Multiple Mechanisms Underlie Displacement of Solitary Hawaiian Hymenoptera by an Invasive Social Wasp (E. E. Wilson and D. A. Holway, Ecology journal)
- Photos from her research and UC San Diego news story
- Erin Wilson's website, Vespularesearch.com