![Photo: Asian Lady beetle.](https://webarchive.library.unt.edu/eot2008/20090509201704im_/http://www.ars.usda.gov/is/pr/2009/ladybeetle090324.jpg)
Compounds in catnip oil may naturally repel the
Asian lady beetle. Photo courtesy of Washington Department of Fish and
Wildlife. |
![For further reading](https://webarchive.library.unt.edu/eot2008/20090509201704im_/http://www.ars.usda.gov/is/graphics/For-further-reading.gif)
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Catnip Compounds Curb Asian Lady Beetles
By Jan
Suszkiw March 24, 2009
Multicolored Asian lady beetles are appreciated by farmers and home
gardeners alike--until the pest-eating insects decide to spend the winter
indoors. The beetle, Harmonia axyridis, becomes a nuisance insect upon
entering homes to escape the cold, sometimes in huge numbers. When threatened,
it releases a yellow liquid that, while nontoxic, smells foul and produces
stains.
Agricultural Research Service
(ARS) scientists have sought to develop beetle-friendly methods of keeping the
helpful predators outside where they belong. Most recently, ARS entomologist
Eric
Riddick and colleagues in Stoneville, Miss., in collaboration with ARS
natural product chemist
Kamal
Chauhan at Beltsville, Md., tested compounds in catnip oil that naturally
repel the beetles, causing them to fly off, stop crawling, move back or turn
away.
In studies at the ARS
Biological
Control of Pests Research Unit in Stoneville, 95 percent of adult male and
female lady beetles altered their course upon encountering filter paper
impregnated with the highest of three doses of the catnip compound
nepetalactone. The researchers chose nepetalactone because it had previously
been shown to repel some species of cockroaches, flies, termites and
mosquitoes.
They also tested nootkatone (a grapefruit extract), iridomyrmecin
(another catnip oil compound), and other plant-based repellents, but none
performed as well as nepetalactone. Turning away--more so than the three other
avoidance behaviors--characterized the beetles' response to the compound,
report Riddick and colleagues in a recent issue of the
Bulletin of Insectology (http://www.bulletinofinsectology.org/pdfarticles/vol61-2008-081-090riddick.pdf).
Ultimately, such observations could lead to a "push-pull strategy,"
combining repellents that deter lady beetles from entering a home's cracks and
crevices with traps that lure the predators to an attractant for collection and
release elsewhere. According to Riddick, the push-pull strategy offers a
friendlier alternative to insecticide spraying and preserves the insects'
usefulness as efficient predators of aphids, scale and other soft-bodied
arthropods that damage plants.
ARS is the principal intramural scientific research agency of the
U.S. Department of
Agriculture.