A Biocontrol for a Wide-Ranging Thrips
O'Brien April 28, 2009
A pest with a voracious appetite may have met its match in a predatory
mite being evaluated as a biocontrol agent by Agricultural Research Service (ARS)
scientists in Fort Pierce, Fla. in collaboration with
University of Florida researchers.
The chilli thrips is an invasive pest that feeds on leaves, turns them
brown, kills new growth and attacks up to 150 crops, including peppers,
strawberries, tomatoes, peanuts, cotton and a variety of ornamentals.
Detected in Palm Beach County, Fla. in 2005, it has spread to 24
Florida counties and parts of Texas, damaging roses and other ornamentals in
both states. Left unchecked, it could reach west to California and north along
the Pacific Coast to Canada, causing losses of up to $3.8 billion annually.
Pesticides are effective, but the chilli thrips may develop resistance
with repeated treatments, and pesticides are not an option for organic
nurseries and gardeners, according to entomologist
L. McKenzie, at the ARS
Horticultural Research Laboratory in Fort Pierce.
Researchers at Fort Pierce and the University of Florida have turned
to two mites, Neoseiulus cucumeris and Amblyseius swirskii, which
have been used commercially to combat other pests since at least 2005. The
researchers put 30 adult chilli thrips on ornamental pepper plants in
greenhouse and outdoor settings, waited a week for thrips larvae to hatch and,
in separate treatments, released 30 mites of each species on the plants. They
checked the plants weekly for four weeks.
Their results, published in
Control, showed that the mites--particularly A.
swirskii--significantly reduced the number of thrips. A. swirskii
left no more than one thrips insect per leaf. That compared with up to 60
thrips larva found on leaves of untreated pepper plants. The work was funded in
part by the American Floral Endowment and
and Nursery Research Initiative.
The researchers have set up a chilli thrips website for gardeners and
commercial growers at
ARS is the principal intramural scientific research agency of the
U.S. Department of