New Silverleaf Whitefly Has Growers
Concerned By Alfredo Flores June 13, 2008
A devastating tropical and subtropical pest that's already considered
one of the world's top invasive species just got a bit more troublesome.
The silverleaf whitefly (Bemisia tabaci) threatens a wide range
of crops. Of the more than 20 known biotypes of this species, two of the most
devastating are the B and Q biotypes. While the B type has been in the United
States since its discovery in 1985, now type Q has been identified in 25
For years, Agricultural Research
Service (ARS) scientists in the
Insects Research Unit at Ft. Pierce, Fla.--led by entomologist
McKenzie and molecular biologists
Shatters and Laura Boykin--have worked with collaborators on extensive
studies of the B and Q biotypes.
Both types of whiteflies can reduce the yield of a broad range of
agricultural, fiber, vegetable and ornamental crops. The aggressive B biotype
arrived here from its native Middle East and Asia Minor range. It threatened
agricultural production throughout the southern United States until new
integrated pest management strategies brought it into check. Now, the Q type
brings new challenges.
The newly arrived biotype was first detected in the United States in
December 2004 on poinsettias from an Arizona retail outlet. Compared to the B
biotype, Q is less susceptible to many pesticide types, which means there are
fewer chemical options for its control. There is also concern that resistance
to insecticidal controls may occur more rapidly in the Q biotype.
With the help of the ARS scientists, a Q biotype task force was set up
to develop new control recommendations. Nationwide monitoring suggests that
these improved recommendations are helping to slow or prevent the movement of
the Q biotype into commercial vegetable fields. For now, rapid implementation
of the new control strategies has greatly reduced control problems.
Detailed information about the task force and its findings is
available online at:
ARS is a scientific research agency of the
U.S. Department of