Fourth International Bemisia Workshop International Whitefly ...

Journal of Insect Science | www.insectscience.org ISSN: 1536-2442
Management of Bemisia Resistance:
Cotton in the Southwestern USA
T. J. Dennehy 1 , B. DeGain 1 , G. Harpold 1 , X. Li 1 ,
D.W. Crowder 1 , Y. Carrière 1 , P. C. Ellsworth 2 , and R.
L. Nichols 3
1 Department of Entomology, University of Arizona, Tucson, AZ,
USA.
Correspondence: tdennehy@ag.arizona.edu
2 University of Arizona, Maricopa Agricultural Center, Maricopa,
AZ, USA
3 Cotton Incorporated, Cary, NC, USA
Bemisia tabaci can be a severe pest of many crops
produced in arid regions of the southwestern United
States including cotton, melons and vegetables. It has
also become an increasingly common problem in
glasshouse production systems. Attempts to control
whiteflies with conventional broad-spectrum
insecticides have had devastating results in many
desert agro-ecosystems. Severely reduced natural
enemy populations have been associated with
resurgences of whiteflies, outbreaks of secondary
pests, and rapid evolution of pest resistance. Under
such conditions, B. tabaci has developed resistance to
essentially all insecticides to which it has been
repeatedly exposed. Such was the case in 1995, when
whitefly numbers reached crisis proportions in Arizona
cotton despite application of 6 to 15 insecticide
treatments per acre. In consultation with researchers in
Israel and the United Kingdom, emergency alternatives
for whitefly control were formulated and implemented
in 1996 that replaced broad-spectrum insecticides
during the early season with once-per-season use of the
insect growth regulators, pyriproxyfen and buprofezin.
Concomitant registration of Bt cotton significantly
reduced treatments of conventional insecticides for
lepidopteran pests. Additionally, neonicotinoid
insecticides provided exceptional whitefly suppression
in the other major whitefly hosts, melons and winter
vegetables. The end result has been over a decade of
unprecedented low insecticide use in cotton, and
equally unprecedented effectiveness of biological
control in cotton fields. Management of Bemisia
resistance in the Southwestern USA is focused
intensively on sustaining effective, selective
insecticides. This includes statewide detection and
isolation of resistance in cotton, vegetables, melons
and glasshouses, and collaborative research to
characterize critical toxicological, genetic and
ecological parameters of resistance in laboratory and
field experiments. I will overview new developments
from this research, including information regarding the
distribution and threat posed by Q biotype.
Novel Measurement of Group Adoption of
IPM in Diverse Cropping Communities
P. C. Ellsworth 1 , J. C. Palumbo 1 , A. Fournier 2 , Y.
Carriere 1 , and C. Ellers-Kirk 1
1 Department of Entomology, University of Arizona, Tucson, AZ,
USA.
Correspondence: peterell@cals.arizona.edu
2 Maricopa Agricultural Center, University of Arizona, Maricopa,
AZ, USA
Integrated pest management (IPM) in the sensitive
environments of the desert Southwest is vulnerable to
the destabilizing impact of mobile polyphagous pests
that are capable of attacking winter vegetables, melons,
and cotton -- most notably, the silverleaf whitefly
(Bemisia tabaci). Because of the year-round growing
season present in desert cropping systems and the
chronic nature of pest incidence, emphases are needed
on area-wide reduction of pest populations through all
means possible. This has led to the development of
IPM programs for these crops that emphasize selective
and other reduced-risk technologies, including insect
growth regulators (IGRs) and neonicotinoid
insecticides for the control of pests. To preserve these
valuable IPM tactics – by protecting them from
resistance – we have developed IPM guidelines for
cross-commodity management of whiteflies that
transcend field or grower borders and depend on group
adoption over large areas, to be effective in area-wide
source reduction and in proactive resistance
management for major reduced-risk technologies
(IGRs and neonicotinoids). We have developed a novel
approach for measuring spatially-relevant adoption of
our IPM guidelines. This new analytical approach
utilizes pesticide-use reporting data and GIS/GPS
technology to understand area-wide adoption of the
cross-commodity guidelines and to further guide future
research, technology transfer, and outreach efforts.
This technique allows us to evaluate IPM and its
implementation and adoption, to a level of
organization that spans multiple crops and pests over
entire ecosystems. Our model system of analysis
should be broadly applicable to the measurement and
improvement of IPM systems worldwide.
Journal of Insect Science: Vol. 8 | Article 4 17