April 2022 - 20

The Potato Association of America mission statement: The PAA and
its allied associations must strongly support the private sector through
Extension, research and commercialization efforts aimed at enhancing
the role of the potato as the premier food source for the 21st century.
CPB insecticide resistance
requires vigilance, stewardship
By Russell L. Groves
Potato Association of America
O
ver the past two decades in the
Midwest,
the neonicotinoid
insecticides have been the
most commonly used management
tool for the Colorado potato beetle
(Leptinotarsa decemlineata).
The
relative
ease
of applying
neonicotinoids at planting (in-furrow
or seed treatment) coupled with new,
inexpensive and generic neonicotinoid
formulations offered in the retail
marketplace have become somewhat
of a disincentive for producers to
transition from these products to
other mode of action (MoA) groups.
The near continuous use of atplant
neonicotinoids
has
continued
to
contribute to resistant beetle
populations in several production areas
of the Eastern and Midwestern U.S. In
the Western U.S., where their use has
become more prevalent over the past
decade, insensitive populations appear
to be emerging in very select locations,
as well as in areas where problematic
populations of Colorado Potato Beetle
(CPB) were not often observed.
Continued reliance on neonicotinoids
accelerate
will
only
resistance
development and result in additional
insecticide inputs to manage these
populations. Resistance management
recommendations for CPB have focused
on rotation of insecticides within the
growing season.
Growers using at-plant neonicotinoids
for early-season beetle control are
encouraged to rotate insecticide MoAs
for later generations to delay resistance
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Spudman.com
The Colorado Potato Beetle has proven to be especially adaptable when it comes to resistance
to pesticides, which makes multiple MoA control essential. Photo: Zeke Jennings
development. Although this short-term
insecticide rotation has prolonged the
utility of neonicotinoid insecticides,
reducing reliance of a single MoA soil
application at planting will improve
the longevity of newer, more reducedrisk
(RR) alternatives. Although the
adoption of these at-plant, soil-applied
neonicotinoid
insecticides has been
regarded as beneficial to the potato
industry by limiting the use of more
broad-spectrum, foliar insecticides
(e.g. carbamates, synthetic pyrethroids,
organophosphates), the continual
emergence of insecticide resistance
underlines the need to explore RR
options and maintain stewardship with
existing registrations.
Control of CPB populations with
neonicotinoid
insecticides has been
declining nationally since the mid2000s.
Laboratory bioassay estimates
have confirmed the suspicion that CPB
resistance to the key neonicotinoids
in our markets (clothianidin,
imidacloprid, thiamethoxam) has
increased throughout the Northeastern
and Upper Midwest potato-producing
regions. Although field-level failures
are uncommon, the duration of beetle
control within the growing season has
declined significantly over time.
A reduced duration of control has
necessitated the use of extra, foliarapplied
insecticides in addition to
the at-plant application. A greater
proportion of growers shifting to these
pest management supplementations
is another indication that insecticide
susceptibility has changed at regional

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April 2022

Table of Contents for the Digital Edition of April 2022