The Crush - May 2020 - 2

[ FEATURE STORY ]
Kron in the North Coast counties on a comprehensive survey of
ant species present in vineyards. Tollerup suggests individual
growers collect ants and contact their farm advisor to assist with
identification, or contact him by email (ketollerup@ucanr.edu) to
assist with identification.
ANT CONTROL MATERIALS AND METHODS
An ant suppression option for agriculture was the broadspectrum insecticide chlorpyrifos, but it is scheduled for phaseout in California this year. Other available ant bait products differ
- based on their chemistry and method of application and based
on the ant species' preferred diet - for sugar-feeding ants such as
Argentine and native gray ants, or for protein/fat-feeding ants
such as pavement and southern fire ants.
Ant baits were primarily developed for residential use and for
use in a bait station. Both liquid and granular baits are available
for use with EPA-approved bait stations. While these can be
effective, and may be practical in smaller vineyards, costs
associated with the deployment and maintenance of bait stations
make them impractical for widespread adoption in commercial
vineyards. Liquid bait products used with bait stations (and
active ingredients) include: Gourmet/Greenway Liquid Ant Bait
(disodium octaborate tetrahydrate) and Tango (S-methoprene).
Researchers are performing trials in vineyards with existing ant
baits and experimental baits, and evaluating different application
methods. Trials show that granular baits applied by broadcast
with a fertilizer spreader or seed spreader pulled by an ATV can
be distributed more quickly and more frequently over a larger
area and can be more practical for larger vineyards. Tollerup said
the California Department of Pesticide Regulation has approved
the addition of food-grade materials to some approved ant baits
in order to improve their attraction for ants and for ant control
efficacy. However, more research is needed to determine what
food-grade additives are the best attractants for sugar-feeding
ants.
Granular bait products (and active ingredients) include:
Altrevin (metaflumizone), Esteem (pyriproxufen), Extinguish
(S-methoprene) and Seduce (spinosad).
The bait's mode of action should also be considered when
selecting treatment. Some bait chemistries are insect growth
regulators (pyrproxyfen, methoprene) that work by sterilizing
the ant colony's queen and preventing larva development. These
baits may take several weeks to reduce foraging activity, but they
can improve longer-term control. Other bait chemistries act as
stomach poisons (metaflumizone) to kill foragers and inside nest
workers and larvae via food sharing. These are faster acting, and
can reduce foraging activity within three to seven days, but they
may not kill the colony, which can repopulate and come back
later in the season.
2 / MAY 2020

Depending on seasonal
and climatic conditions,
and location, ants can
emerge from nests and
begin foraging from March
to May in California
vineyards. Properly timed
applications of both the
faster-acting and the longerterm control chemistries can
be a strategy for seasonlong ant suppression.
Tollerup conducted
experiments in Lodi
vineyards in 2019 using
Ant nest and vine mealybug at base of grapevine.
Altrevin and Esteem bait
Photo: K. Tollerup
products with the addition
of powdered sugar to improve attractiveness and efficacy against
sugar-feeding ants. However, in the trial vineyard and nearby
vineyards, protein-feeding pavement ants were the main species
identified during the growing season. If pavement ant is the
predominate species in Lodi rather than Argentine ant, this is
encouraging, as there are more effective protein baits available
for pavement ants than for the sugar-feeding Argentine ants.
Napa County UCCE farm advisor Monica Cooper has conducted
trials to evaluate commercial and experimental ant baits for control
of Argentine ants in Napa County vineyards. An article by Cooper
and co-researchers in the September 2019 issue of the American
Society for Enology and Viticulture journal Catalyst describes
success using experimental polyacrylamide crystals laced with
a toxin bait (thiamethoxam, Platinum insecticide) applied with
a broadcast spreader to reduce Argentine ant foraging activity.
Experiments using the crystals laced with boric acid, as an option
for organic growers, also suppressed ant foraging activity.
More vineyard trials are needed to evaluate baits such as Seduce,
Altrevin and Esteem for improving ant control of targeted
species based on application timing, amounts and frequencies,
and to evaluate longer-term effects on mealybug populations.
Researchers also continue working with polyacrylamide crystal
bait products to develop them for commercial use.

INFORMATION SOURCES
UC IPM Pest Management Guidelines / ants website:
ipm.ucanr.edu/PMG/r302302111.html
UCANR Guide to Vineyard Ant Identification:
cenapa.ucdavis.edu/files/52736.pdf
Ant Web: World's largest ant database hosted by California
Academy of Sciences: www.antweb.org

http://ipm.ucanr.edu/PMG/r302302111.html http://cenapa.ucdavis.edu/files/52736.pdf http://www.antweb.org

The Crush - May 2020

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