June 2023 - 20

PLANT HEALTH
The Pitchfork
METHOD
O
ften when growers and
integrated pest management
(IPM) managers are thinking
and speaking of controlling pests
with traditional pesticides, we think
of product X being used for pest
problem Z. This is also often the way
people think about biological control.
To be successful with biological
control, however, the pitchfork
approach is something to really
embrace and execute.
Anyone who has used biological
control successfully knows that this
approach requires being proactive.
Biological control is simply not
suitable to control an already raging
pest problem. Rather, it is an approach
that avoids pest problems from
happening in the first place. This
has mainly to do with how biological
control agents (BCAs) mode of action
is, to keep it in pesticide terminology.
The biology, or the mode of action,
of several BCAs is very specific to a
small part of the
life cycle of the
pest problem
that is being
targeted. To
use thrips and
whiteflies
as an example:
THRIPS
In the life
Figure 2. The pitchfork method used here combines four
predators to control three life stages of thrips.
cycle of thrips,
the small and most commonly
used BCA is a predatory mite called
Amblyseius cucumeris, often released
in breeding sachets (Figure 1). This
small predatory mite is preying only on
the first larval stage of thrips, which at
68° F is only 3 days, or 1.5 days at
86° F - only a very small window in
the entire life cycle of thrips. This is the
reason why starting early is so critical
to keep thrips controlled. Besides
feeding on the first larval stage of
thrips, Amblyseius cucumeris also
preys on broad mites.
There are other tools in the toolbox,
however, that are affecting some of the
other parts of the thrips life cycle.
The predatory mite Stratiolealaps
Figure 1.
Breeding sachets in
fall chrysanthemums.
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JUNE 2023 GPNMAG.COM
scimitus (formerly known as Hypoaspis
miles) and the rove beetle Dalotia
coriaria are both generalist predators
living in the top layer of the soil. This
is the space where western flower
thrips pupates, the stage after the two
larval stages. Both these generalist
soil predators have an appetite for the
thrips pupae. After the pupal stage
of thrips, adult thrips will appear if it
has not been " caught " by the three
predators already mentioned.
Orius insidiosus (minute pirate bug)
is a larger predatory insect that can
attack, kill and feed on adult thrips
as well as thrips larvae. To mention
specifically, Orius can kill up to 80
adult thrips per day, only feeding on
a few. It is a true thrips killer, but also
has an appetite for moth eggs and
spider mites. By combining these four
predators, three parts of the life stages
of thrips are being controlled, making it
almost impossible for thrips to become
a problem. Each of these predators is a
prong of the pitchfork (Figure 2).
WHITEFLIES
Many poinsettia growers are using
biological control to prevent whiteflies
from becoming a problem. Similar
to thrips, there are BCAs that are
focused on controlling parts of the
life cycle of whiteflies.
BY RONALD VALENTIN
Biological control can be most effective when using
several biological control agents against one particular
pest problem and its life stages.
http://www.GPNMAG.COM
June 2023

Table of Contents for the Digital Edition of June 2023
