September 2022 - 20

BIOCONTOLS & BIOPESTICIDES
Biocontrol of cranberry pests:
The enemy of my enemy is my friend
By Christelle Guédot and
Didier Labarre
University of Wisconsin
Cranberry growers are always interested
in diversifying their pest management
strategies to reduce inputs, increase
sustainability, and improve environmental
stewardship of the land.
One Integrated Pest Management (IPM)
strategy we do not talk about enough
is biological control. Biological control
is a pest management strategy that can
be integrated within an IPM program
with care for, and understanding of, all
the natural enemies that are present in
agroecosystems. Natural enemies are
represented by very diverse groups of
insects and other arthropods that feed
on pest insects and thereby provide
pest management in a natural and
environmentally-sound approach. Natural
enemies include predators (e.g. spiders,
ladybugs, praying mantis), parasites
who do not kill the host (e.g., flies, mites
and lice), parasitoids (e.g., wasps, flies),
and pathogens (fungi, bacteria, viruses
and nematodes). Biological control can
be implemented according to three
strategies: importation, augmentation, and
conservation biological control.
The first strategy, importation biocontrol
(aka classical biocontrol), is of importance
in the case of new invasive pest species.
In this strategy, researchers return to the
native range of the invasive pest to identify
and collect the natural enemies of the
pest species in its original location. This
is a very lengthy process of about 10 years
that requires quarantine, mass rearing,
evaluations of non-target species in the
Fig. 1. Seasonal occurrence of syrphid flies in wild vs. conventional cranberry.
invaded range and regulatory permits.
For the most part in cranberry, we deal
with native insect pests and therefore
there has not been a historical need for
importation biocontrol of cranberry. This
strategy is currently being implemented for
other fruit insects, such as spotted-wing
drosophila and brown marmorated stink
bug, with increasing success in reducing
these pest populations.
The second strategy is called
augmentation biocontrol. Here, naturallyoccurring
enemies that have been
determined to be effective biocontrol
agents and can be reared in mass in
insect-rearing facilities are released in
the area that needs to be controlled. One
example would be the entomopathogenic
nematodes that are mass reared and
released into cranberry beds to kill several
pests, including flea beetle, cranberry
fruitworm, and sparganothis fruitworm
(Steffan 2022). Another example would
be the minute parasitic wasps of the
genus Trichogramma that lay eggs inside
butterflies and moths' eggs, thereby
preventing them from hatching.
Finally, the third strategy is
conservation biocontrol, in which the
goal is to capitalize on the naturally
occurring natural enemies by providing
habitat and resources for them to thrive
in our agroecosystems and by reducing
pesticide applications that would
negatively impact them.
Natural enemies
Cranberry is a great example of a native
crop embedded into a natural ecosystem
that harbors natural enemy populations
which can be fostered to help reduce pest
populations. A diversity of natural enemies
has been documented to attack our pest
complexes, including syrphid flies (Fig.
1), parasitoid wasps (Fig. 2), predators,
nematodes and others. Natural parasitism
rate varies widely among pest species, with
larval parasitism rates of ~60% for the false
armyworm and sparganothis fruitworm,
~20% for the green spanworm, ~10% for
the blackheaded fireworm, and almost
no parasitism for the brown spanworm
(Drolet et al., 2019).
Some nematode species and strains
can be purchased from companies in the
U.S. or are reared by the Steffan's Lab at
USDA-Agricultural Research Service.
They are either mass reared in bioreactors
or using an alternative host (also called
factice host), which are usually mealworm
larvae. They can then be applied at rates
around a billion per acre. Nematodes are
microscopic and relatively resistant, so they
can be easily mixed with clear water and
sprayed into beds. The key to their efficacy
is to get them washed down into the
ground with water, where they can survive
for multiple days and move around up to
1 meter, looking for a host. Nematodes
NOW ACCEPTING
ORDERS FOR 2023*
*CALL FOR INVENTORY
AND TAKING CUSTOM
ORDERS FOR 2025**
**MINIMUM ORDER = 50 TREES
WAFLER NURSERY
Over 100 VARIETIES of Superior
Quality Apple & Pear Trees
ORDER TODAY! 877.397.0874
WAFLER NURSERY
10748 SLAGHT ROAD | WOLCOTT, NY 14590
INFO@WAFLERNURSERY.COM
WAFLERNURSERY.COM
20 | FruitGrowersNews.com
http://www.waflernursery.com http://www.zenportindustries.com http://www.FruitGrowersNews.com
September 2022

Table of Contents for the Digital Edition of September 2022
