Southeastern U.S. Vegetable Crop Handbook - 2023 - 28

Augmentation: Augmentation is the direct manipulation of natural
enemies to increase their effectiveness. This can be accomplished
by one of two general methods or a combination of
these methods: mass production and/or periodic colonization of
natural enemies. The most commonly used of these approaches
is the first, in which natural enemies are produced in insectaries,
then released either inoculatively or inundatively. For example,
in areas where a particular natural enemy cannot overwinter, an
inoculative release each spring may allow the population to establish
and adequately control a pest. Inundative releases involve
the release of large numbers of a natural enemy such that their
population completely overwhelms the pest.
Augmentation is used where populations of a natural enemy
are not present or cannot respond quickly enough to the pest
population. Therefore, augmentation usually does not provide
permanent suppression of pests, as may occur with importation
or conservation methods. An example of the inoculative release
method is the use of the parasitoid wasp, Encarsia formosa Gahan,
to suppress populations of the greenhouse whitefly, Trialeurodes
vaporariorum (Westwood). The greenhouse whitefly
is a ubiquitous pest of vegetable and floriculture crops that is
notoriously difficult to manage, even with pesticides. Releases
of relatively low densities (typically 0.25 to 2 per plant, depending
on the crop) of Encarsia immediately after the first whiteflies
have been detected on yellow sticky cards can effectively prevent
populations from developing to damaging levels. However,
releases should be made within the context of an integrated crop
management program that takes into account the low tolerance
of the parasitoids to pesticides. It is important to bear in mind
that Encarsia can provide effective control of greenhouse whitefly,
but not sweetpotato whitefly. Therefore, it is critical to identify
which whitefly is present before releasing Encarsia. Another
parasitoid, Eretmocerus californicus has shown promise against
sweetpotato whitefly.
Because most augmentation involves mass-production and
periodic colonization of natural enemies, this type of biological
control has lent itself to commercial development. There are
hundreds of biological control products available commercially
for dozens of pest invertebrates (insects, spidermites, etc.),
vertebrates (deer, rodents, etc.), weeds, and plant pathogens.
A summary of these products and their target pests is presented
in Table 13. The efficacy of these predators and parasites
is dependent on many factors. Management of the target pest
is more likely than 100% control. It is critical to familiarize
yourself with proper usage of these predators and parasites
otherwise you may not achieve satisfactory results and obtain
inconsistent results. Selection of products and suppliers should
be done with care, as with purchasing any product. Review
publications for guidelines on how to purchase and utilize natural
enemies.
Conservation: The most common form of biological control is
conservation of natural enemies which already exist in a cropping
situation. Conservation involves identifying the factor(s)
which may limit the effectiveness of a particular natural enemy
and modifying these factor(s) to increase the effectiveness of
natural enemies. In general, this involves either reducing factors
which interfere with natural enemies or providing resources that
natural enemies need in their environment. The most common
factor that interferes with natural enemy effectiveness is the application
of pesticides. Some cultural practices such as tillage
or burning of crop debris can also kill natural enemies or make
the crop habitat unsuitable. In some crops, accumulation of dust
TABLE 13. PREDATORS AND PARASITES OF VEGETABLE PESTS (CONT'D)
Predators and Parasites
Approx. # North
American Species Pest(s) Controlled or Impacted
WASPS
Aphelinid Wasps *
Aphidiid Wasps *
Braconid Wasps *
Chalcid Wasps *
Cotesia Wasps (Braconid Family) *
Encarsia formosa *
Encyrtid Wasps
Eulophid Wasps
Ichneumonid Wasps *
Mymarid Egg Wasps
Pteromalid Wasps
Scelionid Egg Wasps
Tiphiid Wasps
Trichogramma Wasps *
Thripobius semiluteus (Eulophidae Family)*
Vespid Wasps (hornets, yellowjackets, etc.)
1,000
114
1,000
1,500
200
1
500
3,400
3,100
1,300
3,000
300
225
650
1
200
Aphids on some greenhouse and vegetable crops; mummies of parasitized aphids will be black.
Aphid parasites; mummies turn tan or golden.
Caterpillars on cole crops and potatoes, leafminers in greenhouse crops.
Internal and external parasite of fly and moth larvae and pupae. A few species attack beetles.
Parasites of caterpillars including armyworms, Alfalfa caterpillar, loopers, cabbageworms.
A commercially available Aphelinid wasp, whiteflies on greenhouse/some field crops.
Aphids on some greenhouse crops, Cabbage looper, root maggot.
Colorado Potato Beetle, Mexican Bean beetle, Asparagus beetle, leafminers in field crops.
Caterpillars, eggs, and beetle larvae in: cole crops, corn, Asparagus whiteflies on cole crops and tomato.
Lygus bug, Tarnished Plant bug, carrot weevil. Egg parasite of beetles, flies, grasshoppers, leafhoppers
and many true bugs (Stink bugs, lygeids). Adults are 1/25 inch in size.
Parasites of beetles, flies, and other wasps, cabbage worm, diamondback moth.
Parasite of true bug and moth eggs.
Parasites of Japanese beetles and Tiger beetles.
Moth eggs on cole crops, peppers, sweet corn, and tomatoes. Because only eggs are parasitized,
releases must be timed to coincide with egg laying (use pheromone trap to determine timing).
Controls thrips via parasitism.
Caterpillars, flies, true bugs, beetles, and other wasps are fed to Vespid larvae.
* Insects marked with an asterisk represents species that are available commercially for purchase.
For a list of Biological Control (Beneficial Insects) Suppliers, see http://wiki.bugwood.org/Commercially_available_biological_controls
28
2023 Vegetable Crop Handbook for Southeastern United States

http://wiki.bugwood.org/Commercially_available_biological_controls

Southeastern U.S. Vegetable Crop Handbook - 2023

Table of Contents for the Digital Edition of Southeastern U.S. Vegetable Crop Handbook - 2023