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How to Manage Pests

UC Pest Management Guidelines


Parasitic wasp, Hyposoter exiguae, attacking beet armyworm larva.

Floriculture and Ornamental Nurseries

Biological Control

(Reviewed 3/09, updated 3/09)

In this Guideline:


Many insect and mite pests in floricultural crops have natural enemies that can sometimes keep their populations below economically damaging levels. Using pesticides that do not disrupt natural enemy activity is a key component of integrated pest management programs. Two other important features of a good biological program are clean, dust-free plants and the absence of ant activity. Dust and ants can severerly interfere with control by natural enemies.

When natural enemy populations are not present or are not high enough to reduce pests, they can sometimes be augmented with releases of commercially reared natural enemies. There are two types of augmentative releases: inoculative releases and inundative releases.

Inoculative releases are made when pest populations are low and relatively few natural enemies are released, usually just once or twice a season. The introduced predators or parasites reproduce, and it is their progeny, not the released individuals that are expected to provide biological control. Releasing the mealybug destroyer lady beetle (Cryptolaemus montrouzieri) in spring to control mealybugs is an example of inoculative release.

Inundative releases involve releasing large numbers of natural enemies often several times over a growing season. The released natural enemies are expected to provide biological control. Although they may reproduce, progeny of release individuals generally are not relied on for control. Periodically releasing Trichogramma species (parasitic wasps) to destroy moth eggs is an example of inundative biological control.

A good place to start with augmentation is in situations similar to those where researchers or other pest managers have previously demonstrated success. Guidelines for releasing natural enemies are given for many pests in the individual pest sections of this guideline. Desperate situations where pests are already abundant or damage is common are not a good opportunity for augmentation. Because pest presence is necessary to sustain natural enemies, choose crops where some levels of the target pests and their damage can be tolerated. Begin making releases early in the production cycle. Consider what other pests may occur in the crop and how they can be managed in ways that are compatible with biological control. Make other necessary changes in production practices, for example, by avoiding use of pesticides that harm natural enemies (Table 1).

Increase the likelihood that natural enemy releases will be effective by accurately identifying the pest and its life stages. Parasites and many predators attack only certain pest stages; release the beneficial species when the pest is in its vulnerable life stage or stages. The pest life stage that can be effectively controlled with natural enemies may be different from the pest stage that damages plants. For example, Trichogramma species kill only eggs of moths and butterflies; they are not effective against caterpillars. Trichogramma must be released when moths are laying eggs, before the caterpillars become abundant.

The quality of commercially available natural enemies is not regulated and may sometimes be poor because of production practices, inadequate packaging, or unsuitable conditions during shipping. Evaluate the quantity and quality of each shipment of natural enemies. If beneficials arrive in parasitized hosts, count parasite exit holes in a small sample immediately after parasites arrive. Keep the sample in a suitable place and recount and compare the number of emergence holes about 10 days after deploying the parasite. If natural enemies (typically predators) arrive in a shaker-type container, estimate their numbers and calibrate your application rate by making one shake over a sheet of white paper and counting the number of apparently alive or active natural enemies. Repeat this several times to estimate the average number of predators per shake. If predators or parasitized hosts arrive on leaves, use a hand lens or dissecting binocular microscope to examine the underside of several leaves and estimate the natural enemies per leaf. Contact the supplier immediately if natural enemy quality is unsatisfactory.

Remember that natural enemies are living organisms that require water, food, shelter, and suitable growing conditions. Natural enemies may be adversely affected by extreme conditions such as hot temperatures. Residues of certain pesticides can persist for weeks or months, harming natural enemies long after losing their effectiveness against pest species. Overhead irrigation may drown natural enemies. Many beneficial species stop reproducing under short day length or prolonged cool conditions. Supplemental light may be necessary for some predators and parasites to be effective year-round. Environmental conditions required by natural enemies (such as long days) may not be compatible with production needs of certain crops.

Many natural enemies are commercially available (Table 2) through mail order. A publication listing sources, Suppliers of Beneficial Organisms in North America, can be obtained from the Environmental Monitoring and Pest Management Branch of the California Department of Pesticide Regulation online at www.cdpr.ca.gov or as a printed publication by calling (916) 324-4100 or writing the Department of Pesticide Regulation, Environmental Monitoring and Pest Management Branch, 830 K St., Room 200, Sacramento, CA 95814.

TABLE 1. Pesticide Use Compatibility with Biological Control.1
Chemical name
(trade name)
Range of activity
(affected groups)
Immediate impact on
natural enemies2
Duration of impact on
natural enemies2
abamectin
(Avid)
intermediate
(mites, leafminers)
high to predatory mites, low
for many insects
long to predatory mites and affected insects
acephate
(Acephate) (Orthene 75WP)
(PT 1300 Orthene TR)
broad
(insects & mites)
high intermediate
acetamiprid
(Tristar 70WSP)
broad
(insects)
moderate intermediate
azadirachtin
(Azatin XL)
(Ornazin)
broad
(insects & mites)
moderate short
Bacillus thuringiensis#
(Gnatrol)


(Dipel DF)
(Xentari)
narrow
(larvae of flies such as fungus gnats, mosquitoes)
narrow (caterpillars)
narrow (caterpillars)
none none
Beauveria bassiana#
(BotaniGard WP)
(BotaniGard ES)
narrow
(kills some soft-
bodied predators)
low short
bifenthrin*
(Attain TR)
(Talstar Flowable)
broad
(insects & mites)
high long
bifenazate
(Floramite)
narrow (mites) low short
carbaryl*
(various)
broad
(insects & mites)
high long
chlorfenapyr
(Pylon)
narrow (mites) low intermediate
chlorpyrifos*
(PT DuraGuard)
broad
(insects & mites)
high intermediate
chlorpyrifos/cyfluthrin*
(PT Duraplex)
broad
(insects & mites)
high intermediate
cinnamaldehyde
(Cinnacure)
intermediate
(aphids, thrips & mites)
low short
cyfluthrin
(Decathlon 20WP)
broad
(insects & mites)
high intermediate
cyromazine
(Citation)
narrow
(leafminers)
low short
deltamethrin
(DeltaGard)
broad (insects) high long
dicofol
(Kelthane)
narrow
(pest mites & mites)
high to beneficial mites long to beneficial mites
diflubenzuron
(Adept)
narrow
(fungus gnats)
none none
endosulfan*
(Endosulfon 3EC)
(Endosulfon 50WSB)
broad
(insects & mites)
high long
fenbutatin-oxide*
(Vendex)
narrow (mites) low short
fenpropathrin*
(Tame)
broad
(insects & mites)
high intermediate
fenpyroximate
(Akari)
narrow (mites) moderate short
fluvalinate
(Mavrik Aquaflow)
broad
(insects & mites)
high long
hexythiazox
(Hexygon)
narrow (mite
nymphs & eggs)
high to predatory mites long
horticultural oil#
(various)
broad (exposed
insects and mites)
moderate short to none
imidacloprid
(Marathon 1%G)
(Marathon 60 WP)
(Marathon II)
narrow
(sucking insects)
low (soil applications) high3 (foliar applications) short
lambda-cyhalothrin* (Scimitar) broad (plant bugs, beetles, caterpillars) high intermediate
malathion
(various)
broad
(insects & mites)
high intermediate
methiocarb*
(Mesurol)
broad (insects) high long
neem oil#
(various)
narrow (soft-bodied
insects)
moderate short
novaluron
(Pedestal)
intermediate (thrips, whiteflies, army-worms, leafminers) low short
permethrin
(Astro)
broad
(insects & mites)
high long
potash soap#
(M-Pede)
broad
(insects & mites)
moderate short to none
pymetrozine
(Endeavor)
narrow (aphids, whiteflies) low short
pyrethrin/PBO4
(PT Pyrethrum TR)
broad
(insects)
high short
pyrethrin/rotenone
(Pyrellin E.C. )
broad
(insects & mites)
high short
pyridaben
(Sanmite)
narrow
(mites)
high to predatory mites intermediate
pyriproxyfen
(Distance)
intermediate
(aphids, scale, whiteflies, leafminers, gnats)
low short
s-kinoprene
(Enstar II)
intermediate
(immature insects)
moderate short
spinosad
(Conserve SC)
intermediate (thrips,
caterpillars, leafminers)
high to adult wasp parasites; low to predators intermediate
tebufenozide
(Mimic)
narrow (caterpillars) low short
1 Adapted from Flint, M. L., S. H. Dreistadt, and J. K. Clark. 1998. Natural Enemies Handbook: An Illustrated Guide to Biological Pest Control, ANR Publication 3386.
2 The immediate impact of pesticides on natural enemies is the killing of natural enemies resulting from spraying the pest or its habitat (contact toxicity). Duration of the impact on natural enemies refers to persistent residues that kill natural enemies that migrate in and contact previously treated areas (residual toxicity). Use stated toxicities only as a general guide. The actual toxicity of specific chemicals depends on environmental conditions, application rate and exposure, and the species of natural enemy.
3 High toxicity to hymenopteran insects (honey bees and parasitic wasps)
4 PBO = piperonyl butoxide
* Restricted use material. Permit required for purchase or use.
# Acceptable for use on organically grown ornamentals.
TABLE 2. Some Commercially Available Natural Enemies of Floriculture and Nursery Pests.
Target pest Natural enemy
  Common name Scientific name
aphids aphid midge
convergent lady beetle
lacewings
microbial insecticide
minute pirate bugs
parasitic wasps
Aphidoletes aphidimyza
Hippodamia convergens
Chrysoperla
spp.
Beauveria bassiana
1
Orius insidiosus, O. tristicolor
Aphelinus, Aphidius
spp., Diaeretiella rapae, others
broad mites predaceous mites Neoseiulus spp.
caterpillars egg parasites
parasitic nematodes

larval parasites
microbial insecticides
Trichogramma spp.
Steinernema carpocapsae,
Heterorhabditis bacteriophora
several host-specific ssp.
Bacillus thuringiensis
ssp. kurstaki, Bt ssp. aizawai; Beauveria bassiana; spinosyn (spinosad)1
fungus gnats parasitic nematodes
microbial insecticide
predaceous mite
Steinernema carpocapsae, S. feltiae
Bacillus thuringiensis
ssp. israelensis1
Hypoaspis miles
mealybugs citrus mealybug parasite
lacewings
mealybug destroyer
microbial insecticides
Leptomastix dactylopii
Chrysoperla
spp.
Cryptolaemus montrouzieri
Beauveria bassiana
1
scale insects predaceous lady beetle
red scale parasite
soft scale parasites
Rhyzobius (=Lindorus) lophanthae
Aphytis melinus
Metaphycus helvolus, Microterys flavus
serpentine leafminer parasitic nematode
parasitic wasps
Steinernema carpocapsae
Dacnusa, Diglyphus
spp.
spider mites lacewings
predatory cecidomyiid
predatory mites

Chrysoperla spp.
Feltiella sp.
Amblyseius, Metaseiulus, Neoseiulus, Phytoseiulus spp.
thrips greenhouse thrips parasite
lacewings
microbial insecticide
minute pirate bug
predatory mites
Thripobius semiluteus
Chrysoperla
spp.
Beauveria bassiana1
Orius insidiosus, O. tristicolor
Amblyseius, Euseius, Iphiseius, Neoseiulus
spp., Hypoaspis miles
weevils parasitic nematodes Steinernema carpocapsae,
Heterorhabditis bacteriophora
whiteflies lacewings
microbial insecticide
parasitic wasps
predaceous lady beetle
Chrysoperla spp.
Beauveria bassiana1
Encarsia, Eretmocerus
spp. and others
Delphastus pusillus
white grubs parasitic nematodes Steinernema carpocapsae,
Heterorhabditis bacteriophora
1 These microbial products are registered insecticides.

[Precautions]

PUBLICATION

[UC Peer Reviewed]

UC IPM Pest Management Guidelines: Floriculture and Ornamental Nurseries
UC ANR Publication 3392
Insects and Mites
J. A. Bethke, Entomology, UC Riverside
Acknowledgment for contributions to Insects and Mites:
K. L. Robb, UC Cooperative Extension, San Diego County
H. S. Costa, Entomology, UC Riverside
R. S. Cowles, Connecticut Agricultural Experiment Station, Windsor, CT
M. P. Parrella, Entomology, UC Davis

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