Biological Control in Cherimoyas -------
-By Jake Blehm, President Buena
Ventura, CA 93007
Good Bugs Versus Bad Bugs
Some of the pest problems that plague cherimoyas can be controlled by several species of beneficial insects and mites. The following is a brief description of these organisms and which pests they attack.
It is important to remember that these organisms typically are not used to eradicate a pest, but to bring it under control below "Economic Injury Level" (EIL).
The basic concept of using biological controls as a first option control method is usually referred to as "biointensive" pest management.
"Biointensive" pest management focuses on the least disruptive, biologically based solutions first, resorting to chemical interventions as a last resort to save the crop.
Most growers and pest control advisors recognize that the liberal use of broad spectrum pesticides can cause secondary pest outbreaks which require even more pesticide applications -- thus, the "pesticide treadmill."
Biological controls that cherimoya growers might consider using include:
Green Lacewing --Chrysoperla spp.
A general predator that attacks aphids, small mealybugs,
whitefly, Thrips, small worms, and other pests.
Minute piratebug --
An excellent predator of spider mites and thrips, as well as worms and other pests.
A more specific predator for two-spotted and pacific spider mites. Works well in cool coastal areas, but not in hot interior valleys.
Six-spotted Thrips --Scolothr/ps sexmaculatus
This predatory thrip does not bother plants but will attack several species of spider mites, and other small pests. Works well in higher Summer temperatures.
Mealybug destroyer ~ Cryptolaemus sp.
This ladybeetle does an excellent job on larger mealybug which Lacewing has difficulty controlling. It can survive on other pests, but is not recommended for aphids or mites.
White fly parasite ~ Encarsia formosa
A small wasp that is most effective on Greenhouse Whitefly and other species to a lesser degree. It is generally not recommended for Sweetpotato Whitefly (Bemisia spp.).
Most of these species can be used in combination with selective "soft" Pesticides.
It is highly recommended that growers consult with a knowledgable pest control advisor before purchasing and releasing beneficial organisms.
Entomologists know of many species of insects that are beneficial to man and the environment. It is possible to put beneficial insects to work controlling a number of pest insects. Thus, the term "biological control" is used to describe "good bugs versus. bad bugs."
Although the concept of biological control has been around for centuries, it has been actively used as a type of pest control in the U.S. only for about a century.
Since the 1940s, chemicals had been the most widely used method of pest control, but with the increased costs of such chemicals, increased pest resistance, and the growing concern for the environment, the demand for biological control has grown tremendously.
Cherimoya growers may choose to use only beneficial insects for biological control, or include beneficials in a larger Integrated Pest Management (IPM) program using alternate means of pest management to complement biological control.
Beneficial insects are commonly divided into two generic categories; predators and parasites. The ladybug, or Hippodamia convergens is a commonly known example of a predator that attacks and directly consumes such pests as aphids, spider mites, immature white fly, worms, and a variety of other softbodied insect pests.
A parasite such as the Trichogramma wasp uses the pest as a host, or vehicle to reproduce. The parasite stings the pest insect and lays its eggs inside, or near the pest, thus killing the pest and providing food for the future offspring of the parasite.
In general, beneficial insects all work the same way. They attack the specific pest population, thus reducing it below economic injury levels. It is not usually necessary to totally eliminate the pest population in order to see results. Expert knowledge of release rates and timing is important to achieve the maximium result from a release of beneficial insects.
The green lacewing larvae is known to attack almost any soft-bodied pest insect that it comes in contact with. Its voracious appetite lends to a specific liking for aphids, but lacewing
larvae will also feed on small worms, immature whitefly, mites,
insect eggs, etc..
Although lacewing can be found naturally in planted areas, a steady increase of their population will lend to control or elimination of the pest population. It takes a trained eye to locate their tiny green eggs, each one perched on a minute hair-like stem.
In the larvae stage, they are grayish green in color and are thought to resemble small alligators. As adults, the green lace-wing lives up to its common name by developing its wings that resemble delicate green lace.
Lacewings should be shipped in the egg stage so that they will be hatching into hungry larvae close to the time our growers receive them.
There are several species of Trichogramma parasites that attack over 150 species of moths and butterflies (Lepidopteran pests). Such pests include tomato fruitworm, European cornborer, corn earworm, armyworm, spruce budworm, and several more.
The species of Trichogramma recommended depends on the particular crop and pest situation. Trichogramma are shipped within parasitized moth eggs that are hatching, or ready to hatch by their arrival. The actual parasite is so small, it is said that 4 or 5 of them can sit on the head of a pin.
Fly Parasite (Muscidifurax zaraptor, Spalangia endius )
Fly parasites are beneficial parasitic wasps that attack the pupae of several species of filth breeding flies. They will attack the common housefly, stable fly, blow fly, lesser house fly, garbage fly, horn fly, etc..
There are often some species of fly parasites naturally present where flies breed, but there must be a significant population of them in order to control the pest fly population.
Fly parasites resemble small gnats and will only attack flies in the immature stages. They will not harm humans, plants or animals. The product is shipped in the form of parasitized fly pupae and upon arrival will be hatching, or close to hatching.
(P. persimilis, A. Californicus, M. Occidentalis)
Used for the control of the two spotted spider mite and many other harmful species, Predatory Mites are shipped in the adult stage. It is estimated that one Predatory Mite will consume up to 20 pest mites and/or eggs per day.
Summer 1995 Newsletter
White fly Parasite
(Encarsia spp., Eretmocerous, Delphastus sp.)
These small parasitic wasps attack the Greenhouse white fly, Sweetpotato White fly, and other species in the immature stages (laying eggs in the 3rd and 4th growth stages, and feeding on the 1 st and 2nd stages of white fly). For best results make releases early, when populations of white-fly are relatively low (approxi-. mately 1 adult per leaf).
White fly Parasite
This well known predatory beetle attacks common pests such as aphids, spider mites, immature white fly, worms, and a variety of other soft-bodied in-. sects. The ladybug is naturally occurring, but increased populations of pests is a sign that the ladybug population may need a boost in order to regain control of the pest population.
Cryptolaemus is a predatory beetle used for the control of mealybugs. Also known as the mealybug destroyer, Cryptolaemus is an Australian beetle that is part of the ladybug family. It will attack all species of above ground mealy bugs, and will also feed on aphids and immature scale insects.
Other species available include
Tree Pruning & Shaping
(Begin after fruit set)
Fruit Thinning, if needed Foliar Fertilizer Spray
(When leaves are fully developed-- Mid-Aug. to Mid-Sept.)
Light Pruning, if needed
Winter Fertilizer Program
(Reduce Nitrogen application)
Pest Control, especially ants Continue Irrigation
Pest Control --mealybugs
Winter Maintenance Fertilize Application (Dry Fertilizer) Irrigation as needed
Rodent Control (Gophers, Squirrels, Rats before new generation)
Irrigation as needed
*Fertilizer program should be based on results of fall leaf analysis. Fruit set can be adversely affected by excessive fertilizer applications during the summer months. Fertilize moderately and monitor carefully!
Applications of organic material such as composted manures and mulches are beneficial and can be applied year-round as available.
A free copy of Suppliers Of Beneficial Organisms In North
America is available from: California Environmental Protection
Agency, Dept. of Pesticide Regula-
tion, Environmental Monitoring and Pest Management Branch, 1020 N
Street, Room 161, Sacramento, CA 95814-5604. Phone (916) 324-4100.