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| Biological control of pests Overuse of pesticides can cause secondary pest outbreaks, requiring even more pesticides, which can continue on and on at great cost. A more environmental option is the many species of beneficial predatory insects and mites that can be used to combat some of the cherimoya’s pests. They generally attack a specific pest, reducing their population to a level that won’t affect crop production. Total elimination of the pest population is not always necessary. Expert knowledge of timing and numbers is necessary to get the best results from a release of beneficial insects. Chemicals could be used as a last resort to save a crop. The list below contains some of the many beneficial predatory insects and mites that cherimoya growers can use to control potential cherimoya pests. Most of these species can be used in combination with selective “soft” pesticides. Green lacewing (Chrysoperla spp.) The larvae is known to attack almost any soft-bodied pest insect it comes across. They have a ravenous appetite for aphids, but happily feed on small worms, immature whitefly, mites, insect eggs, thrips, small mealybugs and other pests. Though lacewing are found naturally in planted areas, a steady increase in their population will help control or eliminate the pest population. It takes a trained eye to locate their tiny green eggs, each perched on a minute hair-like stem. In the larvae stage, they are greyish green and are said to look like small alligators. As adults, they live up to their common name by developing wings that resemble delicate green lace. Lacewings should be shipped in the egg stage so that they’ll be hatching into hungry larvae close to the time they’re received. Ladybugs (Hippodamia convergens) This well known predatory beetle attacks common pests like aphids, spider mites, immature whitefly, and many other soft-bodied insects. The ladybug occurs naturally, but increased populations of pests is a sign that ladybug populations may need a boost to regain control. Mealybug destroyer (Cryptolaemus montrouzieri) This predatory Australian beetle, part of the ladybug family, is used to control mealybugs. They attack all species of above-ground mealybugs, and also feed on aphids and immature scale insects. They do an excellent job on larger mealybugs, which lacewing have difficulty controlling. The recommended number of beetles is 600 per hectare, which are released in spring and then die in winter. Minute piratebug (Or/us spp.) An excellent predator of thrips and spider mites (particularly two-spotted and pacific spider mites), as well as worms and other pests. Works well in cool coastal areas, but not in hot interior valleys. Predatory mites (P.persimilis, A.californicus, M.occidentalis) Used to control two-spotted spider mite and many other harmful species. It’s estimated that one predatory mite will consume up to 20 pest mites and/or eggs per day. They are shipped in the adult stage. Six-spotted thrips (Scolothr/ps sexmaculatus) This predatory thrip won’t bother plants and will attack several species of spider mites and other small pests. Works well in higher summer temperatures. Trichogramma (fly parasites) (Muscidifurax zaraptor, Spalangia endius ) Fly parasites are beneficial parasitic wasps that resemble small gnats, and will attack the pupae of several species of filth breeding flies in their immature stages. They will attack the common housefly, blowfly, garbage fly etc, and are harmless to humans, animals and plants. There are often species of fly parasites naturally present where flies breed, but there needs to be a significant population of them to control pest fly populations. There are several species of Trichogramma parasites that attack over 150 species of moths and butterflies (Lepidopteran pests). Such pests include tomato fruitworm, cornborer, armyworm and several more. The species of Trichogramma required depends on the particular crop and pest situation. They are shipped within parasitized moth eggs and, on arrival, will be hatching or close to hatching. The actual parasite is tiny and it’s said that 4 or 5 can sit on a pin head. Whitefly parasite (Encarsia spp., Eretmocerous, Delphastus sp.) These small parasitic wasps attack the greenhouse whitefly, sweetpotato whitefly, and other species in immature stages, feeding on the 1st and 2nd growth stages and laying eggs in the 3rd and 4th. For best results make releases early when populations of whitefly are relatively low (approximately 1 adult per leaf). Back to the top Next – the yearly requirements of cherimoya trees (in New Zealand)
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