General Pest Information I.P.M. Information Price: $0.00 Shipping: $0.00 Part Number: Qty: CONTENTS: 1. A Practical Guide to Biological Control 2. Predaceous Mites for Control of Two-Spotted Spider Mite A Practical Guide to Interiorscape Biological Control * Richard S. Cowles Department of Entomology University of California, Riverside lnteriorscapes have a unique combination of close proximity of plants to public activity in an enclosed space. In this situation, pest management is limited to options that have low risk to humans and "wildlife" such as fish, ducks, or turtles in the interiorscape, and that are minimally disruptive to the activities in the building. Biological control (biocontrol) fits within these restraints: insect pathogens, predators, and parasites are non-toxic to humans, and predators and parasites have the advantage of being able to search out prey. Rather than having to move plants outdoors to treat them with insecticides, or curtail activities in the building so that plants can be sprayed, natural enemies can be released onto infested plants and allowed to find the pests for themselves. Biocontrol agents have several important drawbacks, however. Because they are living organisms, biocontrol agents have needs that have to be met and are adapted to specific conditions. The probability that a biological control release will be successful is thus enhanced by following the rules below: 1. Identify the pest exactly, so that a biocontrol agent known to be effective for this pest can be obtained. Consider the entire pest complex present at a site. If broad-spectrum insecticides must be applied for one pest, than biological control for another pest may not be practical. Some biocontrol suppliers are now contracting with identification services, as part of the initial expense, to be sure that appropriate biocontrol species are being purchased. 2. Check with the biocontrol supplier to make sure that the environmental conditions (temperature, relative humidity, light levels) are within the limits tolerated by the biocontrol agent. Try to find a producer of the beneficial (e.g., Oxnard Pest Control for Cryptolaemus; Biotactics for predatory mites), rather than a middle-man distributor. 3. Plan ahead, so that pesticide applications toxic to the biocontrol agent have a chance to degrade before making a release. A four week wait is often considered necessary. 4. Check the biocontrol agent after receiving them to make sure that they are alive. 5. Monitor the progress of biocontrol. This can involve checking for mummified pests, or use of yellow sticky cards (placed in an inconspicuous area). Yellow sticky cards are contraindicated when using some biocontrol agents (e.g., Leptomastix). 6. Always consider alternative pest management options, such as exclusion (by checking incoming plants for infestations), resistant varieties, cultural control (e.g., irrigation management and choice of potting media for managing fungus gnats; removal of dust to make conditions less favorable for mites), and chemical control (especially the use of insect growth regulators and systemics). Some of these options can complement biological control and will be successful only in planned combination. Control ants, as they interfere with biocontrol. Probably the most important limitation of biocontrol agents is their host specificity. Specificity is a two-edged sword. Having a parasite that seeks out a single scale species, and that reproduces well in this host, works well for managing that species of scale alone. Generalist predators, such as lacewings or convergent lady beetles will feed to some extent on almost any sucking insects and mites, but tend not to be as efficient as a properly chosen specialist predator or parasite. Some interiorscape pests and their natural enemies are given below. The pests are listed in approximately decreasing order of importance: Two-spotted and other spider mites: Predatory mites are suggested, principally because they can reproduce faster than their prey. Mites are commonly released at rates of approximately 20 per sq. meter. Mites should be released directly onto infested leaves. Phytosetulus persimilis is an orange colored predatory mite commonly used in interiorseapes and reputedly most effective in cool, moist (70% RH) conditions. This species is prone to go through a boom-and-bust cycle, where the predator reduces prey to such low levels that the predatory mite population becomes extinct. Metaseiulus occidentalis is a straw colored predatory mite adapted to higher temperatures and lower humidity (>50% RH). This species may be able to survive longer times without food, and so can complement releases of P. persimilis. Fungus gnat: Hypoaspis (Geolaelaps) miles is a soil dwelling generalist predator mite, feeding on collembola, nematodes, early instar fungus gnat larvae, and thrips pupae. This mite should mostly be used for prevention of fungus gnat problems. Once fungus gnats have gotten out of hand, these mites do not seem to significantly decrease the emerging fungus gnat adult populations. Look carefully for these mites in soil where fungus gnats have been a problem - you will often find these mites without ever having bought them from a supplier. Insect pathogenic nematodes, Steinernema carpocapsae and Steinernema feltiae will infect fungus gnat larvae, however the latter species is probably more effective. Different sources of the former species are commercially available in large quantities, product names include "Exhibit" and "Scanmask." My research results suggest that "Exhibit" is not an effective treatment for fungus gnats. Citrus mealybug: Cryptolaemus montrouzieri is a lady beetle predator that lays its eggs near mealybug egg masses (ovisacs), upon which the larvae feed. Larvae are distinctive "wolves in sheep's clothing," looking like large mealybugs themselves. Adults are black with orange heads and rear, and feed most readily on citrus mealybugs. They also will feed on other mealybugs, immature soft scales, and aphids. Recommended release rates are 5 per sq. meter. Leptomastix dactylopii is a small yellowish-brown wasp, and is a specialist parasite of citrus mealybugs. Parasitized mealybugs become barrel shaped mummies, from which the adult wasps later emerge. Recommended release rates are 5 per sq. meter. Soft scales: Many companies sell the Metaphycus helvolus for biocontrol of a variety of soft scale species. This parasite specializes on and successfully reproduces on black soft scale. Development of this parasite's larvae can be abortive in the closely related hemispherical scale, so it is not a sustainable biocontrol agent for this species. It is probably worthless for control of even more distantly related soft scales. Brown soft scale poses special challenges for biocontrol. Effective species of parasites (Microterys neoteri and Metaphycus alberti) may soon be released for propagation by insectaries from Texas A&M. Three additional generalists could be considered, one is a parasite, Coccophagus lycimnia, and the two others are predators, Chilocorus nigrtis and Rhyzobius (=Lindorus) lophanthae. Longtailed mealybug: Adult Cryptolaemus will feed on this pest, however, since longtailed mealybugs produce live young, the adult lady beetles miss an important cue (host eggs) for determining where to lay their eggs. The result can be poor results when using this predator for control of this mealybug. Work is currently being done at Texas A&M for introducing more effective parasites for this pest. Armored scales: One parasite is available, Aphytis melinus, that is known to be effective against California red scale. It is also marketed for control of oleander scale, yellow scale, and dictyospermium scale, however data for control of these pests are lacking. Aphids: Several parasites and predators are available. Since aphids are not commonly a major pest in interiorscapes, the relative merits of each biocontrol agent has not been evaluated. Some possibilities that need to be explored are: Aphidoletes aphidomyza, a predatory midge. Aphidius matricariae, a parasitic wasp. Hippodamia convergens, the convergent lady beetle. Chrysoperla carnea, Chrysoperla comanche, Chrysoperla rufilabris, various lacewing species Greenhouse thrips: The parasitic wasp Thripobius semiluteus is probably a good choice. Predatory mites used for control of western flower thrips are generally ineffective against greenhouse thrips Leafminers: Dacnusa sibirica and Diglyphus isaea are two commonly encountered and commercially available parasites. References: IPM Laboratories Quarterly. Locke, NY. (315) 497-3129 Steiner, M. Y. and D. P. Elliott. 1983. Biological Pest Management for Interior Plantscapes. Alberta Environmental Centre, Vegreville, AB TOB 4L0 Canada Hunter, C. D. 1992. Suppliers of Beneficial Organisms in North America. California Environmental Protection Agency. This publication is available free of charge, just call (916) 654-1141. 1. No endorsement of biocontrol suppliers nor criticism of similar companies not named is intended. ********************************* ********************************************************************** ********************************************************************** ********************************* PREDACEOUS MITES FOR CONTROL OF TWO-SPOTTED SPIDER MITE March 1995 Ann I. King University of California Cooperative Extension 625 Miramontes, Suite 2 Half Moon Bay, CA 9401 (415) 726-9059 (415) 726-9267 (fax) Two-Spotted Spider Mite (Tetranychus urticae) * Life cycle, 7-10 days indoors * Eggs laid on underside of leaves * Likes high temperatures, dry conditions (low relative humidity) * One female lays 50-200 eggs; Can get 13,000,000 mites in 1 month at 80 F Mite Monitoring * Yellow sticky cards do not work -- mites are not winged * Diligent scouting is essential -- at all plant heights; underside of leaves * Mites hitchhike on workers -- spread by workers Work in mite-infested areas at end of day Inspection * Use a 10 X hand lens * Look for eggs, silk, cast skins, excrement, moving adults * Look on underside of leaves * Shake leaves over paper Pesticides Labeled for Mite Control in interiorscapes (Always verify the current label before using the material) * Pyrethrum (X-Clude) * Acephate (Orthene) * Fluvalinate (Mavrik) * Acephate (Acecap) * Permethrin (Pramex) * Dienochlor (Pentac) * Vydate (Oxamyl) * Insecticidal soap (M-Pede) * Horticultural oil (SunSpray) Mite Predators - Why Use Them ? * Lack of registered chemicals for interiorscapes * Reduced pesticides used - cost effective (?) * No licensing, reporting requirements * Worker safety * Environmental safety * Public perception Predaceous Mites * One mite can consume up to 20 spider mite adults or mite eggs per day * Introduce predaceous mites at first sign of spider mite damage * If more than one spider mite per leaf, on average, reduce mite populations with soap or miticide prior to predator release * Avoid using high residual pesticides for 2 to 3 weeks prior to predator release Steps in a Predaceous Mite Control Program 1. Monitor 5. Monitor 2. Identify the pest 6. Repeat releases 3. Select a reputable insectary 7. Monitor 4. Initiate releases early Common Predaceous Mites Phytosejulus persimilis -- most common Phytoselulus Iongipes Metaseiulus occidentalis Amblyseius californicus Amblyseius cucumeds -- less common; also attacks thrips Amblyselus hibisci -- less common Predaceous Mite Preferred Conditions P. persimilis General spider mite predator Prefers relative humidity 60-90% Tolerates temperatures to 100 F, prefers 70-80F Salmon or red color, larger than two-spotted spider mite, pear-shaped P. Iongipes Tolerates lower relative humidity --40% (better for interiorscapes ?) Tolerates temperatures to 100 F M. occidentalis Prefers relative humidities greater than 50% Can take high temperatures if humidity is greaterthan50% Shows some pesticide tolerance More versatile in habitat than others A. californicus Prefers high relative humidity, greater than 67% Tolerates temperatures to 90 F (best at intermediate temperatures) Survives better than others when pest populations are low Slower to consume spider mites than Phytoseiulus spp. Predaceous Mite Release Rates Greenhouses: * 2 predaceous mites per damaged leaf * 2 to 20 per small plant * 20 per square yard of plant material * I predaceous mite per 5 to 25 spider mites on foliage plants Outdoors: * Release 500 predaceous mites per apple tree for maintenance control * Release 1,000 per apple tree for heavy spider mite populations Interiorscapes: * 20 per square meter, directly onto infested leaf surfaces - Keep plants misted Spider mites prefer dry conditions Predaceous mites prefer "wetter" conditions - Reintroduce predaceous mites every 2 to 4 weeks - Expect control in 4 to 6 weeks Other Beneficial Insects & Mites for Spider Mite Control Spider mite destroyer Stethorus picipes Minute pirate bug Orius tristicolor (also for thrips control) Green lacewing Chrysopeda spp. Brown lacewing Hemerobius spp. Ladybugs Hip podamia spp. Other predatory mites Galendromus occidentalis Cecidomyiid fly Feltiella acarivora Dusty wing Conwentzia spp. (C. barrettli) Big-eyed bugs Geocods spp. Predatory thrips Thripidae family Six-spotted thrips Scolothdps sexmaculatus Two Good Sources for Biological Control Agents for lnteriorscape Plants Bunting Biological Buena Biosystems P.O. Box 2430 P.O. Box 4008 Oxnard, CA 93034-2430 Ventura, CA 93007 (805) 986-8265 (805) 525-2525 (805) 986-8267 (fax) (805) 525-6058 (fax) Booklet on Suppliers of Beneficial Organisms --1 or 2 copies at no cost - Call or write to: Attention: Beneficial Organisms in North America Booklet Calif. Department of Pesticide Regulation Environmental Monitoring & Pest Management Branch 1020 "N" Street, Room 161 Sacramento, CA 95814-5624 (916) 324A100 For more than 2 copies, contact: Charles Hunter, Consultant (916) 324A264 SouthWest Plantscape Products 265 Durley Ave Camarillo, Ca 93010 Telephone: (800) 333-7977 (SWPP) Fax: (805) 988-4975 E-Mail: sales@SouthWestPlantscape.com