Biological control can be used in the landscape to maintain the appearance, health and structural integrity of trees and shrubs in an urban setting. Urban foresters and others interested in using biological control should begin by learning to conserve natural enemies that are already present in the landscape. Conservation efforts and augmentation with natural enemies are most likely to be successful when part of an Integrated Pest Management program. The following guidelines will help pest managers maximize the potential for biological control:
Monitor the site regularly to record plant condition, pest and natural enemy abundance, and habitat disturbance.
Use records to develop situation-specific action thresholds and particular control strategies.
Consider the impacts of natural enemies on late season pests when managing pests that occur early in the season.
When thresholds are exceeded, use pesticides most compatible with biological control. Some chemicals can be used without significantly affecting natural enemies, but most of the commonly used insecticides are broad spectrum and have relatively long residual activity. Consult the table below for specific information.
Pesticide Use Compatibility with Biological Control
| Pesticide | Compatiblity1 | Comment |
| Abamectin (actinomycete derived) |
NC | Available for microinjection, but sublethal doses reported to harm mite predators. Broad spectrum. |
| Acephate (organophosphate) |
NC | Available for microinjection, and in soil applied granular formulation. Broad spectrum. |
| Azadirachtin (botanical) |
C | Insect growth regulator derived from seeds of neem tree. Kills immature stages. Pupal stage parasitoids not affected. |
| Bacillus
thuringiensis (bacterial insecticide) |
HC | Three strains that target caterpillars: var. aizawa, var. kurstaki, or var. morrisoni. |
| HC | Targets gnat-like flies including dark-winged fungus gnats and mosquitos: var. israelensis. | |
| HC | Targets beetle grubs: var. tenebrionis | |
| Beauvaria
bassiana (mycoinsecticide) |
C | Kills some soft bodied predators. Short residual. Broad spectrum. |
| Bendiocarb (carbamate) |
NC | Very long residual. Broad spectrum. |
| Bifenthrin (pyrethroid) |
NC | Very long residual. Broad spectrum. |
| Carbaryl (carbamate) |
NC | Repeated use may stimulate spider mite reproduction. Broad spectrum. |
| Chlorpyrifos (organophosphate) |
NC | The chemical standard for borer control. Long residual. Broad spectrum. |
| Cyfluthrin (pyrethroid) |
NC | |
| Diazinon (organophosphate) |
NC | Long residual. Broad spectrum. |
| Dicofol (organochlorine) |
NC | Very long residual miticide. Kills mite predators. |
| Dienochlor (chlorinated hydrocarbon) |
SC | Short toxicity to predatory mites, but not toxic to predatory beetles. |
| Diflubenzuron (insect growth regulator) |
SC | Moderate residual. Kills immature stages. Pupal stage parasitoids are not killed. |
| Dimethoate (organophosphate) |
NC | Long residual. Broad spectrum. |
| Disulfoton (organophosphate) |
NC | Long residual systemic. Broad spectrum. |
| Fenitrothion (organophosphate) |
NC | Long residual. Broad spectrum. |
| Fluvalinate (pyrethroid) |
NC | Very long residual. Broad spectrum. |
| Heterorhabditis
bacteriophora (entomophagous nematode) |
C | Very low toxicity to humans and non-targets. Wasp parasitoids with silken cocoons are not killed. |
| Hexythiazox (thiazolidine) |
HC | Kills only spider mite nymphs and eggs. Long residual. Does not kill predators. |
| Horticultural oil (petroleum oil) |
C | Inactive when dry. Kills soft bodied insects. Pupal stage parasitoids not killed. |
| Imidacloprid (chloronicotinyl) |
NC | Ability to kill predaceous plant bugs can cause spider mite outbreaks. Long residual when systemically applied. |
| Insecticidal Soap (soap) |
C | Inactive when dry. Kills soft bodied insects. Pupal stage parasitoids not killed. |
| Lambda-cyhalothrin (pyrethroid) |
NC | Very long residual. Broad spectrum. |
| Lindane (chlorinated hydrocarbon) |
NC | Very long residual. Broad spectrum. |
| Malathion (organophosphate) |
NC | Moderate residual. Broad spectrum. |
| Methoxychlor (organochlorine) |
NC | Very long residual. Broad spectrum. |
| Neem oil (botanical) |
C | Insect growth regulator derived from seeds of neem tree. Kills immature stages. Pupal stage parasitoids not killed. |
| Oil (see horticultural oil) | ||
| Oxythioquinox (dithiocarbonate) |
NC | Long residual. Broad spectrum miticide. |
| Oxydementon-methyl (organophosphate) |
NC | Long residual. Broad spectrum. |
| Permethrin (pyrethroid) |
NC | Long residual. Broad spectrum. |
| Phosmet (organophosphate) |
SC | Reportedly low impact on spider mite predators in orchards with long history of pesticide use. Effect on predators in landscape unknown. |
| Pyrethrins (botanical) |
SC | Very short residual-but very broad spectrum. Prevents additional injury and sets the stage for future conservation and augmentation efforts. |
| Spinosad (naturalyte) |
C | Very short residual. Toxic to adult wasp parasitoids. Not toxic to some important predators. |
| Steinernema
carpocapsae (entomophagous nematode) |
HC | Very low toxicity to humans and non-targets. Wasp parasitoids with silken coccoons are not killed. |
| Trichlorfon (organophosphate) |
NC | Long residual. Broad spectrum. |
1 HC = Highly compatible, C = Compatible, SC= Somewhat Compatible, NC= Not Compatible
- Cliff Sadof, Purdue University and Michael Raupp, University of Maryland (Adapted from a chapter in an upcoming publication on biological control in urban forests)
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