Biocontrol in Greenhouses
David B. Orr and James R. Baker
Department of Entomology, North Carolina State University
Biological control is a tool to be considered in constructing an integrated pest management scheme for protected crop production. In a complete integrated pest management program, diseases, weeds, and plant growth must be considered as well as insects and mites. But because we are entomologists, this discussion covers insect and mite pests of greenhouse crops only. With IPM, each crop must be considered individually. Some greenhouse crops such as tomato and poinsettia are especially suitable for biocontrol for several reasons. Tomatoes and poinsettias have relatively few insect and mite pests. They are not grown year round so there is a break in the production cycle. Biological control organisms can be used especially effectively for caterpillars, spider mites and whiteflies. Table 1 gives biological controls now commercially available. Table 2 is a list of pesticides that are compatbility with various natural enemies used for biological control in the greenhouse. Following the tables are recommended management practices that simplify the task of setting up a biocontrol program for a greenhouse crop and then there are some sources of natural enemies.
Table 1. Recommended Natural Enemies for Greenhouse Insect Pests
PEST |
NATURAL ENEMY |
RATE |
UNIQUE CHARACTERS |
Aphids |
Aphid Lions Chrysoperla spp. |
Preventative: 1-3/yd,
Monthly, as needed 2 to 3 times 2 to 4 times 3 to 5 times |
Purchase fed larvae that Are packaged individually. Lacewings are cannibalistic and should well dispersed. |
Aphid midge |
Preventative: 1 to 3/yd, Monthly, as needed Control (low infestation): 2 to 5/yd, Biwkly -- 2 to 3 times 2 to 4 times 3 to 5 times |
Drop from plants into soil to pupate. If soil is not directly beneath foliage (i.e. if roots are bagged, etc.), they will die and not reproduce in the greenhouse. Can be kept active by using long-day lights. |
|
Aphid Parasitoids
|
Preventative: 1 to
2/ yd, Bi-weekly, as needed 2 to 3 times 2 to 4 times |
Shipped as live adults, ready to parasitize aphids. |
|
Lady beetle |
|
"Bug Pro" and other synthetic food sources are available to help keep lady in the garden. |
|
Syrphid maggots |
|
May occur naturally where screening is not employed. |
|
Broad mite |
Predaceous mite |
10 to 30 per plant. |
|
Caterpillars |
Aphid lions |
|
Purchase fed larvae that Are packaged individually. Lacewings are cannibalistic and should well dispersed. |
Bacterium |
1 to 5 teaspoons per gallon of water |
Can be used with regular chemical pesticides |
|
Fungus gnats |
|
Yellow sticky cards and potato slices useful for monitoring. |
|
Bacterium |
2 to 8 pints per 100 gallons of water. |
Compatible with most pesticides. |
|
Nematodes |
|
This strain is adapted to warmer soil temperatures. | |
Soil-Dwelling
Mite |
Preventative: 35 to
70/yd, Monthly, as needed 2 to 3 times 2 to 4 times 3 to 5 times |
Will also feed on thrips pupae in the soil. |
|
Leafminers |
Warm Weather |
Preventative: 1 to
3/yd, Bi-Weekly, as needed 2 to 3 times |
|
Warm Weather |
Preventative: 1 to
2/yd, Tri-Weekly, as needed 2 to 3 times |
| |
Mealybugs |
Australian lady
beetle |
Preventative: N/A
2 to 3 times 2 to 3 times 2 to 4 times |
Lady beetles are somewhat sensitive to pesticides including soap. Lady beetles work best at high mealybug populations and not so well with low infestations. |
Parasitic wasp |
2 per sq yd or 5 per infested plant. Repeat 1 or 2 times per year. |
Use in conjunction with the Australian lady beetle. Good control in 2 to 3 months. CITRUS MEALYBUG ONLY. |
|
Mealybug, |
Aphid Lions |
Preventative: 1 to
3/yd, Monthly, as needed 2 to 3 times 2 to 4 times 3 to 5 times |
Larvae are recommended. |
Scale |
Lady beetles (Harmonia
|
Preventative: N/A
2 to 3 times 2 to 3 times 3 to 4 times |
|
Soft scales |
Parasitic wasp |
|
For hemispherical scale, brown soft scale, nigra scale, black scale |
Spider mites |
Predaceous mites |
Preventative: 5 to
9/yd, Monthly, as needed 2 to 3 times 2 to 4 times 2 to 4 times |
Will also feed on thrips pupae in the soil. |
Predaceous mites |
Release all predaceous mites at a rate of 1 per sq ft of crop plus 10 per mite-infested leaf. |
| |
Thrips |
|
|
No really effective biological control organism is available. |
Insidious flower
|
Preventative: N/A
2 to 3 times 2 to 4 times 2 to 4 times Maintenance:
1 to 2/yd, Monthly, Indefinitely |
Goes dormant with short days. Won't stay on plants not bearing pollen. Use in conjunction with Neoseiulus cucumeris. |
|
Predatory |
Preventative: 30 to
90./yd, Tri-Weekly, as needed 3 to 5 times 3 to 5 times 4 to 6 times |
| |
Soil-Dwelling Mite
|
Preventative: 70 to
90/yd, Monthly, as needed 2 to 3 times 2 to 4 times 3 to 5 times |
| |
Predaceous mite |
10 to 200 per plant, then 10 to 50 per plant every 1 to 2 weeks |
| |
Predaceous wasp |
|
Has been found to utilize the western flower thrips in Canada. |
|
Whiteflies |
Fungus |
|
|
The Greenhouse
Whitefly Parasitoid |
Preventative: 4 to
6/yd, Bi-Weekly, as needed 3 to 4 times 3 to 5 times |
Insecticidal soap can be used in conjunction with if applied in the "black scale" or "brown scale " stage. |
|
The Mixed Species
Whitefly Parasitoid |
Preventative: 4 to
6/yd, Bi-Weekly, as needed 3 to 4 times 3 to 5 times |
Use twice as many as Encarsia formosa because this parasite has males. |
|
Whitefly: |
The Mixed Species
Whitefly Parasitoid |
Preventative: 6 to
8/yd, Bi-Weekly, as needed 3 to 4 times 3 to 5 times |
|
Whitefly Destroyer
|
Preventative: N/A
2 to 3 times 2 to 4 times 3 to 5 times |
|
|
Some of the information in the chart above was provided by The Green Spot, Nottingham, NH