Pest Control
Part 2 - Beneficial Insects
It is important to note that before any beneficial predator is introduced into the garden that no chemical sprays or foggers be used 7 days prior to the release. All fungicides, except sulfur burners, may still be applied after the release of predators. The gardener may still make use of yellow sticky whitefly traps even when releasing predator wasps. Some wasps may get caught in the trap, however, the majority will remain in the canopy of the crop. To ensure the survival rate of predators, plants can be lightly misted with plain water. Try to release the beneficials close to the end of the light cycle; this will allow the predators to become acclimatized with their new environment before the new cycle begins.
Pest: Spider Mite (
Tetranychus urticae )
Spider mites feed on plant cells and produce characteristic small, yellowish, speckled feeding marks. Fine, silken webs can be detected on heavily infested leaves and flowers with these plant parts quickly withering and turning brown. Plants can be completely covered in silken webs if infestations are not kept in check. Plants will be stunted, deformed and can easily die.
Life Cycle: Females become active in the spring or as the temperatures warm, and they begin depositing eggs on the undersides of leaves. The eggs hatch in 4 to 5 days and the entire life cycle from egg to adult may require 1 to 3 weeks, depending on the temperature. Spider mite populations can explode under conditions of high temperature (above 85° F.) and low relative humidity (below 60% RH). At 70°F spider mites will go from egg to adult in 15 days, if the temperature is increased to 90°F the same cycle will take only 4 days.
Life Cycle: Females become active in the spring or as the temperatures warm, and they begin depositing eggs on the undersides of leaves. The eggs hatch in 4 to 5 days and the entire life cycle from egg to adult may require 1 to 3 weeks, depending on the temperature. Spider mite populations can explode under conditions of high temperature (above 85° F.) and low relative humidity (below 60% RH). At 70°F spider mites will go from egg to adult in 15 days, if the temperature is increased to 90°F the same cycle will take only 4 days.
Solution 1: Phytoseiulus persimilis
Phytoseiulus persimilis are effective spider mite predators. Each adult female will consume several adult spider mites or 2-3 dozen spider mite eggs and juveniles. Once all the spider mites have been consumed these predators disperse. If spider mites reappear after a few weeks the predators will need to be reintroduced into the garden. Phytoseiulus persimilis are the preferred predator mite when high temperatures are experienced (up to 100°F); these predators can also survive at a lower humidity (40% - 90% RH). The adults and nymphs actively search for their prey and suck them dry.
Application: Shake bottle to mix up the contents. Sprinkle contents on leaves near the mite infestation. Apply predators to every plant in the garden. Do not apply predators directly under a hot bulb; if the plant is under a bulb apply the predators on the lower leaves.
Bottle Size: 2,000 per bottle
Coverage: up to 400 square feet
Solution 2: Amblyseius californicus
Amblyseius californicus prefers lower temperatures (less than 85°F) and higher humidity (65% - 90%) than Phytoseiulus persimilis. However, once all the spider mites have been consumed these predators can survive by feeding on flower pollen. Amblyseius californicus predator mites can also tolerate a wide range of chemical sprays (not including Floramite or Pyrethrum). The adults and nymphs can be found on the underside of the leaves waiting and searching for their prey.
Application: The application is the same as for Phytoseiulus persimilis. For the most effective spider mite control use both Amblyseius californicus and Phytoseiulus persimilis.
Bottle Size: 2,000 per bottle
Coverage: up to 400 square feet per bottle
Pest: Thrips (Thrips tabaci)
Thrips are very tiny insects (about 1/50th of an inch), but signs of their feeding are very noticeable. Thrips (nymphs and adults) scrape plant tissue to induce the flow of plant sap. Thrips will feed on every part of the plant, even the flowers.
Life Cycle: The life cycle of thrips begins with the adult depositing an egg into the plant tissue. After a few days the eggs hatch and the nymphs will feed for 1 to 2 weeks. Most of the fully grown nymphs drop to the growing media and pupate in the media, the remainder will pupate on the plants. Once the adult thrips emerge they climb up the plant to feed, mate and repeat their life cycle. Adult thrips are capable of flying.
Solution
1: Amblyseius cucumeris
Amblyseius cucumeris targets numerous species of thrips. These predators feed on the hatching eggs and the larval stages of thrips. Spider mites are also a favorite food for Amblyseius cucumeris. These predators are most effective at temperatures above 68°F and 75% RH. The adult Amblyseius cucumeris predatory mites actively search for their prey and suck them dry.
Application: Shake bottle well to mix contents. Sprinkle predators on all plants and avoid applying product directly below hot bulbs.
Bottle Sizes: 10,000 and 50,000 per bottle
Coverage: up to 1,000 square feet per 10,000; 1,000 - 5,000 square feet per 50,000
Solution 2: Orius insidiosus
Orius insidiosus feed on numerous species of thrips, aphids, spider mites, butterfly eggs and pollen. Adult predators pierce the eggs, larvae and adults of the pests with their mouth parts and suck out the insides.
Application: Shake bottle to mix up the contents. Sprinkle contents on leaves near the thrip infestation. Apply predators to every plant in the garden. Do not apply predators directly under a hot bulb; if the plant is under a bulb apply the predators on the lower leaves.
Bottle Size: 500 pirate bugs per 500ml bottle
Coverage: Per 500ml bottle: up to 500 square feet
Pest: Aphids (Aphididae)
Aphids feed on plant sap by inserting their mouthparts into plant tissue. They excrete a sugary liquid, or honeydew. The honeydew not only clogs the pores of the leaves, but also encourages the growth of black, sooty mold, which can prevent light from reaching the photosynthetic tissue of the plant. Aphids weaken the plant by draining it's fluids, may cause severe distortion of growth, and are common means of transmitting plant viruses. You may also notice ants in your garden when you have an aphid infestation. Since ants use the honeydew that is excreted by the aphids as a food source, the ants will actually farm the aphids and protect them against predators, so you should try to eliminate the ants before you release the beneficial insects.
Life Cycle: During warm humid conditions, all aphids are born female and therefore all will contribute to population growth. The young are born fully formed and able to feed immediately. They grow rapidly, molting 4 times before they mature, often reaching maturity within a week. Aphids do not require fertilization; ova can start developing within an aphid as soon as it is born. Female aphids will produce 50 - 100 young in a period of 30 days.
Solution 1: Hippodamia convergens - Ladybugs
Hippodamia convergens or Lady Beetles is the most commonly used predator for controlling aphids. Adult beetles have been known to consume up to 100 aphids in a day.
Application: Apply predatory adults on leaves near to infestation. The adults will destroy the aphid colony within a week.
Bottle Size: 8 ounce (4,500 adults), 16 ounce (9,000 adults) and 1 gallon (72,000 adults).
Coverage: 8 ounce bottle: 4 square feet – 900 square feet
16 ounce bottle: 900 square feet – 1,800 square feet
1 gallon bottle: 10,000 square feet – 15,000 square feet
Solution 2: Chrysopa carnea - Lacewings
The preferred food of lacewings are aphids, however, they will also consume thrips, whiteflies and moth eggs. Only the larvae of the lacewing will feed of these pests, the adult lacewing will fly away and will not consume any pests. The larvae of the lacewing are voracious predators and will hunt and attack their prey and then suck out the body fluids from the pest.
Application: Lacewings are available as either eggs or larvae.
Eggs: Lacewing eggs should be kept in the bottle it is shipped in until the eggs change from green to a grey color. Only release eggs once the color change begins to take place. Some of the eggs will hatch in the bottle which is fine as they are shipped with food. The eggs should be stored between 60 - 80°F and 60 - 75% humidity for optimum hatching. Hatching will take place 1-2 days after being shipped.
Larvae: Rotate the bottle gently before use; the gentle rotation will
help mix up the contents without damaging the lacewing larvae. Apply the contents near to the aphid infestation. The larvae can also be placed on top of rockwool blocks, soil or coco growing mediums (do not place the larvae on top of Hydroton rocks). If the aphid infestation persists, lacewing larvae will need to be reapplied once the larvae pupate into adults. The adult lacewing is easy to recognize – a slim green insect with fine wings, about ½” long.
Bottle Size: 5,000 eggs or 900 larvae
Coverage: approximately 450 square feet per bottle
Pest: Whitefly (Trialeurodes vaporariorum)
As with aphids, whiteflies also feed on plant sap. The larvae of the white fly also secrete honeydew which induces the development of a black mould. This black mould is not harmful to the plant, however, it can grow over large portions of the leaf thus reducing photosynthesis.
Life Cycle: White flies can develop from egg to adult in less than 20 days when temperatures are above 85°F. From the egg to adult stage, whiteflies will go through several instars. They will do this while attached to the underside of the leaf. Adults can begin laying 4-10 eggs per day within 1 day after emerging as an adult.
Solution: Encarsia formosa
Encarsia formosa are parasitic wasps that lay eggs directly into the larvae of the whitefly. The parasite egg hatches inside the whitefly larvae and consumes the larvae from within. The parasite pupates inside the larvae and emerges as an adult wasp ready to lay eggs.
Application: Open package carefully in the garden. Bend strips and tear off; start tearing opposite hang-up hole. Suspend the cards two feet from the top of the crop and avoid placing cards directly under the light bulb. Try and place the cards in a shaded area, especially if HID bulbs are being used. Be careful not to touch the pupae as they can easily be damaged. Tiny parasitic wasps (they will not sting humans) will emerge from the pupae and will begin laying eggs in other pest eggs.
Pupae per Card: 1,500 on 10 strips, 3,000 on 10 strips, 7,500 on 50 strips, and 15,000 on 50 strips (5 cards per strip)
Coverage: 10 Strips (1,500): up to 1,000 square feet
10 Strips (7,500): 1,000 – 7,500 square feet
50 Strips: 15,000 square feet
Pest: Moth and Butterfly Larvae
Even though butterflies and some moths are extremely beautiful, their immature larvae can cause big damage to your crops. The larvae will hide on the under side of leaves while it consumes it. In some cases, one worm can devour a whole leaf in 24 hours. These pests will also feed on leaf stalks, branches, fruits and flowers. The telltale signs are large holes on leaves and leave margins and black droppings on the leaves below the holes.
Life Cycle: The life cycle of the moth and butterfly begins with the egg, then the larvae or worms, then comes the pupa and finally the adult moth or butterfly. This process takes a few weeks to several months in some species.
Solution: Trichogramma brassicae
Trichogramma brassicae are parasitic wasps that target the eggs of almost any insect pest especially the eggs of moths and butterflies.
Application: Open package carefully in the garden. Bend strips and tear off, start tearing opposite hang-up hole. Suspend the cards low in the crop; avoid placing cards directly under the light bulb. Be careful not to touch the pupae as they can easily be damaged. Tiny parasitic wasps (they will not sting) will emerge from the pupae and will begin laying eggs in other pest eggs.
Pupae per Card: 50,000 pupae on 250 cards
Coverage: 25,000 square feet
Pest: Larvae in the growing medium (Fungus gnat larvae, white grubs, sciarid fly larvae, etc.)
Solution: Predator Nematodes (Steinernema feltiae)
Beneficial nematodes are applied to the growing medium at the first stage in its life cycle. This first stage is also known as the infectious stage. The young nematodes enter into their host via the pest mouth, respiratory openings or the anus. Once inside the host the nematode releases bacteria which then begin to dissolve the host from the inside. The predatory nematodes then feed on the dissolved host. The predatory nematodes will reach adulthood inside of the host and will produce infective stage juveniles. The host larvae dies in a few days after infection. The juveniles will then exit the dead host and seek out a new host. This cycle takes 7-14 days. It is important that the growing medium does not dry out after the application of predatory nematodes. Nematodes move through the growing medium when it is moist, thus a dry growing medium will limit the movement of the nematode and limit its effectiveness. Predatory nematodes will infest a host of pest larvae living in the growing medium pests such as sciarid fly larvae, white grubs, beetle larvae and even fungus gnat larvae.
Application: Soak the sponge for five minutes in a 5 gallon bucket of water (60-70°F). For hydro systems - stir the water well before applying the solution to the reservoir (only use water in the reservoir when applying predatory nematodes). Initiate a watering cycle as soon as possible after applying to the reservoir. For soil – stir contents in the bucket and apply to soil using a watering can. Drench the soil with the nematode mix and keep soil moist for effective control.
Nematodes per box/sponge: 50 million
Coverage: up to 1,000 square feet per box/sponge
