Article originally published by Marijuana.com
Written by Allie Beckett
Biological pest control is something we’ve gone over briefly in previous Grow Guides, but it’s an important skillset in the realm of organic gardening. In this article, we’re going to be talking about an environmentally-friendly alternative to toxic pesticides.
Biological pest control is an organic farming method that uses living organisms to control pest populations
Biological pest control eliminates the need for chemical pesticides
Over time, we’ve seen that pesticides are not as effective as many once thought. In fact, most destructive pests have developed immunities to our most common pesticides. Pesticides also kill beneficial insects and poison the surrounding ecosystem. Commercial farmers who have made the switch to biological pest control have noticed a significant reduction in the need for pesticides. For example, when the weevil threatened alfalfa production in 1957, and pesticides were not eliminating the pest, farms began implementing a biological control program and ended up reducing their pesticide use by 95%, saving farmers $122 million each year in pesticide and application costs.
Biological pest control increases the health and diversity of your garden
Biodiversity is an incredibly important aspect in maintaining a healthy garden – biodiversity promotes fertility and productivity. The more species you have in your garden, the more resilient it is against pests and disease.
Biological pest control produces clean, pesticide-free cannabis
Using beneficial insects to eliminate your pest infestations is the cleanest and most organic way to keep destructive pest populations at bay. Inhaling, ingesting or exposure to the chemicals in pesticides has been shown to increase the risk of cancer and autoimmune diseases such as rheumatoid arthritis. When growing a medicinal herb, it’s important to provide sick patients with a clean product, free of any harmful pesticides.
Biological pest control helps preserve the surrounding environment
Chemical pest control creates a toxic runoff that is extremely destructive to the native land surrounding your grow. Chemical runoff will travel to a nearby stream or soak into the land, causing lasting damage and killing local species of amphibians, birds and mammals. And once this toxicity affects one species, it travels all the way up the food chain affecting larger mammals and humans. Chemical runoff can also pollute the soil, killing important microbial life and making the soil vulnerable to harmful pathogens. Biological pest control is the number one way to avoid the horrid consequences of pesticides while keeping your crops pest-free.
Biological pest control is healthier for your employees
There are many health risks associated with pesticide usage, and all too often, proper gear is not worn when dispersing these toxic sprays. Pesticides are designed to kill – they do not discriminate between species. The World Health Organization estimates there are 3 million cases of pesticide poisoning each year and up to 220,000 deaths annually. Pesticide exposure symptoms can range from memory loss, uncontrollable mood and reduced motor skills to serious health issues such as cancer, hormone disruption, and problems with reproduction and fetal development. Biological pest control causes no harmful side effects and creates a much safer working environment.
Biological pest control targets only the destructive insects, leaving beneficial insects, birds, reptiles, and other nearby animals alone
Pesticides not only kill the target pest, but also any pest it comes into contact with. This can start an awful reaction up the food chain when other animals, such as birds and reptiles, consume a pesticide-riddled insect. Honeybees and other important pollinating insects are also affected by pesticide use, which is damaging the global cycle of food production as honeybees are crucial for the pollination of many food crops. Many pesticides are not water-soluble, so they are easily carried into rivers and then watersheds where they do not break down. Leaving these toxic chemicals in the homes of frogs, fish, and other water-dwelling creatures has created abnormalities that prevent reproduction. Spraying of pesticides has also had a destructive effect on birds who have come into contact with pesticides in their environment — decrease in breeding, physical deformation, impaired ability to migrate, and death have been reported. However, biological pest control is completely harmless to birds, reptiles, and other animals in the ecosystem because it is a natural form of pest control, working exactly how a healthy ecosystem balances itself in the wild. When implementing biological pest control, you are simply introducing natural predators of the pest causing you issues.
Biological pest control maintains balance in your garden ecosystem
As mentioned above, while pesticides are typically used to target a specific pest, they have a disastrous effect on all insects, including the beneficial ones. Beneficial insects exist to keep the pest populations in check – when a pesticide is sprayed, it wipes out all insects in the garden, creating a serious imbalance. Since pest populations multiply quicker than beneficial insect populations, this imbalance leaves your garden vulnerable to an even bigger pest infestation. Biological pest control maintains balance by adding more of the good guys to fight for your plants. Unlike pesticides, using biological pest control targets and kills the pest you want to eliminate, and nothing else.
Biological pest control saves you money
Researchers of Montana State University report that biological pest controls produce as much as $32 of benefit for every $1 invested – while chemical controls average only $2.50 in benefits for every $1 invested. Biological pest control also has longer-lasting effects than pesticides. Once predatory insects are established, if provided the right environment, they will reproduce and continue to protect your garden for many years. Whereas chemical pesticides need to be reapplied at least once a year, but more likely multiple times per season.
There are three basic types of biological pest control strategies: Importation, augmentation, and conservation. Importation (classical biological control) is when a natural enemy of a pest is introduced into the environment with an infestation. Typically the enemy does not occur naturally in the environment, so it needs to be imported. Augmentation is when locally-occurring natural enemies are bred and released into the environment in higher numbers than they would naturally appear. Conservation is when you enhance your environment to attract existing natural enemies, such as planting nectar-producing crops or hedgerows where the beneficial insects can seek shelter and food.
Importation is the most common form of biological control, especially with cannabis, because many predators used for pest control do not occur naturally in our environment (particularly if your environment is an indoor grow). However, once you establish a beneficial bug population, you can use conservation techniques to keep it alive and thriving.
Types of Beneficial Predators
Ladybugs – ladybugs and their larvae are the most popular form of biological pest control in the cannabis community because they are easy to find at most nurseries, and they feast on common marijuana pests such as aphids and mites. They also like to chomp on other soft-bodied insects such as scale insects and small caterpillars. One ladybug can eat up to 60 insects per day. If ladybugs do not like their environment, they will leave, which is a problem many indoor growers face. Spray your plants with water before you release ladybugs so that they have something to drink while they are feasting. Avoid releasing ladybugs in the heat of the day — evening is preferable. If ladybugs cannot find food, they may become cannibalistic so it’s important to spread them out throughout the garden so each ladybug can find adequate food without resorting to eating each other. Planting flowers throughout your garden will provide shelter, pollen, and nectar to the ladybugs which will help keep them around and encourage them to reproduce — they particularly like dill, fennel, cilantro, wild carrot, and yarrow.
Predatory Mites – there are a variety of predatory mites that can be implemented into your garden to help eliminate problematic mites such as spider mites, broad mites, and russet mites. Phytoseiulus persimilis (persimilis for short) is the most common predatory mite species for combatting spider mites, this predatory species actually survives on a strict diet of spider mites and nothing else. Persimilis can be ordered online and will arrive in a small 100ml bottle that you gently shake out over the leaves of your plants. They are bright red and sometimes stand on their back legs to attack making them quite noticeable. For broad mites and russet mites, which are the newest plague-causing pests, things get a little trickier. Broad mites and russet mites are so small that 80 of them could fit on a spider mite’s leg. They are almost impossible to eradicate with sprays because they can almost always find a small protective pocket of dryness to escape the pesticide. Koppert biological systems have packaged a few species of predatory mites that have shown success in eliminating broad and russet mites. Neoseiulus cucumeris is a species of predatory mite that targets broad mites, spider mites, and thrips while Amblyseius swirskii targets russet, broad, and spider mites as well as thrip and whitefly larvae. Both of these predatory mite species are packaged and sold in convenient sachets that you can hook onto various branches of your plants. Predatory mites are relatively sensitive to hot and dry environments, so if you are growing outdoors in the heat of the summer, look for a predatory mite species called N. Californicus that has shown resistance to heat up to 105 degrees. Since mites are the number one issue facing cannabis growers today, this paragraph is the most valuable information in this article. If you are constantly battling mites, inside or outside, give predatory mites a try, and I guarantee you’ll be surprised at the drastic positive effect they will have on your garden.
Lacewings – Despite their elegant name, Green Lacewings are some of the most voracious beneficial insects on this list. While they only consume pests when they are in their larval state, Lacewing larvae have inherited the nickname “aphid lion” as they can feast on up to 60 whiteflies, aphids, and spider mites per hour. The larvae kill pests by injecting their prey with a paralyzing venom and then drawing the fluids out of the pest for food. Lacewing larvae live about three weeks before they mature into adults and begin eating only nectar and pollen. The lifespan of adults is 4-6 weeks, so if you keep nectar-rich flowers around for the adults in your garden they will be more likely to lay their aphid-feasting larvae there. Lacewings are typically used as predators in a greenhouse environment and should be released in the early morning or evening.
Parasitic Wasps – A.Colemani is a common type of parasitic wasp that will seek out aphids by reading distress signals from aphid-infested plants. Once the tiny wasps have found the infestation, they inject their eggs into the aphids whose bodies serve as food and shelter for the wasp’s larvae. Any surviving aphids emit an emergency pheromone that signals all the other aphids to flee the area.
Beneficial Nematodes are microscopic worms that are an essential component of healthy, living soil. Nematodes patrol the soil and feed on over 200 kinds of bugs when the pests are still in their larval state before they mature and cause damage throughout your garden. Beneficial nematodes feed on the larvae of weevils, Japanese beetles, termites, cucumber beetles, fleas, borers and fungus gnats, just to name a few, before they have the opportunity to reach their adult stages. Nematodes kill pests by piercing them with a bacteria that is harmless to plants, people, and other beneficial insects. Often, nematodes will inject the pest with their larvae which develop and feed upon the pest, killing them from the inside-out. There are a variety of nematode species that target different kinds of pests – Steinernema carpocapsae uses an “ambush” strategy, waiting for the insect to move by and then attacks, while Heterorhabditis bacteriophora do well against soil pests who are more stagnant because these nematodes actively search for pests deeper in the soil. Nematodes do not store or ship very well, so it’s important to find a reputable dealer that is as close as possible so the nematodes can arrive within a day or two.
Hoverflies, sometimes called flower or syrphid flies, are very similar to Green Lacewings in the fact that their larvae have an insatiable appetite for soft-bodied insects such as aphids, mites, thrips, and scale insects, but once they’ve matured to an adult they feed only on nectar and pollen. If you can provide a suitable living environment for hoverflies, they are great to have around as every time they reproduce they send out more workers to destroy any harmful pests in your garden.
Dragonflies, while beautiful, are ruthless predators designed for hunting small flying insects. They are a great beneficial insect to have around if you are combatting gnats, but they also feed on mosquitos, moths, flies, and ants. Surprising to most, dragonflies can fly up to speeds of 35 mph! Having a source of water will help attract dragonfly predators and encourage them to live and reproduce nearby.
The Praying Mantis will help prevent infestations of larger insects such as beetles, flies, and moths. Praying mantises are beneficial both as larvae and as adults, feasting upon any insects they can find. Also designed as a hunter, the praying mantis is the only known insect that can turn its head almost a full 360 degrees and it’s one of the only creatures fast enough to catch flies and moths. However, the downside of including the praying mantis in your garden is that they don’t discriminate what bugs they eat, meaning if they come across beneficial insects they will probably eat them too. Also, if there are not enough pests for them to eat, the preying mantis will become cannibalistic. They aren’t the best option for controlling a pest outbreak, but for preventative pest control, they are great friends to have around the garden.
Spiders, despite their fearful reputation, are an amazing addition to your garden. Spiders will patrol your garden, catching and eating a variety of destructive pests. There are actually two categories of spiders — the web-weavers and the hunters. The hunters are the predators you want guarding your garden as they eat many common cannabis pests such as aphids, mites, leafminers, caterpillars, thrips, cucumber beetles, and flies, just to name a few. Planting flowers and mulching throughout your garden will attract spiders and encourage them to stick around.