Predator mites are carnivores and like what the name sounds, are a type of mite that eats other mites. There are some main differences between the predator and its prey. Where spider mites are herbivores, feasting on your crops, predatory mites are strictly carnivorous and will only eat other bugs.
When cannabis growers hear the dreaded word “mite”, it sets off an image in their minds of this giant infestation of mites coming from seemingly nowhere and eating their crop to the stems. While they don’t start off quite that bad, it’s true that if not kept under control this very small-sized tormentor can turn into a very large problem rather quickly.
Mites are closely related to ticks and even spiders. There are many types of mites and some more common than others.
Spider Mites – these tiny bugs (less than 1-mm long) are probably the most common (and most hated) of all indoor garden pests. They are actually little arachnids and because of their small size you may not notice them until they do serious damage to your plants.
There are two reliable ways to spot an infestation: one, look for spider-like webbing. Two, take a tissue and wipe gently on the underside of leaves–if it comes back with streaks of Spider Mite blood–you know you have mites.
Hemp Russet predator: Amblyseius Anderson
Types of Predatory Mites
One of the first commercially produced biocontrol agents, back in the late 1960s, was Phytoseiulus persimilis, a predatory mite to control two spotted spider mite(TSSM). Since then several other species of predatory mites have been introduced to control a range of different pests: Amblyseius cucumeris, Amblyseius swirskii, Ambyseius californicus and many others.
Anderline biological control agent contains the predatory mite, Amblyseius andersoni. It is a predatory mite that feeds on many types of small arthropod prey and pollen. It is ideal for preventive protection of greenhouse or outdoor ornamentals, vegetables and fruit crop
Amblyseius andersoni Key Features:
Predator of two-spotted spider mite, European red mites, broad mites, cyclamen mites and russet mites. Will also feed on pollen and thrips larvae allowing the population to survive when pest mite populations decrease. Since it is effective at lower temperatures, Amblyseius andersoni can be introduced much earlier in the growing season than other predatory mites.
Two-spotted spider mite
Tomato russet/rust mite
European red mite
History of Release Methods of Predatory Mites
In 1989, a major change was developed that has impacted how many predatory mites are available today. It all started with a single stem flower flask (bottle), in the Netherlands known as ‘Anthurium flesjes.’ One cucumber grower filled some of the flasks with Amblyseius cucumeris and carrier material and placed them in the crop to release predatory mites every day. The results were incredible and many other cucumber growers followed this example. This was the “birth” of CRS sachets (Control Release System) and many growers started using this technique to introduce predatory mites.
How does it work? Amblyseius cucumeris (and several other Amblyseius species) are produced on bran mite species, hence the bran as a carrier. The typical ratio between predatory mite and bran (feeder) mite is 1:10. These sachets are literally an extension of the production that takes place at the biocontrol producers. The main advantage of using breeding sachets versus broadcasting is more than less frequent introductions. It has also been proven repeatedly that the use of breeding sachets gives more consistent and higher levels of predatory mites, which means higher success rates of using biological control.
Modifications for the Ornamental Industry
In the early 2000s, when biocontrol started to become more popular in the ornamental industry, it became clear the CRS system wasn’t suited to ornamental crops. The first development was the gemini sachet (2002), which is two sachets connected together so they can be hung over a mesh crop support wire (like a saddle on a horse) in cut flower production, primarily cut chrysanthemum. As this technique was still labor intensive, the next development was the bugline (2006), later followed by Certirol. This is a long roll of continuous sachets where only every third or sixth sachet is filled with mites; this is rolled out over the mesh crop support wire, saving labor and at the same time creating a ‘mite highway’ for better distribution of mites.
Over time, the concept of release sachets has continued to evolve, with the most recent development starting in Canada in 2014. Several ornamental and vegetable propagators were stapling sachets to plant labels or popsicle sticks to introduce the sachets even earlier in the production process. Timing of establishing predatory mites is “make or break” for success, so the earlier the better. The biocontrol industry responded by developing the sachet on a stick (2014). As these sachets are used in propagation (and outdoors), where overhead mist or water is a given fact, the sachets are produced with water-resistant paper and the exit hole is protected so water cannot get in. Once again, the uptake of this type of sachet was broader than expected, with many growers choosing to switch to the stick sachet because it is easier to place.
Do I Broadcast/Blow or Stick/Hang Predatory Mites?
Despite the invention and uptake of sachets, in some situations Amblyseius predatory mites are still applied by broadcasting or using modified leaf blowers. This is mostly done when it is thought that it is not cost effective to use a sachet.
If blowing, it is important to monitor the survival of the mites and the quality of the distribution, this can be done using a large white cardboard sheet. Gas powered blowers are known to have low survival rates. Another critical issue when broadcasting is using weekly applications, as there is very little reproduction happening in the crop.
Once taking losses and labor into account, many growers realize that blowing or broadcasting weekly at 10 mites per square foot often costs the same as using sachets. The key point is that, in general, breeding sachets have shown to result in more consistent and higher numbers of predatory mites, which means higher success rates of biocontrol programs.
More ways to identify mites:
Know your enemy, Sun Tzu, The Art of War
“If you know the enemy and know yourself, you need not fear the result of a hundred battles.
Gardening had always been my passion, until I learned about organic gardening. That’s a whole new ballgame. So when I was asked to write for this blog, I jumped at the opportunity to research, to learn more about organic gardening and to write about that and other plant-related topics. Thank you for being here, I hope you enjoy these articles at least half as much as I do writing them!