Beneficial Insects for Spider Mites in Cannabis Production

Beneficial Insects for Spider Mites in Cannabis Production
Professor DeBacco
Research Article
GRAMMENOS, G., KOUNELI, V., MAVROEIDIS, A., ROUSSIS, I., KAKABOUKI, I., TATARIDAS, A., & BILALIS, D. (2021). Beneficial Insects for Biological Pest Control in Greenhouse Cannabis Production.
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Greenhouse Study
A greenhouse experiment was conducted in the Agriculture University of Athens.
Cannabis plants were grown in two different greenhouses.
Beneficial insects were released only in one greenhouse (treatment).
Νο additional pesticides were used during the cultivation.
The cultivar used was Futura 75, a monoeicus variety.

Beneficial Insect Release Date
Three weeks after transplantation, beneficial insects were released in the treatment greenhouse in order to assess the efficacy of biological pest management.
Spider Mites Identified
The main pests identified in the greenhouse included…
Two Spotted Spider Mites (TSSM) (Tetranychus urticae)


Pest Population Determination
The measurements of the pest population were taken in the third, fifth, seventh and ninth week.
The number of pests (TSSM) was counted with hand-held digital 1600X microscope in order to quantify the efficiency of beneficial insects.
The average pest populations were measured on ten plants (4 leaves per plant) per greenhouse.

Spider Mites Life Cycle and Identification
Beneficial Insects that Target Spider Mites
Neoseiulus (= Amblyseius) californicus
Significantly cooler and warmer temperatures will slow and/or inhibit reproduction and development.
Higher humidity is generally necessary with higher temperatures; however, N. californicus can persist in low humidity environments with limited food sources.
The slower pace that these predatory mites feed at (5 mites per day) and their ability to sustain themselves on pollen allows them to survive longer in low pest populations.
A full life cycle for N. californicus lasts between one to two weeks and is significantly influenced by temperature.
Beneficial Insects that Target Spider Mites
Feltiella acarisuga (formerly known as Therodiplosis persicae)
Feltiella acarisuga is a pink-brown predatory midge. It gets about 1/12” (2mm) long.
The antennae of the male insect are covered with long hairs, while those of the female are shorter and thicker. The eggs are clear and 1/100” (.25mm) long.
The female adult lays the eggs inside spider-mite colonies.
The larvae begin to prey on the spider-mites immediately after hatching.
The pupae can be found inside the white cocoons along the veins of the leaves. 
TSSM Control
Application Methods
Predators were applied by hanging slow-release sachets (each sachet contains 100 predatory and storage mites) of N. californicus on cannabis plants.

F. acarisuga was introduced by making a hole in the lid and locating the can directly in the middle of the greenhouse
TSSM Numbers Over Time
Plants treated with beneficial insects saw a dramatic decline in spider mite populations.

By week 9 the total was less than two spider mites per plant on average for those plants treated with beneficial insects compared to over 75 in control plants.
A continuous reduction of all pest populations was observed throughout the experiment, approaching zero value per plant

Not Mentioned in the Study… Phytoseiulus persimilis
Phytoseiulus persimilis can help reduce spider mite numbers as well.
Release Phytoseiulus persimilis at first sign of mite infestation.
Once leaf damage is serious, more than 4 mites per leaf, achieving control is more difficult.
P. persimilis are red in color relative to the pest mites they feed on and are best used to combat active mite populations.
P. persimilis will leave the area in search of alternative food sources if pest levels drop too low.
Are Beneficial Insect Worth the Effort?
In short… YES!
Study results indicate that beneficial insects could control pest populations up to 100%.
Pest management with natural enemies is a promising, very effective, safe method for plant protection.


Growers Need to Keep In-Mind
Proper pest identification is very important since this will determine the exact beneficial insect to be used.
This requires frequent scouting.
Timing and rate of beneficial additions are important.

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