Spider mites

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Status : Enemy

I would say that this is a severe pest for our Mexican Pinguicula.

Description : 

Two distinctive forms of glasshouse spider mite exists : yellow spider mites and red spider mites, closely related biologies and producing the same damages.

- The adults : 0.3 mm to 0.5 mm long.

Biology and life cycle :

- Host plants : nearly all plants can host spider mites. Our carnivorous plants even are not safe.
- Fecundity is very high : each female lay about a hundred eggs at a rate of 10 per day with 6 to 7 summer generations.

All the greenhouse can be invade in few weeks. To feed, the mite attacks the leaves for sucking the cellular sap.

Spider mites lives on the lower side of the leaves, in the heart of the plant.which retain humidity and ensure excellent protection against the wind, predators and pesticide treatments.
Its development is optimal between 23 and 30°C and at a relative humidity of less than 50%.

- The generations follow each other and the mite is found in vast numbers. The dissemination of the glasshouse spider mite takes place by the passage from one plant to another (if they touch each other), by ground over small distances, by transport on objects or people or by the wind produced by a fan inside your greenhouse. 

Damage

Spider mites suck plant sap for food. Plant cells turn yellow, which can be seen on the upper surface of the leaf as small yellow spots. This lead to a dryness of the Pinguicula leaves become spotty, and then dry out. This can be letal if attacks are heavy. I don't know if this is the spider mites bites that kill the Pinguicula (if uncontroled) or because this fragilizes the plants and make it less resistant to fungus attack.   

 

Typical damage of spider mites attack during dry and hot summer. The brown tip is the result of the bites of the spider mites in the heart of this Pinguicula. After a well choose chemical treatment, this plant will recover a safe growth.  Photo : Eric Partrat

Solutions :

Biological fight :  

This seems to work quite good : use a predatory mite Phytoseiulus persimilis. A Phytoseiulus mite deposits her approximative 54 to 75 eggs in or close to a spider mite colony. They are distinguished from spider mite by their oval shape, the light orange colour and because they are twice as big.

 

So, under normal circumstances a Phytosiulus population grows faster than a spider mites population. At higher temperatures (above 30°C or 86°F) or at dry weather (humidity below 60%) the spider mite is favoured and biological control is difficult. At low humidity the egg of the predatory mite shrivels.

 

The menu of Phytosiulus nearly exclusively consists of spider mites. An adult Phytoseiulus devours all stages of spider mites consisting of 20 spider mites eggs or larvae, 13 protonymphs or 5 adults (according to litterature).

If the plants touch each other, the predatory mite can spread relatively easily in the greenhouse.

 Two other mites predators can be used : Neoseiulus californicus and Mesoseiulus longipes. Choose weel your predator :

- Phytoseiulus persimilis
Performs well in temperatures ranging from 55 -100° F. (13 - 38 °C.) and relative humidity levels of 55-90%.

- Neoseiulus californicus
Performs well in temperatures ranging from 60 - 90°F. (15 - 32 °C.) and relative humidity levels of 60-90%.

- Mesoseiulus longipes
Performs well in temperatures ranging from 65 -100° F. (18  - 38 °C.) and relative humidity levels of 45-90%.

Suppliers :

USA : 

Home Harvest® Garden Supply, Inc. 

BIOBEST.BE   

 

EUROPE :

BIOBEST.BE

 

MEXICO : BIOBEST.BE 

 

JAPAN : BIOBEST.BE

 

Other country, see distributors of : BIOBEST.BE

Chemical fight : 

Two famillies of insecticids can be use : one is systemic, travelling in the plant, the other is shock action, with immediate action on the pest. 

Go to your garden center and see the products sold againts spider mites.

I prefer using the second family. I spray my plants infected at the end of the afternoon when the sun is over, and few minutes after, I wash my plant with rain water to wash the product. This seems to be effective as plants recovered an healthy look. 

Suppliers :

FRANCE :

I use safely for my Pinguicula this one (shock action):

- KB POLYSECT® 3 PLUS
Hom. n° 9900094
2 g/l Bifenthrin

(pyrethroids)

 

But few minutes after application, I carefully wash my plant with rain water. As spider mites also like dry air, this can help to kill the spider mites. J.J. LABAT from Nature et Paysage, the french carnivorous plants nursery told me that if a chemical traitment is really effective against mites, it is also phytotoxic. It is why I recommand to carefully wash the plant few minutes after application.  

 

This one is also active (Systematic action) and safe for the Pinguicula.

- Bayer Confidor® 200 SL

Hom. n° 8686/B

200g/l imidacloprid 

but I have discovered that the active substance, the imidacloprid could be dangerous for the bees as for Gaucho® so I don't use it now.

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