The Pest

Glasshouse spider mite or two spotted mite (Tetranychus urticae) is one of the most damaging pests which attack horticultural crops. A wide range of crops are affected, both protected and field grown. Spider mites have a rapid reproduction and development which make resistance to chemicals more likely.
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Biological Controls

» AMBSURE (cal) Amblyseius californicus in units of 2,000
» PHYTOSURE (p) Phytoseiulus persimilis in units of 2,000
» PHYTOSURE (pt) Tomato Phytoseiulus persimilis in units of 2,000
» FELSURE (a) Feltiella acarisuga in units of 250 

Ambsure (cal)

Amblyseius californicus is a pale yellow-orangish, pear shaped predatory mite which prefers to feed on spider mites, including Tetranychus urticae (spider mite), Panonychus ulmi (fruit tree red spider mite) and T. cinabarinus (carmine spider mite).  They can also feed on pollen and other arthropod prey when their favoured food is scarce.  

Adults are 1.25 mm in length and can produce over 60 eggs per female.  Adults lay their eggs on hairs on the undersides of leaves near spider mite colonies.  There are three nymphal stages, which also feed on spider mites.  Egg to adult takes 10 days and 5 days at 21°C and 30°C.

Amblyseius californicus is a less effective spider mite predator than Phytoseiulus persimilis, as it is less effective at searching for prey, eats fewer spider mites and the population grows more slowly.  However, it can persist for longer in the crop as it is not reliant on spider mites. 

A. californicus is also more tolerant to pesticide use than P. persimilis and more tolerant to hot dry conditions.  Therefore it is useful in certain crop situations and times of year.  Unlike Phytoseiulus persimilis, A. californicus can be introduced preventatively.  It will not control large outbreaks of spider mite except at high release rates and is best used preventatively or in conjunction with Phytoseiulus.

Amblyseius californicus can only be released under license into permanent protected structures in the UK.

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Phytosure (p) and Phytosure (pt)

Phytoseiulus persimilis is a predatory mite used to control spider mites on a range of vegetables, fruit and ornamental crops in many parts of the world. It feeds only on spider mites and is capable of devouring large numbers.

Although adult Phytoseiulus are quite mobile, they will not move from areas where spider mites are present to search for new outbreaks. This means that predators must be added to each new outbreak of spider as it occurs.

Phytoseiulus can multiply faster than spider mite, but only at higher temperatures. At low humidities, Phytoseiulus will tend to move down into the crop canopy, especially during mid day.

Phytoseiulus adults are orange-red in colour with a shiny appearance. They have long legs and are very active.

BCP supply Phytoseiulus in a small tube with approximately 25ml of vermiculite carrier. This system combines the convenience of sprinkled vermiculite with a simple, but effective, dosing system which ensures that each shot of vermiculite has predators in it.

The reduced volume of carrier means that predators come into contact with the leaf surface very quickly and are unlikely to be knocked off with the vermiculite if the leaf moves. The small volume allows for easy distribution through the crop as several tubes can easily be carried.

BCP identified a problem with ordinary Phytoseiulus establishing on tomatoes due to the toxic hairs on the stems and leaves. A tomato conditioned Phytoseiulus was developed which has vastly improved the predators performance on tomatoes.

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Felsure (a)

Feltiella acarisuga is a naturally occurring predatory midge. It is capable of locating patches of spider mite from a single release site, making it a useful ally to the less mobile Phytoseiulus.

In order to establish Feltiella it is important that there is sufficient food. Feltiella will build up on localised hotspots of spider mite and from there spread to lower infestations.

The adult female midges lay their eggs amongst the spider mite colonies and the resulting larvae prey on all stages of the spider mite. The larvae are slow moving and creamy-brown-yellow in colour. When fully grown they are 1.7-1.9mm in length and 0.4mm in diameter.

Under optimum conditions up to 30 individuals (eggs, larvae and adults) may be consumed in a day and Feltiella can complete a generation in 2 weeks. The pupa is formed inside a white cocoon 1-1.5mm long. The cocoon is spun on to a leaf often on the lower surface near to a vein. The pupa itself is pinky white but becomes yellow and darker as it develops.

The presence of cocoons in the crop provides an easy assessment of how well the predator is establishing.

Feltiella has worked very well on tomatoes, cucumbers and protected strawberries with a potential for control on a range of other crops. It should be used in conjunction with BCP Phytoseiulus.

Some types of ornamentals may not be suitable where the spider mite damage thresholds are so low that the levels of spider necessary to establish the predator cannot be tolerated. However it is ideal for stock plants, and in large ornamental displays.

Directions for Use