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Cucumeris (Neoseiulus cucumeris) - thrips and broad mite predator

Target pests: Thrips, including onion thrips, Thrips tabaci, western flower thrips, Frankliniella occidentalis, plague thrips, Thrips imaginis, and melon thrips, Thrips palmi, (but not greenhouse thrips, Heliothrips haemorrhoidalis, and banded greenhouse thrips, Hercinothrips femoralis); broad mite, Polyphagotarsonemus latus; eriophyiid mites; and cyclamen mite, Phytonemus pallidus

Cucumeris

Neoseiulus cucumeris is a foliar-dwelling mite, predaceous on a variety of small arthropods such as thrips, broad mite and russet mites. It was developed in Europe and North America against thrips in the early 1980s and was discovered a few years ago in greenhouses in Victoria, Australia. It has recently shown promise against onion thrips on onion bulbs in storage.

It feeds on all active stages of mites, but for thrips, only first-stage larvae. Excellent control of onion thrips in stored onions has been achieved. While it will feed on tomato russet mite, hairs on the tomato plant inhibit movement. Hot spot application may be successful.

Cucumeris is supplied in a loose, vermiculite-based medium in punnets containing 40,000 predatory mites per litre. The supplied material may also contain a harmless, slow-moving storage mite to provide food in transit.

Life history and biology

Cucumeris life cycle
Click to enlarge life cycle

Neoseiulus cucumeris is a small, brownish, pear-shaped predatory mite <1mm long. The female can lay about 25-30 tiny oval eggs at a rate of 1-3 a day, which are generally deposited on the undersides of leaves, either on the leaf surface, or on leaf hairs. Predators are often found at the intersections of veins or in pockets where humidity is higher. Males are smaller than females and a darker brown. A white, 6-legged larva hatches from the egg after 1-2 days and develops through two 8-legged nymphal stages before reaching adulthood. The life cycle is completed in 8 days at 25°C and 11 days at 20°C. The Australian strain sold commercially does not hibernate, but its activity is temperature-dependent. Neoseiulus cucumeris can survive very well on some pollens, and will feed on spider mites and other small organisms.

Crop usage

Cucumeris can be used in a variety of crops, including vegetables (cucumber, capsicum, eggplant), ornamentals (gerbera, rose), strawberries, herbs, and bulbs and onions in storage. They have also been employed successfully in reptile enclosures for parasitic mite control. Cucumeris is particularly useful in capsicum, because pollen provides a source of food to build up high populations. It does not establish well in tomato crops, but distribution through slow-release sachets has given good control of thrips in Canada.

Environmental preferences

Neoseiulus cucumeris is a temperate-climate mite and performs best at 20-25°C. Eggs require a relative humidity >65% for a high hatch rate. No development takes place at <13°C and >32°C.

Application information

Storage and handling: Cucumeris should be used within 24 hours of receipt and kept at 15-25°C during release. Store out of direct sunlight at 12-20°C if necessary.

Release method(s): For ease of distribution, dilute each litre of Cucumeris with 3L of pre-moistened vermiculite on receipt. For this, use fine grade (#2) vermiculite, add 50 mL water/litre, and mix well to ensure it is evenly moist. Leave for 24 hours and remix before adding Cucumeris. Mix gently again and spread evenly throughout the crop. For seedlings, sprinkle over seedling trays before transplanting. For transplants such as capsicum, pile 1-2 mL undiluted Cucumeris at the base of the stem so predators can walk up the stem. For tall crops, apply to foliage and try to avoid material falling onto pathways and between bags and pots. To prevent wastage and reduce labour, future plans are for distribution through slow-release, water-resistant sachets hung from or over leaf petioles, as is common practice overseas.

Timing of application: Cucumeris is best used as a preventative treatment from very early in the crop, particularly against thrips. Temperature should be at least 20°C during the day to achieve effective control.

Release rates: Cucumeris should be released at a rate of 50-100 predators/m2 of cropping area (1 L of diluted mix per 100-200m2). Use the low rate in capsicum and the high rate in cucumber for western flower thrips. Reapply after two weeks. In high value and susceptible crops, continue releases at higher rates every two weeks. In capsicum, once flowers are present and predators are established, no further releases should be necessary, because pollen assists in establishing high populations. In stored onions, release rate is 400 mL (16,000 predators) per tonne, scattered evenly across the top of each bin prior to stacking.

Monitoring control success: Examine leaf undersides from different strata using a 10x hand lens, or use a 3.5x headband magnifier, which allows better scanning. Predatory mites should be visible on the underside of the leaves, often alongside veins. Blow gently on the surface to encourage movement and visibility. Success is most likely when predatory mite numbers on leaves exceed numbers of thrips larvae, or the percentage of leaves with predators exceeds the percentage with thrips. Predators may also be found under the calyx of fruit and flowers, wherever the humidity is higher and thrips larvae are hatching from eggs.

Tips for best results

For thrips, only the tiny, first-stage larvae are eaten, so it is important to release predators early, and to control adult thrips by trapping them with sticky traps and/or by screening vents and doorways to prevent swarms from entering the greenhouse. In cucumbers, different thrips species prefer different plant strata. Release mostly on lower leaves for onion thrips and upper to middle leaves for WFT. For broad mite, release in growing tips. Go for overkill of pests by releasing often. For thrips, use with Hypoaspis-M and nematodes applied at ground level.

Quality control

Mix well and shake a little material onto a white surface at 20-25°C. Check for small, brown, active mites using a 10x hand lens. Sieving through screens and microscopic examination is necessary to adequately assess numbers.

Pesticide compatibility

While Neoseiulus cucumeris is sensitive to fewer pesticides than Encarsia formosa and other parasitoid wasps, the toxicity of wet sprays and residues of pesticides considered for use should be checked before starting a release program. Egg laying and prey consumption may be severely affected even if mites appear live.

Technical resources

Cucumeris technical sheet (160 kb)