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Neoseiulus (Amblyseius) cucumeris

Neoseiulus cucumeris (Oudemans), was first described in 1930 and is a broad-profile predator living on the deciduous part of the plant. It has been recognized worldwide as an agent of biological protection of a wide range of crops against a number of pests (whiteflies, thrips, mites, aphids, and psyllids). Its ability to survive by feeding on pollen, in the absence of prey, makes the entomophage one of the most easily adaptable and accessible natural enemies of phytophages in greenhouse complexes and greenhouses. Due to the wide range of hosts and the ability to survive on plant pollen, it was classified as a type III predator.

For the first time Neoseiulus was described in France, acariphage individuals were found in a melon affected by a spider mite (Tetranychus). In the following years, it was repeatedly described and ranked among other species of mites around the world due to lack of equipment and external similarity. Thanks to the many mentions, the mite has received the same set of names. It was not until 1989 that it was finally described as Neoseiulus cucumeris and classified as a genus. At the moment, this name is the most common, but the old names have not gone away, and the mite can be found under such names as:

Distribution

Neoseiulus cucumeris is widely distributed due to the high level of adaptation and commercial use around the world.

Description and biology

Neoseiulus cucumeris is a soft—bodied translucent mite, from pale brown to sometimes yellow-brown, depending on the food consumed. The adult mite has a pear-shaped shape and a length of 0.5-1.0 mm. Due to the small size, it is quite difficult to detect mites with the naked eye, therefore it is necessary to use optics with an increase of at least x10. Also, without proper experience and knowledge, it will be difficult to find differences between Neoseiulus cucumeris, Amblyseius swirskii and Neoseiulus californicus.

Life cycle

The life cycle of Neoseiulus cucumeris consists of 5 stages: egg, larva, 2 nymphal stages (protonymph and deutonymph) and imago. At +25C, this process takes 8-13 days, and the life span of the imago is 27-36 days.

Eggs of Neoseiulus cucumeris are oval, translucent, white, about 0.15 mm in diameter. The imago of the female lays 35-40 eggs throughout her life. Eggs are laid on the surface of the leaf, on the domatia or on the hairs along the middle vein on the underside of the leaves, and sometimes on the hairs of the petiole. The larvae emerge from the eggs after about 3 days and moult into protonymph after 2 days. The duration of the nymphal stages is 7-10 days, after which the mite becomes an adult. The duration of the developmental stages may vary depending on the available food sources. For example, even though Neoseiulus is able to live and reproduce by feeding exclusively on pollen, if there are victims in its diet, fertility, survival rate and life expectancy will be higher.

Attitude towards victims

Neoseiulus cucumeris is an aggressive predator of several pests, usually found on the lower surface of leaves or inside flowers. It eats immature (larval) stages of such species as thrips: western flower thrips, tobacco (onion) thrips, melon thrips, thrips intonsa and chilli thrips; Asian citrus psyllid;tobacco whitefly and phytophagous mites: broad mite, cyclamen mite, spider mite and tomato russet mite.

Commercially available Neoseiulus cucumeris are able to suppress a wide range of pests, but we can expect variations in their behaviour depending on the region (due to allopatric speciation). The variation of their predation potential in relation to the target pest may also vary in situations with one or more pests. Since these mites prefer to feed on easily accessible prey on the host plant, in the case of severe infestation of the plant with pests such as whitefly, thrips or spider mite, a lower level of control of flower thrips can be expected. Thus, in the case when several pests inhabit different parts of the plant, an increase in the number and/or speed of introduction of the predator may be required to achieve the desired level of control.

Economic significance

Neoseiulus cucumeris was the first Phytoseiidae mite that was found to feed on thrips, but until 1980 its use as a bioagent controlling the pest population was little studied. However, over the past 4 decades, due to growing concerns about the risks (resistance, environment, health) associated with chemical control, the use of alternative pest control strategies has attracted considerable attention. In this context, the use of universal predators that can act as a broad-spectrum insecticide is highly encouraged.

In recent years, various Neoseiulus cucumeris delivery systems have been created to improve their survival and population growth in commercial crop production systems. Buckets (100,000 individuals) or containers (50,000 individuals) allowing direct release to fields, greenhouses, and nurseries. These systems are predatory mites Neoseiulus cucumeris and mites Tyrophagus putrescentiae, which they eat until the moment of release, mixed with bran or vermiculite. The rates of application of mites may vary depending on the culture, climatic conditions, types of pests and their density. The average recommended rate of application is from 50 to 100 predator individuals per square metre. There is also a slow-release system (controlled release method), in which mites, together with a dispersing medium and temporary food, are in bags (1000 individuals / bag) for placement on the plant. Due to the porous structure of the sachet, predator nymphs are gradually released and moved to the plant in the following weeks after their application.

Although predatory mites aggressively feed on several types of harmful organisms, it takes time for them to find prey, reproduce and spread, so you should not wait for an instant result. For this reason, Neoseiulus cucumeris is very often used as a means of preventive struggle. Neoseiulus cucumeris can be integrated with certain insecticides (buprofezin, pymetrozine, flonicamid, phenoxycarb) for a more powerful effect on the phytophagous population. However, chemicals such as abamectin, acephate, bifenthrin, chlorphenapir, cyfluthrin, esfenvalerate, fipronil, imidacloprid, spinosad and thiamethoxam can be toxic to Neoseiulus cucumeris and negatively affect the life cycle of the predator. Therefore, when choosing bioagents and insecticides, it is always better to consult a specialist once again.