What is Phytoseiulus persimilis?
Phytoseiulus persimilis It is a predatory mite belonging to the Phytoseiidae family, widely recognized in agriculture for its ability to naturally control pest mite populations of the genus Tetranychus, in particular the well-known common red spider (Tetranychus urticae). Its importance is such that it has been introduced and used in numerous horticultural and ornamental crops, especially in greenhouse production systems, where environmental conditions favor the proliferation of these pests.
This mite stands out for being a specific predator, that is, it feeds almost exclusively on mites from the Tetranychidae family. This species has revolutionized biological pest control, significantly reducing the use of chemical phytosanitary products and contributing to sustainable agricultural production.
Taxonomy and origin
- Kingdom: Animalia
- Division: Arthropods
- Class: Arachnida
- Subclass: Acari
- Superorder: Parasitiformes
- Order: Mesostigmata
- Family: Phytoseiidae
- Subfamily: Amblyseiinae
- Gender: Phytoseiulus
- Species: Phytoseiulus persimilis
Native to temperate and subtropical regions, Phytoseiulus persimilis It was identified in South America and has since been used in different latitudes due to its ability to adapt to new conditions, as long as certain humidity and temperature values ​​suitable for its performance are maintained.
Morphological characteristics of Phytoseiulus persimilis
El Phytoseiulus persimilis It is easily recognizable by its intense color oranged Red in the adult stage, which clearly differentiates it from other predatory mites and its main prey, the red spider. Adults have an oval and stylized morphology, with eight long legs which give them great mobility.
- The females They are slightly larger, measuring approximately 0,6 mm in length, while the males are slightly smaller, flatter and elongated.
- Both sexes lack eyes, so they rely on their sensory organs on their first pair of legs – they flap them up and down – to detect the volatiles emitted by damaged plants and thus locate their prey.
The immature forms (larvae, protonymphs and deutonymphs) are smaller in size, with shades ranging from translucent light pink to reddish as their development progresses.
Biological cycle of Phytoseiulus persimilis
The life cycle of this mite is parallel to that of its prey, the Red spider, and is composed of several phases:
- Egg: Phytoseiulus persimilis eggs are oval, about twice the size of spider mite eggs. They initially appear light pink and translucent, darkening slightly as they mature. Females generally lay their eggs near or within spider mite colonies, which makes it easier for the young to find food immediately after hatching.
- Larva: After hatching, the larva possesses only three pairs of legs and remains inactive unless disturbed. In this state, the larva does not feed or show significant mobility.
- Protonymph and Deutonymph: Upon entering the protonymph stage, the mite develops its fourth pair of legs and immediately begins feeding. Both protonymphs and deutonymphs are similar in appearance to adults but are smaller and more intensely colored.
- Adult: Adults emerge after their final nymphal molt and continue feeding actively. They have their characteristic reddish-orange color and are noted for their agility and activity, especially at high temperatures.
There is no rest period or inactivity during the nymphal stages, which allows the complete life cycle to be quite rapid under favorable environmental conditions.
Life cycle length and environmental factors
The duration of the biological cycle of Phytoseiulus persimilis varies depending on the ambient temperature and humidity. In general:
- The complete cycle, from egg to adult, can be completed in just a week under optimal conditions (warm temperatures and high relative humidity).
- The ideal conditions for rapid and effective development are temperatures between 20 and 30 ° C and a relative humidity greater than 75%Low humidity or excessive heat slows development and reduces predatory effectiveness.
- In unfavorable situations, the life cycle can be prolonged, and reproduction and predatory capacity are negatively affected.
Feeding and predatory behavior
Phytoseiulus persimilis is a voracious and specialized predatorIts diet consists almost exclusively of mites of the genus Tetranychus in all their stages: eggs, larvae, nymphs and adultsAmong its prey are:
- Tetranychus urticae (common red spider)
- Tetranychus cinnabarinus
Consumption depends on the density of available prey and the number of predators present, as well as temperature and humidity. In the presence of abundant food, an adult female can consume up to 20 spider mite eggs or five adults per day, thus keeping pest populations under control.
Phytoseiulus persimilis is unable to survive if the prey mite population disappears, which shows its high specificity and the limited impact they have on other auxiliary or beneficial species.
Optimal conditions for the effectiveness of Phytoseiulus persimilis
- Temperature: Rapid development between 20 and 30 ºC, slowing down at lower temperatures.
- RH: Above 75% for optimal feeding and reproductive activities. Low humidity levels impair the survival and development of eggs and larvae.
- Presence of dams: Maximum effectiveness is achieved when there are colonies of red spider mites. If the infestation decreases significantly, the populations of Phytoseiulus persimilis also decrease.
- Chemical insulation: Its use should be integrated with biological control programs where the application of chemical phytosanitary products is minimal or non-existent, prioritizing methods compatible with auxiliary organisms.
Advantages of using Phytoseiulus persimilis in biological control
The use of Phytoseiulus persimilis It has numerous agronomic and environmental advantages in crop protection:
- High degree of specificity, avoiding risks to other beneficial insects and pollinators.
- Proven effectiveness against red spider infestations in horticultural, fruit and ornamental crops, both in greenhouses and outdoor crops.
- Reduction in the use of chemical pesticides, reducing waste and improving food safety.
- Easy integration into integrated pest management programs.
- Rapid reversal of infestation foci in optimal conditions.
Recommended applications and doses of Phytoseiulus persimilis
In commercial agriculture, Phytoseiulus persimilis It is marketed in different formats adapted to the needs of the producer:
- Containers containing 2.000, 5.000, 10.000 or even 100.000 individuals, mixed with sawdust or vermiculite as a support for their transport and release.
Application rates vary depending on the severity of the infestation and the phenological stage of the crop, but it is recommended to begin release when the first symptoms of red spider are detected. In general, preventive or curative doses range from 10 and 20 individuals per square meter or more in severe attacks.
History and evolution of the use of Phytoseiulus persimilis in biological control
The use of Phytoseiulus persimilis Worldwide, it marked the beginning of modern biological control in intensive crops. Its first practical applications arose after the success of experiments in European greenhouses, where the predatory mite made it possible to manage critical red spider infestations in crops such as cucumber, tomato, pepper and strawberry.
Pioneering companies specializing in the breeding and distribution of auxiliary organisms, such as Syngenta Bioline and Koppert, have decisively contributed to the expansion of this phytoseiid's use, allowing its availability today on a global scale and in new application technologies.
Symptoms of red spider infestation and role of Phytoseiulus persimilis
infestation by Red spider It is recognized by the appearance of small yellow or whitish spots on the leaves, fine cobwebs and the general weakening of the plants, which in severe cases can lead to loss of productivity or death of the crop.
Phytoseiulus persimilis It acts quickly on all stages of the pest, moving nimbly along the underside of leaves and locating concentrations of red spider eggs, larvae, and adults. Its predatory action results in:
- Visible reduction of the pest mite population in just a few days.
- Reduction of foliar damage and improvement of crop vigor.
- Prevention of re-infestation when periodic releases are integrated.
Compatibility with other auxiliary and phytosanitary organisms
Phytoseiulus persimilis shows a high compatibility with most beneficial insects used in integrated pest management, since it does not prey on other auxiliaries. However, its success depends on the absence of toxic pesticide residues in crops, especially broad-spectrum acaricides, which can negatively affect their populations.
It is recommended to use selective phytosanitary products only when absolutely necessary and to apply them prior to the release of the predator, thus allowing for adequate colonization and persistence of Phytoseiulus persimilis.
Limitations and practical considerations
Although Phytoseiulus persimilis is very effective, it has some limitations to consider:
- Their survival rate is directly linked to the presence of their prey; if the pest disappears completely, predator populations also decline.
- Adverse environmental conditions (low relative humidity, extreme temperatures) reduce its effectiveness and speed of intervention.
- In very extensive crops or widespread infestations, it is recommended to combine the release of Phytoseiulus persimilis with other integrated management strategies and frequent monitoring.
Recommendations for release and handling in the field
- Periodically monitor for signs of spider mite infestation and estimate the population to determine the optimal application time.
- Distribute predators evenly over the crop, focusing on areas with a higher pest density.
- Avoid indiscriminate chemical treatments before and after release.
- Promote a suitable environment in the greenhouse or open field, ensuring stable humidity and temperature.
- Combine with other compatible auxiliary organisms for comprehensive control.
Ecological and economic importance of Phytoseiulus persimilis
The use of Phytoseiulus persimilis in modern agriculture not only contributes to the conservation of agricultural ecosystems, but also represents important economic advantages for the farmer:
- Allows to obtain products free of chemical residues, more attractive to demanding consumers and markets.
- Reduces costs associated with recurring phytosanitary treatments.
- It promotes biodiversity and the resilience of the agroecosystem to new pests.
Understand in depth the characteristics, needs and life cycle of Phytoseiulus persimilis It's key to getting the most out of this natural ally of farmers. Its rational use, combined with proper monitoring and other integrated management tools, makes this small mite one of the pillars of biological crop protection against red spider mites and reduces dependence on chemical products, protecting plant health, the environment, and sustainable agricultural production.