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AcariAcariMesostigmataMesostigmata

Key for the main ACARI orders and subordersKey for the main ACARI orders and suborders1. 1-4 pairs of dorso-lateral or dorso-ventral stigmata, posterior to the coxae II

ParasitiformesParasitiformes 22- stigmata not visible posteriorly to the coxae II; AcariformesAcariformes

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2. Palptarsus without claws; stigmata back to coxae IV or latero-dorsal to the region between coxae II-III; presence of stigmatic plate; hypostome transformed in a piercing organ provided with recurved teeth

IxodidaIxodida

- Palptarsus with a terminal, subterminal, or basal claw; with 1-2 pairs of stigmata in the region between coxae II-III and III-IV, commonly ventro-lateral; peritreme usually present; tritosternum generally present

MesostigmataMesostigmata

3. 2 segmented palps, stigmata absent AstigmataAstigmata

- sometimes minute palps but with 3-5 segments; stigmata present or absent44

4. stylet-like or hooked chelicerae, raraly chelate ProstigmataProstigmata

- chelicerae tipically chelate OribatidaOribatida

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Mainly predators, free-living in the soil and in decaying organic matter.

Some species are adapted to the parassitism on Vertebrates and Invertebrates.

Size length between 0.2 and 2 mm.

MESOSTIGMATA

Dermanyssus gallinae

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MESOSTIGMATA

Usually the digitus mobilis and fixus can develop a chela.

Dermanyssina and Parasitina males have a spermatodactyl on the digitus mobilis.

The female is often provided with an accessory pore for sperm insemination between the III and IV pair of legs.

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Female reddish, 600-940 µm long, male 520-540 µm long.

Edaphic mite, free-living in the soil, largely spread and easy to rear.

It lives mainly in the most superficial layers of the soil, but also in storehouses.

Largely polyphagous, predators of: mites, spring-tail larvae, other insects and nematodes.

MESOSTIGMATA: Laelapidae – Hypoaspis aculeifer

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MESOSTIGMATA: Laelapidae – Hypoaspis aculeifer

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The female lays eggs for a long time as a consequence of its longevity (from 48 to 100 days at 25°C).

MESOSTIGMATA: Laelapidae – Hypoaspis aculeifer

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It can survive also for 5 months without its elective prey.

Arrhenotoky (partenogenesis), the eggs are laid in the soil crevices and on organic matter in groups of 15-50 units which can be the result of more gravid females.

Egglaying

Egg

Larva

ProtonymphDeutonymph Adult

days0 10 20 30

MESOSTIGMATA: Laelapidae – Hypoaspis aculeifer

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MESOSTIGMATA: Laelapidae – Hypoaspis aculeiferMESOSTIGMATA: Laelapidae – Hypoaspis aculeifer

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Tube of 1 liter containing 10.000 or 25.000 mites.

MESOSTIGMATA: Phytoseiidae

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Mean length: ~500 µm; ♂ smaller.

Shape: oval or pear-shaped, often subpentagonal, dorso-ventrally flattened; ♂ pear-shaped.

Generally yellowish or pale yellow, sometimes pinkish, often the colour depends on the ingested food for 24-30 hours; integument smooth and glossy.

MESOSTIGMATA: Phytoseiidae

(from Hoy, 2011)11

Gnathosoma with chelate chelicerae; ♂ provided with the spermatodactyle; 5-segmented palps rich in sensilla.

Leg I with a sensorial function and helping to capture the prey.

PHYTOSEIIDAE

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Large dorsal plate with, at most, 20 pairs of setae, a variable number of pores and integument more or less smooth or reticulated.

PHYTOSEIIDAE

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Three ventral plates, accessory pores for insemination (= sperm induction pores), a genital pore, stigmata and peritremes.

PHYTOSEIIDAE

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Males guarding quiescent Dn.

Postembrionic development: E, L, Pn, Dn.

Eggs are laid singly or in small groups on the undersurface of the leaves, close to the main veins.

Female-biased sex ratio: commonly about 2.5 females to 1 male.

Tetranychus urticaeTetranychus urticae

Phytoseiulus persimilisPhytoseiulus persimilis

PHYTOSEIIDAE

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Egg fertilization (podospermy insemination) and parthenogenesis (pseudoarrhenotocky).

PHYTOSEIIDAE

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Larvae of some species usually do not feed.

Overwintering: mated ♀♀ in sheltered places; scarcely resistant to low temperature.

Diapause induced by short day-light; temperature seems to have a secondary role.

Role of feeding pygments (e.g.: β-carotene).

Considerable adaptations to the variable ecological conditions; living in the soil, on numerous plant species and sometimes also on stored food.

PHYTOSEIIDAE

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Biologic parameters (fertility, longevity, development rate, etc.) depend on the phytoseiid species, prey species, population density of the prey, environmental conditions (climate, alternative food).

Usually males develop more quickly than females.

PHYTOSEIIDAE

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PHYTOSEIIDAE

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A ♀ of A. andersoni (Chant) lays 1.3-2 eggs per day in about 99 days, while a ♀ of P. persimilis Athias-Henriot lays an average of 2.4 eggs per day in about 30 days.

PHYTOSEIIDAE

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Development rate is faster than that of the phytophagous mites, in the same conditions of humidity and temperature.

Fertility lower than that of their preys, especially tetranychids.Longevity is very close between preys and predators.

PHYTOSEIIDAE

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They are usually on the undersurface of the leaf.

PHYTOSEIIDAE

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They are able to find the prey thanks to:

•kairomones (volatiles and non volatiles) emitted by the prey and contained in the silk, exuviae, eggs and faecis.

•Synthetic volatiles produced by spider mite infested plants

Tetranychus urticae (adult) (egg) (web)

Phytoseiulus persimilisPhytoseiulus persimilis

Faecis of Faecis of Tetranychus urticaeTetranychus urticae

PHYTOSEIIDAE

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• Obligatory predatorso Phytoseiulus persimilis, o Metaseiulus occidentalis

(unable to develop or reproduce on alternative foods such as pollen or honey – case of cannibalism or intraguild predation)

• Generalist predators (Typhlodromus pyri)• Generalist and facultative predators

o oligophagouso polyphagous (Typhlodromus exhilaratus)

Two categories with respect to the prey density:- at low prey density;- at high prey density (monophagous or oligophagous).

The predators prefer to feed on juveniles and eggs.

PHYTOSEIIDAE: trophic regime

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PHYTOSEIIDAE: species applied in augmentative biological control

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Produced by non selective aa.ii. (broad spectrum chemicals).

Insecticides: pyrethroids (deltamethrin, cypermethrin, etc.), organ-fosphorates and carbammates at broad spectrum.

Fungicides (dithiocarbammates: mancozeb, maneb, metiram, propineb, zineb, others against Plasmopara): toxicity is usually inferior than that of the main insecticides, but they are applied repeteadly, especially with small phytoseiid populations.

It can be distinguished:- direct effects (mortality, fertility reduction) and - indirect effects (disappearance of alternative preys).

PHYTOSEIIDAE: side effects of pesticides

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These aa.ii. cause a reduction of the control capacity of the pests:A < 25%B = 25-50%C = 50-75%%D > 75%- value non available* a.i. with acaricides proprierties, too.** values also for bifenthrin, cyfluthrin, cypermethrin, deltamethrin, fenpropathrin, permethrin

Toxicity and persistance of some pesticides on Phytoseiulus persimilis

insecticides fungicides acaricides

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Techniques for predator release:• Sheltering places• Cane method• Direct release• Release

Genetic improvements

• Selection of strains

a) resistent to pesticides (e.g., Metaseiulus occidentalis resistant to abamectin, OPs, carbaryl, sulfur),

b) with particular prey preference,

c) inability to diapause under greenhouse conditions during winter,

d) for improved high-temperature tolerance

• production of transgenic predators (maternal microinjection)

PHYTOSEIIDAE

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Cane method release:

• Sprouted canes of 2 years with 5-10 overwintering ♀♀/node

PHYTOSEIIDAE

Phytoseiulus persimilis

Mobile individuals brilliant orange

Egg orange-pink

Obligatory predator of Tetranychus urticae (acaricide on legs).

Considerably active and with a huge ability in searching for the prey.

Cycle span:-15°C 25 days-20°C 9 days-25°C 5 days

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Tab 10 – Influence of humidity and temperature on the development of the eggs in P. persimilis.

% hatching

Phytoseiulus persimilis

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Optimum rate of population increase is at 32°C; warm and damp climate; maximum predatory activity is carried out at 65-75% di R.H.Tetranychids: optimum rate of population increase is at 35°C; warm and less damp climate.

Required water.It doesn’t reproduce if it does not fed on its prey.Cannibalism.Residual side effects of pyrethroids and dimethoate.

Phytoseiulus persimilis

Development phase and fertility are longer/higher than those of the prey at 15-18°C, 55-95% R.H. Fertility: ~ 75 eggs/female (17-26°C).

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Bio-firm item: active instars mixed with dispersing material (wet vermiculite). Applied in inundative programmes.

Take care of:- release mites as soon as you can;

- storing at 8-10°C at most for 24 h; temperature must be > than 4°C;

- do not expose the box to the sun light or warming directly;

- rotate horizontally the closed container before application;

- release should be done placing horizontally the container, having care that the highest predator concentration will be released in the most infested places.

Phytoseiulus persimilis

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Doses depend on:- infestation level - average number of phytophagous mite/leaf,

number of infesting clusters. Prey:predator ratio → 15:1 e 30:1;

- sensitivity of the crop;

- environmental conditions: high temperature and dried climate favour T. urticae, therefore a higher dose of predators is needed and the release should be done at a lower threshold;

- vegetative stage of the crop: contact between plants.

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