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Acari Mesostigmata

Acari Mesostigmata. 1. Key for the main ACARI orders and suborders. 1-4 pairs of dorso- lateral or dorso- ventral stigmata , posterior to the coxae II Parasitiformes 2 - stigmata not visible posteriorly to the coxae II; Acariformes 3

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Acari Mesostigmata

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  1. Acari Mesostigmata 1

  2. Key for the main ACARI orders and suborders • 1-4 pairs of dorso-lateral or dorso-ventralstigmata, posterior to the coxae II Parasitiformes2 • - stigmatanotvisibleposteriorly to the coxae II; Acariformes3 • 2. Palptarsuswithoutclaws; stigmata back to coxae IV or latero-dorsal to the regionbetweencoxae II-III; presence of stigmaticplate; hypostometransformed in a piercing organprovided with recurvedteethIxodida • - Palptarsuswith a terminal, subterminal, or basalclaw; with 1-2 pairs of stigmata in the regionbetweencoxae II-III and III-IV, commonlyventro-lateral; peritremeusuallypresent; tritosternumgenerallypresentMesostigmata • 3. 2 segmentedpalps, stigmataabsentAstigmata • sometimes minute palpsbutwith 3-5 segments; stigmatapresent or absent4 • 4. stylet-likeor hookedchelicerae, raraly chelate Prostigmata • cheliceraetipically chelate Oribatida

  3. MESOSTIGMATA 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. Dermanyssus gallinae

  4. 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.

  5. MESOSTIGMATA: Laelapidae – Hypoaspisaculeifer 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.

  6. MESOSTIGMATA: Laelapidae – Hypoaspisaculeifer

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

  8. Egg laying Larva Adult Deutonymph Protonymph Egg 0 10 20 30 days MESOSTIGMATA: Laelapidae – Hypoaspisaculeifer 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.

  9. MESOSTIGMATA: Laelapidae – Hypoaspisaculeifer MESOSTIGMATA: Laelapidae – Hypoaspis aculeifer Tube of 1 liter containing 10.000 or 25.000 mites.

  10. MESOSTIGMATA: Phytoseiidae

  11. MESOSTIGMATA: Phytoseiidae 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. (from Hoy, 2011)

  12. PHYTOSEIIDAE 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.

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

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

  15. PHYTOSEIIDAE 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. Phytoseiuluspersimilis Tetranychusurticae

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

  17. PHYTOSEIIDAE 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.

  18. PHYTOSEIIDAE 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.

  19. PHYTOSEIIDAE

  20. PHYTOSEIIDAE 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.

  21. PHYTOSEIIDAE 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.

  22. PHYTOSEIIDAE They are usually on the undersurface of the leaf.

  23. PHYTOSEIIDAE • They are able to find the preythanks to: • kairomones (volatiles and non volatiles) emitted by the prey and contained in the silk, exuviae, eggs and faecis. • Syntheticvolatilesproduced by spider mite infestedplants Tetranychus urticae (adult) (egg) (web) Phytoseiulus persimilis Faecis of Tetranychus urticae

  24. PHYTOSEIIDAE: trophic regime • Obligatorypredators • Phytoseiuluspersimilis, • Metaseiulusoccidentalis • (unable to develop or reproduce on alternative foodssuchaspollen or honey – case of cannibalism or intraguildpredation) • Generalistpredators (Typhlodromuspyri) • Generalist and facultativepredators • oligophagous • polyphagous (Typhlodromusexhilaratus) 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.

  25. PHYTOSEIIDAE: speciesapplied in augmentativebiological control

  26. PHYTOSEIIDAE: side effects of pesticides • 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).

  27. Toxicity and persistance of some pesticides on Phytoseiulus persimilis insecticides fungicides acaricides 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

  28. PHYTOSEIIDAE • 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) Techniques for predator release: • Sheltering places • Cane method • Direct release • Release

  29. PHYTOSEIIDAE Cane method release: • Sprouted canes of 2 years with 5-10 overwintering ♀♀/node

  30. Phytoseiuluspersimilis • Obligatory predator of Tetranychusurticae (acaricide on legs). • Considerablyactive and with a hugeability in searching for the prey. • Cyclespan: • 15°C 25 days • 20°C 9 days • 25°C 5 days Mobile individualsbrilliantorange Eggorange-pink

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

  32. Phytoseiuluspersimilis 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). 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.

  33. Phytoseiuluspersimilis Bio-firm item: activeinstarsmixed with dispersingmaterial (wet vermiculite). Applied in inundativeprogrammes. Take care of: - release mitesassoonasyou can; - storingat 8-10°C atmost for 24 h; temperature must be > than 4°C; - do notexpose the box to the sun light or warmingdirectly; - rotate horizontally the closed container beforeapplication; - release should be doneplacinghorizontally the container, having care that the highest predator concentrationwill be released in the mostinfestedplaces.

  34. 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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