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Acari Heterostigmata

Acari Heterostigmata. 1. PROSTIGMATA. Morphological and ecological adap-tations. Chelicerae are stylet-like, hooked, rarely chelatae; basal segments can be sometimes fused in part or totally. Stigmata are on the gnathosoma or anteriorly on the propodosoma. HETEROSTIGMATA.

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Acari Heterostigmata

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  1. Acari Heterostigmata 1

  2. PROSTIGMATA Morphological and ecological adap-tations. Chelicerae are stylet-like, hooked, rarely chelatae; basal segments can be sometimes fused in part or totally. Stigmata are on the gnathosoma or anteriorly on the propodosoma.

  3. HETEROSTIGMATA Stigmata are present only on the female.

  4. PYEMOTIDAE Adults ~250 µm long, yellowish. Stylet-like chelicerae. A strong sexual dimorphism: ovigerous female is tipically pear-shaped and swollen.

  5. PYEMOTIDAE Polymorphism (phoretic reasons) more or less evident which can be assessed in one sex or (usually) in both sexes for some Pyemotes. Embryonic and post-embryonic development (nymphs are absents) in the adult female. 2-4 ♂♂ emerge at first and later ♀♀ (90% of the progeny is composed by females) from a mated ♀; vice versa, a vergin ♀ produce only ♂♂ (arrhenotocky).

  6. PYEMOTIDAE The mites look for the host, pierce the integument, cause the host paralysis and a progressive digestion of the tiessues. Pyemotes scolyti and P. parvoscolyti paralyze the scolityd larvae within 24 hours; P. beckeri, P. ventricosus and P. tritici paralize the victim whitin 5 min. Effects on the man: allergic reactions, dermatisis, icthy, fevers, headache, backache, asthma.

  7. PYEMOTIDAE Two days after the host infestation, the ♀ starts to swoll and become physogastric within 2-3 days. The ♀ starts to produce directly new individuals within 4-5 days and it continues for about 2 weeks. The neonate ♀♀ of some species (P. herfsi and P. scolyti) must find an host within 2 (at 40% of R.H.) -7 (at 100% og R.H.) days.

  8. PYEMOTIDAE Pyemotes tritici and P. ventricosus are frequent in warehouses where they prey insect eggs, larvae and adults (Lepidoptera, Coleoptera, Diaspids, etc.). Characteristics: 1) high reproductive fitness, 2) short life cycle (4-7 days per generation), 3) all instars develop into a gravid ♀♀ which do not require secondary hosts or other food sources, 4) ♀♀ are the 98% of the population, 5) ♀♀ mate soon after the emergence and start immediately the host search, 6) easy rearing.

  9. PYEMOTIDAE Pyemotesscolytigroup - valuablenaturalenemies of scolityds; phoresy on one or more species of Scolitydae; theyfeed on the juveniles; insectadults are used for dispersal. Pyemotesventricosusgroup (includingP. tritici and P. ventricosus) - non phoretic; feed on numeroushostsincludedadults. Pyemotes tritici(straw- or hay-itch mite) parasitizes more than 100 species of storedgraininsects (mainly Coleoptera, Hymenoptera and Lepidoptera). Pyemotesventricosusisassociated to xylophagousbeetles or Honeybees.

  10. SITEROPTIDAE Adults are ~250 µm long, pale yellowish. Short and pointed chelicerae. Strong sexual dimorphism, the gravid female is tipically pear-shaped and physogastric. Siteroptes avenae Siteroptes graminum

  11. SITEROPTIDAE The ♀♀ are provided with a pair of membranaceous pockets of integumental origin in ventral position (sporotechae). In Siteroptes reniformis complex, the techae are posterior to the base of leg IV. Each techa can store 1 conidiospora of Nigrospora sp. (specialized mutualistic symbiosis - dissemination). Nigrospora spp., especially N. oryzae (Berk. & Br.), causes damages to cotton, mais, sorghum, wheat, etc.

  12. SITEROPTIDAE In S. cerealium complex, the techae are anterior to the leg III base. In S. avenae, the sporotechae are about 20 μm long and about 10 μm wide. In other species, the techae can have a larger size also.

  13. SITEROPTIDAE These sporotechae can contain numerous conidiosporae (up to ~12) of Fusarium spp. and Botrytis spp. (specialized mutualistic symbiosis - dissemination). S. avenae vectors F. poae (Peck) (causal agent of the bud rot on carnation and silver tip of cereals) and F. avenaceum. Reared also on other Fusarium.

  14. PYGMEPHORIDAE: Pediculastermesembrinae Adult ~250 µm long, yellowish with a white median and longitudinal strip on the dorsum.

  15. PYGMEPHORIDAE: Pediculastermesembrinae The ♂♂ have atrophic gnathosoma, legs IV modified and very strong. The gravid ♀♀ are physogastric, also 1 mm of diameter. Polymorphic females are known; they are involved in phoresy.

  16. PYGMEPHORIDAE: Pediculastermesembrinae Reproduction: egg fertilization and arrhenotocky; oviparous; ~160 eggs/♀ in 5 days. The ♂ mates with the nymph ♀ (neotenic) of the same generation (sexually mature). The physogastry occurs already after 24 hours and after 48 hours the ♀ reaches the maximum development. Sex ratio: 100 ♀♀ to 1 ♂. Duration of a generation: Temperature days 15°C 7.6 20°C 4.8 25°C 3.9

  17. PYGMEPHORIDAE: Pediculastermesembrinae Dispersal mainly by natural passive transportation (wind) and phoresy (sciarids strictly associated to the fungal environment, as Lycoriella mali and other flies).

  18. PYGMEPHORIDAE: Pediculastermesembrinae Frequent in mushroom greenhouses. Damages.

  19. Fungalspeciespreferences° Agaricusbisporus--- Pleurotuseryngii--- Chrysoniliasitophila++ Cladobotryumdendroides++ Mycogone perniciosa +++ Trichodermaviride+ ° ability of the mite in feeding and reproducing on the used substrate. The number of the + or – indicates the preference degree. Trichoderma

  20. TARSONEMIDAE About 530 species. Mainly with tropical and subtropical distribution.

  21. TARSONEMIDAE Size: 100-300 µm long. Shape: subcylindric. Colour:semitranslucent and shiny, yellow, white or pale in appearance. Smoothintegument.

  22. TARSONEMIDAE Gnathosoma is capsule-like, with short and thin cheliceral stylets, reduced pedipalps, with 2-3 segments. (Courtesy of A. Di Palma)

  23. TARSONEMIDAE male ♂ slightly smaller than the ♀, with strong leg IV and genital plate or papilla (it contains the aedeagus, accessory genital organs). ♀ subglobose, tread-shaped leg IV. female male female

  24. TARSONEMIDAE Partenogenesis mainly for arrhenotocky. ♂ aploid and ♀ diploid. ♀♀ deposit 1 to 5 eggs per day, with most species producing 10 to 20 eggs in total. Life cycle usually requires about a week. Sex ratio: (1 male vs 3÷20 females). No information on diapause. Postembryonic development: E, L, “quiescent larva” (= pharate pupa) and Ad. Iponemus spp. ♀♀ have developed physogastry and lay groups of eggs.

  25. TARSONEMIDAE Favourableenvironmentalconditions: high relative humidity and temperature, scarcelighting, protected by the directlighting. • Trophicbehaviour: • mycophagous, • saprophagous, • parasite(Acarapiswoodi in the honeybeetracheae), • predators,

  26. TARSONEMIDAE • Trophicbehaviour: • phytophagous. • Theyfeed on tissues with thincellwalls:fungi and soft plantorgans (buds, small fruits, vegetative tips, etc.). Delphinium Symptoms: irregulardevelopment of stems and their productions, rust.

  27. TARSONEMIDAE: control Sampling: • symptom direct observations (distorsions) • sampling of plants or their parts and direct observations under microscope or mite extraction • random and/or localized samplings (close to the greenhouse openings) Control: • taking off and destruction of infested plants as soon as they are spotted; • treatments of the crops by sulfur, and other aa.ii. (possibly translaminar) against the mobile individuals; • treatments of sapling by hot water (temperature and duration of the application depend on the species – 43.5°C for 30 minutes against Phytonemus pallidus) or chemicals (fumigations in cells).

  28. Phytonemuspallidus(greenhouse and cyclamen pale mite) Hosts: plantscultivated in protected and semi-protectedenvironments (strawberry), ornamentalplants (begonia, cyclamen, chrysanthemum, fuchsia, geranium, gerbera, petunia, Saintpaulia, etc.). Distribution: wide in North America, Europe, Asia. Morphology: pinkishorangeasadult; femalesabout 250 μm long. (from Hoy, 2011)

  29. Phytonemuspallidus(greenhouses and cyclamen pale mite) Biology: Eggslaid (1-2 per day, 12-16 in total) in groupsclose to the leafsheaths, on youngunfoldingleaves. ♀♀ overwinter in group (closeleafsheaths of strawberries). Life cyclelasts 10-14 days in optimalconditions. Mainly disperse by stolons and infestedbulbs.

  30. Phytonemuspallidus(greenhouses and cyclamen pale mite) Largest populations can be found on the vegetative tips. It causes deformed, blistered and reduced leaves, scanty flowering, malformed flowers and fruits with an irregular development (for strawberries). The symptoms on the leaves are increasing from the outermost to the innermost.

  31. Polyphagotarsonemuslatus(broad mite, citrus silver mite, yellow tea mite or tropical mite) ♀ amber yellowish or greenish, ~ 190 µm long, with an indistinct white strip in the middle of the dorsal side. ♂ lack the strip and is only about half size of ♀♀. Egg of~ 80 µm, with multiple parallel rows of whitish tubercles longitudinally placed.

  32. Polyphagotarsonemuslatus Polyphagous (over 100 species), indoor and outdoor, water melon, melon, cucumber, aubergine, pampkin, zucchini, tomato, pepper, potato, bean, gerbera, lemon, cotton, tea, tobacco, bean, dahlia, etc. In Sicily it has been reported on lemon; in Lazio e Campania it has been reported in greenhouses (pepper, aubergine, gerbera) and in field (bean, dahlia, potato). Particularly active and dangerous in tropical and subtropical environments. Strongly sensitive at low temperature.

  33. Polyphagotarsonemuslatus Eggs laid in the depressions of the lemon fruits, close to the buds and leaf veins. Egg-laying: lasts 7-11 days ~ 40 eggs/♀ (2-4 eggs/day) isolated or in small groups of 2-4 eggs Lyfe cycle: 4-8 days at 28-30°C (70-80% di R.H.) 7-10 days at 18-20°C (70-80% di R.H.) It tends to form small colonies.

  34. Polyphagotarsonemuslatus Phoresy on tibiae and tarsi of green peach aphid (Myzus persicae), sweet potato whitefly (Bemisia tabaci), greenhouse whitefly (Trialuerodes vaporariorum).

  35. Polyphagotarsonemuslatus Symptoms induced by injected toxins: - on lemon, infestations on fruits can cause suberous areas (yellowish, brownish, silver) ± large on the fruit surface. Possible crevices. - stems: reduced development, malformations, dying; - leaves: silvering, reduced lamina, crisped lamina, dying, phylloptosis; - suberosis and net necrosis of the soft organs; - flower: abortion.

  36. Polyphagotarsonemuslatus On the lemon: - It is suggested to collect 4 fruits/tree (1 for each orientation) in the inner part (damper) of the canopy; the fruit diameter should be <3 cm (at the highest lemon sensitiveness). The sampling should be carried out on the 5% of the trees. - The infestation is generally localized, it should be avoided a wide treatment on the whole field.

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