Acari Heterostigmata 1 PROSTIGMATA Morphological and ecological adaptations. 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. 2 HETEROSTIGMATA Stigmata are present only on the female. 3 PYEMOTIDAE Adults ~250 µm long, yellowish. Stylet-like chelicerae. A strong sexual dimorphism: ovigerous female is tipically pear-shaped and swollen. 4 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 ♂♂ 5 (arrhenotocky). 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. 6 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. 7 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. 8 PYEMOTIDAE Pyemotes scolyti group - valuable natural enemies of scolityds; phoresy on one or more species of Scolitydae; they feed on the juveniles; insect adults are used for dispersal. Pyemotes ventricosus group (including P. tritici and P. ventricosus) - non phoretic; feed on numerous hosts included adults. Pyemotes tritici (straw- or hay-itch mite) parasitizes more than 100 species of stored grain insects (mainly Coleoptera, Hymenoptera and Lepidoptera). Pyemotes ventricosus is associated to xylophagous beetles or Honey 9 bees. 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 graminum Siteroptes avenae 10 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. 11 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. 12 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. 13 PYGMEPHORIDAE: Pediculaster mesembrinae Adult ~250 µm long, yellowish with a white median and longitudinal strip on the dorsum. 14 PYGMEPHORIDAE: Pediculaster mesembrinae 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. 15 PYGMEPHORIDAE: Pediculaster mesembrinae 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 16 PYGMEPHORIDAE: Pediculaster mesembrinae Dispersal mainly by natural passive transportation (wind) and phoresy (sciarids strictly associated to the fungal environment, as Lycoriella mali and other flies). 17 PYGMEPHORIDAE: Pediculaster mesembrinae Frequent in greenhouses. mushroom Damages. 18 Fungal species preferences° Agaricus bisporus --Pleurotus eryngii --Chrysonilia sitophila ++ Cladobotryum dendroides ++ Mycogone perniciosa +++ Trichoderma viride + ° ability of the mite in feeding and reproducing on the used substrate. The number of the + or – indicates the preference degree. Trichoderma 19 TARSONEMIDAE About 530 species. Mainly with tropical subtropical distribution. and 20 TARSONEMIDAE Size: 100-300 µm long. Shape: subcylindric. Colour: semitranslucent and shiny, yellow, white or pale in appearance. Smooth integument. 21 TARSONEMIDAE Gnathosoma is capsule-like, with short and thin cheliceral stylets, reduced pedipalps, with 2-3 segments. (Courtesy of A. Di Palma) 22 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 23 TARSONEMIDAE Partenogenesis mainly for arrhenotocky. ♂ aploid and ♀ diploid. Postembryonic development: E, L, “quiescent larva” (= pharate pupa) and Ad. Iponemus spp. ♀♀ have developed physogastry and lay groups of eggs. ♀♀ 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. 24 TARSONEMIDAE Favourable environmental conditions: high relative humidity and temperature, scarce lighting, protected by the direct lighting. Trophic behaviour: • mycophagous, • saprophagous, • parasite (Acarapis woodi in the honey bee tracheae), • predators, 25 TARSONEMIDAE Trophic behaviour: • phytophagous. They feed on tissues with thin cell walls: fungi and soft plant organs (buds, small fruits, vegetative tips, etc.). Delphinium Symptoms: irregular development of stems and their productions, rust. 26 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). 27 Phytonemus pallidus (greenhouse and cyclamen pale mite) Hosts: plants cultivated in protected and semi-protected environments (strawberry), ornamental plants (begonia, cyclamen, chrysanthemum, fuchsia, geranium, gerbera, petunia, Saintpaulia, etc.). Distribution: wide in North America, Europe, Asia. Morphology: pinkish orange as adult; females about 250 μm long. (from Hoy, 2011) 28 Phytonemus pallidus (greenhouses and cyclamen pale mite) Biology: Eggs laid (1-2 per day, 12-16 in total) in groups close to the leaf sheaths, on young unfolding leaves. ♀♀ overwinter in group (close leaf sheaths of strawberries). Life cycle lasts 10-14 days in optimal conditions. Mainly disperse by stolons and infested bulbs. 29 Phytonemus pallidus (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. 30 Polyphagotarsonemus latus (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. 31 Polyphagotarsonemus latus 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. 32 Polyphagotarsonemus latus 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. 33 Polyphagotarsonemus latus Phoresy on tibiae and tarsi of green peach aphid (Myzus persicae), sweet potato whitefly (Bemisia tabaci), greenhouse whitefly (Trialuerodes vaporariorum). 34 Polyphagotarsonemus latus 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. 35 Polyphagotarsonemus latus 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. 36