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AcariAcariAstigmataAstigmata

ASTIGMATA

Size: 0.2-1.2 mm.Shape: globose, oval, elongated, soft and usually smooth cuticle; from white pearly to yellow-brown, sometimes pigmented; opisthosoma generally oval.

ASTIGMATA

Chelicerae (ch) generally chelate and proviced with tooth.

Palps (p) 2-segmented, appressed to the chelicerae.

ASTIGMATA

Stigmata and tracheae absent; respiration by means of the integument (high relative humidity is required).

p

ch

Ontogenetic development: L, Pn, Dn (hypopus), Tn, Ad.

Mainly in soils rich in decaying organic matter (litter, organic fertilizer, dungs, nests, etc.), on fungi and storehouses.

ASTIGMATA

(from Hoy, 2011)

Habitus: - phytophagous, - zoophagous (scabies, Hemisarcoptes predator of mealy bugs,

allergenic agents, etc.), - mycophagous, - saprophagous.

Acarus siro Sarcoptes scabiei Demodex

ASTIGMATA

phytophagous zoophagous

Size: 0.5-1 mm.

Economic importance is, however, related mainly to the stored food.

ACARIDAE

Trophic behaviour: phytophagous (flower bulbs some plants), mycophagous, saprophagous, on stored food (grain, dried fruit, nut, cheese, spices, cereals, pet food).

Favourable environmental conditions: they require high relative humidity (>60%, 80-90%) and protection from the direct lightening.

Acarus ♂

Mainly oviparous.Dn absent or as obligatory or facultative

hypopus.

They cause:- damages to the stored food (flours,

pastas, cheeses, biscuits, sugar, dried fruits) which become dusty and unmarketable,

- dermatitis, allergic reactions, asthma.

Guanine in faecis stimulates the development of microrganisms which provoke a notable and further deterioration of the stored food.

Fungal symbiosis.

ACARIDAE

Preventive means:- respect of hygienic rules and cleaning of storehouse habitat;- reduction of the relative humidity at values inferior to 60%;- storing of seeds with a content of water inferior to 13%;- application of controlled atmosphere.

Curative means:- fumigation of the storehouses (laborious operation, specialised

operator requirements, operator risks, etc.)- damaged materials must be taken away;- sanification of the storehouses by means of pyrethroids;- physical treatments by means of heat: immersion in water at 50-

60°C per 1-2 minutes or by high radio frequency.

ACARIDAE: control

ACARIDAE: identification

Acarus siroAcarus siro: on flours and grain (that have absorbed moisture); frequently associated to Aspergillus, Penicillium and Eurotium.

Thermic thresholds: 3-30°CGood resistance to scarce availability of oxygen.

Tyrophagus putrescentiaeTyrophagus putrescentiae: prefers products at high content of fats and proteins (salami, cheeses, moulds on the surfaces of these products). It lives also in mushroom tunnels and damages were observed on cucumber and melon. It can carry viable spores in its digestive tract as well as on the outside of the body.

ACARIDAE

Tyrophagus similisTyrophagus similis: omnivorous (organic substrates, fungi included). Found on cucumber, melon, spinach, etc.

It is well-adapted on fresh plant tissues rich of proteins as cotyledon leaves or apical leaves; common in the soil.

ACARIDAE

Tyrophagus similis pest of spinach

Tyrophagus similis Damages on spinach

ACARIDAE: Rhyzoglyphus robini

Body size: 0.3-0.6 mm.

ACARIDAE: Rhyzoglyphus robini

Males and females mate several times a day. Males may remain in copula for 20 minutes to 6 hours.

A generation: 7-27 days at 26-13°C – facultative hypopus.

ACARIDAE: Rhyzoglyphus robini

It infests bulbous (onion, garlic, etc.) and florals plants (Amaryllis, hyacinth, narcisus, gladiolus, lily, freesia, etc.), potatoes, grains; root of vegetables, vines, wheat, oats and other crops; decaying vegetable (e.g. fallen fruits) and animal matter.

It prefers damaged bulbs.

It deeps gradually among the bulb scales.

Spread bacteria and fungi (Fusarium, Pseudomonas, etc.).

ACARIDAE: Rhyzoglyphus robini

Monitoring:- direct observation of symptoms (rot and

distortion appearance)- sampling of plants or their parts (bulbs) and

direct observation under a dissecting microscope.

ACARIDAE: Rhyzoglyphus robini

Agronomic control:- solarization of the soil used for bulb production.

Physical control:- bulb treatment by water at 37-41°C per 2-3 hours- Bulb storing at -2°C.

Chemical control:- Resistance to OPs.

Biological control:- release of Hypoaspis aculeifer (10 predators per 100 bulbs, after

heat treatment; 100-500 predators per m2).

ACARIDAE: Rhyzoglyphus robini