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1 AcariMesostigmata. Key for the main ACARI orders and suborders Parasitiformes2 1.1-4 pairs of dorso-lateral or dorso-ventral stigmata, posterior to.

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Presentation on theme: "1 AcariMesostigmata. Key for the main ACARI orders and suborders Parasitiformes2 1.1-4 pairs of dorso-lateral or dorso-ventral stigmata, posterior to."— Presentation transcript:

1 1 AcariMesostigmata

2 Key for the main ACARI orders and suborders Parasitiformes2 1.1-4 pairs of dorso-lateral or dorso-ventral stigmata, posterior to the coxae II Parasitiformes2 Acariformes3 - stigmata not visible posteriorly to the coxae II; Acariformes3 Ixodida 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 Ixodida Mesostigmata - 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 Mesostigmata Astigmata 3.2 segmented palps, stigmata absentAstigmata 4 -sometimes minute palps but with 3-5 segments; stigmata present or absent4 Prostigmata 4.stylet-like or hooked chelicerae, raraly chelateProstigmata Oribatida -chelicerae tipically chelateOribatida 2

3 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 3

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. 4

5 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 5

6 6

7 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 7

8 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. Egg laying Egg Larva Protonymph Deutonymph Adult days 0102030 MESOSTIGMATA : Laelapidae – Hypoaspis aculeifer 8

9 9 Tube of 1 liter containing 10.000 or 25.000 mites.

10 MESOSTIGMATA : Phytoseiidae 10

11 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

12 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 12

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

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

15 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 urticae Phytoseiulus persimilis PHYTOSEIIDAE 15

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

17 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 17

18 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 18

19 PHYTOSEIIDAE 19

20 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 20

21 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 21

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

23 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 persimilis Faecis of Tetranychus urticae PHYTOSEIIDAE 23

24 Obligatory predators o 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 oligophagous o 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 24

25 PHYTOSEIIDAE : species applied in augmentative biological control 25

26 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 26

27 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 fungicidesacaricides 27

28 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 28

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

30 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°C25 days -20°C9 days -25°C5 days 30

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

32 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). 32

33 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 33

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. 34


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