Transcript MESOSTIGMATA

Acari
Mesostigmata
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Key for the main ACARI orders and suborders
1. 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
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
- 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
3. 2 segmented palps, stigmata absent
Astigmata
- sometimes minute palps but with 3-5 segments; stigmata present or absent 4
4. stylet-like or hooked chelicerae, raraly chelate
Prostigmata
- chelicerae tipically chelate
Oribatida
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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
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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.
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MESOSTIGMATA: Laelapidae – Hypoaspis aculeifer
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.
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MESOSTIGMATA: Laelapidae – Hypoaspis aculeifer
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MESOSTIGMATA: Laelapidae – Hypoaspis aculeifer
The female lays eggs for a long time as a consequence of its
longevity (from 48 to 100 days at 25°C).
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MESOSTIGMATA: Laelapidae – Hypoaspis aculeifer
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
Larva
Protonymph
Adult
Deutonymph
Egg
0
10
20
days
30
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MESOSTIGMATA
: Laelapidae
– Hypoaspisaculeifer
aculeifer
MESOSTIGMATA: Laelapidae
– Hypoaspis
Tube of 1 liter containing
10.000 or 25.000 mites.
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MESOSTIGMATA: Phytoseiidae
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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.
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(from Hoy, 2011)
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.
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PHYTOSEIIDAE
Large dorsal plate with, at most, 20 pairs of setae, a
variable number of pores and integument more or
less smooth or reticulated.
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PHYTOSEIIDAE
Three ventral plates, accessory pores for insemination (= sperm
induction pores), a genital pore, stigmata and peritremes.
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PHYTOSEIIDAE
Males guarding quiescent Dn.
Postembrionic development: E, L,
Pn, Dn.
Eggs are laid singly or in small
groups on the undersurface of the
Phytoseiulus persimilis
leaves, close to the main veins.
Female-biased sex ratio: commonly
about 2.5 females to 1 male.
Tetranychus urticae
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PHYTOSEIIDAE
Egg fertilization (podospermy insemination) and parthenogenesis
(pseudoarrhenotocky).
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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
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food.
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.
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PHYTOSEIIDAE
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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
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2.4 eggs per day in about 30 days.
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.
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PHYTOSEIIDAE
They are usually on the undersurface of the leaf.
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PHYTOSEIIDAE
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
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PHYTOSEIIDAE: trophic regime
• 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.
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PHYTOSEIIDAE: species applied in augmentative
biological control
Phytoseiid species
Target/s
Phytoseiulus persimilis
Tetranychus urticae
Metaseiulus occidentalis
Tetranychus spp.
Amblyseius cucumeris
Thrips and spider mites, cyclamen and broad mites in
greenhouses
Neoseiulus degenerans
Thrips and spider mites
Amblyseius californicus
Tetranychus spp.
Neoseiulus barkeri
Thrips larvae in greenhouses
Amblyseius swirskii
Whiteflies, thrips, and other small insects in greenhouses
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PHYTOSEIIDAE: side effects of pesticides
Produced by non selective aa.ii. (broad spectrum chemicals).
Insecticides: pyrethroids (deltamethrin, cypermethrin, etc.), organfosphorates 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).
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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,
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permethrin
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
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PHYTOSEIIDAE
Cane method release:
• Sprouted canes of 2 years with 5-10
overwintering ♀♀/node
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Phytoseiulus persimilis
Obligatory predator of Tetranychus
urticae (acaricide on legs).
Considerably active and with a
huge ability in searching for the
prey.
Cycle span:
-15°C
-20°C
-25°C
Mobile individuals
brilliant orange
Egg orange-pink
25 days
9 days
5 days
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Phytoseiulus persimilis
Tab 10 – Influence of humidity and temperature on the development
of the eggs in P. persimilis.
% hatching
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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).
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.
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Phytoseiulus persimilis
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.
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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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