PLANT PROTECTION 1 – Pests, Diseases and Weeds

PLANT PROTECTION 1 – Pests, Diseases and Weeds
ALLIED PESTS - Spiders
Class Arachnida, Order Araneida
NO. SPECIES IN
AUSTRALIA
SOME
DISTINCTIVE
FEATURES
LIFE CYCLE
Scientists estimate that there are more than 10,000 species in Australia, only
about 2,500 have been described. Only a few spiders are poisonous. Most are
beneficial and could be used as indicators of environmental health because
they respond to disturbance, are abundant and easily sampled.
www.ento.csiro.au/education/allies/araneae.html
Lucid Key: Spiders of Australia www.lucidcentral.org/
ADULT Body 1. Two main body regions (cephalothorax (fused head
and thorax) and abdomen).
2. No antennae or wings.
3. No compound eyes, 8 simple eyes (some only have 3).
No true jaws. Fangs and chelicerae.
4. Lung ‘books’ and/or spiracles for breathing.
5. All spiders spin silk from various types of silk glands.
Many spin webs to climb on and to catch insects for
food, others form nets, triplines, etc. Females of most
species enclose their eggs in a silk egg sac. Spiderlings
use silk for dispersion after hatching.
Legs 1. Four (4) pairs of walking legs.
2. Limb regeneration. When a limb is lost, there is no
bleeding, a thin membrane grows over the stump. After
1-2 moults a new limb grows from the stump but it never
quite reaches the same length as its predecessor.
There is a gradual metamorphosis - egg, nymph (several stages) and
adult. Some spiders take several years to reach maturity.
Redback
Females
are about
10 mm long
The red colour
warns of poison
METHODS OF
FEEDING
Large spiders
may feed on
birds in Qld
ADULT
NYMPH
Spiders have a liquid diet and do not eat solid food. They feed on other
spiders, insects, slaters, native snails and frogs, caught either directly by
ground dwelling spiders or in webs of web spinners. Spiders kill their
prey by means of a poison (venom) which is pumped through sharp
hollow fangs located near the mouth and injected into the victim. The
spider then squeezes out juice from its prey and sucks it up into its
stomach. Most spiders are nocturnal, hunting for prey at night.
Cannibalism occurs amongst spiders especially where there is
overcrowding, females may eat males.
Insects and allied pests - Spiders (Arachnida, Araneida) 209