ADAPTIVE FEATURES
1.
exoskeleton -
protection from harm & desiccation,
lots of muscle attachment,
provides for a light (low weight) body that
allows flight
2.
complete metamorphosis --
allows same insect to capitalize on different niches (habitat & food),
also resting stages for harsh conditions (usually egg or
pupal stage)
3.
flight -
for survival from threat,
dispersal into new habitats,
gather food from large areas,
find mates at a distance
4.
small size - exoskeleton restricts size, but …
they have a reduced life cycle time period
can complete critical
portions of the life cycle in a short season
or can have several
generations in a single year
they require less food per
individual
they can utilize a great variety of
habitats
5.
adaptable critters
due to short life cycle, can
readily adapt to a changing environment (consider that it takes about 20
years for a human to reproduce, whereas many insects can produce several
generation in a single year)
6.
diverse feeding habitats
herbivore, omnivores, scavenger, predators
(carnivores), parasites/parasatoids;
on trees they feed on all parts (buds, cones/seeds,
leaves, phloem, wood, roots, sap, etc.)
7.
quiescence & diapause -
quiescence - simplest dormancy - temporary response to
immediate adverse conditions (i.e. low temp), insect resumes activity and
development as soon as favourable conditions return;
diapause - arrested development induced by certain factors
in advance of adverse conditions (i.e. photoperiod & temp changes in
fall, dormant in preparation for winter), it persists for some time after
adverse conditions have passed (i.e. they do not emerge on a warm winter day)
8.
movement - 3 categories:
spread - local movement within
favourable area,
dispersal - movement from a normally
favourable to somewhere else,
migration - directed movement from one
favourable area to another favourable area
9.
high reproductive potential - discussed elsewhere
(fecundity, length of life cycle, sex factor, polyembryony,
parthenogenesis)
10.
defense mechanisms
behavioral - jump, fly, crawl, motionless (walking stick), brown
juice of grasshopper
morphological - spines, spurs, hairs, exoskeleton, chewing mouth
parts, stingers
chemical - distasteful (monarch butterfly larva eat milkweed
(cardiac glycosides), adults have this concentrated in wings, bird eats and
vomits, no longer eats monarch butterflies, lady bugs taste bad – recognize
colorations); poison / irritant, stink bug, centipede (strychnine - almond)
shelter - inside plants, in duff, rolled leaf, tents, cases, etc.
colour patterns - camouflage, warning (ladybug, monarch), mimicry
(viceroy butterfly looks like monarch, flies that look like wasps), deceptive
(eye spots to scare, bring attention to less vital or more protected part of
insect)