Glandular system is otherwise called as secretary system.
Exocrine glands (glands with duct).
Mandibular glands: Secrete saliva in caterpillars when salivary glands are
modified into silk glands. In queen bee it secretes queen substance.
Pharyngeal glands: Secrete bee milk or royal jelly in nurse bee.
Tenant hairs: Secrete sticky fluid found in pulvilli of legs and helps in
ceiling walking in house flies.
Osmeteria (Forked gland): Eversible gland in the thorax of papilionid
larva with defense function.
Milk glands: Modified accessory gland nourishing larva developing in
uterus.
Androconia (Scented scales): Secretions of glandular scales of male
pierid butterflies to attract the opposite sex.
Endocrine glands (glands without duct)
Corpora cardiaca: It consist of paired bodies fused in middle and have
both nervous tissues and glandular tissues.
Corpora allata: It is a paired gland attached to corpora cardiaca and
secretes juvenile hormone (JH) there by inhibit metamorphosis.
Precocene is an anti JH
which induce precocious metamorphosis and death in insects.
Prothoracic glands: Paired gland present in ventrolateral part of
prothorax of larva and is degenerated in adults. It secretes the moulting
hormone ecdysone.
Weismann's ring: Formed by the fusion of carpora cardiaca, carpora
alleta, prothoracic glands and hypocerebral ganglion to secrete puparium
hardening hormone.
Ametabola: (No metamorphosis)
Hemimetabola: (Incomplete metamorphosis)
Paurometabola: (Gradual metamorphosis)
Holometabola: (Complete metamorphosis)
Scarabaeiform : Body is `C' shaped, stout and subcylindrical.
Pupa of mosquito is called tumbler.
Chrysalis is the naked obtect pupa of butterfly.
Entomophily - Insect pollination
Cantharophily -beetle pollination
Myophily -fly pollination
Sphecophily- Wasp pollination
Myrmecophily- ant pollination
Melittophily-bee pollination
Phalaenophily-moth pollinated
Psycophily- butterfly pollinated
‘Phytotelmata' (Plant held water containers)
Thanatosis is Many beetles and weevils feign dead which is a form of defense
against a predator which prefers live prey.
Tentacles is Varying number of paired movable processes are present on the
body of the larvae of butterflies grouped in the family Danaidae.
Bee venom is produced from acid glands which are the modified accessory
glands.
Oviparity: Majority of female insects, are oviparous, lay eggs. Embryonic
development occurs after oviposition by utilizing the yolk, e.g.Head louse, moths.
Viviparity: Unlike oviparous, here initiation of egg development takes place
within the mother. The life cycle is shortened by retention of eggs and even
developing young within the mother.
Four our main types of viviparity are observed
in different insect groups.
Ovoviviparity
Pseudoplacental viviparity
Haemocoelous viviparity
Adenotrophic viviparity
Arrhenotoky: Produce male e.g. bee
Thelytoky: produce female e.g. aphids
Amphitoky / deuterotoky: produce both male and female e.g. Cynipid
wasp.
Nutrition for a large number of developing embryo
cannot be supplied by the original egg and is acquired from the host's
haemolymph through a specialized enveloping membrane called trophamnion.
Eggs: The first stage of development in all insects is egg. Majority of insects
are oviparous. Egg stage is inconspicuous, inexpensive and inactive. Yolk
contained in the egg supports the embryonic development. Eggs are laid under
conditions where the food is available for feeding of the future Youngones.
Eggs are laid either individually or in groups. The outer protective shell of the
egg is called chorion. Near the anterior end of the egg, there is a small opening
called micropyle which allows the sperm entry for fertilization.
Larval stage is the active growing stage. It is the immature stage between the
egg and pupal stage of an insect having complete metamorphosis. This stage
differs radically from the adult.
Hairy caterpillar : The body hairs may be dense, sparse or arranged in tufts.
Hairs may cause irritation, when touched. e.g. Red hairy caterpillar.
Slug caterpillar : Larva is thick, short, stout and fleshy. Laval head is small
and retractile. Thoracic legs are minute. Abdominal legs are absent. Abdominal
segmentation is indistinct. Larva has poisonous spines called scoli distributed all
over the body. Such larva is also called platyform larva.
Semilooper : Either three or four pairs of prolegs are present. Prolegs are
either wanting or rudimentary in either third or third and fourth abdominal
segments. e.g. castor semilooper.
Looper : They are also called measuring worm or earth measurer or inch
worm. In this type, only two pairs of prolegs are present in sixth and tenth
abdominal segments. e.g. Daincha looper.
Eucepalous : Larva with well developed head capsule with functional
mandibles, maxillae, stemmata and antennae. Mandibles act transversely. e.g.
Wriggler (larva of mosquito) and grub of red palm weevil.
Hemicephalous : Head capsule is reduced and can be withdrawn into thorax.
Mandibles act vertically.
e.g. Larva of horse fly and robber fly.
Acephalous : Head capsule is absent. Mouthparts consist of a pair of
protrusible curved mouth hooks and associated internal sclerites. They are also
called vermiform larvae. e.g. Maggot (larva of house fly)
Chrysalis : It is the naked obtect pupa of butterfly. It is angular and
attractively coloured. The pupa is attached to the substratum by hooks present
at the terminal end of the abdomen called cremaster. The middle part of the
chrysalis is attached to the substratum by two strong silken threads called gridle.
Tumbler : Pupa of mosquito is called tumbler. It is an obtect type of pupa. It
is comma shaped with rudimentary appendages. Breathing trumpets are
present in the cephalic end and anal paddles are present at the end of the
abdomen. Abdomen is capable of jerky movements which are produced by the
anal paddles. The pupa is very active.
0 Comments