Insect mouthparts.pdf

Morphology of Insect mouthparts

2. Presented by
Ch.NagaSatyasri
M.Sc(Ag)-I year
STUDY OF MOUTH
PARTS IN INSECTS

3. DIFFERENT TYPES OF
MOUTHPARTS
Biting and Chewing type
Chewing and lapping type
Lacerating and sucking type
Piercing and sucking type
Sponging type
Siphoning type
Mask type
Degenerate type

4. BITING AND CHEWING MOUTH
PARTS
ORDER: ORTHOPTERA, eg: grasshopper
Mouth parts are typical mandibulatetype useful
for biting, chewing and consisting of
Labrum (upper lip)
Mandibles (Istpair of jaws)
Maxillae (first maxilla-2nd pair of jaws)
Labium (second maxilla or lower lip-3
rd
pair of
jaws)
Hypopharynx(tongue).

5. Labrum:
A simple plate like structure situated below
the clypeus on the anterior side of the head
and moves up and down.
The functions of the labrum are to close the
front of the moth cavity, protect the mandibles,
guide the food into the mouth.

6. Mandibles:
Paired un segmented, heavily sclerotizedjaws
lying immediately below the labrum.
Articulate with the headcapsuleside wise by
means of two joints; ginglymusand condyl.
Possess two types of teeth; incisors and
molars.
Adopted for cutting and masticating the food
material.

7. Maxillae:
Paired segmented structures lying below the
mandibles.
Each maxilla bears a feeler-like organ, the palpus
(which discharges a gustatory or tasting function).
Have two segments, the basal cardoand apical
stipes.
Palpusarise on a lobe of the stipescalled the
palpifer.
Stipesbears two lobe like structures at its apex
(outer simple galeaand inner jaw like structure
lacinia)
Functionally maxillae are of accessory jaws, their
laciniaaiding mandibles in holding the food.

8. Hypopharynx:
A short tongue like structure located above
the labium and between the maxillae.
The ducts from salivary glands open on or
near the base of hypopharynx.
Labium:
Lies behind the maxillae
Derived by the fusion of the second pair of
maxillae, hence also referred as the second
maxillae.

9. Divided by transverse suture (labial suture) into
two portions, basal postmentumand distal
prementum
Postmentumis usually divided into basal
submentumand distal mentum.
Prementum bears a pair of palpicalled labial
palpiand a group of apical lobes which
constitute the ligula.
Labial palpiarise on lateral lobes of the
prementum called palpigers.
Ligulaconsists of a pair of small lobes in the
middle, inner glossaeand outer paraglossae.
Labial palpiact as sense organs comparable to
the gustatory function of maxillary palpi.

10. Biting and chewing mouth parts

11. Insect Mouthparts
Labrum
Mandible
1st Maxilla
Labium (2nd maxilla)
Hypopharynx

12. Biting and chewing
mouthparts

13. Feeding mechanism :
Thelabrumorupperliphelpstheinsecttopullthe
foodintothemouth.
Mandiblesmasticatethefood.Theycutoffthefood
material.Smallteethpresentineachmandiblework
againstthoseoftheoppositeforeffectivegrinding.
Themaxillaeaidinholdingthefoodinmouthwhileit
chewedbymandibles.Theyalsoaidinbreakingup
thefood.
Bothmaxillaeandmandiblesmovesideways.
Labialpalpiworkssimilartothatofmaxillarypalpi.
Themaxillaeandlabiumhelpsinpassingthefood
intooesophagus

14. Grasping Type
Mandibles –slender, elongate, curved at their
ends bearing 1-3 sharp teeth. Extreme
development in males of many of the Lucanidae
and Chiasognathus
Maxillae –Single-lobed in lucanidscalled “mala”
Other parts–normal
Soldiers of Termites –Large, twisted,
asymmetrical mandibles with peculiar “snapping
action”. Some posses salivary or frontal glands
(adhesive secretions).
Examples : Soldier termites and stag beetles
(Lucanids)

15. Grasping Type
Soldier termite

16. GRASPING AND SUCKING TYPE
Mandibles and maxillae –long, exerted adopted for
seizing the prey
Mandibles –sickle –shaped and armed with teeth.
Grooved along their ventral surface and a lobe or
maxillae (perhaps lacinia) similar in size and shape fits
each groove forming a pair of imperfect suctorialtubes.
Blood imbibed by means of pumping action of pharynx.
Maxillary palpi–absent; labium –greatly reduced,
labial palps-variable or aborted
Examples: larvae of Antlionsand Aphid lions,
Lampyridlarvae.

17. GRASPING AND SUCKING TYPE
Antlionlarva

18. . SCRAPING TYPE
Mouthparts–adopted for dealing with liquid and soft
food.
Labrum –membranous and concealed
Mandibles–membranous, thin, sometimes
concealed, incapable of biting, used for mouldingwax
mud, dung etc.
Maxillae –inverted with long hairs, used for feeding
pollen (in pollen feeders)
Ligulasometimes atrophied, galeae–free
Examples: Pollen feeders (e.g. Yucca moth,
Tegeticulayuccasellafeeding on Yucca filamentosa)
dung beetles (Scarabaeinae)

19. Dung beetle

20. BITING AND MASTICATION AND LICKING
TYPE
Mandibles –eventually biting nature
Maxillae–Comparatively little modified, palpsare 6-
segmented
Laciniae–reduced to small scales
Galeae–broad membranous lobes
Labium–large shield –shaped prementum; bearing
4-segmented labial palps
Ligula–curiously elongated paraglossaeand a wide
bilobedglossa.
Examples: Vespulagermanica(worker) and the
Primitive bee (Hylaeus)

21. BITING AND MASTICATION AND LICKING TYPE
Vespulagermanica

22. SIPHONING OR SIMPLE SUCKING
TYPE
Order: Lepidoptera,e.g.: butterflies and moths
Mandibles totally absent. Majority of Lepidoptera
mandibles are wanting and maxillae to form a
suctorialproboscis
Maxillae is composed of elongated galea. Each galea
of maxilliaelongated, semi-circular towards inner
side. Galeaof both the sides meet together forming
into a tubular structure, proboscis.
Observe the coiled proboscis beneath the head.
Liquid food is imbibed through groove formed by
galea

23. All other mouth parts highly reduced.
When fully developed mouth parts, maxillary palpiare
5 or 6 segmented.
Labium reduced to small ventral plate.
Hypopharynxis present on floor of mouth.
Feeding mechanism:
When not in use, proboscis is spirally coiled and
beneath the thorax.
It presents an extraordinary variation in length. Eg.
Sphingidae, Danaus.
According to Breitenbackthey are often developed
into denticulate spines.
Proboscis extended by blood pressure. Eastham and
Eassa(1955).

25. SIPHONING
OR SIMPLE
SUCKING
TYPE

26. PIERCING AND SUCKING TYPE
Order : Hemiptera
Mandibles and maxillae being modified to form
slender bristle like styletwhich rest in grooved labium.
Both pairs of styletsare hollow seta-like structures.
These styletsback into prothorax(Cranston and
Sprague, 1961).
Styletswithdrawn into a pocket connected with the
channel of the labium.
Mandibularstyletsform anterior (outer) pair and
posterior pair of stylets(inner) constitute part of
maxilla.
Dorsal styletas a suction canal.

27. Ventral styletas a salivary canal.
Labium no part in perforating the tissue of host plant.
Hypopharynxis highly specialized in Hemiptera.
Salivariumis modified into a powerful salivary pump.
Feeding mechanism:
At rest rostrum is flexed beneath the body.
In most Hemipterastyletsare only slightly longer than
the rostrum. Eg. Aphididae, Lygus.
In Coccoideastyletsare forced deeper and deeper
into the plant.
Mandibles are first pushed then followed by maxillae.

28. PIERCING
AND
SUCKING
TYPE

30. SPONGING TYPE
Eg: HOUSEFLY.
Mandibles are absent.
Maxillae are represented by a pair of maxillary palp.
Labium is divided into basal rostrum, middle haustellum
and distal labellarlobes. Labella are tranversedby
small channels known as pseudotrachiawhich
converge at one point and open into the food channel.
Epipharynxand hypopharynxtogether form the food
channel which leads to Oesophagous

33. Mode of feeding: It is used for food which is
either liquid or readily soluble in saliva. While
feeding after dissolving the food by saliva, the
labella is thrust into the liquid food as a result
the pseudotracheaeget filled with the liquid by
capillary action. The food is then passed
through the food channel to the Oesophagous
Eg. Houseflies

34. CHEWING AND LAPPING TYPE
Eg: HONEYBEES
Mandibles and labrum are of chewing type and
help in bolding the food.
Maxillae and labrum are elongated and united.
There are suspended from the cranium and
articulate to it through the base of the maxillae.
Maxillae:
Palpsare very small
Galeawith its concaves inner surface forms a
roof over the glossaand fits length wise against
labial palps. In this way a food channel is formed.

35. Labium:
Palpsare long and form food channel with galea
Glossaeare fused to form a channeled organ
termed as alaglossawhich can reach deep into
nectar of blossoms.
Mode of feeding: The mandibles and labrum
help in holding food / prey. In honey bees the
labrum is used for molding wax into cells.
Regarding intake of nectar king, Imm’sand
Snodgrass gave their own view.

36. King’s Views: After sucking the nectar with
the tip of glossa, it is retracted into labial palp
and galea, where the latter squeezes off the
nectar which is deposited at the base of the
glossain a small cavity formed by the
paraglossa. Finally as a result of bending of
the labium upward, the base of the glossa
comes near the mouth cavity and the
accumulated nectar is sucked into the
Oesophagousby the action of the pharyngeal
pump.

37. CHEWING AND LAPPING TYPE

38. MASK TYPE
Thesearemodifiedbitingandchewingtype.
Labrum,mandibles,maxillae,hypopharynxaretypically
developedasinbitingtypeofmouthparts.
Labium–inthenymphthisorganismodifiedforprehensile
purposeandisknownasmask.
Theprementumandpostmentumaremarkedlylengthened.
Theligulaisundividedandrepresentedbyamedianlobewhich
isfusedwiththeprementum.
Thelabialpalpiaremodifiedtoformalaterallobeseachofwhich
carriesonitsoutersideamovablehook.
Thesehookswhichhelpincatchingtheprey.
Ex:Dragonflynaiads.

39. Naiad

40. DEGENERATE TYPE
Eg: MAGGOTS
In maggots, a definite head is always absent.
The mouth parts are highly reduced and are
represented y one or two mouth spines or hooks.
Hypopharynx, clypeus and associated scleritesof
the head form upper pharyngeal skeleton or
hypopharyngealscleritearound the beginning of
the alimentary canal.

41. DEGENERAE TYPE

42. Lacerating and sucking or rasping
and sucking type
Order: Thysanoptera. eg. Thrips.
Labrum, labium and bases of maxillae combine
and unite to form a mouth cone.
Both maxillae and the left mandible are modified
as stylets.
Right mandible rudimentary.
Hypopharynxreduced.

43. Thrips

44. Chewing and Lapping Type
•(e.g. Honey bee)
•This type of mouthparts are possessed by
Honey bee wherein, the Labrum& Mandibles
remain more or less similar as that of the
Generalized type, whereas the other
components viz. (Maxillae & Labium) are
greatly modified.
•Labrum; It is narrow and quite simple.
Mandibles: They are blunt dumbleshaped and
are not toothed.
•They are not used for feeding but are useful for
moulding wax into cells for comb (next)
building.

45. Libium: The glossaeare greatly elongated to
form a hairy, flexible tongue. The glossa
terminates into a small circular spoon shaped
lobe called flabellum, which is useful to lick the
nectar. Labial palms are elongate and four
segmented.
MaxillolabialStructures: MaxillobialStructures
are modified to form the lapping tongue. The
tongue unit consists of the two galeaeof
maxillae, two labial Palpiand elongated flexible
hairy glossaof labium.

46. Feeding Mechanism: The galeaefit tightly
lengthwise, against the elongated labial palps
and they in turn roof over the elongated
glossae(tongue) to form a temporary food
channel through which saliva is discharged. The
tongue (glossae) is trusted into flower, which
gets smeared with nectar. It is then retracted
between labial palps& galeae. Nectar is then
squeezed by galeaeand is deposited in the
cavity formed by the paraglossae. Accumulated
nectar is then drawn into oesophagus by the
pharyngeal pump.

47. Honey bee

48. Cheliceratemouthparts
Itmeansthe‘claw-bearers’,inreferencetothe
claw-orfang-shapedmouthpartsthat
characterizethegroup.
cheliceratesaredefinedbytheirjaws.Whereas
mostmodernarthropodshavechewing
mouthpartscalledmandibles,thejawsof
chelicerates—thechelicerae,whichgivethe
groupitsname—areusuallyshapedlikeclaws
orpincersandaremostlyusedforgraspingand
tearinguppreyMostcheliceratesarepredators,
andmostcatchlivepreywhichisthenchewedor
dismemberedusingthechelicerae.

49. The aquatic horseshoe crabs and eurypterids
haverowsof teeth on the inner sides of their
leg coxae(the segment where the leg joins the
body), and these ‘gnathobases’ chew up the
food before it is passed to the mouth.
This style of feeding is only practical in water;
arachnids tend instead to regurgitate enzymes
onto their food and begin the digestion process
in front of the mouth, sometimes in a special
‘preoralcavity’.

50. Numerousgroupsofmiteshavegivenupon
beingpredators,andasagrouptheyshowthe
greatestdiversityofhabitatsandfeeding
strategies:theyincludeblood-suckingparasites
andfeedersonplantsapordecayingmaterial.
Seaspidersuniquelyhaveaproboscisandeither
preyonsedentaryanimals,suckinguptheirbody
fluids,or—insomecases—activelyhunt
movingprey.

51. Cheliceratemouthparts

54. In carnivorous chewing insects, the mandibles can
be modified to be more knife-like, whereas in
herbivorous chewing insects, they are more
typically broad and flat on their opposing faces
(e.g., caterpillars).
In male stag beetles, the mandibles are modified to
such an extent that they do not serve any feeding
function, but are instead used to defend mating
sites from other males.

55. STAG BEETLE

56. In ants, the mandibles also serve a defensive
function (particularly in soldier castes)

57. Soldier castes

58. In bull ants, the mandibles are elongate and
toothed, used as hunting (and defensive)
appendages.

59. In bees, which feed primarily by use of a
proboscis, the primary use of the mandibles is to
manipulate and shape wax, and many wasps have
mandibles adapted to scraping and ingesting wood
fibres.

60. Potter wasps use their mandibles to mix droplets of
water with clay while constructing a nest.

61. The defining feature of the orderHemipterais the
possession of mouthparts where the mandibles and
maxillae are modified into a proboscis, sheathed
within a modified labium, which is capable of
piercing tissues and sucking out the liquids. For
example, true bugs, such asshield bugs, feed on
the fluids of plants. Predatory bugs such
asassassin bugshave the same mouthparts, but
they are used to pierce the cuticles of captured
prey.

62. Assassin bug

63. Myriapodmouthparts are similar to those of
chewing insects, although there is some variation
between the myriapodclasses. A labrumis present
but sometimes is not obvious and forms an upper
lip, often in association with anepistome. The
labium is formed by first maxillae in diplopoda
forming the gnathochilarium. The preoralcavity so-
formed contains paired mandibles and any maxillae
which are present.

64. Myriapod

65. Forcipules
Centipedes, in addition to their mouthparts, possess
a pair of "poison claws", or forcipules. These, like
themaxillipedsof crustaceans, are modified legs
and not true mouthparts. The forcipulesarise from
the first body segment, curving forward and to the
midline. The tip is a pointed , which has an
opening from a venom gland. The forcipulesare
used to capture and poison prey.

66. Ventral view of forcipulesof a centipede,
arising from the first body segment

67. Crustaceanscomprise a number ofclasses, with
various feeding modes supported by a range of
adaptations to the mouthparts. In general, however,
crustaceans possess paired mandibles with
opposing biting and grinding surfaces. The
mandibles are followed by paired first and second
maxillae. Both the mandibles and the maxillae have
been variously modified in different crustacean
groups for filter feeding with the use of setae.

69. Insects provide an astonishing variety of
unusual structures from feathery antennae to
mouth parts that look like they belong to some
creature.
Here we have the elaborate mouth parts of a blowfly