Mouth Parts in Insects Dr Shubhada Rahalkar Dept

Mouth Parts in Insects Dr Shubhada Rahalkar Dept. of Zoology Govt. Bilasa Girls P. G. College, Bilaspur (C. G. )

Biting and Chewing type of Mouth parts • • Mandibles: These are hard jaws meant for gripping and biting, Maxillae Secondary jaws, usually past the primary jaws for further destruction of the prey. Labrum The upper lip of the mouth, commonly found in insects Labium The lower lip of the mouth, again Ex: Cockroch, Grasshopper

Biting and Chewing type of Mouth parts

Evolution of Mouth parts Biting & Chewing Type Lapping & Chewing type Siphoning type Piercing & sucking type

Lapping and Chewing type • Maxillae and labium are fused into a single structure. The sucking tube (tongue) is formed by the fusion of the glossae of the labium, sometimes together with the paraglossae. Maxillae • galeae are enlarged and modified to form a cutting appendage used by short tongue bees to cut holes in flowers. • Laciniae are lost and the maxillary palps reduced.

Siphoning Type • The sucking tube (proboscis) is formed from the maxillae galeae with the food channel running down the center. Outer • walls of the galeae alternate scleritized and membranous rows. This arrangement facilitates coiling (think of a vacuum hose). • Extension of the proboscis is accomplished by blood pressure. Coiling is automatic.

Siphoning Type • Mandibles are completely lost in most derived groups. • Labrum is reduced to a small transverse sclerite and the labium is reduced to a small flap. • Labial palps however are large. • Sucking pump is formed by the cibarium and the pharynx. Muscle attachments are similar to those in the Hymenoptera. • The sucking pump is absent in some Lepidoptera that do not feed as adults

Piercing and Sucking type • • • Proboscis: Found in order Hemiptera 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 that feed on plants, Predatory bugs such as assassin bugs and blood sucked out, each through different tubes.

Piercing and Sucking type • • Stylet: Paired mandibles and maxillae together forming the stylet, which is used to pierce an animal's skin. During piercing, the labium remains outside the food item's skin, folding away from the stylet. Saliva containing anticoagulant s, is injected into the food item and blood sucked out, each through different tubes.

Sponging Type • • Sucking tube (proboscis) is a composite structure that includes the labrum, hypopharynx and labium. The tube is divisible into a basal rostrum bearing the maxillary palps, a median flexible hautellum and two apical labellae. The labellae are broad sponging pads, equipped with pseudotracheae along which food passes to the oral aperture Mandibles are completely lost. The sucking pump is formed from the cibarium and its dilator muscles.

Sponging Type • The labellum's surface is covered by minute food channels, formed by the interlocking elongate hypopharynx and epipharynx, which form a tube leading to the oesophagus. The food channel draws liquid and liquified food to the oesophagus by capillary action.

Biting Muscids • • • Biting Muscids (tsetse flies, stable flies) Piercing, sucking tube is a composite structure as in the lapping Muscids. However, the haustellum is elongate and rigid, and the distal labellar lobes are small and bear rows of prestomal teeth on their inner walls. The labrum and labium interlock to form the food canal within which lies the hypopharynx enclosing the salivary duct.