Feeding & Digestion - Insect Gut Morphology & Diet (Vocabulary)

Vocabulary flashcards covering mouthparts, diets, gut regions, and saliva features from the lecture notes.

Mouthparts (ancestral form: chewing)

Chewing is the original mouthpart form; many insects have modified mouthparts, and some adults do not feed.

Piercing and sucking

Mouthparts adapted to pierce tissues and suck fluids (seen in Heteroptera and some Diptera).

Rasping and sucking

Mouthparts adapted to rasp surfaces and suck up fluids (notably in thrips).

Chewing and lapping

Mouthparts combine chewing with licking/lapping for fluid intake (as in bees).

Siphoning

Mouthparts adapted to siphon nectar or fluids (common in Lepidoptera).

Detritivores

Organisms that consume soil containing dead/decaying plant and animal debris and associated microorganisms.

Fungivore (mycophagy)

Diet that involves consuming fungi.

Xylophagous (xylophagy)

Diet that involves consuming wood.

Coprophagous (coprophagy)

Diet that involves consuming dung or excrement.

Necrophagous

Diet that involves consuming dead or decaying animals.

Gut morphology

Insect gut structure and function reflect diet; patterns relate to solid vs liquid and plant vs animal food, with holometabolous insects potentially occupying different categories at different life stages.

Solid-diet gut

Wide, straight, short gut with strong musculature and protection from abrasion.

Liquid-diet gut

Long, narrow, convoluted gut designed for maximal contact with liquid food and water removal to concentrate nutrients.

Plant diet characteristics

Low nutrient levels, continuously available, no need for large gut storage.

Animal diet characteristics

High, well-balanced nutrients, intermittently available, requiring larger gut storage capacity.

Foregut

Ingestion, storage, grinding, and transport of food to the midgut.

Midgut

Site of digestive enzyme production and nutrient absorption.

Hindgut

Absorption of water, salts, and other valuable molecules; end segments of digestion.

Pharynx

Anterior part of the foregut involved in ingestion.

Esophagus

Tube connecting the pharynx to the crop; transports food.

Crop

Food storage area in the foregut.

Proventriculus

Grinding organ (gizzard-like) between foregut and midgut.

Ventriculus

Main digestion section of the midgut (stomach/gastric chamber).

Gastric caecum

Digestive pouch connected to the midgut, increasing surface area for digestion.

Ileum

Hindgut segment involved in continued digestion/absorption.

Cecum

Storage sac associated with midgut regions in some insects.

Peritrophic matrix

Thin membrane that separates midgut epithelium from food, protecting tissue and aiding digestion.

Malpighian tubules

Excretory organs at the junction of the midgut and hindgut; regulate salt, water, and nitrogenous wastes.

Pylorus

Muscular sphincter between the midgut and hindgut controlling flow.

Rectum

Final hindgut segment where water reabsorption and waste processing occur.

Colon

Hindgut segment involved in water and electrolyte reabsorption and waste transport.

Anus

External opening at the end of the digestive tract.

Saliva

Fluid aiding ingestion: dilutes food, adjusts pH/ions, and contains digestive enzymes.

Hemipteran saliva

In some hemipterans, digestive enzymes are secreted into food; saliva is alkaline and can form a proteinaceous sheath.

Proteinaceous saliva sheath

Solidifying saliva around mouthparts that guides stylets, prevents fluid loss, and reduces plant defenses by absorbing necrosis-inducing compounds.

Labrum

Upper lip component of the mouthparts.

Beak

Elongated piercing mouthpart used to penetrate tissues.

Stylets

Thin piercing structures that penetrate to access fluids.

Labium

Lower lip supporting mouthparts; can contribute to forming a sheath around stylets.

Monophagous

Feeding on a single prey or plant species.

Oligophagous

Feeding on a few closely related species, usually within the same family.

Polyphagous

Feeding on many different species across different families.

Holometabolous insects and diet

Insects undergoing complete metamorphosis can occupy different dietary categories at different life stages.