Fatty acids

Definition

Carboxylic acids with aliphatic hydrocarbon chains, saturated or unsaturated, that serve as core building blocks of lipids and key metabolic substrates in arthropods. In insects and arachnids, fatty acids function in energy storage, cellular membrane structure, waterproofing of the cuticle, and as precursors for pheromones and defensive compounds. Essential fatty acids such as linoleic acid and α-linolenic acid must be obtained from dietary sources in many insects, making them critical in nutritional ecology and artificial rearing protocols.

Etymology

From fat (Old English fætt, meaning containing fat or oil) + acid (Latin acidus, sour), referring to their derivation from natural fats and their acidic carboxyl group.

Example

The cuticular hydrocarbons and wax esters that prevent desiccation in desert tenebrionid beetles are synthesized from long-chain fatty acids; honey bees require dietary polyunsaturated fatty acids for proper brood development and immune function.

Synonyms

• carboxylic fatty acids

Related Terms

• lipids
• triglycerides
• phospholipids
• cuticular hydrocarbons
• pheromones
• essential fatty acids
• metabolism
• overwintering physiology
• nutritional ecology

Usage Notes

Specialists distinguish saturated (no double bonds), monounsaturated (one double bond), and polyunsaturated (multiple double bonds) fatty acids by their metabolic roles and physical properties. In arthropod studies, chain length and desaturation patterns are often diagnostic for species, caste, or physiological state. Do not confuse free fatty acids (non-esterified) with those bound in complex lipids; the former are more metabolically active and can be cytotoxic at high concentrations.