pheromone glands

Definition

Specialized secretory structures that synthesize and release pheromones—volatile chemical signals used for intraspecific communication. In arthropods, these glands exhibit extraordinary anatomical diversity, ranging from single-celled epidermal glands to complex, multicellular organs with associated reservoirs, ducts, and evaporative surfaces. Location, morphology, and chemistry correlate tightly with signaling function: alarm pheromones often emanate from mandibular or abdominal glands for rapid dispersal, sex pheromones frequently involve abdominal or genital structures for controlled release, and trail-marking glands typically open at the abdomen or tarsi. Many glands are sexually dimorphic or activated only during specific behavioral states.

Etymology

From Greek pherein (to carry) + hormon (stimulating), plus glandula (Latin, small acorn/gland)

Example

The female silkworm moth (Bombyx mori) possesses a paired pheromone gland at the intersegmental membrane between the eighth and ninth abdominal segments; eversion of this gland exposes the secretory epithelium to air currents, releasing bombykol to attract males from kilometers downwind. In contrast, the honey bee's Nasonov gland, located on the dorsal surface of the seventh abdominal tergite, releases geraniol and other compounds when workers fan their wings over the exposed gland surface to orient returning foragers to nest entrances or floral resources.

Synonyms

• scent glands
• odoriferous glands

Related Terms

• Pheromone
• Semiochemical
• Exocrine gland
• Morphology
• epidermal gland
• Nasonov gland
• mandibular gland
• Dufour's gland
• pygidial gland
• sternal gland
• tarsal gland

Usage Notes

Specialists distinguish pheromone glands from general exocrine glands by functional criterion: the secretion must be demonstrated (or strongly inferred) to mediate intraspecific communication. Many structures historically called pheromone glands—such as the pygidial defense glands of ground beetles—are now recognized as primarily allomone-producing (interspecific defense) rather than pheromonal. The term "scent gland" is sometimes used interchangeably but can ambiguously include defensive secretions; context determines appropriate usage. Gland terminology often combines location and function: "mandibular gland" specifies position, while "aggregation pheromone gland" specifies function; the same structure may be referenced either way depending on disciplinary tradition.