Trichomes and insects

Definition

The functional and ecological relationships between plant trichomes—hair-like epidermal outgrowths—and insects, encompassing defensive, nutritional, mutualistic, and habitat-provisioning interactions. Trichomes may be glandular (secretory, producing secondary metabolites, resins, or mucilage) or non-glandular (structural, providing physical barriers). Insects respond to trichomes through behavioral avoidance, morphological adaptations (such as specialized tarsi or cutting mandibles), or exploitation (using trichome exudates as food or nesting material). These interactions shape herbivory patterns, pollinator fidelity, predator-prey dynamics, and plant community structure.

Etymology

Trichome: Greek trichōma, from thrix (hair); insect: Latin insectum, from insecare (to cut into).

Example

Glandular trichomes on wild tomato (Solanum habrochaites) secrete acylsugars that repel whiteflies (Bemisia tabaci) and trap small-bodied insects; conversely, the specialist herbivore Manduca sexta (tobacco hornworm) possesses hooked tarsal claws that enable locomotion on dense tomato trichomes, demonstrating an evolutionary arms race between plant defense and insect counter-adaptation.

Related Terms

• plant defense
• glandular trichome
• non-glandular trichome
• herbivory
• induced defense
• secondary metabolite
• host-plant resistance
• Phytophagy
• epidermal outgrowth
• mutualism
• tritrophic interaction

Usage Notes

The phrase typically emphasizes bidirectional interactions rather than trichomes alone. Specialists distinguish between constitutive trichome defenses (always present) and inducible responses triggered by herbivory. 'Pubescence' is sometimes used interchangeably with dense non-glandular trichomes, though pubescence strictly refers to the hairy appearance rather than individual structures. When discussing insect resistance breeding, 'trichome-based resistance' specifies the mechanism, whereas 'antixenosis' or 'antibiosis' describes the outcome. Note that some insects actively seek trichome-rich plants: certain parasitoid wasps use trichome density as a cue for host presence, and specialist herbivores may sequester trichome compounds for their own defense.