Focussing on the contact: the insect tarsi and their environment.

Jabaud, Laure; Moussian, Bernard

Immediate contact of the proximal environment occurs in insects at the tips of their legs, the tarsi. In principle, they are a chain of usually five cuticle tubes equipped with surface structures mediating adhesion to the substratum and sensory and glandular cells that serve perception of and response to environmental cues. To accommodate these functions in an ecological context, the decoration of tarsi with these elements is species dependent. The diversity of tarsi evolved through modulation of patterning and morphological events during formation that are well studied. By contrast, implementation of these programs by functional differentiation has been less analysed. As appendages touching the source of nutrition and potentially harmful xenobiotics including plant secondary metabolites and anthropogenic molecules (pollutants and insecticides), tarsi play a dual role: they prevent penetration of toxins but allow uptake and detection of nutrients and water. The physico-chemical barrier against especially hydrophilic molecules is constituted by the cuticle that consists of a chitin-protein matrix and surface lipids that may absorb but not repel hydrophobic molecules. Entry sites of xenobiotics are potentially cuticular pore canals that serve as routes for lipid deposition, pores at the tips of gustatory cells and glandular ducts. New data suggest that tarsi have the ability to deposit proteins and lipids that besides lubrication and trailing assist insect defence systems through extracorporeal detoxification. The aim of this review is to reveal questions at the rather neglected interface of molecular genetics, histology and function of tarsi for formulation of modern insect population management strategies.

METABOLITES; PLANT metabolites; INSECT populations; XENOBIOTICS; MOLECULAR genetics

Entomologia Generalis, 2024, Vol 44, Issue 6, p1409

0171-8177

Academic Journal

10.1127/entomologia/2024/2860