The wax-secreting glands of Eriocampa ovata L. (Hymenoptera: Tenthredinidae): ultrastructural observations and chemical composition of the wax

Abstract

Larvae of the red-backed alder sawfly, E. ovata, in all instars except the last, exhibit external accumulations of wax. Approximately 93% of the hexane-extractable wax consists of primary alcohols ranging in chain length from 20-32 C. The major component is hexacosan-1-ol. Wax is secreted from specialized cuticular modifications found only on tergites and distinguishable from surrounding cuticle by the presence of cupular papillae. A single thread of wax exudes from the apical crater of each papilla. One feature peculiar to cuticle lining the craters is the presence of vast numbers of epicuticular filaments. These may represent channels for the transport of wax. The underlying glandular cells are modified columnar, ductless epidermal cells which, during wax secretion, exhibit organelles characteristic of lipid-producing cells. There are no wax secreting areas or similarly modified epidermal cells in the last larval instar.