Water Bound in Elytra of the Weevil Liparus glabrirostris (Küster, 1849) by NMR and Sorption Isotherm (Coleoptera: Curculionidae)

Abstract

Scanning electron microscopy micrograms of the elytra of Liparus glabrirostris showed a different dorsal and ventral surface and a multilayered inner structure. Hydration kinetics, sorption isotherm, and proton free induction decays are measured for hydrated elytra of the weevil species Liparus glabrirostris (Coleoptera: Curculionidae) in the atmosphere with controlled humidity. Very tightly bound water fraction with the mass ∆m/m0 = 0.037± 0.004, and very short hydration time, tightly bound water ∆m/m0 = 0.034± 0.009, and hydration time t1 = (3.31± 0.93) h, and finally loosely bound water fraction with t2 = (25.5± 7.8) h were distinguished. The sorption isotherm is sigmoidal in form, with the mass of water saturating primary water binding sites equal of ∆M/m0 = 0.036. The proton free induction decays show the presence of solid signal (well fitted by a Gaussian function) from elytra (T ∗ 2G ≈ 18 μs), the immobilized water fraction (T ∗ 2L1 ≈ 120 μs) and mobile water pool (T ∗ 2L2 ≈ 300 μs). The hydration dependence of the water bound in elytra of L. glabrirostris, L/S is linear showing the absence of water-soluble solid fraction and negligible content of water pool “sealed” in pores of the structure.