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

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 Δ m/$m_0$ = 0.037 ± 0.004, and very short hydration time, tightly bound water Δ m/$m_0$ = 0.034 ± 0.009, and hydration time $t_1^{h}$ = (3.31 ± 0.93) h, and finally loosely bound water fraction with $t_2^{h}$ = (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 Δ M/$m_0$ = 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 ($T_{2L_1}$* ≈ 120 μs) and mobile water pool ($T_{2 L_2}$* ≈ 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.