@article {22871, title = {Haemolymph viscosity in hawkmoths and its implications for hovering flight}, journal = {Proceedings of the Royal Society B}, volume = {290}, year = {2023}, pages = {20222185}, chapter = {20222185}, abstract = {

\"Viscosity determines the resistance of haemolymph flow through the insect body. For flying insects, viscosity is a major physiological parameter limiting flight performance by controlling the flow rate of fuel to the flight muscles, circulating nutrients and rapidly removing metabolic waste products. The more viscous the haemolymph, the greater the metabolic energy needed to pump it through confined spaces. By employing magnetic rotational spectroscopy with nickel nanorods, we showed that viscosity of haemolymph in resting hawkmoths (Sphingidae) depends on wing size non-monotonically. Viscosity increases for small hawkmoths with high wingbeat frequencies, reaches a maximum for middle-sized hawkmoths with moderate wingbeat frequencies, and decreases in large hawkmoths with slower wingbeat frequencies but greater lift. Accordingly, hawkmoths with small and large wings have viscosities approaching that of water, whereas hawkmoths with mid-sized wings have more than twofold greater viscosity. The metabolic demands of flight correlate with significant changes in circulatory strategies via modulation of haemolymph viscosity. Thus, the evolution of hovering flight would require fine-tuned viscosity adjustments to balance the need for the haemolymph to carry more fuel to the flight muscles while decreasing the viscous dissipation associated with its circulation.\"

}, keywords = {AGRIUS, CERATOMIA, DOLBA, ENYO, EUMORPHA, HAEMOLYMPH, HEMARIS, HOVERING, HYLES, MANDUCA, PHYSIOLOGY, SPHINGIDAE, VISCOSITY, XYLOPHANES}, url = {https://doi.org/10.1098/rspb.2022.218}, author = {Brasovs, A. and Palaoro, A.V. and Aprelev, P. and Beard, C.E. and Adler, P.H. and Kornev, K.G.} } @article {22311, title = {Contribution of the maxillary muscles to proboscis movement in hawkmoths (Lepidoptera: Sphingidae){\textemdash}an electrophysiological study}, journal = {Journal of Insect Physiology}, volume = {49}, year = {2003}, pages = {765{\textendash}776}, chapter = {765}, abstract = {

\"The role of the maxillary muscles in the uncoiling and coiling movements of hawkmoths (Sphingidae) has been examined by electromyogram recordings, combined with video analysis. The maxillary muscles of adult Lepidoptera can be divided into two groups, galeal and stipital muscles. The galea contains two basal muscles and two series of oblique longitudinal muscles, which run through the entire length of the galea. Three muscles insert on the stipes, taking their origin on the tentorium and on parts of the cranium and gena, respectively. Proboscis extension is initiated by an elevation of the galea base caused by the basal galeal muscles. The actual uncoiling of the proboscis spiral is accompanied by rapid compressions of the stipites which are caused by two of the stipital muscles. The study provides strong support for the hypothesis that uncoiling is brought about by an increase of hemolymph pressure by the stipites forcing hemolymph into the galeae. Recoiling is caused by the contraction of both sets of oblique longitudinal galeal muscles supported by elasticity of the galea cuticle. Finally, the remaining stipital muscle pulls down the galea base which brings the coiled proboscis back to its resting position where it is held in the U-shaped groove of the labium without further muscle activity.\"

}, keywords = {ACHERONTIA, ADULT FEEDING, ADULT MORPHOLOGY, AGRIUS, MANDUCA, MUSCULATURE, NEOCOCYTIUS, NEUROLOGY, PANOGENA, PHYSIOLOGY, PROBOSCIS, SPHINGIDAE, SPHINX, XANTHOPAN}, doi = {10.1016/S0022-1910(03)00113-6}, author = {Wannenmacher, G. and Wasserthal, L.T.} }