Nectar feeding by the hovering hawk moth Macroglossum stellatarum: intake rate as a function of viscosity and concentration of sucrose solutions

JOSENS, R; FARINA, W

JOURNAL OF COMPARATIVE PHYSIOLOGY A-SENSORY NEURAL AND BEHAVIORAL PHYSIOLOGY

Springer

Año: 2001 vol. 187 p. 661 - 665

0340-7594

 Although nectar feeding in insects has long been studied, the knowledge of teh effect of nectar energy content on the ingestion dynamics separately from teh viscosity on the fluid is very limited. To determine teh effects of both factors on the feeding behavior of the hovering hawk moth Macrolossum stellatarum, we developed a method to independently manipulate sucrose concentrarions and viscosity. The intake rate was analyzed as a function of sucrose concentration, the concetration at constant viscosity (kept constant by adding tylose, an inert polysaccharide), and of the different viscosities of a 30 % weight/weight (w/w) sucrose solution (by adding different amounts of tylose). By increasing the concentration, and thus its viscosity, the solution intake rate (in microl/s) decreased beyond a 20% w/w sucrose solution. For a 30% sucrose solution, the intake rate decreased with increasing viscosity. At constant viscosity, the solution intake rate decreasde beyond a 30% w/w sucrose solution. However, if we considered the quantity of sucrose ingested per unit time (sucrose intake rate), the same fitted maximum was attained for both series in which the sucrose concentration changed (33.6%w/w). Results suggest that the gustatory input affects the dynamics of fluid ingestion separatele from the viscosity.