Fig. 4.

Exemplary recordings of electrophysiological activity in medial sensilla styloconica on the maxillary galea of fifth instar H. armigera reared on normal artificial diet, on artificial diet containing strychnine or on artificial diet containing strophanthin-K. Stimulus solutions tested and dietary experience: a Control (KCl 2 mM), normal artificial diet-reared caterpillars. b Strychnine 1 mM, normal artificial diet-reared caterpillars. c Strychnine 1 mM, caterpillars reared on artificial diet containing strychnine. d Strychnine 1 mM, caterpillars reared on strophanthin-K-containing diet. e Strophanthin-K 1 mM, normal artificial diet-reared caterpillars. f Strophanthin-K 1 mM, caterpillars reared on artificial diet containing strychnine. g Strophanthin-K 1 mM, caterpillars reared on artificial diet containing strophanthin-K. h Mixture of strychnine and strophanthin-K (both 1 mM), normal artificial diet-reared caterpillars. The onset of the stimulations occurred at the beginning of each trace. Arrows “1” and “2” point at two different spike types that strophanthin-K or its mixture with strychnine elicited from the medial sensilla styloconica. Arrow “1” refers to the more abundant larger amplitude spike type, arrow “2” refers to the less abundant smaller amplitude spike type. i Inositol 10 mM, normal artificial-diet reared caterpillars. j Inositol 10 mM, caterpillars reared on artificial diet containing strychnine. k Inositol 10 mM, caterpillars reared on artificial diet containing strophanthin-K