RESPONSES OF MAXILLARY STYLOCONIC RECEPTORS TO STIMULATION BY SINIGRIN, SUCROSE AND INOSITOL IN 2 CRUCIFER-FEEDING, POLYPHAGOUS LEPIDOPTEROUS SPECIES

Chemosensory cells in the lateral and the medial styloconic sensillia on the galea of larval Mamestra configurata and Trichoplusia ni were i nvestigated electrophysiologically. Sinigrin, sucrose, inositol and po tassium chloride (KCl) were tested on both sensilla of each species. O ne of the four cells in both the lateral and medial sensilla of T. ni was sinigrin-sensitive, whereas in M, configurata, one cell in only th e lateral sensillum was sinigrin-sensitive. The lateral sinigrin-sensi tive cell of T. ni was eightfold more sensitive than the corresponding cell of M. configurata. One cell in the lateral sensillum of both spe cies was sucrose-sensitive. The medial sensillum of M. configurata hou sed an inositol-sensitive cell but no cell sensitive to inositol was p resent in T. ni. One cell in the lateral and medial sensilla of both s pecies was KCl-sensitive. Adaptation and dose-response data are given for the sinigrin-sensitive cells in both species. These are discussed in the context of deterrent-sensitive cells reported from other Lepido ptera. Comparative physiological and evolutionary aspects are consider ed and the general concepts of the lepidopteran deterrent cell is disc ussed.