Electrophysiological responses of the terminal sensilla on the maxillary palps of Locusta migratoria (L.) to some electrolytes and non-electrolytes.

It has been shown that the maxillary palps of Locusta migratoria (L.) play an important part in food selection when the insect has not been deprived of food for a long period (Blaney & Chapman, 1970; Blaney, Chapman & Wilson, 1973). The receptors primarily concerned are those on the flexible dome at the distal tip of the palp, and in the fifth instar larvae of Locusta there are about 370 of these sensilla on the dome of each maxillary palp. The fine structure of these sensilla (Blaney, Chapman & Cook, 1971) corresponds to that generally ascribed to contact chemoreceptors (Lewis, 1970; Slifer, 1970) and a chemoreceptive function has been confirmed by Haskell & Schoonhoven (1969) using electrophysiological techniques. This paper describes part of an electrophysiological study to determine the role of these receptors in food selection, and in this preliminary investigation an examination is made of the responses of the receptors to some electrolytes and non-electrolytes.