OA inhibition requires neuropeptides encoded by nlp-6, 7, 8 and 9 released from multiple sensory neurons. (A–C) Wild-type, mutant and transgenic animals were examined for aversive responses to 100% 1-octanol off food in the presence and absence of OA (4 mM). Black bars, wild-type or null animals; grey bars, wild-type or null animals expressing a transgene; hatched bars, RNAi in wild-type animals. Data are presented as a mean±s.e. and analysed by two-tailed Student's t-test. *P<0.001, significantly different from wild-type animals under identical test conditions; **P<0.001, significantly different from null animals under identical test conditions; ***P<0.01, significantly different from wild-type animals under identical test conditions.