Effect on path length by silencing of gustatory-receptor-expressing GRNs. Mean±s.e.m. path lengths are shown. Effect on path length by silencing of gustatory-receptor-expressing GRNs. Mean±s.e.m. path lengths are shown. A significant difference between tetanus toxin (TNT) and impotent tetanus toxin (IMPTNT) was noted in Gr43aGAL4, Gr64aGAL4 and Gr64e-GAL4 flies, whereas silencing of Gr5a had no significant effect. Tests were performed using 200 mmol l−1 sucrose (Student's t-test, **P<0.01, n=10). Satoshi Murata et al. J Exp Biol 2017;220:3231-3237 © 2017. Published by The Company of Biologists Ltd