Expression of Ir92aScer\UAS.cBa under the control of Scer\GAL4Ir76a.PB results in the ac4 sensilla becoming sensitive to stimulation by ammonia in an olfactory assay. 1,4-diaminobutane does not activate the ac4 sensilla expressing Ir92aScer\UAS.cBa under the control of Scer\GAL4Ir76a.PB.