EFFECTS OF AGE, SEX AND HUNGER ON THE ANTENNAL OLFACTORY SENSITIVITY OF TSETSE-FLIES

The effects of age on electroantennogram (EAG) responses were investigated in male and female Glossina morsitans morsitans and comparative studies on the effects of starvation and sex on the EAG in G.m.morsitans, G.austeni, G.tachinoides and G.fuscipes fuscipes were made. Stimuli were the vapours of 1-octen-3-ol, 4-heptanone, 3-nonanone and acetone. EAG decreased with age in both sexes of G.m.morsitans, responses in 5-day-old flies already being significantly lower than those in 1-day-old flies. In G.m.morsitans and G.tachinoides, EAG responses of males were higher than those of females. In G.austeni and G.f.fuscipes, however, the reverse was found. With increasing starvation EAG sensitivity increased in both sexes of G.m.morsitans and G.tachinoides. In G.austeni and in G.f.fuscipes no clear effects of starvation were observed. Response spectra of the individual species to the four odour substances did not change with increasing hunger. It is concluded that receptor sensitivity may be modulated depending on the insect's needs. Possible mechanisms of regulation and significance of this modulation are discussed