Abstract:
Life-history parameters and the fitness of tephritid flies are closely linked
to diet. Studies of locomotor behaviour can provide insights to these links, although
little is known about how locomotor behaviour is influenced by diet. In the present
study, video recordings of Queensland fruit flies Bactrocera tryoni Froggatt (Diptera:
Tephritidae) (‘Q-flies’) that are maintained individually in cages are used to determine
how diet affects the activity patterns (flight, walking, grooming, inactivity) of males
and females at ages ranging from 4 to 30 days. The frequency and total duration of
activities over 10-min trials are affected by diet, age and sex. Supplementation of
diet with hydrolysed yeast results in a higher frequency and duration of flight in flies
of all ages and both sexes. The effect of diet on other activities varies with age.
Q-flies fed sugar only increase walking frequency steadily from 4 to 30 days posteclosion,
whereas flies fed sugar+yeast have higher walking frequencies at 4 and
10 days than flies fed sugar only, although they then exhibit a sharp decline at 30 days
post-eclosion. The frequency and duration of inactivity remain consistent in flies fed
sugar+yeast, whereas flies fed sugar only exhibit a marked increase in inactivity from
4 to 30 days post-eclosion. Compared with older flies, 4 day-old Q-flies fed sugar only
spend considerably more time grooming. The potential of activity monitoring as a
quality control test for flies that are mass-reared for use in sterile insect technique
programmes is discussed.
