One day prior to experimentation, female B. tryoni were
removed by placing a 1 L plastic container into the cage. The
container was baited with 1 mL of apple juice applied to a
rolled paper towel taped onto the lower side of the container
lid. Flies entered through two small entrance holes made of
irrigation-pipe joiners (13 mm × 10 mm) at the opposite side
of the container wall. Almost all flies collected were females.
Flies were then transferred into cages (9 L plastic containers
covered with mesh for ventilation) in a cold room (7–8°C).
Each cage contained either 20 (in bioassays using apple) or 40
(in bioassays using artificial fruit) females, yeast hydrolysate
and sugar cubes. Water was sprayed onto the cage walls. Cages
were transferred into a room maintained at 25 ± 1°C and 14:10
(light : dark) prior to experimentation.
Bioassays using artificial fruit
Essential plant and vegetable oils were tested separately at
five concentrations on 14-to-21-day old B. tryoni females. The
vegetable oils were tested at concentrations of 1–5 mL/L,
except for palm, which was tested at 4–10 mL/L. The essential
oils were tested at 2–18 mL/L for lemon-scented tea tree,
peppermint and honey myrtle, 10–50 mL/L for lemon-scented
gum, lemon-scented ironbark, narrow-leaved peppermint and
broad-leaved peppermint, and 20–100 mL/L for lemon. Palm
oil was heated in a microwave oven for 1 min prior to use, as
it solidified in storage.