discs were counted, and partial discs were pressed between microscope slides and scanned
(Visioneer OneTouch scanner). Surface area of each disc fragment as a proportion of uneaten
leaf disc surface area was determined using ImageJ (1.37v). A sample of each size of leaf discs
was dried daily to constant mass at 60 C and weighed. The approximate daily dry matter intake
for each insect was then calculated as number of discs consumed estimated dry mass per disc.
Daily mass-specific intake was calculated using estimates of daily body mass computed from
periodic body mass measurements, as described below.
Each insect was weighed weekly, at the end of each instar (defined as the day when no
food was eaten in preparation for ecdysis), at first oviposition, and at death. Insects were also
photographed at these times (Nikon Coolpix 3200), and body lengths at the end of each life-
history stage were then determined using ImageJ. Body length was measured as the distance
between the base of the antennal socket and the end of the tergum on the terminal abdominal
segment. Measurements of body size at the end of each instar for AL insects were then fitted to
the allometric equation ln(y) = ln(a) + bln(x), where y = body mass and x = body length. Relative
body mass (as an index of body condition) of insects in all treatment groups at the adult molt was
assessed as the ratio between measured body mass and body mass predicted by the AL allometric
equation (Perrin et al. 1990). Specific growth rate (SGR) of each insect in each life-history stage
was calculated as:
SGR = 100*(lnBMf lnBMi)/t
where BMf is body mass at the end of a stage, BMi is body mass at the beginning of a stage, and
t is the time in that stage.
During each day of adulthood, all eggs laid by each female were collected and individually
weighed. Average egg mass was calculated as the mean mass of individual eggs for each female.