Collection of pupae
Time of larviposition was recorded, including whether or not larvae
produced were viable (Baldry et al. 1992). Production of
non-viable offspring was considered a spontaneous abortion (‘abortion’
hereafter). It was not possible to record egg abortions as they were not
visible on the pupal tray due to their small size. For pupae collected
at the start of the week (Monday morning), we consulted the last 72
hours of video recordings to determine the exact day of larviposition
(S1 File). For aborted larvae, however, because of the small size of
early larval stages, we could not determine the abortion date for those
aborted over the weekend. Hence, they could have occurred on either
Friday post-feeding, Saturday, Sunday or Monday pre-feeding. They were
recorded as occurring on the Friday.
We measured the wet weight of pupae, to 0.1 mg, as an indicator of pupal
size and therefore a proxy for maternal investment. Wet weight was
previously found to correlate with pupal volume in field flies and does
not require destructive sampling (Hargrove 1999). Of the pupae produced,
we selected 70% of samples to track emergence, assigned using a random
number generator in the data recording spreadsheet (Fig 1). The
remaining 30% we destructively sampled for fat analysis in order to
quantify how wet weight correlates with fat reserves.