Fig. 1. ¹³C values (mean ± s.e.m.) of inseminated spermathecae from experiment 1. The adult labelling treatments were: U–U, no label; U–L, adult labelling only; L–U, larval labelling only; and L–L, larval and adult labelling. N, number of samples analysed. The dotted line indicates the threshold value of 2 s.d. above mean ¹³C of virgin females. Virgin (V) and standard (St) samples are included. Values excluded from analyses are: 9.97 (L–L), –12.51 (V) and, –13.29, –18.20 (St). Dissection treatments: I, females dissected immediately after mating; II, females isolated and dissected 3 days after mating. Values with different letters are significantly different at P<0.05 for I (lower case), or II (upper case).