Egg-stage desiccation reduces developmental success and reveals line-dependent Wolbachia-associated costs in the Mediterranean fruit fly, Ceratitis capitata.

The Mediterranean fruit fly (medfly), Ceratitis capitata (Wiedemann, 1824) is a major agricultural pest, and egg desiccation is a critical constraint during handling and mass-rearing, as even short periods without moisture may compromise developmental success and downstream adult performance. The Wolbachia-medfly symbiosis is a relatively recently established artificial association, generated less than three decades ago using Rhagoletis cerasi as the Wolbachia donor. In this study, we evaluated the effects of egg-stage desiccation on developmental success and subsequent adult performance in three medfly lines differing in Wolbachia status: the uninfected Benakeion line, the wCer2-infected 88.6 line, and the wCer4-infected S.10.3 line. Eggs were exposed to desiccation for 0-24 h at 4-h intervals before transfer to larval diet, and hatching, pupation, and adult emergence were recorded. Adult survival without food and water provision was also assessed for flies emerging from the 0, 8, and 10 h egg-desiccation treatments. Under control conditions, Benakeion showed the highest hatching and developmental success, S.10.3 the lowest, and 88.6 intermediate performance. Egg-stage desiccation strongly reduced developmental success, with the clearest losses after prolonged exposure. Baseline developmental performance differed among lines, with Benakeion showing the highest egg-based success, S.10.3 the lowest, and 88.6 intermediate values. Baseline-normalized profiles and binomial generalized linear models showed that the strongest evidence for a line-specific proportional response to desiccation occurred at hatching, whereas cumulative pupation and emergence were driven mainly by desiccation duration and baseline line differences. In the adult follow-up, line identity rather than egg-stage desiccation was the main determinant of of survival under starvation-dehydration stress. Among desiccated-origin adults, S.10.3 again showed the weakest performance. These results indicate that egg-stage desiccation primarily acts at the hatching bottleneck and that the wCer4-infected S.10.3 line shows the strongest line-associated performance cost. Beyond providing insight into the Wolbachia-medfly artificial symbiosis, our findings are directly relevant to egg-handling and strain-evaluation protocols in medfly mass-rearing systems for sterile insect technique (SIT), incompatible insect technique (IIT) or other related genetic insect pest control applications.