Reduced cost of superparasitism is achieved in Diachasmimorpha longicaudata through an early elimination of supernumerary larvae

F. DEVESCOVI; M.M. VISCARRET; J. L. CLADERA; D. F. SEGURA

Congreso; Third International Entomophagous Insects Conference; 2013

The solitary endoparasitoid Diachasmimorpha longicaudata, used in Argentina as a biological control agent, is experimentally and massively reared on Ceratitis capitata. A potential problem in the rearing process is given by superparasitism (SP; ovipositions in a previously parasitized host), resulting in intraspecific larval competition and wastage of eggs. Our aim was to determine the timing of supernumerary larvae elimination and to evaluate its consequences on biological quality parameters. We first studied supernumerary larvae elimination by recording dead and alive larvae within hosts dissected at 72, 96 and 120 h after parasitization. To evaluate the effects of SP, C. capitata larvae were exposed to D. longicaudata females so as to obtain increasing levels of SP (LSP): 0 (control), 1 (control), 2, 3, 5 and 10 eggs/host. Adult emergence and survival, female fecundity and progeny sex ratio were evaluated. For LSPs > 1 all supernumerary larvae were eliminated before reaching second instar, i.e. 96h/120h after parasitization. No parasitoids emerged from LSP 0 and LSP 10, and emergence among the remaining LSPs (1 to 5) was not statistically different. Neither male nor female survival, female fecundity and progeny sex ratio were affected by LSP. Our results suggest that a rapid elimination of supernumerary larvae causes an undetectable effect on the parasitoid larva that succeeds to the adult stage. Apparently, the consumption of host tissues or physiological changes produced by supernumerary larvae before being eliminated is negligible, except for extremely high levels, where the host larva is overexploited.