Supernumerary Larvae Elimination and Effects of Superparasitism in Diachasmimorpha longicaudata (Hymenoptera: Braconidae)

F. DEVESCOVI; M.M. VISCARRET; C.A. CONTE; J. L. CLADERA; D. F. SEGURA

Bangkok

Congreso; The 9th International Symposium on Fruit Flies of Economic Importance; 2014

Background: The use of Diachasmimorpha longicaudata as a biological agent against fruit fly pests has been successfully implemented in many countries. In Argentina, it is experimentally and massively reared on Ceratitis capitata. Here, we evaluated the effects of superparasitism (SP), a phenomenom that can negatively affect the efficiency of the rearing process, on the fitness of the wasps. To understand the potential costs of SP, we determined the time at which supernumerary larvae are eliminated at different levels of superparasitism (LSP).Methods: Supernumerary larvae elimination was tested for different LSPs by recording the number, developmental stage and state of parasitoid larvae found in each dissected pupae at 72, 96 and 120 h after parasitization. In order to evaluate the effects of SP, C. capitata larvae were exposed to female parasitoids as to obtain: 0 (control), 1 (control), 2, 3, 5 and 10 eggs/host. For each LSP, parasitoids emergence (%), adult survival, female fecundity and sex ratio of females? offspring were evaluated. Results: Larvae elimination took place at first instar, progressively until 120 h after parasitization and was delayed at increasing LSP. At that time, only one second instar per host was found. No parasitoids emerged from LSP 0 and LSP 10, and the percentage of emergence among the remaining LSPs (1 to 5) was not statistically different. Male and female survival, female fecundity and progeny sex ratio were not affected by LSP. Conclusions: At intermediate LSPs, a rapid elimination of supernumerary larvae causes a negligible effect on the adult parasitoid. These evidences could indicate that host discrimination ability has lower adaptive value than originally considered as there is no cost of SP to the emerged wasps, at least at the most common LSP found in nature (< 5 larvae/host).