Effect of maternal age on primary and secondary sex ratios in the ectoparasitoid wasp Pachycrepoideus vindemmiae

Abstract

Sex allocation is defined as the allocation of resources to produce male and female offspring during reproduction, and it is an important topic in evolutionary biology. As organisms with special haplo-diploid sex determination, parasitoid wasps are particularly suited for the study of sex allocation. However, most studies focused on the secondary sex ratio (i.e., the eclosion sex ratio) because the oviposition ratio (the primary sex ratio) is difficult to study, especially in parasitoid species. The primary sex ratio may differ from the secondary sex ratio due to larval mortality and self-superparasitism.The present study used microsatellites to explore the effects of female age on the primary and secondary sex ratio (male proportion) of the solitary ectoparasitoid Pachycrepoideus vindemmiae (Rondani) (Hymenoptera: Pteromalidae). The primary sex ratio showed a significant decreasing trend as the oviposition days increased, and the secondary sex ratio significantly increased. Self-superparasitism, i.e., laying more than one egg in a host, was the cause of the variation in the secondary sex ratio in P. vindemmiae. When females practiced self-superparasitism, they tended to lay female eggs. The application of microsatellites helped explore and improve the understanding of the primary sex ratio and self-superparasitism in this ectoparasitoid species.

Isolation, culture and characterization of Arsenophonus symbionts from two insect species reveal loss of infectious transmission and extended host range

“…The contrast with A. nasoniae a Nv makes sense in light of differences in the ecology of the host species : N. vitripennis is a gregarious parasitoid that commonly exhibits superparasitism in which two female wasps utilize the same fly pupa, providing an opportunity for horizontal transmission within the shared environment ( Grillenberger et al, 2009 ). Pachycrepoideus vindemmiae , in contrast, lays a single egg per host fly, and rarely superparasites ( Li et al, 2022 ). Thus, the difference in transmission modes in these A. nasoniae strains reflects in part distinct opportunities for horizontal transmission associated with differences in host biology.…”

Isolation, culture and characterization of Arsenophonus symbionts from two insect species reveal loss of infectious transmission and extended host range in the apicola-nasoniae group

“…The contrast with strain Nv makes sense in light of differences in the ecology of the host species ; Nasonia vitripennis is a gregarious parasitoid that commonly exhibits superparasitism in which two female wasps utilize the same fly pupa, providing a opportunity for infectious transmission within the shared environment (33). Pachycrepoideus vindemmiae , in contrast, lays a single egg per host fly, and rarely superparasites (34). Thus, the difference in Arsenophonus transmission modes reflects in part distinct opportunities for horizontal transmission associated with differences in host biology.…”