The expanding genetic toolbox of the wasp Nasonia vitripennis and its relatives

Abstract

The parasitoid wasp Nasonia represents a genus of four species that is emerging as a powerful genetic model system that has made and will continue to make important contributions to our understanding of evolutionary biology, development, ecology, and behavior. Particularly powerful are the haplodiploid genetics of the system, which allow some of the advantages of microbial genetics to be applied to a complex multicellular eukaryote. In addition, fertile, viable hybrids can be made among the four species in the genus. This makes Nasonia exceptionally well suited for evolutionary genetics approaches, especially when combined with its haploid genetics and tractability in the laboratory. These features are complemented by an expanding array of genomic, transcriptomic, and functional resources, the application of which has already made Nasonia an important model system in such emerging fields as evolutionary developmental biology and microbiomics. This article describes the genetic and genomic advantages of Nasonia wasps and the resources available for their genetic analysis.

Keywords: Nasonia; genomics; haplodiploid; hybrid genetics; model organisms.

Figure 1

Life cycle of Nasonia wasps. Both mated (A) and virgin (A′) females will readily lay eggs. Mated females (B) will produce predominantly (80–90%) fertilized eggs, while virgins (B′) can only lay unfertilized eggs. (C and C′) Embryos will develop into legless, simplified larvae. (D) If the mother experienced cold and short-daylight environments, she is more likely to program her offspring to enter diapause, which occurs in the last larval instar. Diapause larvae can survive for more than a year and require an extended cold period to progress in development. (E and E’) As holometabolous insects, Nasonia undergo an extended pupal stage. (F and F’) Adults deriving from fertilized eggs will normally be diploid females, while those from unfertilized eggs will be haploid males.

Figure 2

Phylogenetic relationships and approximated divergence times among Nasonia species. Adapted from Werren and Loehlin (2009a) and Werren et al. (2010).

Figure 3

Haplodiploid genetics in Nasonia. Males are indicated by an arrow extending from the head and smaller wings. A hypothetical orange (or) mutation is used throughout the figure. (A) A mutation induced in a germ-line cell of a parental-generation male can be screened in the F₂ progeny of the male’s virgin daughters. (B) Behavior of a recessive mutation in the Nasonia genetic system. (C) Behavior of a visible mutation and an induced lethal recessive mutation that is not linked. (D) Behavior of a visible mutation and a lethal recessive mutation that are linked. All nonrecombinants carrying the or mutation die, so only relatively rare recombinant orange offspring are observed in F₂.

Figure 4

Live imaging in Nasonia. Nasonia embryos were injected with mRNAs encoding Histone::RFP (magenta, marking chromosomes) and Life Actin::GFP (green, marking f-actin) according to the protocols of Benton et al. (2013). Embryos shown are undergoing the eighth (A) and tenth (B) synchronous syncytial divisions of early embryogenesis. No dechorionation was necessary for injection or microscopy.