Host acceptance and sex allocation of Nasonia wasps in response to conspecifics and heterospecifics

Abstract

Species recognition is an important aspect of an organism's biology. Here, we consider how parasitoid wasps vary their reproductive decisions when their offspring face intra-and interspecific competition for resources and mates. We use host acceptance and sex ratio behaviour to test whether female Nasonia vitripennis and Nasonia longicornis discriminate between conspecifics and heterospecifics when ovipositing. We tested pairs of conspecific or heterospecific females ovipositing either simultaneously or sequentially on a single host, using strains varying in their recent history of sympatry. Both N. vitripennis and N. longicornis rejected parasitized hosts more often than unparasitized hosts, although females were more likely to superparasitize their own species in the sequential treatment. However, sex ratio behaviour did not vary, suggesting similar responses towards conspecifics and heterospecifics. This contrasts with theory predicting that heterospecifics should not influence sex ratios as their offspring do not influence local mate competition, where conspecifics would. These non-adaptive sex ratios reinforce the lack of adaptive kin discrimination in N. vitripennis and suggest a behavioural constraint. Discrimination between closely related species is therefore context dependent in Nasonia. We suggest that isolating mechanisms associated with the speciation process have influenced behaviour to a greater extent than selection on sex ratios.

Exposure to the neonicotinoid imidacloprid disrupts sex allocation cue use during superparasitism in the parasitoid wasp Nasonia vitripennis

“…Interestingly, their results suggest that the sex ratio cue may travel more slowly through the host or travel to a lesser extent than the clutch size cue. Similarly, Ivens et al (2009) showed that female Nasonia responded to whether their co-foundresses were con-specifics or hetero-specifics in terms of their oviposition decisions, but they did not respond in terms of their sex allocation decisions (see also Grillenberger et al, 2009).…”

“…Similarly, Ivens et al . () showed that female Nasonia responded to whether their co‐foundresses were con‐specifics or hetero‐specifics in terms of their oviposition decisions, but they did not respond in terms of their sex allocation decisions (see also Grillenberger et al ., ).…”

Testing Models of Facultative Sex Ratio Adjustment in the Pollinating Fig Wasp Platyscapa Awekei

“…Hetero‐specific females ovipositing in the same patch can lead to misinformation. Nasonia vitripennis is reported to reduce its clutch size and increase its sex ratio when hosts are previously parasitized by the closely related Nasonia giraulti (Grillenberger et al 2009) and Nasonia longicornis (Ivens et al 2009), and even more distantly related parasitoids (Wylie 1973). Similar to Wylie (1973), King and Skinner (1991b) found that pupae death leads to a reduced clutch size, but they found no difference in sex ratio.…”

Chemical Ecology of the Parasitoid Wasp Genus Nasonia (Hymenoptera, Pteromalidae)

“…In addition to general host quality, Nv females are able to discriminate between parasitized and non-parasitized hosts (Wylie, 1965;King and Rafai, 1970;Holmes, 1972;Werren, 1980;King and Skinner, 1991;Shuker and West, 2004) and are even able to distinguish hosts pre-parasitized by conspecific females from those previously parasitized by heterospecific ones (Ivens et al, 2009). In general, pre-parasitized hosts are rejected more often (Ivens et al, 2009). If females decide to oviposit nonetheless, fewer offspring and higher relative numbers of males are produced (Wylie, 1965;Holmes, 1972).…”