Superparasitism Drives Heritable Symbiont Epidemiology and Host Sex Ratio in a Wasp

PLoS Pathogens

Steven R. Parratt¹  Gregory D. D. Hurst¹  Martijn A. Schenkel¹  Crystal L. Frost¹  Kayla C. King¹  Annabel Rice¹ 

[1] Institute of Integrative Biology, University of Liverpool, Liverpool, United Kingdom

关键词: Parasitic diseases;    Pupae;    Sex ratio;    Epidemiology;    Oviposition;    Animal behavior;    Species extinction;    Parasite evolution;   

DOI  :  10.1371/journal.ppat.1005629

学科分类：生物科学（综合）

来源: Public Library of Science

【 摘 要 】

Heritable microbial symbionts have profound impacts upon the biology of their arthropod hosts. Whilst our current understanding of the dynamics of these symbionts is typically cast within a framework of vertical transmission only, horizontal transmission has been observed in a number of cases. For instance, several symbionts can transmit horizontally when their parasitoid hosts share oviposition patches with uninfected conspecifics, a phenomenon called superparasitism. Despite this, horizontal transmission, and the host contact structures that facilitates it, have not been considered in heritable symbiont epidemiology. Here, we tested for the importance of host contact, and resulting horizontal transmission, for the epidemiology of a male-killing heritable symbiont (Arsenophonus nasoniae) in parasitoid wasp hosts. We observed that host contact through superparasitism is necessary for this symbiont’s spread in populations of its primary host Nasonia vitripennis, such that when superparasitism rates are high, A. nasoniae almost reaches fixation, causes highly female biased population sex ratios and consequently causes local host extinction. We further tested if natural interspecific variation in superparasitism behaviours predicted symbiont dynamics among parasitoid species. We found that A. nasoniae was maintained in laboratory populations of a closely related set of Nasonia species, but declined in other, more distantly related pteromalid hosts. The natural proclivity of a species to superparasitise was the primary factor determining symbiont persistence. Our results thus indicate that host contact behaviour is a key factor for heritable microbe dynamics when horizontal transmission is possible, and that ‘reproductive parasite’ phenotypes, such as male-killing, may be of secondary importance in the dynamics of such symbiont infections.

【 授权许可】

CC BY