Pillbug: A Toolbox for Feminisation

Wolbachia-induced feminisation is an extended phenotype that has been observed in only three models: isopods, butterflies and leafhoppers. Even among these, the process of feminisation differs markedly, especially since sexual differentiation is coordinated body-wide by a hormone in isopods, whereas in insects it is a chromosomally determined process and enforced cell by cell. For isopods, Armadillidium vulgare has contributed substantially to an understanding of Wolbachia-mediated feminisation, because a wide array of know-how and methods has been tailored to this model. Here, we describe establishment and maintenance of Wolbachia-infected laboratory lineages from animals collected in the field, the grafting of an androgenic gland to demonstrate the mode of action of Wolbachia (i.e. the disruption of the Androgenic Hormone pathway), and transinfection of naïve adults with Wolbachia. Finally, we describe selection of a ZZ genetic background in lineages created from transinfected WZ females, which is necessary to benefit from a property intrinsic to the naturally infected lineages: In a ZZ background, the vertical transmission rate of Wolbachia directly equates to the female ratio in the progeny. These protocols provide the essential framework for investigating molecular aspects of Wolbachia-induced feminisation.