Preliminary characterization of a new Aedes albopictus strain obtained by horizontal transfer of Wolbachia from Culex pipiens
M. Calvitti1, R. Moretti1, R. Bellini2 & S.L. Dobson3
1BAS-Biotec_Agro, C.R. ENEA Casaccia (Roma), Italy;
2CAA ”G.Nicoli” Crevalcore (BO), Italy;
3Dept. Entomology, University of Kentucky (Lexington), KY, USA
Wolbachia (Rickettsiales) is a maternally inherited endosymbiont present in a wide range of insects. Depending on hosts and bacterium strains, the infection may induce Cytoplasmic Incompatibility (CI), a phenomenon of non-viability of embryos resulting from mating of males carrying a specific Wolbachia strain with females that are uninfected or are infected by a different
Wolbachia strain. The release of CI males has the potential for the genetic control of insects,
following the principles of the sterile insect technique. Aedes albopictus is reported to be uniformly superinfected with two Wolbachia strains (wAlbA and wAlbB) throughout its geographical
distribution. Infected males were proved to be fully incompatible with artificially obtained aposymbiotic females.
In this work, we report on the attempt to infect an aposymbiotic strain of Ae. albopictus (RT) with a Wolbachia strain drawn from Culex pipiens embryos (wPip strain). Further experiments were
designed to study the supportive host background and the adaptation of the wPip Wolbachia strain to the new recipient host and evaluate the infection dynamics key parameters like (i) CI level and (ii) maternal inheritance in the new host-Wolbachia association.
About 7.6% of the Ae. albopictus embryos survived the microinjection procedure. About 11% of the adults developed from microinjected embryos were infected with Wolbachia wPip strain. The progeny obtained from two females were found infected and used to establish the new transinfected Ae. albopicuts line (RTP) and then perform the subsequent tests.
CI was very high in all crosses between RTP males and females characterized by a different infection status. No viable eggs (i.e. high CI) were found in the reciprocal cross between normal superinfected males and RTP females as well. Maternal inheritance was found close to 100%.
Further studies are focusing on the analysis of the potential fitness costs associated with the new infection in terms of immature and adult survival, fecundity and egg hatching rate.
Results are discussed in relation to the possibility of using the new Ae. albopictus–Wolbachia symbiosis as suitable system for the study and development of CI-based strategies for the suppression of the vector population.