Design and Testing of Effective Primers for Amplification of the orf7 Gene of Phage WO Associated with Andricus hakonensis

Wolbachia in Black Spiny Whiteflies and Their New Parasitoid Wasp in Japan: Evidence of the Distinct Infection Status on Aleurocanthus camelliae Cryptic Species Complex

Wolbachia, an alphaproteobacterial reproductive parasite, can cause profound mitochondrial divergence in insects, which might eventually be a part of cryptic speciation. Aleurocanthus camelliae is a cryptic species complex consisting of several morphospecies and/or haplotypes that are genetically different but morphologically indistinctive. However, little is known about the Wolbachia infection status in these tea and Citrus pests. Thus, this study aimed to profile the diversity and phenotypic characteristics of Wolbachia natural infections in the A. camelliae cryptic species complex. A monophyletic strain of Wolbachia that infected the A. camelliae cryptic species complex (wAlec) with different patterns was discovered. Whiteflies that are morphologically identical to Aleurocanthus spiniferus (Aleurocanthus cf. A. spiniferus in Eurya japonica and A. spiniferus in Citrus) were grouped into uninfected populations, whereas the fixed infection was detected in A. camelliae B1 from Theaceae. The rapid evolution of wAlec was also found to occur through a high recombination event, which produced subgroups A and B in wAlec. It may also be associated with the non-cytoplasmic incompatibility (CI) phenotype of wAlec due to undetectable CI-related genes from phage WO (WOAlec). The current discovery of a novel cryptic species of A. camelliae led to a discussion about the oscillation hypothesis, which may provide insights on cryptic speciation, particularly on how specialization and host expansion have been recorded among these species. This study also identified a parasitoid wasp belonging to the genus Eretmocerus in A. camelliae, for the first time in Japan.

High Levels of Multiple Phage WO Infections and Its Evolutionary Dynamics Associated With Wolbachia-Infected Butterflies

Wolbachia is a maternally inherited bacterium that is widely distributed among arthropods, in which it manipulates the reproduction of its hosts. Phage WO is the only bacteriophage known to infect Wolbachia, and may provide benefit to its host or arthropods. We screened for the presence of phage WO in Wolbachia-infected butterfly species for the first time, to investigate their diversity and evolutionary dynamics. All Wolbachia-infected butterfly species, including members of the families Hesperiidae, Lycaenidae, Nymphalidae, Papilionidae, and Pieridae, were found to harbor phage WO. Interestingly, 84% of 19 butterfly species, which were infected with a single Wolbachia strain harbored high levels of multiple phage types (ranging from 3 to 17 types), another three species harbored one or two phage types. For Wolbachia strains (ST-41, ST-19, ST-125 and ST-374) shared among various butterfly species, their host insects all harbored multiple phage types, while two Wolbachia strains (ST-297 and ST-wPcau) were found to infect one butterfly species, whose insect hosts harbored a single phage type, suggesting that horizontal transfer of Wolbachia between insects increased the likelihood of exposure to phages, resulting in increased phage genetic diversity. Twelve horizontal transmission events of phage WO were found, which shared common phage WO types among different Wolbachia strains associated with butterflies. Most horizontal transfer events involved different Wolbachia supergroups (A and B). Horizontal acquisition of phage WO might also occur between eukaryotes without Wolbachia transfer. Furthermore, 22 putative recombination events were identified in 13 of 16 butterfly species which harbored multiple phage types. These results showed that horizontal transfer of Wolbachia caused it to be exposed to the phage gene pool, and that horizontal transmission of phage WO, as well as intragenic recombination were important dynamics for phage WO genome evolution, which effectively promoted the high level of phage WO diversity associated with butterflies.