Sex-Specific Wolbachia Infection Patterns in Populations of Polygraphus proximus Blandford (Coleoptera; Curculionidae: Scolytinae)

Abstract

<i>Wolbachia</i> symbionts are maternally inherited bacteria that are widely distributed among Arthropoda hosts. <i>Wolbachia</i> influence their host biology in diverse ways. They may induce reproductive abnormalities, protect hosts against pathogens and parasites, or benefit hosts through metabolic provisioning. The progeny of an infected female are ordinarily infected with <i>Wolbachia</i>; however, <i>Wolbachia</i> have no future in male host progeny because they cannot transmit the symbiont to the next generation. Here, we analyze native and invasive populations of the four-eyed fir bark beetle (<i>Polygraphus proximus</i>) for <i>Wolbachia</i> prevalence and symbiont genetic diversity. This species is a dangerous pest of Siberian fir (<i>Abies sibirica</i>) forests. The native range of <i>P. proximus</i> includes the territories of the Russian Far East, Japan, Korea, and Northeast China, whereas its invasive range includes West Siberia, with further expansion westward. Surprisingly, we revealed a difference in the patterns of <i>Wolbachia</i> prevalence for males and females. Infection rate and <i>Wolbachia</i> titers were higher in females than in males. ST-533, the only haplotype of <i>Wolbachia</i> supergroup B, was associated with a minimum of three out of the five described mitochondrial haplotypes.