High-prevalence male-killing Wolbachia in the butterfly Acraea encedana

Abstract

Inherited bacteria which kill males during early development are widely distributed throughout the insects, but have been little studied outside of a single family of beetles, the Coccinellidae. We have investigated a male‐killing bacterium discovered in the butterfly Acraea encedana. This bacterium belongs to the genus Wolbachia and is identical in wsp gene sequence to a male‐killer in the closely related butterfly A. encedon, suggesting that it has either recently moved between host species or was inherited from a common ancestor of the butterflies. The prevalence of Wolbachia is remarkably high, 95% of females are infected and only 6% of wild caught butterflies are male. Measurements of the vertical transmission efficiency were used to calculate that this high prevalence is the result of infected females producing at least 1.79 times the number of surviving daughters as uninfected females (lower confidence limit is 1.25).

Distribution and Evolutionary Impact of Wolbachia on Butterfly Hosts

“…This phenomenon has been reported in Lepidoptera [27], Coleoptera, Diptera and Pseudoscorpiones [4]. This is undisruptive to the bacterium, because its transmission is favor by female and helps in its spreading.…”

Heritability of Sex Tendency in a Harpacticoid Copepod, Tigriopus Californicus

“…Under cytoplasmic inheritance, sex is determined by intracellular parasites (or other selfish genetic elements) that distort the sex ratio toward the transmitting sex, usually the female (Bull 1983). Theoretical models indicate that cytoplasmic sex factors can eventually cause the extinction of the nontransmitting sex (Hamilton 1967;Hatcher et al 1999) and extremely female-biased sex ratios have been found in natural populations (Jiggins et al 2000).…”

The impact of male-killing bacteria on the evolution of aphidophagous coccinellids

“…This suggests that the vertical transmission of these bacteria is a function of the male-killers themselves, not of their host. Conversely, in two species of butterfly, Acraea encedon and Acraea encedana, both of which are infected with the same strain of Wolbachia (showing no difference in over 5000 nuclear and mitochondrial nucleotides sequenced), vertical transmission efficiencies of 1.0 and 0.96 respectively have been recorded (Jiggins et al, 1998(Jiggins et al, , 2000(Jiggins et al, , 2001. Here, the vertical transmission appears to be host dependent.…”