Wolbachia reproduction manipulation hypothesis. To test if Wolbachia involved in
sex ratio modulation in this insect, isolated lines of Wolbachia-infected (W+) wasps
and uninfected or cured (WÀ) wasps were generated using tetracycline treatment.
Using these lines, different crosses including infected female-infected male, infected
female-uninfected male, uninfected female-infected male, and uninfected femaleuninfected male, were created and different wasp reproduction parameters were
analyzed. The results showed that, with the exception of the cross between infected
males and uninfected females – which produced only male progeny, in the other
three crosses both male and female progeny, were produced. Considering that sex
determination in hymenopterans is based on haplodiploidy system in which males
are haploid and females are diploid, the results indicated that Wolbachia induced CI
in the H. hebetor. It was also shown that the presence of Wolbachia in both male and
female increase the fitness of H. hebetor. Moreover, the results provide evidences
that Wolbachia may modulate sexual behavior of the wasp as the infected females
mated with infected males at a higher rate compared to uninfected males (Bagheri
et al. 2019a). This study confirmed that Wolbachia induces CI and can modulate
behavior of H. hebetor. Taking the initial evidence of behavioral modulation
induced by Wolbachia, in a follow up study, Bagheri et al. (2019b) tested whether
this behavioral modification persists in a situation like inbreeding that may result in
progeny with low fitness. CI strains of Wolbachia cause the diploid eggs obtained
from infected males and uninfected females not to hatch. Inbreeding in H. hebetor
leads to the production of homozygous individuals (diploid males). Diploid males
have a lower survival rate and do not produce viable offspring. Therefore, female
wasps avoid mating with the same brood as themselves. This behavior reduces
mating between siblings and, as a result, arrhenotoky increases. It was shown that
sib subgroup mating and female progeny were higher in Wolbachia-infected lines
than the uninfected sib mates. These results indicate that Wolbachia promoted fertile
sib mating in H. hebetor. It was also shown that Wolbachia reduces inbreeding
depression effects (Bagheri et al. 2019b). By promoting successful sex with siblings
and increasing the probability of female progeny, Wolbachia enhance their transmission to the next generation and also mitigate inbreeding depression. This is an
undescribed effect of Wolbachia (symbiont) on the host reproduction.
The presence of prophage WO in the Wolbachia-infected H. hebetor was also
reported (Nasehi et al. 2019). It was shown that prophage WO is present in both
males and females from different populations of the wasp. Neither WO nor cif genes
were detected in the tetracycline-treated wasps (Nasehi et al. 2019).
13.2.1.4 Wolbachia in Fruit Flies
The Wolbachia has found to be involved in some biological interactions including
CI in some species of fruit flies (Zabalou et al. 2004). Karimi and Darsouei (2014),
collected the specimens of various populations from several fruit flies species
including Dacus ciliatus (cucurbit fly), Rhagoletis cerasi (cherry fruit fly), Ceratitis
capitata (Mediterranean fruit fly), Myiopardalis pardalina (melon fly) and
522
M. Mehrabadi et al.
sex ratio modulation in this insect, isolated lines of Wolbachia-infected (W+) wasps
and uninfected or cured (WÀ) wasps were generated using tetracycline treatment.
Using these lines, different crosses including infected female-infected male, infected
female-uninfected male, uninfected female-infected male, and uninfected femaleuninfected male, were created and different wasp reproduction parameters were
analyzed. The results showed that, with the exception of the cross between infected
males and uninfected females – which produced only male progeny, in the other
three crosses both male and female progeny, were produced. Considering that sex
determination in hymenopterans is based on haplodiploidy system in which males
are haploid and females are diploid, the results indicated that Wolbachia induced CI
in the H. hebetor. It was also shown that the presence of Wolbachia in both male and
female increase the fitness of H. hebetor. Moreover, the results provide evidences
that Wolbachia may modulate sexual behavior of the wasp as the infected females
mated with infected males at a higher rate compared to uninfected males (Bagheri
et al. 2019a). This study confirmed that Wolbachia induces CI and can modulate
behavior of H. hebetor. Taking the initial evidence of behavioral modulation
induced by Wolbachia, in a follow up study, Bagheri et al. (2019b) tested whether
this behavioral modification persists in a situation like inbreeding that may result in
progeny with low fitness. CI strains of Wolbachia cause the diploid eggs obtained
from infected males and uninfected females not to hatch. Inbreeding in H. hebetor
leads to the production of homozygous individuals (diploid males). Diploid males
have a lower survival rate and do not produce viable offspring. Therefore, female
wasps avoid mating with the same brood as themselves. This behavior reduces
mating between siblings and, as a result, arrhenotoky increases. It was shown that
sib subgroup mating and female progeny were higher in Wolbachia-infected lines
than the uninfected sib mates. These results indicate that Wolbachia promoted fertile
sib mating in H. hebetor. It was also shown that Wolbachia reduces inbreeding
depression effects (Bagheri et al. 2019b). By promoting successful sex with siblings
and increasing the probability of female progeny, Wolbachia enhance their transmission to the next generation and also mitigate inbreeding depression. This is an
undescribed effect of Wolbachia (symbiont) on the host reproduction.
The presence of prophage WO in the Wolbachia-infected H. hebetor was also
reported (Nasehi et al. 2019). It was shown that prophage WO is present in both
males and females from different populations of the wasp. Neither WO nor cif genes
were detected in the tetracycline-treated wasps (Nasehi et al. 2019).
13.2.1.4 Wolbachia in Fruit Flies
The Wolbachia has found to be involved in some biological interactions including
CI in some species of fruit flies (Zabalou et al. 2004). Karimi and Darsouei (2014),
collected the specimens of various populations from several fruit flies species
including Dacus ciliatus (cucurbit fly), Rhagoletis cerasi (cherry fruit fly), Ceratitis
capitata (Mediterranean fruit fly), Myiopardalis pardalina (melon fly) and
522
M. Mehrabadi et al.