substitution rate, and nucleotide distances in infected and uninfected populations of
T. brassicae and T. evanescens were evaluated by analyzing partial sequences of the
COI gene (mtDNA). Seventeen strains of Wolbachia were detected among the
Trichogramma populations. Of these, 94% were identified as members of the A
supergroup. Also, a new Wolbachia subgroup named Tbr belonging to the A
supergroup was discovered. The effects of Wolbachia infection on mtDNA variation
indicated that haplotype frequencies were higher in infected populations than
uninfected populations. Nucleotide diversity in infected populations was lower
than uninfected populations of T. brassicae and T. evanescens. Cophylogenetic
relationships revealed no congruence between Wolbachia strains and mtDNA of
their host. Overall, the results showed that Wolbachia affect several genomic criteria
of Trichogramma and therefore impact mtDNA diversity.
Following these studies, the arising question was about relation between status of
Wolbachia infection and qualitative characteristics of T. brassicae reared on cold
stored eggs of the host. An increase in host storage time negatively affects some
qualitative characteristics of T. brassicae such as fecundity, longevity, wing deformity, and sex ratio (Nazeri et al. 2015). However, there was no significant difference
between the parasitism rates of thelytokous and arrhenotokous wasps (Nazeri et al.
2015).
Wolbachia infected Trichogrmma can produce female offspring via gamete
diploidization without mating. Nazeri et al. (2015) indicated Wolbachia infection
in T. brassicae resulted in prolonged developmental time, a higher rate of wing
deformity, and lower fecundity and emergence rate. Thus, before mass production of
the wasp begins, potential negative impacts of Wolbachia infection should be
evaluated.
Another addressed issue was possible influence of Wolbachia on overwintering
population of Trichogramma. Rahimi et al. (2017) measured the overwintering
ability of infected and uninfected populations of T. brassicae. The results indicated
both strains were able to overwinter but the Wolbachia infected wasps had reduced
ability. The presence of Wolbachia in T. brassicae also affects diapause. Wolbachia
infection makes disturbance on the clock gene expression which consequently
reduces the percentage of diapause (Rahimi et al. 2017).
13.2.1.3 Wolbachia in Habrobracon hebetor
Habrobracon hebetor (Hym.: Braconidae) is an important parasitoid wasp of some
lepidopteran larvae that is commercially produced and used in biological control
programs in Iran. Considering the importance of sex ratio in parasitoid wasps and the
reproductive manipulations induced by Wolbachia that may affect this sex ratio,
Bagheri et al. (2019a) screened different populations of H. hebetor to see if they
were infected with Wolbachia. They found a high prevalence of infection in all
populations. Wolbachia persisted during ontogeny of H. hebetor throughout their
life cycle. Their initial observations showed that some crosses in H. hebetor resulted
in high male progeny while others produce more female progeny which supports the
13 Insect Pathogenic Viruses, Microsporidians and Endosymbionts
521
T. brassicae and T. evanescens were evaluated by analyzing partial sequences of the
COI gene (mtDNA). Seventeen strains of Wolbachia were detected among the
Trichogramma populations. Of these, 94% were identified as members of the A
supergroup. Also, a new Wolbachia subgroup named Tbr belonging to the A
supergroup was discovered. The effects of Wolbachia infection on mtDNA variation
indicated that haplotype frequencies were higher in infected populations than
uninfected populations. Nucleotide diversity in infected populations was lower
than uninfected populations of T. brassicae and T. evanescens. Cophylogenetic
relationships revealed no congruence between Wolbachia strains and mtDNA of
their host. Overall, the results showed that Wolbachia affect several genomic criteria
of Trichogramma and therefore impact mtDNA diversity.
Following these studies, the arising question was about relation between status of
Wolbachia infection and qualitative characteristics of T. brassicae reared on cold
stored eggs of the host. An increase in host storage time negatively affects some
qualitative characteristics of T. brassicae such as fecundity, longevity, wing deformity, and sex ratio (Nazeri et al. 2015). However, there was no significant difference
between the parasitism rates of thelytokous and arrhenotokous wasps (Nazeri et al.
2015).
Wolbachia infected Trichogrmma can produce female offspring via gamete
diploidization without mating. Nazeri et al. (2015) indicated Wolbachia infection
in T. brassicae resulted in prolonged developmental time, a higher rate of wing
deformity, and lower fecundity and emergence rate. Thus, before mass production of
the wasp begins, potential negative impacts of Wolbachia infection should be
evaluated.
Another addressed issue was possible influence of Wolbachia on overwintering
population of Trichogramma. Rahimi et al. (2017) measured the overwintering
ability of infected and uninfected populations of T. brassicae. The results indicated
both strains were able to overwinter but the Wolbachia infected wasps had reduced
ability. The presence of Wolbachia in T. brassicae also affects diapause. Wolbachia
infection makes disturbance on the clock gene expression which consequently
reduces the percentage of diapause (Rahimi et al. 2017).
13.2.1.3 Wolbachia in Habrobracon hebetor
Habrobracon hebetor (Hym.: Braconidae) is an important parasitoid wasp of some
lepidopteran larvae that is commercially produced and used in biological control
programs in Iran. Considering the importance of sex ratio in parasitoid wasps and the
reproductive manipulations induced by Wolbachia that may affect this sex ratio,
Bagheri et al. (2019a) screened different populations of H. hebetor to see if they
were infected with Wolbachia. They found a high prevalence of infection in all
populations. Wolbachia persisted during ontogeny of H. hebetor throughout their
life cycle. Their initial observations showed that some crosses in H. hebetor resulted
in high male progeny while others produce more female progeny which supports the
13 Insect Pathogenic Viruses, Microsporidians and Endosymbionts
521