Infection status of Wolbachia in Ostrinia species

Wolbachia infection has been reported in four species in the Ostrinia furnacalis species complex (Lepidoptera: Crambidae), namely O. furnacalis, Ostrinia scapulalis, Ostrinia orientalis, and Ostrinia zaguliaevi (Kageyama et al , 2004) Based on detailed analyses of their biological and genetic traits, it was recently proposed that O. scapulalis and O. orientalis are mor-

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Figure 13.8 (Color figure follows p. 238.) Genitalia preparations of E. hecabe adults that emerged after larval antibiotic treatment . (a) and (b): Sexually intermediate genitalia obtained after antibiotic treatment from the first to fourth instar stages of an insect line doubly infected with wHecCI and wHecFem . (c): Male genitalia from a nontreated insect line singly infected with wHecCI . (d): Female genitalia from a nontreated insect line singly infected with wHecCI . Blue arrowheads indicate male traits (bicuspid apex of valva), and pink arrowheads indicate female traits (papilla analis). Bar, 1 mm . (Adapted from Narita, S ., Kageyama, D., Nomura, M., and Fukatsu, T. (2007a) . Appl. Environ. Microbiol . 73: 4332-4341. With permission .)

Figure 13.8 (Color figure follows p. 238.) Genitalia preparations of E. hecabe adults that emerged after larval antibiotic treatment . (a) and (b): Sexually intermediate genitalia obtained after antibiotic treatment from the first to fourth instar stages of an insect line doubly infected with wHecCI and wHecFem . (c): Male genitalia from a nontreated insect line singly infected with wHecCI . (d): Female genitalia from a nontreated insect line singly infected with wHecCI . Blue arrowheads indicate male traits (bicuspid apex of valva), and pink arrowheads indicate female traits (papilla analis). Bar, 1 mm . (Adapted from Narita, S ., Kageyama, D., Nomura, M., and Fukatsu, T. (2007a) . Appl. Environ. Microbiol . 73: 4332-4341. With permission .)

phological variants and form a single species designated O. scapulalis (Frolov et al ., 2007) . Although O. furnacalis and O. scapulalis are closely related, they are clearly distinct species that are commonly found in Japan . O. furnacalis mainly feeds on maize, whereas O. scapu-lalis feeds on legumes and a wide range of plants Among O. furnacalis and O. scapulalis, nearly 5% of wild-caught females are infected with Wolbachia (Kageyama et al ., 1998, 2002, 2003a) (Figure 13 . 10) . In each of the two Wolbachia genes, i . e ., wsp (555 bp) and ftsZ (1025 bp), DNA fragment sequences were found to be identical among different individuals within species and among different species, suggesting that they are infected with a single strain of Wolbachia The Wolbachia-induced reproductive manipulations have been relatively well examined in O. furnacalis and O. scapulalis and were found to be substantially the same Thus, the Wolbachia-induced reproductive manipulations in Ostrinia are hereafter described for these two species

Figure 13.9 What determines the sex of E. hecabe? (a): Mothers singly infected with wHecCI produce wHecCI-infected offspring with 1:1 sex ratios . (b): Mothers doubly infected with wHecCI and wHecFem produce offspring consisting of all or nearly all females in the normal condition (left and middle) . Approximately 80% of the offspring are doubly infected (left), while 20% of the offspring spontaneously lose wHecFem (middle) . When offspring are treated with an antibiotic (tetracycline) during larval development, they develop as intersexes (right) These results suggest that not only wHecFem but also wHecCI may play important roles in feminizing genetic males of E. hecabe.

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