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A novel approach using microsporidia to estimate the flight route of the common cutworm, Spodoptera litura (Lepidoptera: Noctuidae)

Imura, Yuji, Hatakeyama, Yoshinori, Takahashi, Moe, Ohbayashi, Takashi, Mizobe, Shinji, Iwano, Hidetoshi
Applied entomology and zoology 2019 v.54 no.2 pp. 185-192
Nosema, Pleistophora, Spodoptera litura, Vairimorpha, Vavraia, biopesticides, cutworms, flight, fungi, host specificity, parasites, phylogeny, ribosomal RNA, sequence analysis, spores, China, Japan, Taiwan
Microsporidia are unique fungi that exist as obligate intracellular parasites. Approximately 40% of the known microsporidian strains infect various insects. Due to their high host specificity, microsporidia have potential use as powerful biological pesticides. Here, we analyzed microsporidian strains isolated from the common cutworm, Spodoptera litura Fabricius (Lepidoptera: Noctuidae) of Japan and Taiwan, which is considered a pest insect. Two experiments were performed: a comparison of spore size and a phylogenetic analysis using small subunit ribosomal RNA gene sequencing. We then estimated the flight routes of S. litura by using the phylogenetic relationships of the isolated microsporidian strains as a marker. An analysis of spore size indicated that the test strains comprised three groups: Pleistophora, Nosema or Vairimorpha, and Trachipleistophora or Vavraia. The results of the phylogenetic analysis suggested a classification into five genera, including Vavraia. The genus Vavraia was first detected from lepidopteran insects in Japan. We estimated the sources and flight routes of S. litura using phylogenetic data for the genera Nosema and Trachipleistophora. In this study, we used microsporidia as a novel marker to estimate sources and flight routes of S. litura from Ogasawara and Southern China to mainland Japan, demonstrating the usefulness of this approach.