Recent discoveries of armyworms in Japan and their species identification using DNA barcoding

Abstract

Long columns of migrating larval sciarid armyworms were discovered in central and northern Japan, specifically Kanagawa, Gunma, Miyagi and Akita prefectures, as well as Hokkaido. This is the first examination of armyworms in East Asia. In Europe, armyworms have been identified as Sciara militaris, belonging to the family Sciaridae (sciarid flies or black fungus gnats), by rearing them to adulthood. In Japan, we were unable to obtain live samples for rearing; therefore, DNA barcodes were obtained from the samples of armyworms collected in the Gunma and Miyagi prefectures. The DNA barcodes were compared with those obtained from the following samples: pupae of S. militaris from UK, adults of Sciara kitakamiensis, Sciara humeralis, Sciara hemerobioides, Sciara thoracica, Sciara helvola and Sciara melanostyla from Japan, and adults of one undescribed Sciara species from Malaysia. Neighbour-joining, maximum parsimony, and maximum likelihood analyses revealed that the armyworms discovered in Japan are S. kitakamiensis. Although adults of this species have been recorded in several locations in Japan, this is the first report of migrating larval armyworms. DNA barcodes were effectively used to link different life stages of this species. The average intraspecific and interspecific pairwise genetic distances of the genus Sciara were 0.3% and 12.6%, respectively. The present study illustrates that DNA barcodes are an effective means of identifying sciarid flies in Japan.

Developmental ecdysteroid titers and DNA puffs in larvae of two sciarid species, Rhynchosciara americana and Rhynchosciara milleri (Diptera: Sciaridae)

“…Gregarious behavior is not uncommon in the Sciaridae (Pratt 1899;Steffan 1974;Eberhard and Flores 2002;Shin et al 2013;Sutou et al 2011). According to Shin et al (2013), it is most frequently observed in larvae of the Sciarinae and Chaetosciara groups.…”

DNA barcoding of Bradysia (Diptera: Sciaridae) for detection of the immature stages on agricultural crops

“…DNA barcoding provides significant support for the rapid and accurate identification of morphologically cryptic species (Armstrong and Ball ; Sutou et al. ; Shin et al. ).…”

“…; Sutou et al. ). However, confirming that the species was associated with the damaged plants is difficult, and may lead to error, where more than two species emerged from the same habitat (Shin et al.…”

“…The identification of immature stages directly from damaged plants using DNA barcoding would facilitate the study of sciarid pests (Sutou et al. ; Shin et al. ).…”

“…Within Sciaridae, the genus Sciara was evaluated by barcoding the COI region to identify the ‘Armyworm’ species occurring in Japan (Sutou et al. ). Other Sciaridae DNA barcodes have been used to assess the genetic diversity of B .…”