Detection of Two Biotypes of Liriomyza chinensis (Diptera: Agromyzidae) in Japan.

The larva of stone leek leafminer, Liriomyza chinensis (Kato), is known to infest alternately just below the epidermis and inner surface of hollow cylindrical leaves of allium crops, resulting in the formation of discontinuous linear mines (mine form: discontinuous). However, after the fall of 2016, a novel mine form of the same species (mine form: continuous) was detected in Welsh onion fields of Kyoto Prefecture, Japan. We hypothesized that these mine forms were associated with flies having different genetic backgrounds; hence, we compared the mine forms and the partial mtCOI gene of flies collected from Welsh onion fields from 2018 to 2019. The results demonstrated that the flies that emerged from different mine forms could be classified into two haplogroups, i.e., flies displaying a discontinuous mine form were of haplogroup A, whereas those that displayed continuous mines were of haplotype B. Additionally, using populations of these flies reared in the laboratory, we confirmed that the mine form of the larvae of haplotype A on Welsh onions was discontinuous, whereas that of haplotype B was continuous. We named the population that exhibited a discontinuous mine form as biotype A and the population displaying a continuous mine form as biotype B.

Taxonomic and biological notes on Pristiphora ribisi Togashi, 1990, (Hymenoptera, Tenthredinidae) injurious to gooseberries and currants.

Taxonomic and biological notes are given for the East Asian sawfly Pristiphora ribisi Togashi, 1990, injurious to Ribes. The following new synonyms of this species are proposed: Pristiphora (Pristiphora) anivskiensis Haris, 2006, syn. nov., Pristiphora (Pristiphora) nigrocoreana Haris Zsolnai, 2007, syn. nov. and Pristiphora grossulariae Anon., 1912 [a primary homonym of Pristiphora grossulariae Walsh, 1866], syn. nov. The lectotype of Pristiphora grossulariae Anon., 1912 is designated. Redescriptions of the adult and immature stages are given. The male is described for the first time. The life history and host plants are summarized. Its close relative, Pristiphora appendiculata (Hartig, 1837), is excluded from the fauna of Japan.

T929I and K1774N mutation pair and M918L single mutation identified in the voltage-gated sodium channel gene of pyrethroid-resistant Thrips tabaci (Thysanoptera: Thripidae) in Japan.

Pyrethroid-resistance in onion thrips, Thrips tabaci, has been reported in many countries including Japan. Identifying factors of the resistance is important to correctly monitoring the resistance in field populations. To identify pyrethroid-resistance related genes in T. tabaci in Japan, we performed RNA-Seq analysis of seven T. tabaci strains including two pyrethroid-resistant and five pyrethroid-susceptible strains. We identified a pair of single point mutations, T929I and K1774N, introducing two amino acid mutations, in the voltage-gated sodium channel gene, a pyrethroid target gene, in the two resistant strains. The K1774N is a newly identified mutation located in the fourth repeat domain of the sodium channel. Genotyping analysis of field-collected populations showed that most of the T. tabaci individuals in resistant populations carried the mutation pair, indicating that the mutation pair is closely associated with pyrethroid-resistance in Japan. Another resistance-related mutation, M918L, was also identified in part of the resistant populations. Most of the individuals with the mutation pair were arrhenotokous while all individuals with the M918L single mutation were thelytokous. The result of differentially expressed gene analysis revealed a small number of up-regulated detoxification genes in each resistant strain which might be involved in resistance to pyrethroid. However, no up-regulated detoxification genes common to the two resistant strains were detected. Our results indicate that the mutation pair in the sodium channel gene is the most important target for monitoring pyrethroid-resistance in T. tabaci, and that pyrethroid-resistant arrhenotokous individuals with the mutation pair are likely to be widely distributed in Japan.