A simple molecular identification method of theThrips tabaci(Thysanoptera: Thripidae) cryptic species complex

Abstract

The onion thrips (Thrips tabaci Lindeman, 1889) is a key pest of a wide range of crops because of its ecological attributes such as polyphagy, high reproduction rate, ability to transmit tospoviruses and resistance to insecticides. Recent studies revealed that T. tabaci is a cryptic species complex and it has three lineages (leek-associated arrhenotokous L1-biotype, leek-associated thelytokous L2-biotype and tobacco-associated arrhenotokous T-biotype), however, the adults remain indistinguishable. T. tabaci individuals were collected from different locations of Hungary to create laboratory colonies from each biotypes. Mitochondrial COI (mtCOI) region was sequenced from morphologically identified individuals. After sequence analysis SNPs were identified and used for CAPS marker development, which were suitable for distinguishing the three T. tabaci lineages. Genetic analysis of the T. tabaci species complex based on mtCOI gene confirmed the three well-known biotypes (L1, L2, T) and a new biotype because the new molecular evidence presented in this study suggests T-biotype of T. tabaci forming two distinct (sub)clades (T1 and T2). This genetic finding indicates that the genetic variability of T. tabaci populations is still not fully mapped. We validated our developed marker on thrips individuals from our thrips colonies. The results demonstrated that the new marker effectively identifies the different T. tabaci biotypes. We believe that our reliable genotyping method will be useful in further studies focusing on T. tabaci biotypes and in pest management by scanning the composition of sympatric T. tabaci populations.

Reproductive Isolation in the Cryptic Species Complex of a Key Pest: Analysis of Mating and Rejection Behaviour of Onion Thrips (Thrips tabaci Lindeman)

“…Further findings support distinct lineages and confirm that the T and the L1 lineages reproduce by arrhenotoky, while the L2 lineage reproduces by thelytoky [59][60][61][62][63][64]. However, most of these studies focused on mtDNA for separation, and no efforts were made to screen for reproductive isolation.…”

“…It seems well established that the L1 and L2 lineages can occur in sympatric populations, and both occur and breed well on cabbage and Allium plants [57,67,68], while the T lineage has a pronounced preference for tobacco [51,57], a plant on which the L lineages fail to survive [69]. Note, that while all three T. tabaci lineages can be found in Europe [57,64], it seems that the T lineage is absent in the USA [70]. While the other two lineages can also transmit it, the T lineage is the most efficient vector of Tomato spotted wilt virus (Tospoviridae), which is probably the most important plant pathogen transmitted by the onion thrips [51,69,71,72].…”

Frontiers Approaches to the Diagnosis of Thrips (Thysanoptera): How Effective Are the Molecular and Electronic Detection Platforms?

“…CAPS is highly reproducible, co-dominant, and can be performed with a low quantity of DNA (50–100 ng). CAPS markers can discriminate the three cryptic lineages (L1, L2, and T) of T. tabaci based on the SNP in the COI fragment [ 170 ]. The main limitation of CAPS markers is that they require sequence data for primer design, and sometimes it is difficult to find polymorphisms because of the small size of the amplified fragment.…”

The Existence of Deuterotokous Reproduction Mode in the T. tabaci (Thysanoptera: Thripidae) Cryptic Species Complex

“…The eggs in the leaf discs have checked with an under-light stereomicroscope. The dead mothers were preserved in 96% alcohol and their mitochondrial cytochrome c oxidase subunit I (MT-COI) gene was sequenced to confirm the lineage (Farkas et al 2020). The hatched first and second instar larvae were individually transferred to new tubes with fresh leaf discs and raised to the pupal stage.…”