Cytogenetic and molecular evidence for two species in the Anopheles barbirostris complex (Diptera: Culicidae) in Thailand

Abstract

Seventeen isolines of Anopheles barbirostris derived from animal-biting female mosquitoes showed three karyotypic forms: Form A (X2, Y1) in five isolines from Phetchaburi province; Form B (X1, X3, Y2) in three and eight isolines from Chiang Mai and Ubon Ratchathani provinces, respectively; Form C (X2, Y3) in one isoline from Phetchaburi province. All 17 isolines exhibited an average branch summation of seta 2-VI pupal skins ranging from 12.1-13.0 branches, which was in the limit of A. barbirostris (6-18 branches). Of the 12 human-biting isolines from Chiang Mai province, five isolines showed Form B (X2, Y2), and seven isolines exhibited a new karyotypic form designated as Form E (X2, Y5). All of 12 isolines had an average branch summation of seta 2-VI pupal skins ranging from 22.4-24.5 branches, which was in the limit of Anopheles campestris (17-58 branches). Thus, they were tentatively designated as A. campestris-like Forms B and E. Hybridization between A. campestris-like Forms B and E showed that they were genetically compatible, yielding viable progeny for several generations suggesting conspecific relationships of these two karyotypic forms. Reproductive isolation among crosses between A. campestris-like Form B and A. barbirostris Forms A, B, and C strongly suggested the existence of these two species. In addition, the very low intraspecific variation (genetic distance<0.005) of the nucleotide sequence of ITS2 of the rDNA and COI and COII of mitochondrial DNA of the seven isolines of A. campestris-like Forms B and E supported their conspecific relationship. The large sequence divergence of ITS2 (0.203-0.268), COI (0.026-0.032), and COII (0.030-0.038) from genomic DNA of A. campestris-like Forms B and E and the A. barbirostris Forms A, B, and C clearly supported cytogenetic and morphological evidence.

Genetic compatibility between Anopheles lesteri from Korea and Anopheles paraliae from Thailand

“…These methods are useful for solving taxonomic problems of some sibling species complexes, e.g., Anopheles dirus (Baimai et al 1987), Anopheles maculatus (Thongwat et al 2008), An. minimus (Somboon et al 2001 and Anopheles barbirostris (Saeung et al 2007). Likewise, the status of subspecies or cytological races of Anopheles can be elucidated by the same approach of cytogenetic study as exemplified in An.…”

“…sinensis (Choochote et al 1998, Park et al 2008, An. barbirostris species A1 (Saeung et al 2007), Anopheles campestrislike taxon ) and An. peditaeniatus (Choochote 2011).…”

“…lesteri and three iso-female lines (ipR1, ipN1, ipS1) of An. paraliae were arbitrarily selected for crossing experiments to determine post-mating reproductive isolation by employing the techniques previously reported by Saeung et al (2007). Study on salivary gland polytene chromosomes of 4th instar larvae of F 1 -hybrids from the crosses followed the techniques of White et al (1975) and Kanda (1979).…”

Susceptibility of Anopheles campestris-like and Anopheles barbirostris species complexes to Plasmodium falciparum and Plasmodium vivax in Thailand

“…campestris-like Forms B (Chiang Mai), E (Chiang Mai & Sa Kaeo) and F (Ayuttaya & Udon Thani) and An. barbirostris species A1 (Chiang Mai), A2 (Phetchaburi), A3 (Kanchanaburi) and A4 (Chiang Mai) were established based on morphological, cytogenetic and molecular investigations and crossing experiments, as previously reported by Saeung et al (2007Saeung et al ( , 2008, Suwannamit et al (2009) and Thongsahuan et al (2009). These colonies were successfully reared using the methods of Choochote et al (1983) and Kim et al (2003) in an insectary room at 27 ± 2ºC and 70-80% relative humidrelative humidity (RH).…”

“…campestris-like and An. barbirostris species A1, A2, A3 and A4 (Saeung et al 2007, 2008). Little is known about the potential vector for P. falciparum and/or P. vivax in these five sibling species members; thus, intensive comparison of their vector-competence is needed to elucidate their potential vector status.…”