Revisiting the Hybridization Processes in the Triatoma brasiliensis Complex (Hemiptera, Triatominae): Reproductive Isolation between Triatoma petrocchiae and T. b. brasiliensis and T. lenti.

Luiza Maria Grzyb Delgado,João Aristeu Da Rosa,Amanda Ravazi,Jader De Oliveira,Maria Tercília Vilela De Azeredo-Oliveira,Cleber Galvão,Yago Visinho Dos Reis,Elaine Folly-Ramos,Ana Beatriz Bortolozo De Oliveira,Heloisa Pinotti,Isabella Da Silva Masarin,Maurício Lilioso,Kaio Cesar Chaboli Alevi,Fernanda Fernandez Madeira

doi:10.3390/insects12111015

Luiza Maria Grzyb Delgado, João Aristeu Da Rosa + Show 12 more

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https://doi.org/10.3390/insects12111015

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Simple SummaryAlthough all triatomines are potential vectors of Chagas disease, there are species with greater or lesser vectorial importance. Therefore, the correct identification of triatomine species is essential for vector control programs. In general, triatomines are identified by external morphological characters. However, some species are very similar or even morphologically identical, making the use of complementary analyses for the correct identification of species important. For this reason, this study focused on the use of experimental crosses to assess the specific status of species of the Triatoma brasiliensis species complex. The crosses did not result in hybrids, demonstrating that there are pre-zygotic reproductive barriers installed between T. petrocchiae and the other species of the T. brasiliensis complex (which confirms the specific status of the species according to the biological species concept). On the basis of the results above, we demonstrated that T. petrocchiae is reproductively isolated from T. b. brasiliensis and T. lenti. Furthermore, we suggest that T. petrocchiae is the species most derived from the T. brasiliensis complex.Triatoma petrocchiae is a species morphologically similar to T. b. brasiliensis (which resulted in a synonymization event); despite this similarity, genetic, morphological, and experimental crossbreeding studies confirmed the specific status of T. petrocchiae. Considering that both species have been reported living in sympatry and that, for a long time, most species of the T. brasiliensis complex were considered only chromatic variants of T. b. brasiliensis, we carried out experimental crosses between T. b. brasiliensis and T. petrocchiae (to confirm whether these species are reproductively isolated) and between T. lenti and T. petrocchiae (to assess whether T. petrocchiae also presents prezygotic isolation with the other species of the T. brasiliensis complex). Reciprocal experimental crosses were conducted, and weekly, the eggs were collected, counted, and separated in new containers to assess the hatch rate. Neither cross resulted in hybrids, demonstrating that there are pre-zygotic reproductive barriers installed between T. petrocchiae and the other species of the T. brasiliensis complex. On the basis of the results above, we demonstrated that T. petrocchiae is reproductively isolated from T. b. brasiliensis and T. lenti. Furthermore, we suggest that T. petrocchiae is the species most derived from the T. brasiliensis complex.

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Triatomines (Hemiptera, Triatominae) are hematophagous insects of great importance to public health, as they are considered the main form of transmission of the protozoan Trypanosoma cruzi (Chagas, 1909) (Kinetoplastida, Trypanosomatidae), the etiological agent of Chagas disease [1]
The T. brasiliensis complex is a grouping of endemic species from Brazil [13] composed of six species and two subspecies that share a common ancestry: T. b. brasiliensis Neiva, 1911, T. b. macromelasoma Galvão, 1965, T. juazeirensis Costa and Félix, 2007, T. sherlocki Papa et al, 2002, T. petrocchiae Pinto and Barreto, 1925, T. lenti Sherlock and Serafim, 1967, T. bahiensis Sherlock and Serafim, 1967, and T. melanica Neiva and Lent, 1941 [14,15,16,17,18]
To ensure that the T. brasiliensis complex triatomines collected in Paulo Afonso, Bahia, were correctly identified as T. b. brasiliensis and T. petrocchiae, we evaluated some specimens collected in this municipality that were deposited in the entomologic collections of the Faculty of Public Health of the University Insects 2021, 12, x FOR PEER REVIEWof Sao Paulo, Brazil (Figure 2)

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Introduction

Triatomines (Hemiptera, Triatominae) are hematophagous insects of great importance to public health, as they are considered the main form of transmission of the protozoan Trypanosoma cruzi (Chagas, 1909) (Kinetoplastida, Trypanosomatidae), the etiological agent of Chagas disease [1] (a neglected disease that affects about 8 million people and results in 10,000 deaths per year [1]). The genus Triatoma Laporte, 1832 is the most representative (81 species) and the most morphologically diversified [6,7] This genus is paraphyletic [8,9], and species are grouped into complexes and subcomplexes [9,10,11,12]. Triatoma petrocchiae is a species morphologically similar to T. b. Brasiliensis and T. petrocchiae from Paulo Afonso, Bahia, Brazil, and observed that these species did not produce viable hybrids. Brasiliensis and T. petrocchiae and, above all, these species share the same ecological niche Considering that these species have been reported living in sympatry [26,27] and that, in 1971, most species of the T. brasiliensis complex were still considered only chromatic variants of T. b. On the basis of the assumptions above, we carried out experimental crosses between T. b. brasiliensis and T. petrocchiae (to corroborate the results of Espínola [23]) and between T. lenti and T. petrocchiae (to assess whether T. petrocchiae presents prezygotic isolation with the other species of the T. brasiliensis complex)

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