Hybrids versus parental species: ¿What the similarities or differences in the wing phenotype of triatomine insects tell us?

Álvaro Lara ¹ María Laura Hernández ^2,3* César Yumiseva ¹ Mario J. Grijalva ^1,4 Anita Gabriela Villacís ^1*

• ¹ Centro de Investigación para la Salud en América Latina (CISeAL), Pontificia Universidad Católica de Ecuador, Quito, Ecuador, Quito, Pichincha, Ecuador
• ² Unidad Operativa de Vectores y Ambiente (UnOVE). Centro Nacional de Diagnóstico e Investigación en Endemo-Epidemias (CeNDIE- ANLIS Malbrán). Santa María de Punilla., Cordóba, Argentina
• ³ Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Argentina, Córdoba, Córdoba, Argentina
• ⁴ Infectious and Tropical Disease Institute, Department of Biomedical Sciences, Heritage College of Osteopathic Medicine, Ohio University, Athens / Ohio, United States

The genus Panstrongylus is one of the most important of the subfamily Triatominae which groups the vectors of the Trypanosoma cruzi, the etiological agent of Chagas disease (CD), particularly Panstrongylus chinai and P. howardi, has drawn attention for its role in the disease's transmission. These species exhibit notable ecological and morphological differences. Previous studies have investigated aspects such as morphometry, cytogenetics, and ecological niches, including experimental crosses between these species that resulted in viable F1 hybrids. However, no F2 generation was produced, as the eggs laid were empty and failed to hatch, limiting the study to F1 hybrids.We analyzed wing morphometric traits (size and shape) from 262 individuals, including P. chinai, P. howardi, and their hybrids using geometric morphometry techniques. The goal of this study was to expand on previous findings by analyzing the wing morphometric and environmental adaptations of P. chinai, P. howardi, and their hybrids (♀P. howardi × ♂P. chinai) to determine whether the hybrids exhibited similarities in wing size and shape, regardless of the maternal or paternal phenotype.Results: Differences in centroid size between the parental species (larger in P. howardi), but not among the hybrids were observed. The females showed greater similarity in shape between P. howardi and the ♀P. chinai × ♂P. howardi hybrids, while for males, was among hybrids.Discriminant analysis was more effective with parental groups than with hybrids. The K-means algorithm classified the parental species and hybrid groups well, although with low percentages in assignment to groups and a different number of groups than expected.The smaller wing size in hybrid offspring may reflect lower fitness, possibly due to genetic effects or lack of viability. Geometric morphometry effectively distinguishes between parental species and hybrids, supporting previous research in Triatominae. The study suggests that environmental and reproductive pressures may influence these species and examines the dispersive capabilities of triatomines, contributing to the understanding of hybridization processes.