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ARS Home » Plains Area » Kerrville, Texas » Knipling-Bushland U.S. Livestock Insects Research Laboratory » Cattle Fever Tick Research Unit » Research » Publications at this Location » Publication #377871
Research Project: Integrated Pest Management of Cattle Fever Ticks

Location: Cattle Fever Tick Research Unit

Title: Morphometrics of Amblyomma mixtum in the state of Veracruz, Mexico

Author
item AGUILAR-DOMINGUEZ, MARIEL - University Of Veracruzana
item ROMERO-SALAS, DORA - University Of Veracruzana
item SANCHEZ-MONTES, SOKANI - University Of Veracruzana
item SERNA-LAGUNES, RICARDO - University Of Veracruzana
item ROSAS-SAITO, GRETA - Institute De Ecologia - Mexico
item CRUZ-ROMERO, ANABEL - University Of Veracruzana
item Perez De Leon, Adalberto - Beto

Submitted to: Pathogens
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/27/2021
Publication Date: 4/29/2021
Citation: Aguilar-Dominguez, M., Romero-Salas, D., Sanchez-Montes, S., Serna-Lagunes, R., Rosas-Saito, G., Cruz-Romero, A., Perez De Leon, A.A. 2021. Morphometrics of Amblyomma mixtum in the state of Veracruz, Mexico. Pathogens. 10. https://doi.org/10.3390/pathogens10050533.
DOI: https://doi.org/10.3390/pathogens10050533

Interpretive Summary: Recent molecular and structural, or morphological, studies indicate that Amblyomma mixtum is the proper scientific name for a tick that was known before as A. cajennense in some parts of the Americas. The tick A. mixtum is one of the most economically important external parasites of cattle in Mexico. But, it can also bite humans and wildlife. This tick species also transmits disease-causing agents of veterinary and public health importance. Studies have shown that populations of A. mixtum in Mexico have high gene flow levels and exhibit low genetic structure. However, there is a knowledge gap on the variability of structural features between populations of A. mixtum living in different ecological regions. In this study we assessed morphological differentiation between A. mixtum populations across the ten ecological regions of the state of Veracruz in Mexico. This was done by collecting and identifying ticks from those ecological regions as A. mixtum and then analyzing them by electron microscopy. Measurement of different structural features were obtained for morphometric analysis. Scarce variation was detected in male and female A. mixtum from the different ecological regions. These findings complement our previous studies confirming the specific identity of this tick species in Veracruz state as A. mixtum. Despite its ability to colonize diverse ecosystems and to parasitize different host species, A.mixtum remains morphologically stable in this region. These findings are consistent with previous reports of lack of genetic differences between A. mixtum populations across the state of Veracruz in Mexico.

Technical Abstract: A. mixtum formerly considered as A. cajennense, is the second tick of importance in bovines of the Mexican tropic since is an important vector of pathogens. However, little is known about its intraspecific variability and the differentiation between populations. For this reason, the aim of this research was to determine by electron microscopy the morphological variability of the populations present in the state of Veracruz, Mexico. 40 males and 40 females were subjected to analysis, using a JEOL IT300 LV microscope. The measurements obtained were analyzed to determine the species. For each variable analyzed, the basic descriptive statistics were determined. Subsequently, an analysis of main components for females and males was carried out. The clusters were calculated with the out-tree method and a dendrogram was made to group the specimens according to their morphometric characteristics. These analyzes were performed with SAS® version 9.2 software. With 10 main components, 77% of the morphological variation of the ticks is explained, which evidences a scarce variation between female specimens of the same species, while the dendrogram grouped six clusters of specimens with similar characteristics. As in females and males the morphometric variability was described in eight main components, which evidences a scarce variation between male specimens of the same species, while the dendrogram grouped in six clusters the specimens with similar morphometric characteristics, with these results and the taxonomic keys it was determined that the only species from the A. cajennense complex distributed in the state of Veracruz is A. mixtum.