Dragonflies and damselflies in Hidalgo and Puebla, insects adapted to high altitudes

The study of how animals and plants are distributed along environmental gradients can provide evidence of factors that promote the great diversity of species in the world and why it is so difficult to study.

Odonates, also known as cordyceps, are an order of insects with 6,403 species at present and in the Americas are subdivided into two suborders known as Anisoptera (dragonflies) and Zygoptera (damselflies). These insects are known to be present in freshwater bodies, since they lay their eggs in water and the larvae (also known as naiads) are aquatic. In addition, they indicate the quality of the environment and are predators of disease vectors that affect humans such as mosquitoes, bedbugs, among others.

In Mexico there are about 15 families, 83 genera and 371 species of dragonflies and damselflies; however, few studies have been conducted on the relationship between altitude and these insects, but researchers conclude that there is an increase in the number of species at low altitudes and that the number decreases with increasing altitude.

My research project during my Master of Science in Biodiversity and Conservation at the Autonomous University of the State of Hidalgo, I developed it in an altitudinal gradient ranging from 100 to 2,450 meters, in five places where the San Marcos River crosses, one of these sites is in the state of Hidalgo and four in Puebla.

For the study, adult odonates were captured in different types of habitats such as lotic (flowing water, river flow), lentic (temporary ponds, pools) and riverbank vegetation. The captured specimens were sacrificed in acetone to maintain their coloration, an important element to identify the species, as well as to keep them in a better state for future research. All specimens were deposited in the Odonata Collection of the Biological Research Center of the Autonomous University of the State of Hidalgo (COD-UAEH), and are available for those interested in these insects.

Among other results of this research, the same altitudinal trend was found as in previous research, where there is a decrease in the number of species as altitude increases. In addition, nine families, 38 genera and 87 species were recorded.

According to the analyses, about 90% of the species of the gradient were recorded, estimating that more than 100 species could be found in the river. The site with the highest altitude (Tenango de Doria, Hidalgo at 2,450 meters altitude) recorded the lowest number of species, only 13. In Chila de Juárez, Puebla (at 1,600 meters altitude) 25 species were obtained. Xilepa, Puebla (at an altitude of 1,000 meters) had 28 species. In Tlacuilotepec, Puebla (450 meters altitude) 37 species were recorded and finally, in the lowest altitudinal floor located at 100 meters altitude (Coronel Tito Hernández, Puebla) the highest number of species was found with 51.

Number of species per suborder at each altitude.

The analyses showed that the altitudes of 1,000 and 1,600 meters have a difference of 61% (lower); while the other altitudes have more differences between them (from 84 to 98%). Some of the species found in a large part of the gradient are tolerant to changes in temperature, pollution and even water scarcity (for example, Libellula croceipennis or Telebasis salva).

Telebasis salvage collected at Coronel Tito Hernandez, Puebla

For example, at 2,450 meters, species tolerant to cold climates were observed(Rhionaeschna jalapensis, Ischnura denticollis), while at the lowest altitude (100 meters) there are species adapted to high temperatures such as Neoerythromma cultellatum or Cannaphila insularis.

Rhionaeschna jalapensis collected in Tenango de Doria, Hidalgo.

The species found in this study present different types of distributions: wide (Mexico and other countries) and more restricted to a few states of the Mexican Republic. The San Marcos River is located in the Mexican Transition Zone where components of North and South America cross, presenting an interesting mixture from migratory species such as Anax junius or Erythrodiplax umbrata, to Hesperagrion heterodoxum which is the only existing species of this genus in the world and is endemic to Mexico.

Migratory species Anax junius collected in Xilepa, Puebla.

Mexican endemic species Hesperagrion heterodoxum collected in Tenango de Doria, Hidalgo.

This study helps us to understand how altitude affects odonate diversity at local and regional levels and how the different components (altitude, freshwater bodies, microhabitats and vegetation) play an important role that should be taken into account in all types of scientific research, since the relationship of all the factors constitute a relevant aspect that could tell us more about the biology, ecology or behaviors of the different living beings that inhabit this world.