Abstract
Termites are social insects of economic importance that have a worldwide distribution. Identifying termite species has traditionally relied on morphometric characters. Recently, several mitochondrial genes have been used as genetic markers to determine the correlation between different species. Heavy metal accumulation causes serious health problems in humans and animals. Being involved in the food chain, insects are used as bioindicators of heavy metals. In the present study, 100 termite individuals of Anacanthotermes ochraceus were collected from two Saudi Arabian localities with different geoclimatic conditions (Riyadh and Taif). These individuals were subjected to morphological identification followed by molecular analysis using mitochondrial 12S rRNA gene sequence, thus confirming the morphological identification of A. ochraceus. Furthermore, a phylogenetic analysis was conducted to determine the genetic relationship between the acquired species and other termite species with sequences previously submitted in the GenBank database. Several heavy metals including Ca, Al, Mg, Zn, Fe, Cu, Mn, Ba, Cr, Co, Be, Ni, V, Pb, Cd, and Mo were measured in both collected termites and soil samples from both study sites. All examined samples (termite and soil) showed high concentrations of metals with different concentrations and ratios. Generally, most measured metals had a significantly high concentration in soil and termites at Taif, except for Ca, Cd, Co, Cr, Cu, Mg, and Ni showing significantly high concentrations at Riyadh. Furthermore, termites accumulated higher amounts of heavy metals than the soil at both locations. The mean concentrations of the measured metals in soil samples were found to be in the descending order Ca ˃ Al ˃ Mg ˃ Zn ˃ Fe ˃ Cu ˃ Mn ˃ Ba ˃ Cr ˃ Co ˃ Be ˃ Ni ˃ V ˃ Pb ˃ Cd ˃ Mo, while it was Ca ˃ Mg ˃ Al ˃ Fe ˃ Zn ˃ Cu ˃ Mn ˃ Be ˃ Ba ˃ Pb ˃ Cr ˃ V ˃ Ni ˃ Cd ˃ Mo ˃ Co in termite specimens. The mean concentrations of the studied metals were determined in the soil and termite specimens at both locations. In addition, the contamination factor, pollution load index (PLI) and degree of contamination were calculated for all studied metals in different samples, indicating that both studied sites were polluted. However, Taif showed a significantly higher degree of pollution. Thus, the accurate identification of economically important insects, such as termites, is of crucial importance to plan for appropriate control strategies. In addition, termites are a good bioindicator to study land pollution.
Highlights
Termites are an interesting group of social insects that are widely distributed in low-land tropical ecosystems, where they can make up to 95% of the soil insect biomass [1]
According to the present results, A. ochraceus was naturally recorded in both localities under investigation; this is consistent with data reported by Ahmad [39] and Roonwal and Rathore [40], whom stated that species of the genus Anacanthotermes belonging to the family Hodotermitidae are characterized as the termites of Blattodea
Our analysis suggests that the first one was monophyletic, and more extensive taxon sampling will be required for the determination of the second one; this was consistent with the opinion of Inward et al [49]
Summary
Termites are an interesting group of social insects that are widely distributed in low-land tropical ecosystems, where they can make up to 95% of the soil insect biomass [1]. Anacanthotermes is an Old-World genus of harvester termites in the Hodotermitidae. They are distributed in the deserts and semi-deserts of North Africa, the Middle East, and southwest Asia, including Baluchistan and southern India [5]. Molecular tools have become ways to complement the value of morphological taxonomy in addition to understand the evolutionary relationships among species. Molecular taxonomy based on mitochondrial DNA has proved to be an efficient alternative to the identification of species and determines their phylogenetic relationships [9,10]. DNA sequences of the mitochondrial genes of cytochrome oxidase subunit II (COX II) and the large (16S) and small (12S) subunits of ribosomal RNA (r RNA) have been used extensively for molecular diagnostics and to conduct comparative genetic analyses to study taxonomy, gene flow, colony characterization, and genetic variations [4,11]. Genetic diversity in subterranean termites was studied using the random amplified polymorphic DNA (RAPD) markers [12]
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