Bioavailability of heavy metals and their effects on the midgut cells of a phytopaghous insect inhabiting volcanic environments

Abstract

Organisms living in volcanic environments are chronically exposed to metals, either as particles or associated with gases, from volcanic emissions, being therefore potential sentinels of the effects derived from such exposure. Concentrations of Ca, Cd, Cu, Mg, Mn, Pb, Rb, and Zn were measured in soil, grass (Lolium perenne), and larvae of Pseudaletia uninpuncta captured in sites exposed and non-exposed to volcanic activity. The midgut epithelial cell morphometry and apoptosis of P. unipuncta larvae were also analyzed. Larvae from the site with volcanic activity showed higher levels of Cu, Mn, Rb and Zn. Metals such as Pb, Cd and Mg levels of P. unipuncta larvae were similar between sites. Apoptosis was higher in cells from digestive epithelium of larvae exposed to volcanic activity. Soils and grass not exposed to volcanic activity showed higher levels for most of the analyzed elements with the exception of Rb. Such result when compared with metal levels of larvae may reveal that bioavailability of elements differs between sites. The higher levels of Cd, Zn and Mg in soils and grass from the site with no volcanic activity are probably related to the severe artificial fertilization in the studied pastures. Such result, when compared with metal levels of larvae, suggest that the bioavailability of metals differs between sites. IntroductionIn São Miguel Island (Azores, Portugal) volcanic activity is manifested, among other ways, by the occurrence of hydrothermal vents, and soil degassing (Cruz, 2003;Ferreira et al., 2005). Consequently, organisms living in such environment may be continually exposed to metals, either as particles or associated with gases (Hansell et al., 2006). The association between changes in the digestive epithelium and the occurrence of apoptosis under chronic metal and metalloid exposure, originated by volcanic activity, has been previously found in terrestrial (e.g., earthworms, and snails) and marine invertebrates (e.g., limpets) (Amaral and Rodrigues, 2005;Zaldibar et al., 2006;Cunha et al., 2008). Thus, it is important to look for organisms that can be used as biological indicators or sentinels for the presence of those pollutants under such conditions, and in which one can rapidly measure several biomarkers of exposure and/or effects. The relationship between the accumulation of metals and their biomagnification in edible plants, insects, such as Lepidoptera larvae, and higher consumers, such as predators, has been shown in recent studies (Vickerman and Trumble, 2003;Dauwe et al., 2004;Mulder and Breure, 2006). Such studies indicate the important role of insects as links in metal transport

Morphometry of the epidermis of an invasive megascoelecid earthworm (Amynthas gracilis, Kinberg 1867) inhabiting actively volcanic soils in the Azores archipelago

“…concentrations. It has been recorded previously that the high mineralisation and trace element bioavailability in Furnas soils and water together, together with diffuse degassing phenomena, do influence the tissue accumulation of metals by representatives of the local fauna (Cruz et al, 1999;Cunha et al, 2008;Rodrigues et al, 2008;Viveiros et al, 2009). Tissue metal concentrations (especially Zn and Cu) in earthworms at the end of the experimental exposure to Furnas soil were found to be almost two-fold higher than the soil concentrations, and even similar to what was found in earthworms living in, or inoculated into, polluted sites (Ruiz et al, 2009).…”

“…The extant volcanic activity in certain terrestrial locations on São Miguel, one of the nine islands comprising the Azores archipelago, provide good ''field-laboratories'' for investigating aspects of the capacity of soil-dwelling macroinvertebrates to inhabit natural habitats continuously receiving potentially toxic chemical inputs in a milieu conducing bioavailability (Amaral et al, 2006b;Cunha et al, 2008;Rodrigues et al, 2008).…”

Ecological Risk Assessment Of Heavy Metals In Sediments Of A Riverine Wetland, Huaihe River Watershed, China

“…Contamination from heavy metals has become a worldwide environmental concern due to their persistence and bioaccumulation and for causing serious environmental problems to the human environment [1][2][3]. In an aquatic system, heavy metals can migrate from the water to sediments and some of these pollutants can be desorbed from the sediments and…”

Transcriptional response of two metallothionein genes (OcMT1 and OcMT2) and histological changes in Oxya chinensis (Orthoptera: Acridoidea) exposed to three trace metals

“…plants to insects (Vickerman and Trumble, 2003;Mulder and Breure, 2006). Indeed, phytophagous insect (Pseudaletia uninpuncta) larvae collected from volcanic environments showed higher levels of Cu, Mn, Rb and Zn, and higher levels of apoptosis in cells from digestive epithelium due to larval chronical exposures to metals as compared with those unexposed to the volcanic activity (Rodrigues et al, 2008). Several studies have also demonstrated the relationship between the tissues damages and the accumulation of excess metals in insect body (Kawakami et al, 2013).…”