Human activities can have dramatic impacts on animal populations around urban areas with heavy metal contamination being a primary cause of hazardous effects. Insects as residents of ecosystems are especially susceptible to heavy metal... more
Human activities can have dramatic impacts on animal populations around urban areas with heavy metal contamination being a primary cause of hazardous effects. Insects as residents of ecosystems are especially susceptible to heavy metal contamination and have the potential to serve as indicators for environmental stresses .To better understand the effect of heavy metals pollution on terrestrial insect, the detection of different heavy metals was investigated. The following metals cadmium (Cd), copper (Cu), zinc (Zn) and lead (Pb) were found and their concentrations were estimated in soil samples from either polluted or reference site. As the Cd concentration was significantly high in the polluted site, its concentration in the tissues of the studied insect Blaps polycresta (Coleoptera:Tenebrionidae), was investigated as well as the antioxidant defense system and lipid peroxidation biomarkers. The results of insect's tissues in polluted site showed a significant decrease in the activity of antioxidant enzymes, glutathione S-transferase (GST), superoxide dismutase (SOD), catalase (CAT), and reduction in the level of glutathione (GSH). In addition, there was a significant decrease in the total protein content. On the other hand a significant increase of transaminases (AST, ALT), and lipid peroxidation (LPO) levels was found. In conclusion, insect can be considered as a good bioindicator species for environmental heavy metals pollution especially by cadmium that accumulates in soft tissues and has deleterious effects.
X-ray analysis was applied to estimate the percentages of heavy metals in ovarian tissues of the tenebrionid beetle, Blaps polycresta. Calcium, phosphorus, sulfur, cadmium, copper, and zinc were the most common detected metals in ovaries... more
X-ray analysis was applied to estimate the percentages of heavy metals in ovarian tissues of the tenebrionid beetle, Blaps polycresta. Calcium, phosphorus, sulfur, cadmium, copper, and zinc were the most common detected metals in ovaries of insects collected from reference and polluted sites. Only cadmium showed significantly higher percentages in the polluted ovaries compared with the reference ones. Ultrastructure investigation revealed severe alterations in polluted ovaries both in the tropharium and in the vitellarium. Contraction of nuclear membrane of trophocytes was observed; therefore, cavities and spaces appeared in the cytoplasm followed by nuclear pyknosis. In the vitellarium, fragmentation of chromatin materials in nuclei of the follicular cells was detected. The cytoplasm was poor in the rough endoplasmic reticulum and mitochondria. Damage of yolk bodies occurred in addition to break off in the layer of microvilli. Accumulation of electron-dense vesicles and multivesicular bodies were observed in both reference and polluted ovaries. These alterations in ovarian ultrastructure of B. polycresta show the severe impact of cadmium pollution on cell organelles of insects and could be used as an interesting tool for monitoring heavy metals inside the body organs due to soil pollution.
In June 17, 2016 the first author (Andrey Kovalchuk) visited the Krakatau Archipelago in the Sunda Strait and ascended the crater of Anak Krakatau volcano in Indonesia. During this exploration (and as well additional travel) he made a... more
In June 17, 2016 the first author (Andrey Kovalchuk) visited the Krakatau Archipelago in the Sunda Strait and ascended the crater of Anak Krakatau volcano in Indonesia. During this exploration (and as well additional travel) he made a series of observations, documented photographically, of insects and some plants, and of the landscapes. Whereas significant investigations of Krakatau have been made in the past, these new observations show that the situation with the biota is changing fast. Ecosystems of the island can be classified as impulse- unstable, so that every new eruption stimulates change. It was observed that a large area of burned forest (after the famous eruption in 2012) extended to approximately 1/3 of the southern coastline, and the ecosystem was dramatically affected (especially butterflies). Despite these current changes, no ongoing comprehensive investigations of the island's ecosystems are currently occurring.
Ultrastructure alterations in spermiogenesis of the ground beetle, Blaps sulcata (Coleoptera: Tenebrionidae) were studied in normal adult males and in two male groups irradiated by gamma rays of 3 and 16 μSv/h dose rate. Ultrastructure... more
Ultrastructure alterations in spermiogenesis of the ground beetle, Blaps sulcata (Coleoptera: Tenebrionidae) were studied in normal adult males and in two male groups irradiated by gamma rays of 3 and 16 μSv/h dose rate. Ultrastructure examination of irradiated sperms revealed many alterations both in the head and in the flagellum regions of mature sperm. Alterations of the head region included nuclei with uncondensed chromatin materials and irregular nuclear envelope. Abnormal flagella contained malformed mitochondrial derivatives and damaged axonemes in addition to the absence of accessory bodies. Bi- and multi-flagellate sperms (with two, three, and four axonemes) were the most common alterations. Sperm cells with residual bodies were also obtained. Agglutinated sperms and sperms with enlarged and/or vacuolated cytoplasm were common. Sperm abnormalities were more pronounced in males irradiated by 16 μSv/h dose rate than those irradiated by 3 μSv/h. Spermiogenesis alterations indu...
X-ray analysis was applied to estimate the percentages of heavy metals in ovarian tissues of the tenebrionid beetle, Blaps polycresta. Calcium, phosphorus, sulfur, cadmium, copper, and zinc were the most common detected metals in ovaries... more
X-ray analysis was applied to estimate the percentages of heavy metals in ovarian tissues of the tenebrionid beetle, Blaps polycresta. Calcium, phosphorus, sulfur, cadmium, copper, and zinc were the most common detected metals in ovaries of insects collected from reference and polluted sites. Only cadmium showed significantly higher percentages in the polluted ovaries compared with the reference ones. Ultrastructure investigation revealed severe alterations in polluted ovaries both in the tropharium and in the vitellarium. Contraction of nuclear membrane of trophocytes was observed; therefore, cavities and spaces appeared in the cytoplasm followed by nuclear pyknosis. In the vitellarium, fragmentation of chromatin materials in nuclei of the follicular cells was detected. The cytoplasm was poor in the rough endoplasmic reticulum and mitochondria. Damage of yolk bodies occurred in addition to break off in the layer of microvilli. Accumulation of electron-dense vesicles and multivesicu...
Little is known about ultrastructural alterations induced by heavy metals pollution in insects. Therefore, the main objective of the present study is to elucidate ultrastructural changes in sperm formation of the tenebrionid beetle, Blaps... more
Little is known about ultrastructural alterations induced by heavy metals pollution in insects. Therefore, the main objective of the present study is to elucidate ultrastructural changes in sperm formation of the tenebrionid beetle, Blaps polycresta as a biomonitor of heavy metal soil pollution. Metal percentages in testicular tissues of adult insects collected from reference and polluted sites were estimated using energy-dispersive X-ray microanalysis (EDX). Only cadmium, among eight detected metals, showed significantly higher percentages in the polluted testes compared with the reference ones. Ultrastructure investigation revealed severe alterations both in spermatogenic and spermiogenic stages of the polluted insects. Some cells were totally eroded. No spermatozoa were observed in all the examined cysts. Most degenerations were confined to the flagella of spermatids having enlarged vacuolated cytoplasm and malformed mitochondrial derivatives. Groups of multiple axial filaments were appeared in the form of bi-and tetra-flagellate spermatids. Electron dense vesicles were observed in almost all stages of the polluted testes. It is a novel trend in which ultrastructural alterations in sperm formation of insects could be used as a promising biomonitoring and risk assessment tool for heavy metal soil pollution.
Human activities can have dramatic impacts on animal populations around urban areas with heavy metal contamination being a primary cause of hazardous effects. Insects as residents of ecosystems are especially susceptible to heavy metal... more
Human activities can have dramatic impacts on animal populations around urban areas with heavy metal contamination being a primary cause of hazardous effects. Insects as residents of ecosystems are especially susceptible to heavy metal contamination and have the potential to serve as indicators for environmental stresses .To better understand the effect of heavy metals pollution on terrestrial insect, the detection of different heavy metals was investigated. The following metals cadmium (Cd), copper (Cu), zinc (Zn) and lead (Pb) were found and their concentrations were estimated in soil samples from either polluted or reference site. As the Cd concentration was significantly high in the polluted site, its concentration in the tissues of the studied insect Blaps polycresta (Coleoptera: tenebrionidae), was investigated as well as the antioxidant defense system and lipid peroxidation biomarkers. The results of insect's tissues in polluted site showed a significant decrease in the a...
In June 17, 2016 the first author (Andrey Kovalchuk) visited the Krakatau Archipelago in the Sunda Strait and ascended the crater of Anak Krakatau volcano in Indonesia. During this exploration (and as well additional travel) he made a... more
In June 17, 2016 the first author (Andrey Kovalchuk) visited the Krakatau Archipelago in the Sunda Strait and ascended the crater of Anak Krakatau volcano in Indonesia. During this exploration (and as well additional travel) he made a series of observations, documented photographically, of insects and some plants, and of the landscapes. Whereas significant investigations of Krakatau have been made in the past, these new observations show that the situation with the biota is changing fast. Ecosystems of the island can be classified as impulse- unstable, so that every new eruption stimulates change. It was observed that a large area of burned forest (after the famous eruption in 2012) extended to approximately 1/3 of the southern coastline, and the ecosystem was dramatically affected (especially butterflies). Despite these current changes, no ongoing comprehensive investigations of the island's ecosystems are currently occurring.
