Carabid beetles are among the most important groups of beneficial arthropods in the agroecosystem food chain where they are predators of many pests (including aphids, lepidopterans, slugs and Diptera). Previous studies have been shown that they are good models to investigate the negative effects of agrochemical used in agricultural management practices on natural enemies of insect pests. In ecological immunology, variation on immune capacity of insects is an early warning, highly sensitive biomarker to monitor the sub-lethal effect of toxicants introduced into environment as a result of industrial or agricultural activity. However, morpho-functional data about immune system of carabid are absent in spite of their ecological relevance. In this study, we have investigated the immune function of Pterostichus melas italicus (Dejean, 1828) for their use in eco-toxicological monitoring. This species is a generalist predator, eurytopic and thermophilous and it is very common in Calabrian (South Italy) agroecosystems (i.e. olive grove) and acts as a predator against insect pests (i.e. Bactrocera oleae). Tests performed on adult involve a general screen of immune function and include: characterization of circulating hemocytes, phagocytosis in vivo and phenoloxidase activity. The cellular population has been characterized by light and electron microscopy analysis and four morphotypes of circulating hemocytes were found: prohemocytes (1.1±0.35%), plasmatocytes (76.13±7.00%), granulocytes (13.40±5.84%), oenocytoids (1.93±0.96%). The phagocytosis assays were performed in vivo by injection of 0.9 µm carboxylate-modified polystyrene latex beads in order to identify the hemocyte types involved in phagocytosis. After non-self challenge treatment, specimens showed a decrease of granulocyte and prohemocyte percentages (6.13±3.36% and 0.80±0.41% respectively) and a non-specific immune response involving phagocytosis performed by plasmatocytes (42.50±3.39%). Moreover the plasmatic phenoloxidase (PO) activity has been evaluated spectrophotometrically recording the formation of dopachrome by a non-enzimatic reaction from DL-DOPA substrate and it was expressed as absorbance units at 492nm/μL of hemolymph. The PO level was low in unstimulated specimens (0.0521±0.0026 A492/µL at 30’; n=20), while we detected an increase of PO activity (0.0816±0.0153 A492/µL at 30’; n= 26) after the activation of the prophenoloxidase (proPO) into PO with methanol.
Characterization of hemocytes and plasmatic prophenoloxidase from adults of Pterostichus melas italicus Dejean, 1828 (Coleoptera, Carabidae)
GIGLIO, Anita;Brandmayr P;
2013-01-01
Abstract
Carabid beetles are among the most important groups of beneficial arthropods in the agroecosystem food chain where they are predators of many pests (including aphids, lepidopterans, slugs and Diptera). Previous studies have been shown that they are good models to investigate the negative effects of agrochemical used in agricultural management practices on natural enemies of insect pests. In ecological immunology, variation on immune capacity of insects is an early warning, highly sensitive biomarker to monitor the sub-lethal effect of toxicants introduced into environment as a result of industrial or agricultural activity. However, morpho-functional data about immune system of carabid are absent in spite of their ecological relevance. In this study, we have investigated the immune function of Pterostichus melas italicus (Dejean, 1828) for their use in eco-toxicological monitoring. This species is a generalist predator, eurytopic and thermophilous and it is very common in Calabrian (South Italy) agroecosystems (i.e. olive grove) and acts as a predator against insect pests (i.e. Bactrocera oleae). Tests performed on adult involve a general screen of immune function and include: characterization of circulating hemocytes, phagocytosis in vivo and phenoloxidase activity. The cellular population has been characterized by light and electron microscopy analysis and four morphotypes of circulating hemocytes were found: prohemocytes (1.1±0.35%), plasmatocytes (76.13±7.00%), granulocytes (13.40±5.84%), oenocytoids (1.93±0.96%). The phagocytosis assays were performed in vivo by injection of 0.9 µm carboxylate-modified polystyrene latex beads in order to identify the hemocyte types involved in phagocytosis. After non-self challenge treatment, specimens showed a decrease of granulocyte and prohemocyte percentages (6.13±3.36% and 0.80±0.41% respectively) and a non-specific immune response involving phagocytosis performed by plasmatocytes (42.50±3.39%). Moreover the plasmatic phenoloxidase (PO) activity has been evaluated spectrophotometrically recording the formation of dopachrome by a non-enzimatic reaction from DL-DOPA substrate and it was expressed as absorbance units at 492nm/μL of hemolymph. The PO level was low in unstimulated specimens (0.0521±0.0026 A492/µL at 30’; n=20), while we detected an increase of PO activity (0.0816±0.0153 A492/µL at 30’; n= 26) after the activation of the prophenoloxidase (proPO) into PO with methanol.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
