| Most invertebrates relied on its immune defense systems to resist the invasion of foreign pathogens,remove foreign bodies from its own body,deal with erratic environmental changes as well as maintain the physiological balance of the body.Despite the lack of the special acquired immune response system shared by the vertebrates,the invertebrates had an efficient natural immune response system.The natural immune response system included two parts,respectively cellular immunity and humoral immunity.Encapsulation,which belonged to a type of cellular immunity,mainly referred to the process of hemocytes adhering to and accumulating on the surface of larger invaders and then stacking to form a "sheath" when foreign substances invade into the hemocoel.This process was often accompanied by melanism of foreign substances.At present,there are scarce studies focusing on the innate immunity of the spider.In this paper,the effects of UV irradiation and treatment of Bacillus thuringiensis(Bt)insecticide on the encapsulation index,total hemocyte count as well as activity of phenoloxidase in Larinioides cornuta were studied,in order to further explore the defensive characteristics of organisms and the mechanism of encapsulation,provide reference materials for the innate immunity of invertebrates and the protection and utilization of spiders.The main research contents and results were as follows:1.Observation on hemocytes in L.cornuta:For spiders,the hemocytes played a crucial role in the cellular immunity.The thesis studied the different forms of hemocytes of L.cornuta under the microscope,the effect of Giemsa staining and Wright-Giemsa staining on hemocytes were compared.The results showed that the common hemolymph of L.cornuta mainly includes five types,which were prohemocytes,plasmatocytes,granulocytes,oenocytoids and adipocytoids.Giemsa staining clearly colored the nucleus of granulocytes and adipocytoids in purple-red color,and the staining effect on the particulate matter in the cells was poor.However the Wright-Giemsa staining clearly stained the nucleus and cytoplasm of both granulocytes and adipocytoids.The nucleus was baby blue and the cytoplasm was blue-purple.2.Effects of UV Irradiation and the treatment of Bt pesticide on the total hemocyte count and encapsulation of L.cornuta:Spiders were irradiated 2h of the UV lamp of 20 watts,at a distance of 50cm,and then continued to feed under normal conditions.The total hemocyte count and encapsulation index were measured and compared to those parameters measured in untreated spiders at 2h,6h,24h,3d,5d and 8d after UV irradiation.L.cornuta were firstly treated with different concentrations of insecticide(0.1849mg/L,0.5547mg/L,1.664mg/L,4.992mg/L,14.976mg/L)which measured by dipping method,and then continued to feed under normal conditions.The total hemocyte count and encapsulation index were recorded at 4 and 12 days.Results indicated that there were significant differences in the total hemocyte count and encapsulation index at 6h,24h,3h,5d(p<0.05).However,the mean value of hemocytes in 2h was 6.17×106/mL,slightly less than the control,but the difference was not significant.The mean value of the encapsulation index in 8d was 42.3%,which was not significant compared with the control.UV irradiation could significantly reduce the total hemocyte count,notably inhibit the encapsulation of spiders in the early days.After the treatment of Bt insecticide,the total hemocyte count were significantly reduced at 4d,at the concentration of 4.922 mg/L,the total hemocyte reached the least and the encapsulation index was also significantly decreased.At 12d,the total hemocyte count was significantly lessened,and so did the encapsulation index.The encapsulation index was the lowest when the insecticide concentration was 0.5547 mg/L.To conclude,the usage of Bt insecticide caused the definite inhibition of the total hemocyte count and encapsulation of L.cornuta.3.Effects of UV Irradiation and the treatment of Bt pesticide on activity of phenoloxidase in L.cornuta:During the formation of the encapsulation,melanism often accompanied,and phenoloxidase was the key enzyme in the process of melanization.The effect of UV irradiation and Bt insecticide on the phenoloxidase activity were determined by double antibody enzyme-linked immuno sorbent assay.The results showed that after UV irradiation,The activity of phenoloxidase reached the highest value after 2h of normal feeding.The activity of PO was higher than that of the control at 2h and 6h after normal feeding.At 5d and 8d,PO activity was lower than that of the control,but the difference was not significant.UV irradiation could evidently restrain the activity of phenoloxidase at 24h and 3d.After treatment with Bt insecticide,the activity of phenoloxidase fluctuated slightly after 4 and 12days of normal feeding.The treatment of Bt insecticide could change the activity of phenoloxidase,but the difference was not significant compared with the control. |
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