| In the paper, a new bioassay method of insecticidal activity, using Artemia nauplii as a model organism, was established. The possibility of Artemia nauplii as a biological screening model for insecticidal activity was investigated by measuring the sensitivities to different insecticides. And the rapid screening method for insecticidal activity was established by studying the impacts of different environmental factors on the results of Artemia nauplii bioassay method. Then the Artemia nauplii bioassay method was applied to screening insecticidal activities of leaf extracts of 62 kinds of bamboo, and the screening results were compared with that of traditional bioassay model to verify the accuracy of Artemia nauplii screening model. The main results were summarized as following:1. The results of sensitivity research showed thatⅡ~Ⅲperiod of Artemia nauplii was most sensitive to toxicant, and Artemia nauplii had different sensitivities to different insecticides. In addition to monosultap and methomyl, Artemia nauplii showed high sensitivities to the selected insecticides. The LC50 of abamectin and hexaflumuron after 48h were 0.02 mg/L, 0.023 mg/L.The LC50 of triazophos, pyridaben, chlorpyrifos, fipronil were 0.58 mg/L, 0.72 mg/L, 1.04 mg/L, 5.97 mg/L. The LC50 of carbaryl, thiocyclam, dichlorvos, cartap, MTMC, deltamethrin were 17.48 mg/L, 18.12 mg/L, 24.69 mg/L, 26.91 mg/L, 30.90 mg/L, 33.33 mg/L. The LC50 of monosultap and methomyl were 443.37 mg/L, 535.91 mg/L. It could be concluded that Artemia nauplii showed high sensitivities to the majority of selected insecticides, and Artemia nauplii bioassay method could be used as a screening model for insecticidal active substances.2. The research about environmental factors'impact on the results of Artemia bioassay method showed that salinity, pH, organic solvents, temperature, light cycle would affect the survival rates of Artemia nauplii. The survival rate of Artemia nauplii was only 5.03%, when the salinity of artificial seawater was 1‰, and Artemia nauplii could not survive in the water without salts. The survival rate of Artemia nauplii was 28.86% at pH 4.5, and could not survive at pH 3. Temperature, more than 35℃, could affect the survival rates of Artemia nauplii. It was 30.63% at 40℃, 2.06% at 45℃. Long light cycle could alse affect the survival. The survival rate of Artemia nauplii was only 75.57% at a light cycle of 24L-0D. Ethyl acetate, acetonitrile showed high toxicity to Artemia nauplii. At the concentration of 1%, the survival rates were 22.6%, 7.35%, and at the presence of hexane, dichloromethane, petroleum ether, toluene, benzene, Artemia nauplii could not survive. In addition, the volume of tested solution did not have an impact on the survival rate of Artemia nauplii. The Artemia nauplii bioassay method based on the above studies was: Salinity of solution should be in 5‰~120‰; Temperature could be controlled in 10℃~35℃; pH ranged at 5~10; Light cycle should not exceed 18L-6D; Materials under test could be diluted using acetone, methanol, ethanol.Then Artemia nauplii and 1.5ml solution under test were added to the 24-hole culture plate. After 48h, the number of death individuals and the total number of the tested Artemia nauplii were observed under a microscope to calculate the mortality rates, and evaluated the biological activity of the materials.3. The results of screening insecticidal activities in leaf extracts of 62 kinds of bamboo showed that the extracts performed different biological activities to Artemia nauplii at concentration of 1.0g/L. The extracts of Ch. quadrangularis, P. amarus, D. oldhami, B. multiplex, Ph. pubescence, Phyllostachys heteroclada Oliver, Ac. gigantean, Br. densiflorum had higher biological activities, and the corrected mortalities of Artemia nauplii were respectively achieved 100%, 97.82%, 93.11%, 92.14%, 86.43%, 84.80%, 84.79%, 75.10%, and the LC50 were respectively 144.2 mg/L, 323.9 mg/L, 388.6 mg/L, 399.1 mg/L, 436.9 mg/L, 474.7 mg/L, 565.6 mg/L, 631.8 mg/L. The corrected mortalities ranged at 40%~70%, under the effections of Sh. Chinensis et al 19 kinds of bamboo, 20%~40% under the effections of Ba. Cerosissima et al 14 kinds of bamboo, less than 20% under Phyllostachys bambusoides et al 21 kinds of bamboo, among which Phyllostachys acuta, Bambusa multiplex, Ps. amabilis, In. latifolius, De.minor var amoenus had no biological activities to Artemia nauplii.4. The results of screening insecticidal activity in leaf extracts of 62 kinds of bamboo, using aphid as bioassay model showed that the extracts of Ch. quadrangularis, P. amarus, D. oldhami, Ph. pubescence, B. multiplex had high biological activities, and the corrected mortalities of aphid were respectively achieved 86.25%, 81.25%, 80%, 78.75%, 74.5%. The corrected mortalities ranged at 40%~70%, under the effections of Phyllostachys heteroclada Oliver et al 8 kinds of bamboo, 20%~40% under the effections of Sasa fortunei et al 11 kinds of bamboo, and less than 20% under Phyllostachys bambusoides et al 21 kinds of bamboo, among which Phyllostachys acuta, Bambusa multiplex, Bambusa rihida, Ps. amabilis, De.minor var amoenus had no biological activities to aphid. It could be concluded that the results of two methods of screening showed the same general trend. Bamboo leaves extracts of which displayed high activity to Artemia nauplii also showed good biological activity to aphids, which displayed low activity to Artemia nauplii also showed poor biological activity to aphids, and even performed non-poisoned, and the activities of majority of bamboo extracts to Artemia nauplii were significantly higher than that to aphids. The results above proved that the use of Artemia nauplii as a screening model for bioactive material was reliable.Artemia nauplii as a screening model for bioactive substances has advantages of source with a wide range, simple operation, short time-consuming, less amount of compound. And as a low cost, high efficiency bioassay method, Artemia nauplii can greatly enhance the screening efficiency, and has great significance on the development of new pesticides.
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