| In China Cassava green mite (Mononychellus mecgregori) was found for the first time in Danzhou, HaiNan in 2008. At present M. mecgregori have spreaded to some cassava plantations of Hainan, Guangxi, Guangdong and Yunnan, and the harm that M. mecgregori cause is getting greater. By studying the development and reproduction of the M. mecgregori fed on Manihot esculenta, Hevea brasiliensis, Chaenomeles speciosa, Codiaeum variegatum and Mangifera indica, comparing contents of nutrients and secondary metabolites in leaves of the 5 host plants, and the activity of the protective enzymes that include PPO, POD, CAT, SOD, AsA POD and α-NA/β-NA EST of the M. mecgregori after they fed on the 5 host plants,and the differences in the activity of protective enzymes that contain POD, CAT and PPO in the leaves which were hurted by M. mecgregori of the 5 host plants, and the differences of the relative quantitative expression of th genes of POD,CAT and SOD enzymes between the various instar mites’bodies of the M. mecgregori fed on cassava and rubber, the main results indicated as follows:(1) The growth and development of the M. mecgregori fed on the 5 host plants were the significant differences (P< 0.05). the M. mecgregori can complete generation development on the leaves of cassava and rubber, and there were no significant differences in vavious instar of the mites, and fed on rubber leaves, the mites taked 8.45 and 8.95 d to finish its F0 and F1 generation repectively, when F0 and F1 generation of the mites fed on cassava leaves were 8.10 and 8.45 d repectively, but the larve of the FO generation of the M. mecgregori only survived for 3.70,1.80 and 1.60 d on papaya’s, codiaeum’s and mango’s leaves. The offspring sex ratio of F0 and F1 generation were 80.80% and 88.50% on the cassava’s leaves, while those were 80.20% and 80.60% on the rubber’s leaves. The eggs laid by per female had the very significant difference between cassava, rubber and papaya, codiaeum, mango. The average fecundity were 47.60,37.20 eggs per female fed on rubber’s and cassava’s leaves, when those were 2.40,1.96 and 1.20 eggs per female fed on papaya’s, codiaeum’s and mango’s leaves. The next generation mites lay 50.70 and 44.50 eggs per female fed on leaves of rubber and cassava. The average survival ratio of the adult fed on rubber’s and cassava’s leaves was very significantly different from papaya, codiaeum and mango. They were 19.0, 17.0,6.5,6.0 and 5.5 d among rubber, cassava, papaya, codiaeum and mango. In addition, the most of the mites died after they fed on papaya, codiaeum and mango for 3 day, then until the 7th day, none were survival, at the same time, plenty of mites died after they being on cassava and rubber for 8 day.(2) This paper discussed contents of chloroplast pigment, nutrients including sugar(S), nitrogen(N), S/N, vitaminC(Vc), free amino acids and secondary metabolites including total phenolics, proline, Malondialdehyde and tannin among the leaves of the 5 host plants. The results showed that the contents of chloroplast pigment and the nutrients that not including sugar(S) and nitrogen(N) were significantly more in the leaves of cassava and rubber than those in the papaya’s, codiaeum’s and mango’s. On the contrary, the contents of the secondary metabolites were significantly more in the leaves of papaya, codiaeum and mango than those in the cassava’s and rubber’s. Among the 5 host plants, S/N had no significant differences between cassava’s and rubber’s, but cassava’s and rubber’s were significantly lower than papaya’s(1.17), codiaeum(1.16) and mango(1.27). In conclusion, the lower content of chloroplast pigment, vitaminC(Vc) and free amino acids and the higher content of S/N, total phenolics, proline, Malondialdehyde and tannin were the may reason why the M. mecgregori lay few eggs, and died in few day in the leaves of papaya, Codiaeum and mango.(3) By comparing the activity of protective enzymes including PPO, POD, CAT, SOD, AsA-POD and α-NA/β-NA EST in the larve fed on the 5 host plants for 1 d and in adults fed on the 5 host plants for 3 d, and found that the activity of the protective anzymes in the larve fed on cassava’s and rubber’s leaves for Id were significantly higher than ones’fed on papaya’s, codiaeum’s and mango’s and in the adults fed on cassava’s and rubber’s leaves for 3d were also significantly higher than those fed on papaya’s, codiaeum’s and mango’s, but the mites fed on cassava’s the rubber’s leaves had no significant difference among the protective enzymes’ activity. At the same time, this paper also discussed how much the activity of the protective enzymes including POD, CAT, and PPO in the leaves of the 5 host plants damaged by the M. mecgregori increased, the results suggested that the activity of POD, CAT, and PPO in the leaves of papaya, codiaeum and mango hurted by the M. mecgregori rose more significantly than cassava’s and rubber’s, and the increasing of the activity of the proactive enzymes in the leaves of cassava weren’t significant different from rubber’s except CAT’s. So the M. mecgregori lay few eggs, and died in few day in the leaves of papaya, codiaeum and mango was mainly caused that the activity of the M. mecgregori’s protective enzymes was reduced and the 5 host plants’protective enzymes were gone up.(4) Preliminary study on the differences of the relative quantitive expression of the POD, CAT, and SOD genes in various instars of the M. mecgregori fed on cassava’s ang rubber’s leave by RT-PCR. The results indicated that the relative quantitive expression of the POD, CAT, and SOD genes in various instars of the M. mecgregori fed on cassava’s leaves were all higher than those fed on rubber’s, however, the relative quantitive expression of the POD, CAT, and SOD genes in various instars of the M. mecgregori fed on cassava’s leaves weren’t significantly higher than those fed on rubber’s, that maybe an good examplation for the growth and development of the M. mecgregori on cassava were the same as those on rubber, meanwhile, that was a good instance to study on the host selectivity of the M. mecgregori at the molecular level. |
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