| Octodonta nipae (Maulik)(Coleoptera:Chrysomelidae) is an invasive pest which infest many species of palms in South China. Owing to the differentiation of ecology habitat, its adaptation had an obvious variation in different host plants. On the base of pervious research about host selection of O. nipae (Maulik), we presented the evidence to show the efffects of nutrition in the palm leaves from four plant species, including Phoenix canariensis, Trachycarpus fortunei, Phoenix hanceana and Livistona chinensis, on feeding and fecundity of O. nipae (Maulik) reared in laboratory. Significant differences were determined in four nutrition contents of different palm leaves. We determined the primary nutrition of palm plants which influenced the feeding and fecundity through principal components analysis. The difference in volatiles of different palm leaves was analyzed. Then we compared the difference of three enzyme systems in O. nipae at each developmental stage reared on these different palm leaves. We mastered the interaction effect between host plants and insects to improve the scientific foundation for researching its invasive mechanism. The main results are as following:Significant differences were determined in four nutrition contents of different palm leaves. The results indicated that O. nipae had a preference to the four tested palm species. O. nipae obviously preferred to P. canariensis and T. fortunei, but the lowest tendency was detected for L. chinensis. Free amino acids, soluble sugar and soluble protein were the most abundant materials in P. canariensis, with the quantity of1.13%,1.05%and19.50%, respectively. However, compared with the other three contents, the crude fat of L. chinensis was measured with the highest quantity of7.04%. Through the method of principal component analysis, the free amino acid, soluble sugar and soluble protein were the principal factors to affect the feeding and fecundity of O. nipae, with the contribution rate of56.13%,26.72%and13.67%, respectively. The obvious correlations were found between the feeding and fecundity of O. nipae and the three materials of palm leaves, respectively. The secondary volatile substances were analyzed by gas chromatography mass spectrometer in host plants, and determined32kinds of chemical. The results showed significant differences were determined in four different palm leaves. Five substances were found only in P. canariensis, but they were not found in the three other plams. In addition, three contents in P. canariensis had obviously higher than those in other palm leaves. Suggesting these substances are possible to play a role in the host selection.Obvious differences were determined in the activity of three protective enzymes (Catalase, Peroxidase and Superoxide dismutase) of larvae, pupa and adult of O. nipae reared on three different young host leaves(P. canariensis, T. fortunei, P. hanceana) in laboratory. The activity of three protective enzymes was significantly different in individuals from different plants. In each developmental stage, the activities of catalase (CAT) and superoxide dismutase (SOD) of O. nipae reared on P. canariensis were higher than the others. However, the peroxidase (POD) activity in P. hanceana was the highest. In larvae, the POD and SOD activity increased with its development, and their activities in adults were higher than those in pupa and larvae, respectively. These differences of enzyme activity may explain the different fitness obtained in O. nipae (Maulik) reared on various palm leaves from the perspective of chemical ecology.The activity of three detoxification enzymes (Carboxylesterase, Glutathione-S-transferase and Acetycholinesterase) was compared in O. nipae at each developmental stage after eating three different palm plants. The results indicated all the three enzymes had obvious difference among the three host spear leaves. At the stage of larvae, the enzyme activities increased with the increasing instars. For the pupal stage, the activities decreased to the lowest points in all developmental duration. While after hatching, the enzymes of the adult insects began to rise. However, the activities of carboxylesterase (CarE) and acetycholinesterase (AchE) in adults were higher than the larvae, the glutathione-S-transferase (GST-SH) activity was lower than the larvae. O. nipae which feed on P. canariensis had the highest activities of GST-SH and AchE, the second highest was that on T. fortunei, and the lowest activity was found in O. nipae fed on P. hanceana. The activity of CarE was the highest in O. nipae feeding on T. fortunei. The second was that on P. canariensis. Meanwhile, it was remain the lowest on P. hanceana.After rearing the three different palms, the activities of the metabolize enzymes (γ-glutamyltransferase, Alaninetransaminase and Aspartate aminotransferase) were measured in each developmental stage of O. nipae, with the comparison of their difference. The results indicated significant differences in O. nipae of all the three host spear leaves. At the larvae, the enzyme activity increased with growing old. The γ-glutamyltransferase (γ-GT) activity in O. nipae which reared on T. fortunei had an unobvious difference. Similarly, the alaninetransaminase (ALT) in O. nipae on P. hanceana had an unobvious change. The palm leaf beetles on P. canariensis had the highest activities of γ-GT and aspartate aminotransferase (AST) in three populations. However, ALT activity was the highest of which fed on P. hanceana.The most useful primers were set and selected from8microsatellite sequences from Brontispa longissima (Gestro) which belonged to the same superfamily with O. nipae to resesrch the genetic diversity of its populations through the method of SSR markers. We found that they had no specificity in populations of O. nipae, then they cannot be used to the research of its genetic diversity. |
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