| This paper reported the olfactorial and visual regulation of Myzus persicae. It can be divided into screening of plant-derived repellents, phototaxis bioassay, and communication between M. persicae and ladybirds. The main results are summarized as follows:(1) Choice response of M. persicae alates to 30 aroma plants were tested. The response indices of M. persicae alates to Kaempferia galangal, Angelica dahurica, and Citrus tangerine were 0.6368,0.5198, and 0.5058, respectively, being the highest among the tested materials, significantly better than that of methyl salicylate, a compound being reported having repellent effect on many aphid species previously.(2) compared the repellent effects of K. galangal, C. tangerine, and methyl salicylate. The results showed that the repellence of plant materials were significantly better than that of methyl salicylate, but the soxlet extracts of K. galangal and C. tangerine acted antagonistically. Rinsed with different volume ratios of petroleum ether and diethyl ether, the active fractions of C. tangerine was the 3:7 fraction, and the active fractions of K. galangal rinse was the 10:10,7:3, and 2:8 fractions, respectively. The active fractions of K. galangal and C. tangerine were combined each and identified by GC-MS analysis, showing that d-limonene and ethyl p-methoxy cinnamate were the main components of C. tangerine and K. galanga, respectively.(3) On the basis of above results, the author tested the repellent effects of 58 common plant-derived volatiles on wingless M. persicae. Five compounds, E2, Z6-nonadienal, citral, cinnamaldehyde, camphor, and dibutyl phthalate had extremely significant repellent effects, whose corresponding repellent percentages were 28.63%, 17.74%,28.24%,23.90%, and 20.73%, respectively; Borneol, Z9-octadecenoic acid, and 6-methyl-5-hepten-2-one had significant repellence, whose repellent percentages were 21.63%,22.41%, and 22.32%, respectively. Comparison of the chemical structures of the active compounds shows that the common structures were conjugated olefine aldehydes or 7,7-dimethyl-bicycle [2.2.1] heptane.(4) Bioassays on the phototactic response of alate and apterous Myzus persicae to different monochromatic lights were conducted using filters. The results showed that the alate aphids were significantly attracted to the monochromatic lights with wavelength ranging from 490 nm to 550 nm. Among the spectra, two yellowish green lights,538.9 nm and 549.9 nm, elicited the strongest behavioral response of the alates, with the mean displacements 25.29 cm and 22.97 cm, respectively, and followed by 491.5 nm (blue green). But the yellow monochromatic light (576.0 nm) was unattractive. There were not clear peaks in the phototactic response profile of apterous aphids whose maximum relative mean displacement was only 1.41.(5) Based on colour blending simulation, the author introduced variable-size Simplex method to optimize two variables of virtual coloured trap of alate Myzus persicae (Macrosiphini, Aphidinea):? (angle starting from R vector clockwisely) and Ib (Intensity of blended colour). The bioassay result shows that optimal? values shifted dramatically among the blended colours with different intensities. The maximum relative mean displacements of the aphids exposed to the colours with intensities of 10,25,50,100, and 200, peaked at 190°,85°,35°,100°, and 345°, respectively. Ever increasing light intensity, alate M. persicae showed lower selective phototactic response to colours with different hues; additionally, Simplex optimization showed that the optimal colour parameters were?=134.38°,Ib=61.25.(6) The choice responses of the alates to various CMYK colours were conducted by computer simulation. Results of the L25(56) experiment showed that the factorial effects were as follows:Y>M>K>C. Theoretically, the expected optimal combination of the CMYK parameters should be C=25%, Y=25%, M=100%, and K=0%, and a verification test showed that the response index (RI) of this colour reached up to 0.7778. All the CMYK parameters had not significant effect on RI values of the simulated colour, when the levels of C, M, Y, and K were set in the ranges of [10%, 40%], [10%,40%], [85%,100%], and [0%,15%], respectively.(7) To clarify the simultaneous color contrast in the visual perception of alate M. persicae, the author conducted an experiment on its choice behaviour to 64 dual-color-matched patterns, then optimized the parameters of the matched pattern with solid red background and solid black spots using L9(34) orthogonal array design. Among the 64 patterns, solid red background matched solid black spots exhibited the strongest repellence, while homogeneous yellow and homogeneous green exhibited the strongest attractancy, and which decreased when matched with other colour spots. Matched as background, white or blue showed no simultaneous color contrast with other colours, and yellow, purple, cyan, green, and red had extremly significant simultaneous color contrast with other colours; matched as spots, red or purple showed no simultaneous color contrast with other colours, and white, cyan, green, yellow, and black had extremly significant simultaneous color contrast with other colours. The aphids distributed in the pattern area of "red background plus black spots" were extremly more than that of homogeneous red or black background, suggesting that black and red had strong simultaneous color contrast, and the matched pattern had remarkable repellent effect on alate Myzus persicae. The optimal combination of dual-color-matched pattern of red and black was as follows: background R value (in CMYK mode)=200, spot Gamma value=0, spot main diameter=10 px. The possible ecological significance of this pattern lies in the simulation of the body patterns of some ladybird species.(8) The recognition of apterous Myzus persicae to the elytra color pattern and the volatiles emitted from Propylaea japonica adults was determined in the laboratory. The result of choice response bioassay shows that the aphids had the ability of detecting the presence of their natural enemy and exhibited an initiative avoidance to reduce the risk of predation. Visual sense played a primary role when visual and olfactory cues were presented simultaneously, and the aphids could also recognize P. japonica via olfactory sense at the absence of visual cue, indicating that the cues were redundancy for predator recognition. The result of the dose-response bioassay shows that there was positive linear relationship between the repellent percentage of M. persicae and the dose of P. japonica extract, the critical dose for recognition was within the range of 0.3-0.6 P. japonica equivalent, and the repellence of 1.2-1.5 P. japonica equivalent was equal to that of 20 live P. japonica adults.(9) n-hexane extract of the whole bodies of P. japonica adults was chemically indentified. Alkanes were the most rich components showing no remarkble smells, andβ-caryophyllene was the only component showing remarkble smell. Therefore, it can be speculated that it should play an important role in the communication of aphids and ladybirds. However, some previous studies indicated that B-caryophyllene could appease the aphid clony by inhibiting the release of E-β-farnesene being an alarming pheromone of most aphid species, so it shouldn’t repel the aphids; on the other hand, this compound was identified from another ladybird species, Harmonia axyridis, which was considered as their aggregation pheromone, to protect the limited food resource, the ladybirds should repel other individuals. |
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