| The English green aphid Sitobion avenae is the dominant species pest of winter wheat in Huang-Huai-Hai plain, China. It is not only harm to wheat leaves and juice of wheatear by piecing and sucking directly, but also as a vector of plant virus diseases, and making heavily damage to wheat. Facing the damage caused by the major pest,Onefold chemical control can often induce some serious problems,such as the destruction of biodiversity,environmental pollution. In order to solve those problems, the concept of ecological regulation to pest is proposed by Ding Yanqing, using biodiversity for ecological regulation on pest causes people ' s attention. This paper investigated the ecological effects of wheat-pea and different aphid-resistant wheat varieties intercropping to S. avenae and its natural enemies. The main results are as follows:1. Efects of wheat-pea intercropping on Sitobion avenae and the functional groups of its main natural enemiesTo investigate the effects of species diversity in wheat field on ecological regulation to Sitobion avenae (Fabricius), the intercropping patterns of wheat and pea, by the planting row of pea : wheat in 2:2, 2:4, 2:6 and 2:8 were plotted in Langfang Experimental Station of Institute of Plant Protection, Chinese Academy of Agricultural Sciences, and the field cultivar monoculture of wheat was planted as control. Population dynamics of apterae and alatae S.avenae, population dynamics, species richness, diversity index and evenness of main natural enemies, and wheat and pea yield parameters were investigated and analyzed. The results showed that, compared with monoculture of wheat, the population densities of apterae S. avenae in aphid peak period were very significantly lower in the intercropping treatments(P<0.01). Although population dynamics of functional groups of natural enemie showed a similar trend with time, wheat-pea intercropping could preserve and augment natural enemies more than monoculture of wheat, and there were higher population densities of ladybeetles and aphid parasitoids, and higher species richness and diversity index of natural enemies, but lower evenness index. in each intercropping field. The land utilization rate was different in variational planting patterns, and LER Value (Land Equivalent Ratio) of different wheat-pea intercropping pattern incresed by 17%~31%. To some extent, the LER improved with increasing of wheat planting ratio. An optimal mode for design wheat intercropped with pea in the field was deduced.2. The effect of using genetic diversity of wheat varieties for ecological regulation on Sitobion avenaeTo study the effect of intercropping of different wheat varieties on ecological regulation to Sitobion avenae, and to make use of the increase of genetic diversity in wheat field to control the aphid and to protect it's main natural enemies. An investigation was conducted at the Langfang Experimental Station of Institute of Plant Protection. The results showed that, compared with monocultures, cv. Beijing 837, the apterae population densities of S. avenae in intercropping pattern were significantly lower during aphid peak period, and the cascade of population densities was that cv. Beijing 837 monoculture > intercropped with cv. Zhengzhou831 > intercropped with cv. KOK > intercropped with cv. Hongmanghong > intercropped with cv. JP2 > intercropped with cv. Zhongsiwumang, and the spatial distribution of S. avenae were changed from aggregated pattern to uniform one. In aphid parasitoids peak period, there were higher population densities of aphid parasitoids in each intercropping field with the very significant level of P<0.01. The thousand grain weight of the wheat and the theoretical yield were more increasing with the significant level of P<0.05. Above all, the intercropping of wheat varieties of different resistance to aphids with the field cultivar could own an obvious advantage in ecological regulation to S. avenae.3. The effect of intercropping between wheat and pea on spatial distribution of Sitobion avenae based on GISIn order to research the effect of biodiversity on spatial distribution of Sitobion avenae in wheat, the population density of S. avenae were investigated in wheat fields in Langfang Experimental Station of Institute of Plant Protection, using wheat intercropped with pea by different patterns, the field cultivar monoculture as control. Using the Geographical Information System(GIS) and the traditional analysis methods of spatial distribution, the Kriging-interpolation figures, aggregation indices, Iwao and Taylor′s regression models were analyzed. The results show that the spatial distribution of S. avenae is mainly aggregation distribution in different patterns, but the degrees of aggregation are difference, 22pattern > 26pattern > 24pattern > wheat monoculture > 22pattern; From the Kriging-interpolation figures, we know that wheat aphids distribution is mianly around the field during early stage, and spread to the middle of field gradually. There are many aggregation centers mostly at wheat monoculture and 22patterns plots during aphid peak period. Compared with each intercropping field, there were higher population densities of aphid in field cultivar monocultures with the very significant level of P<0.01. Although, the reasonable biodiversity in wheat could control the population of wheat aphid effectively, the spatial distribution is still not changed.4. Identification of volatiles from field wheat varieties of different resistance to aphidsAdopting dynamic head-space and GC-MS,volatiles of wheat varieties of different resistance to aphids at its filling stage in natural state were successfully collected and analyzed. 47 volatile components were identified, including 32 alkanes, 5 esters, 4 alcohols, 3 aldehydes, 2 terpenoids, 2 olefins, 1 aethers and 1 dikones; Alpha.-Pinene which can protect plants from infestation is also included, and the contents of longifolene reduced with raising of resistance of wheat to aphids.
|
PDF Full Text Request