Occure Law Of Wheat Aphids And Effect Of Growing Models On Its Populations In Tianshui, Gansu Province

Wheat aphid population dynamics in wheat fields were systematicly investigated in Tianshui of Gansu Province. At the same time, paper studied the number of wheat aphids occurred in different varieties of wheat by intercropping, mixturecropping and wheat with other crops intercropping. The results are as follows:1 Wheat aphid population dynamics in Tianshui of Gansu ProvinceGangu`s wheat aphid population dynamics was investigated from 2007 to 2009 in this Paper. The results showed that the wheat aphid were discoveried in the end of March or the earlier of April, then the number increased in the last ten days of April and the first ten days of May. Rapidly rise period was in the middle ten days of May, and it reached to maximum in the last ten days of May, but wheat aphid number decreased quickly and disappeared at the first ten days of June.At the same time, the amount of Wheat aphids per 100 plants in Maiji during the last ten days of May and the average temperature of April from 1995 to 2008 were investigated. We analysised the data and get a linear equation y=114.21x-440.69 (r1=0.9565) and polynomial equation y=12.702x2-219.36x +1735.2 (r2=0.9669), and r1,r2 > r0.01, it excellently showed the relationship between the amount of wheat aphid occurred in the last ten days of May and the average temperature of April.2 Effect on the amount of wheat aphids by wheat varieties with intercropping and mixturecropping modelEffect of various wheat varieties combinations on the wheat aphid amount was studied, and the five varieties of wheat were dealt by intercropping, mixturecropping with two,three,four,five varieties respectively. the results showed that there are 13 within 17 intercropping combinations have certain effect on wheat aphids amount, and the average control effect was 13.14% in each intercropping combinations, and the change was between -23.69～45.6%. Compare the amount of wheat aphids per 100 plants of intercropping in wheat flowering and wheat filling stage with monocultural wheat, The results showed that amount of wheat aphid which occurred in lantian6/lantian1, shi7816/95-108, and lantian6/lantian1/lantian13 combinations were significantly lower than that of the corresponding monocultural wheat,while the amount of wheat aphid occurred in other 14 intercropping combinations at least significantly lower than one of all monocultural whea(tP<0.05). The 16 witnin 17 combinations had a certain effect on amount of wheat aphids, the average control effect was 31.15% in each mixturecropping combinations,and the change was between 6.25%～63.35%. Compare the amount of wheat aphids per 100 plants of mixturecropping in wheat flowering and wheat filling stage with monocultural wheat, the results showed that amount of wheat aphid which occurred in lantian13/lantian6, lantian6/lantian1, shi7816/95-108, lantian6/lantian1/lantian13, lantian6/lantian1/95-108/lantian13 and lantian1/95-108/lantian13/shi7816/lantian6 combinations were significantly lower than that of the corresponding monocultural wheat,while the amount of wheat aphid occurred in other 11 mixturecropping combinations at least significantly lower than one of all monocultural wheat(P<0.05)3 The effect on the amount of wheat aphids by the intercropping of wheat with different cropsThe intercropping of wheat with Maize, Sunflower or Soybean had effect on the amount of wheat aphids during the flowering and filling stage. The results showed that the wheat aphid amount of the wheat intercropping with Maize, Soybean or Sunflower were significantly lower than that of wheat monoculture (P<0.05). And among these three intercropping conditions, the wheat aphid amount was the lowest in the wheat- maize intercropping, while was the highest in the wheat-soybean intercropping(P<0.05).