The Study On Several Technical Measures For Preventing And Controlling Rice Stem Borers And The Effects Of Transgenic Rice On Non-Target Organisms

Rice stem borers were major rice pests in China, which were wide in occurrence area and had heavy damage on the rice, and had become a major limiting factor in rice production, so effective control of them would great significance on rice grain yields and ensureing the supply of our country's. Rice stem borers currently were mainly controlled by chemical pesticides, which not only leaded to "3R" problem and effected the diversity of biological communities in the paddy fields and destroyed ecological balance but also effected human and animal health, food security. This paper mainl assessed the various techniques for controlling rice stem borer in terms of effect, arthropod community as well as eggs amounts and trapping effect under field conditions. Above those, IPM for controlling rice stem borers were proposed. We also studied the effects of transegenic insect-resistant rice on arthropod community and diversity in paddy field, as well as target pests may generated resistance to transegenic insect-resistant rice. These provide theoretical and practical evidence for commercial production of genetically modified rice.1 Agricultural control in paddy fieldAgricultural control measures included timely plowing ahead, scientific fertilization, and scientific water management, low-pile harvest and agriculture integrated control. Agricultural control had good control effects for the stem borer, eggs of SSB decreased from 42.85 percent to 80.00 percent comparing with the control in different types of rice,the effects of SSB were 45.88 percent in early rice and 53.95 percent in later rice, control effect of yellow rice borer was 90.68 percent, control effect of irrigation farming was35.84 percent; At the same time, agricultural control measures can significantly increase the number of the predatory and parasitic insects and decrease the number of herbivorous insects; In addition, Agricultural control significantly increased the rice arthropod diversity and maintained the balance of biological communities.2 Chemical control in paddy fieldField experiments that eight chemical pesticide(Chlorantraniliprole 20% SC, fipronil 80% WG, Chlorpyrifos 48% EC, indoxacarb 15% EC, monosultap 90% WP, Acephate 30% EC, Hong Rui, HongJing13) for controllng YSB were tested in Daye in 2008, The results show that Chlorantraniliprole 20% SC has better effects at the end of egg hatching than the peak and it was also similar to the CK in terms of Simpson index, Shannon-Wiener diversity index (H), evenness index, community dissimilarity index. So, Chlorantraniliprole 20% SC will be a better choice for controlling Yellow stem borer considering all the above factors and Chlorpyriphos 48%EC can be another.The pesticides for controlling SSB were selected in Ezhou, Daye, Dangyang in 2009. The results showed that 25% chlorpyrifos and HongDu had good control effect in Daye, control effects were seperately 80.81 percent,80.81 percent and 74.81 percent,75.59 percent after 10 and 25 days; Hongdu,Hongjing 1,40% Chlorpyrifos EC and 75%Acephate wp was better for Ezhou,the control effects for early and later rice were 93.04 percent,89.74 percent,91.58 percent,94.51 percent,96.01 percent 88.89 percent, 92.02 percent and 96.90 percent; control effects of Monosultap·Bt in Dangyang.were 96.73 percent and 67.38 percent after7 and 15 days.Various pesticide treatments can increase the number of predators, reduce the number of herbivores and have no difference compared to control groups on the main parameters arthropod community, indicating the various pesticides had non-negative effects on arthropod communities, which may be related to smaller plot or sampling error.3 Sex pheromone in paddy fieldThe effects of Sex Pheromone for controlling rice stem borer were studied by basin traps and triangular trap, the density of traps were three per 667m2. Moth quantities attracted changed with the type of rice and the weather, the overall moth quantities was very small(0.35N/pot/day), resulting in control effects fluctuations between 26.23% and 61.88% in different test sites. Control range of sex pheromone was 2.5m from the lure. The effects on YSB, SI2009521A was better than SI20093241.At the same time, Sex pheromone control can increase the number of predatory insects, and there were obvious advantages in the main parameters of arthropod community.4 Frequency-oscillated light in paddy fieldControl effect of the light trapping had been studied with the Frequency-oscillated light, density of 150 m/light, the results show that the trapping moths were larger,26.2N /light/night for YSB, ratio of male and female was 1.51:1, the average rate of fecundity was 20.7 percent; in Ezhou, the total trapping moths of three lights for SSB were 1185 N, sex ratio was 5.24:1, The average rate of fecundity were 21.68 perceent; Dangyang, the total trapping moths of three lights for SSB were 7886 N, sex ratio for the second generation and the third generation was 1.86:1 and 1.75:1, the average rate of fecundity were 21.43 percent and 25.05 percent. the trapping efficiency of female moths was better than male moths. Eggs redueced from 53.53% and 77.98%, compared with the control, control effects were betten than 60 percent, the range of control was 30-50m from the position of FLT.Trapping zones can increase the number of predators, reduce the number of herbivores, the main parameters of arthropod community were inconsistent with with the control.5IPM in paddy fieldThe trial mainly conducted in Ezhou and Dangyang, various single control measurs were combined for controlling SSB, results showed that integrated zone can not only reduce the occurrence and damage of SSB, reduce the eggs above 50 percent, the borer damage was lower 2 percent, control effects fluctuateed between 38.77% and 82.21%, increased yield (15.8 percent for early rice and 7.53 percent for later rice, but also can reduce uses and frequency the pesticide, protect the ecological environment, then ecological control has played a role.6 Effects of transgenic insect-resistance rice on arthropod communities in paddy fieldsDominant groups of arthropod functional groups between Bt and control rice fields is basically the same:dominant groups of herbivorous insects Including the rice leaffoller, Cnaphalocrocis medinalis of Pyralidae and the white planthopper and brown planthopper of Delphacidae; parasitic insects were mostly Muscidae, Braconidae and Ichneumonidae; spiders had absolute advantage of predators; neutral insects wre mainly Culicidae and Chironomidae.There were no difference between transgenic rice fields and control fields in the composition and dominance of the four functional groups. The main parameters of arthropod community in addition to that species richness fluctuated between the inter-annual, there is no difference with the control in terms of another three parameters of Simpson's index, Shannon-Winner index and evenness index. Bray-Curtis distance index of transgenic insect-resistancerice and the control field were small, so community similarity were high.In general the effects of transgenic insect-resistant rice on the field of arthropod communities were relatively small, there were no negative impact on arthropod community.Ddynamic changes of non-target insectsDelphacidae and Cicadellidae and main predatory spiders were basically the same between Bt rice control,as well as the composition of main predatory spider, though slight changes between inter-annual Transgenic rice shows no negative impact on non-target insects including Delphacidae and Cicadellidae and dominated predatory spiders.7 Resistance of rice stem borer to transgenic riceGenetically modified insect-resistant rice cultivation, whether the first year or continuous cultivation of a decade, had relatively high resistance levels, in the field or the net enclosures, natural or artificial pests, the amount of insects more or less. rate of borer damage was less than 1.5% and rate of leafroll wasless than 12.62%. But it also should be noted that Bt toxic protein would change in the expression on continuous cultivation, there were the trends that stripped stem borer may resistance to Bt rice under the certain selection pressure and certain degree of pest amounts.Those results showed that the agricultural control and Frequency- oscillated light can effectively reduce eggs, the effec of sex pheromone relucted due to various factors; chemical pesticides also had good effects and a lots of pesticides had been selected; Transgenic resistant rice had better control on stem borers and badly control onsucking pests. All the individual technical measures can reduce the number of herbivores, increase the number of predators, and no adverse effects on the arthropod community. Based on the evaluation results, the TPM was that:breeding resistant varieties and basing on agricultural control, giving natural enemies for biological control and using light trapping, combined with chemical pesticides.