Effects of Transgenic Bt Rice on the Food Consumption, Growth and Survival of Cnaphalocrocis medinalis (Guenée) Larvae

The transgenic rice KMD1, expressing a synthetic CrylAb gene from Bacillus thuringiensis, showed effective resistance to the older （third-to fifth-instar） larvae of the rice leaf-folder （RLF）, Cnaphalocrocis medinalis （Guenee） in laboratory bioassay. Significant declines were revealed in food consumption and growth of the older RLF nymphs fed on the cut-leaves of transgenic KMD1 plants. The increase rate of food consumption by larvae fed on KMD1 was drastically lower than those on Xiushui 11. Food consumption was varied with different instars when the larvae fed on the Bt rice. Those of fourth- and fifth-instar larvae were different compared to the third-instar, lower than those on the non-transgenic rice but still increased a little when the feeding time prolonged. It is indicated that younger RLF larvae are more sensitive to Bt rice than older ones. Also, about 81%, 78% and 68% of the third-, fourth- and fifth-instar RLF larvae died within 72 hours bioassay period on KMD1 leaves, respectively. These results demonstrated that Bt-transgene in KMD1 rice confers substantial protection against infestations with older RLF larvae.

Impact Assessments of Transgenic cry1Ab Rice on the Population Dynamics of Five Non-Target Thrips Species and Their General Predatory Flower Bug in Bt and Non-Bt Rice Fields Using Color Sticky Card Traps

A 2-yr field study was conducted to assess the effects of transgenic japonica rice（KMD1 and KMD2） with a synthetic cry1 Ab gene from Bacillus thuingiensis Berliner on population dynamics and seasonal average densities of five thrips species including Stenchaetothrips biformis（Bagnall）,Frankliniella intonsa（Trybom）,F.tenuicornis（Uzel）,Haplothrips aculeatus（Fabricius）,Haplothrips tritici（Kurd） and their general predatory flower bug,Orius similis Zheng as compared to the parental control rice line using the white,blue and yellow sticky card traps.Population dynamics and seasonal average densities of these five thrips species and their general predatory flower bug were not significantly affected by rice type.Additionally,the white sticky card trap was suggested to be the most suitable for monitoring the population of these five thrips species and their general predator.These results show that our tested Bt rice lines do not interrupt the population of non-target thrips species and their general predatory flower bug in the field,and also cannot result in more occurrence of these thrips species in the rice ecosystem.

Lethal and Sub-Lethal Effects of Transgenic Rice Containing cry1Ac and CpTI Genes on the Pink Stem Borer, Sesamia inferens(Walker)

Lethal and sub-lethal effects of transgenic rice containing cry1Ac and CpTI genes on the pink stem borer, Sesamia inferens, were studied to collect information for ecological risk assessment on insect-resistance of transgenic rice. In vitro insect-feeding bioassays were conducted to evaluate the lethal and sub-lethal effects of transgenic rice lines （II YouKF6 and KF6） containing cry1Ac＋CpTI genes on S. inferens at four different growth stages, viz., seedling, tillering and elongation, booting, and milk and maturing. Transgenic rice at seedling stage showed significantly high lethal effect on S. inferens with the shortest lethal duration for 50 and 100% individuals and the highest corrected mortalities after feeding on transgenic lines at this stage for 3 and 6 d. Followed by tillering and elongation stage, 50 and 100% S. inferens were dead after feeding on transgenic lines at this stage for 4 and 10 d, respectively. Moreover, corrected mortalities for 6 d feeding on transgenic lines at this stage were significantly higher than that at booting, and milk and maturing stages. Lethal effect of KF6 on S. inferens decreased significantly at booting stage. Lethal duration for 50% S. inferens significantly extended and its corrected mortalities for 6 d feeding also declined remarkably. However, lethal effect of II YouKF6 on S. inferens did not decrease significantly at this stage. Transgenic rice at booting, and milk and maturing stages did not show significant lethal effect to S. inferens and it showed the longest lethal duration for 50% individuals and the lowest corrected mortalities for 3 and 6 d feeding. A few larvae of S. inferens could survive, pupate and emerge on these two transgenic lines at booting, and milk and maturing stages. Sub-lethal effect of two transgenic lines on S. inferens also differed significantly between different developmental stages. Continuously feeding on transgenic rice lines at seedling, and tillering and elongation stages delayed the development of larvae and pupae and decreased pupation rate, but no effect was observed on eclosion rate. Larval development was significantly inhibited after feeding on transgenic rice at booting stage, but no obvious effect was observed in pupal stage, pupation and eclosion rate. There were no significant differences for larval and pupal development, pupation, and eclosion rates between feeding on transgenic and control rice lines at milk and maturing stage. Larval and pupal weights significantly declined, but no influence was observed on fecundity when S. inferens infested on transgenic rice at any stage. These showed that there were significant differences in lethal and sub-lethal effects of transgenic rice on S. inferens among developmental stages, and the effects gradually decreased with the increase of growth stages of rice plant.

No detrimental effect of Bt maize pollen containing Cry1Ab/2Aj or Cry1Ac on adult green lacewings Chrysoperla sinica Tjeder

Adult Chrysoperla sinica Tjeder is a common pollen feeder in maize fields. They are thus directly exposed to insecticidal proteins by consumption of genetically engineered maize pollen containing Bacillus thuringiensis(Bt) proteins. Here we assessed the potential effects of Cry1 Ab/2 Aj-or Cry1 Ac-containing Bt maize pollen on the fitness of adult C. sinica via a dietary-exposure assay under laboratory conditions. Survival, pre-oviposition, fecundity and adult dry weight did not differ between adult C. sinica consuming Bt or the corresponding non-Bt maize pollen. The stability of the Cry protein in the food sources and uptake of the Cry protein by adult C. sinica during the feeding experiment were confirmed by ELISA. These results demonstrate that adult C. sinica are not affected by the consumption of Cry1 Ab/2 Aj-or Cry1 Ac-containing maize pollen, suggesting that production of Bt maize expressing cry1 Ab/2 Aj or cry1 Ac genes will pose a negligible risk to adult C. sinica.

Transgenic cry1Ab/vip3H+epsps Rice with Insect and Herbicide Resistance Acted No Adverse Impacts on the Population Growth of a Non-Target Herbivore, the White-Backed Planthopper, Under Laboratory and Field Conditions

Numerous Bt rice lines expressing Cry protein derived from Bacillus thuringiensis Berliner （Bt） have been developed since 1989. However, the potential risks posed by Bt rice on non-target organisms still remain debate. The white-backed planthopper （WBPH）, Sogatella furcifera （Horváth）, is one of the most economically important insect pests of rice in Asian countries and also one of the main non-target herbivores of transgenic rice. In the current study, impacts of transgenic cry1Ab/vip3H＋epsps rice （G6H1） with both insect and herbicide resistance on WBPH were evaluated to ascertain whether this transgenic rice line had potential risks for this sap-sucking pest under laboratory and ifeld conditions. The laboratory results showed that no signiifcant difference in egg developmental duration, nymphal survival rate and female fecundity was found for WBPH between G6H1 and its non-transgenic isoline （XS110）. However, the development duration of nymphs was signiifcantly shorter and female longevity signiifcantly longer when WBPH fed on G6H1 by comparison with those on its control. To verify the results found in laboratory, a 3-yr ifeld trial was conducted to monitor WBPH population using both the vacuum-suction machine and beat plate methods. Although the seasonal density of WBPH nymphs and total density of nymphs and adults were not signiifcantly affected by transgenic rice regardless of the sampling methods, the seasonal density of WBPH adults in transgenic rice plots was slightly lower than that in the control when using the vacuum-suction machine. Based on these results both from laboratory and ifeld, it is clear that our tested transgenic rice line will not lead higher population of WBPH. However, long-term ifeld experiments to monitor the population dynamics of WPBH at large scale need to be conducted to conifrm the present conclusions in future.

Thrips-mediated impacts from transgenic rice expressing Cry1Ab on ecological fitness of non-target predator Orius tantilus(Hemiptera:Anthocoridae)

Various rice lines have been genetically modified with genes from Bacillus thuringiensis（Bt） to continuously produce Bt insecticidal proteins against lepidopteran larvae. The Bt insecticidal protein constantly expresses in the plants to create an opportunity for non-target herbivores to acquire and convey the protein to their predators or parasitoids across trophic levels. This paper evaluates the effects of Bt rice（namely, Kemindao 1（KMD1） and Kemindao 2（KMD2）） expressing Cry1 Ab as compared to its non-Bt control line, Xiushui 11 on non-target predator Orius tantilus（a generalist predatory anthocorid of thrips） under laboratory and field conditions. To measure several biological parameters such as total nymphal duration and fecundity of this bug, it was reared on thrips and pollens of KMD1 and KMD2 as compared to their control under laboratory conditions. By comparison with the control, Bt rice did not significantly affect main life-history characteristics（total nymphal duration, female adult longevity, oviposition period and fecundity） of this anthocorid preying on Bt rice-fed thrips along with Bt rice pollens, except that the fecundity of this predator for KMD1 was distinctly lower as compared with KMD2 or the control. Enzyme-linked immunosorbent assay（ELISA） results showed that no Cry1 Ab protein was detected in this predator fed on thrips or rice pollen from Bt rice but was in Bt rice pollens. With the beat plate, plastic bag and color trap sampling methods, two-year field monitoring of O. tantilus abundance demonstrated that Bt rice had no significant detrimental effects on the population dynamics and seasonal average densities of this predatory anthocorid as compared with the control. Thus, it is suggested that growing our tested Bt rice（KMD1 and KMD2） producing Cry1 Ab will pose a negligible risk to the anthocorid, O. tantilus.

一种低亮度非均匀光照文档图片快速二值化方法

二值化是光学文字识别(OCR)的重要步骤,直接影响到光学文字识别的成功率。目前基于亮度分割局域二值化算法效果好,但是过程复杂、运算耗时。快速二值化算法流程简单、噪声敏感。低亮度图片一般有不可忽略的噪声,并且文字对比度低。为获取低对比度文字,快速二值化算法需对亮度梯度敏感,但是也会导致快速二值化结果文字断裂、丢失、背景噪声大。为实现高质量快速二值化,本文采取非局域均值滤波算法抑制噪声,同时避免过度平滑图片。采用改进的Bradley算法提取低对比度文字,并解决了文字断裂等问题。最后采用膨胀腐蚀算法抑制二值化噪声。本方法适用于非均匀低亮度和高亮度的图片。实验结果表明,本方法在非均匀高亮度下,表现和其他快速二值化算法相同。在非均匀低亮度下,提取文字更多、文字断裂更少、噪声更小。本方法二值化结果的OCR召回率达到了93.5%。