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昆虫病原线虫在长期储存方面的劣势影响其广泛应用。脱水休眠是昆虫病原线虫感染期幼虫在缺水条件下进入的一种生命暂停现象,是昆虫病原线虫对抗恶劣环境的一种策略。本文介绍了昆虫病原线虫脱水休眠的研究现状,对其诱导方法、生理生化和分子机理等方面的研究进展进行了综述。 相似文献
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采用叶碟法测定了36个昆虫病原线虫共生细菌菌株对小菜蛾Plutella xylostella二龄幼虫的拒食作用,其中10个菌株对小菜蛾幼虫的选择性和非选择性拒食率高于75%。以嗜线虫致病杆菌Xenorhabdus nematophilus All菌株为代表,研究了对小菜蛾有拒食作用的物质与细菌生长过程、型变、pH值、温度、有机溶剂之间的关系。结果表明:拒食物质产生于细菌的对数增长期和稳定期,在稳定期最高,拒食率达85%左右;次生型菌液未能分泌足够的拒食物质,其拒食率在20%以下。在-80℃-100℃的范围内,其拒食率均在81%以上。pH3-11范围内,对拒食物质稳定性有一定影响,选择性拒食率变化不大,均在96%以上;非选择性拒食率变化明显,pH值为3、5、7、11时,非选择性拒食率下降至23.1%-34.9%。拒食物质可与氯仿、石油醚、乙酸乙酯、正己烷、乙醇相溶,其提取液对小菜蛾拒食率均在80%以上。 相似文献
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Transgenic crops having alien genes from different sources are getting popularity. A Rice (Oryza sativa L.) containing gene from Bacillus thuringiensis, a soil bacterium, was assessed to study the potential risks of transgenic plants on environment. The crop was found resistant to target insect pests. Rice variety Basmati-370 transformed with two insecticidal genes, crylAc and cry2A, was grown under field conditions for several years. Data were collected at different stages of the plant growth. Fate of Cry protein in soil, effect of Bt protein on non-target insects, risks of vertical and horizontal gene flow were evaluated. No potential hazard was found at all levels. Bt protein was unstable and degraded significantly in soil within 30 days after harvesting the crop. No harmful effects were found on non-target insects (insects other than order lepidoptera). Maximum gene flow of 0.02% was observed at close spacing and no evidence of horizontal gene transfer to Rhizobium spp. was found. In conclusion, the transgenic rice plants transformed with Bt genes have no harmful effects on the environment. 相似文献
998.
膜荚黄芪传粉昆虫的研究(英文) 总被引:1,自引:0,他引:1
[目的]研究膜荚黄芪传粉昆虫的种类及其传粉特点,为膜荚黄芪的育种奠定理论基础。[方法]以膜荚黄芪为研究对象,调查膜荚黄芪传粉昆虫的种类及访花行为。日活动规律观测在晴天进行,7:00~18:00每1h绕样地走1圈,约用时间3min,记录每一时间段出现在视野里的不同昆虫种类和数量。盛花期在样地于晴天7:00~18:00对每种传粉昆虫固定1头进行跟踪观测,用秒表记录其在花上停留时间。访花频率采用追踪法,尽可能连续记录其整个访花过程及时间。[结果]膜荚黄芪访花昆虫共有16种,其中红光熊蜂、明亮熊蜂、蜜蜂、狭带贝食蚜蝇和斑缘豆粉蝶为主要传粉昆虫;主要传粉昆虫的日活动规律出现单峰型、双峰型和直线型3种,活动高峰期有一定交错。在正常气候条件下,蜜蜂和食蚜蝇呈双峰活动规律,蜜蜂在7:30~11:00和13:30~15:00有高峰,食蚜蝇在早晨和傍晚有高峰;斑缘豆粉蝶在11:00~13:00出现1个活动高峰,为单峰型;红光熊蜂和明亮熊蜂在1d中的数量比较稳定,除了在1d中最热的一段时间,都可观察到它们的传粉活动,为直线型。红光熊蜂和明亮熊蜂的每小花停留时间相似,分别为(2.05±0.07)s和(2.57±0.05)s,蜜蜂的每小花停留时间为(3.78±0.13)s,食蚜蝇为(5.28±0.16)s,斑缘豆粉蝶的每小花停留时间最长,达(46.72±2.79)s。红光熊蜂访花频率最高,为11.4次/min,明亮熊蜂、蜜蜂、食蚜蝇的访花频率处于中间状态,分别为10.7、7.1、2.7次/min,斑缘豆粉蝶访花频率最低,为0.9次/min。昆虫的传粉频率与停留时间呈负相关关系。[结论]昆虫访花行为对植物与传粉者相互作用等方面产生直接影响,对理解植物多样性与生殖生态过程具有重要意义。 相似文献
999.
With environmental and food safety issues becoming one of the greatest concerns of the public, active plant compounds play more and more important roles in pest controlling. Fern to their particular status in plant taxology and co-evolution are of great significance for application as new pesticides due with insects. In this study, methanol extracts were distilled from wild fern and gymnosperm of 54 species of 22 families collected from Shiwandashan Mountain in Guangxi Zhuang Autonomous Region of China. Insecticidal activities of the methanol extracts were assayed on both adult house fly (Musca domestica) and mosquito (Aedes albopictus). Significant insecticidal activities were exhibited in the methanol extracts of five species, Cupressusfunebris (leaves and stems), Cycas acuminatissima (roots), Keteleeria fortunei (leaves and stems), Onychium japonicum (whole plant), and Pinus taiwanensis var. Darning shanensis (leaves and stems). Applications of the extracts of these plants resulted in higher than 50% mortalities in 4th instar larvae of A. albopictus at 24 h after treatment. The methanol extracts from 13 species possessed insecticidal activities against the adult of M. domestica at 48 h after treatment with higher than 90% mortalities. The extensive screening results showed that these fern and gymnosperm were highly potential to be botanical insecticides. The findings provide a feasible and valuable basis for further investigation. 相似文献
1000.
Many species of insect egg can be targeted individually or (and) collectively for cryopreservation by vitrification. However, there has been no report on cryopreservation of honeybee eggs by vitrification. In an attempt to define a preliminary procedure of cryopreservation of honeybee eggs by vitrification, queen honeybee born worker eggs (worker eggs) were stored through vitrification in liquid nitrogen up to 1 h, and then post-vitrification survival of the vitrified worker eggs in vitro and their hatching rates during maturation in vivo were observed using microscopic and close visual inspections. The procedure of cryopreservation by vitrification included dechorionation with sodium hypochlorite and permeabilization with isopropyl alcohol; equilibration by addition of loading solution (i.e., 25% vitrification storage solution) and dehydration by gradual replacement of loading solution with vitrification storage solution; cooling in liquid nitrogen vapor right before droplet vitrification in liquid nitrogen; and recovery in liquid nitrogen vapor right after storage in liquid nitrogen, thawing at temperature of thawing medium (5% sucrose in TC 100-insect medium) and rehydration by gradual replacement of vitrification storage solution with rehydration solution (5% fetal bovine serum in TC 100-insect medium). It was found that among the worker eggs experiencing cyropreservation by vitrification, 1.25% of them were successfully passed through the four life stages, viz., egg, larva, pupa, and adult. In summary, it can be inferred that although a majority of worker eggs were dead after cyropreservation by vitrification, a few of them were developed into larvae, pupae, and finally emerged as adults. 相似文献