麦长管蚜和禾谷缢管蚜对小麦挥发物的触角电位反应

采用活体蚜虫测定法,利用EAG技术比较分析了麦长管蚜Sitobion avenae和禾谷缢管蚜Rhopalosiphum padi有翅及无翅成蚜对小麦挥发物及麦蚜取食诱导挥发物组分的嗅觉反应,揭示了两种麦蚜的嗅觉变异特点。结果表明：麦长管蚜对水杨酸甲酯、反-2-己烯醛、反-2-己烯醇、-6-甲基-5-庚烯-2-酮和-6-甲基-5-庚烯-2醇的反应较强,禾谷缢管蚜对水杨酸甲酯、反-3-己烯乙酸酯、-6-甲基-5-庚烯-2-酮和-6-甲基-5-庚烯-2-醇的反应较强,并得到了剂量反应曲线。麦长管蚜的有翅和无翅成蚜对6-甲基-5-庚烯-2-酮、反-2-己烯醇和水杨酸甲酯的反应差异显著;禾谷缢管蚜的有翅和无翅成蚜对反-2-己烯醇、辛醛、里那醇、水杨酸甲酯和反-3-己烯乙酸酯的EAG反应差异显著,其原因与禾谷缢管蚜迁移及转主为害的生物学特性有关。     

中华草蛉、龟纹瓢虫和异色瓢虫对B型烟粉虱的捕食功能反应

室内研究了中华草蛉Chrysopa sinicaTjeder、龟纹瓢虫Propylaea japonica(Thunberg)和异色瓢虫Leis axyridis(Pallas)对B型烟粉虱Bemisiatabaci(Gennadius)若虫的捕食功能反应和寻找效应。结果表明,3种天敌成虫和幼虫的捕食量均随着猎物密度的增加而上升,当猎物增加到一定水平,捕食量趋向稳定,捕食功能反应曲线符合HollingⅡ型方程。异色瓢虫、中华草蛉和龟纹瓢虫成虫和幼虫对烟粉虱若虫的捕食量差异显著,理论最大日捕食量分别为417,263,156头和625,238,108头。3种天敌对烟粉虱若虫的寻找效应随着天敌密度的增加而下降,干扰作用逐渐增强,其寻找效应表现为龟纹瓢虫(0.5656)>异色瓢虫(0.4371)>中华草蛉(0.4029),对烟粉虱的控制能力表现为异色瓢虫>龟纹瓢虫>中华草蛉。     

麦长管蚜和禾谷缢管蚜对小麦植株挥发物及蚜害诱导挥发物的行为反应

用四臂嗅觉计测定了麦长管蚜Macrosiphum avenae和禾谷缢管蚜Rhopalosiphum padi对小麦植株挥发物及麦蚜取食诱导挥发物的行为反应,揭示了2种麦蚜的嗅觉及小麦植株的诱导防御反应特点.在所选的13种小麦植株挥发物及蚜害诱导挥发物组分中,6-甲基-5-庚烯-2-酮、6-甲基-5-庚烯-2-醇和水杨酸甲酯对这2种蚜虫表现出强的驱拒作用;反-2-己烯醛对麦长管蚜的有翅和无翅蚜的吸引作用最强;反-2-己烯醇对禾谷缢管蚜的无翅蚜吸引作用最强,反-3-己酰醋酸酯对禾谷缢管蚜有翅蚜的吸引作用最强.说明麦蚜取食能诱导小麦植株的防御反应,麦长管蚜和禾谷缢管蚜及其不同蚜型间嗅觉反应的特点不同.     

虫害诱导的小麦挥发物促进异色瓢虫对麦蚜的控制作用

【目的】充分利用虫害诱导的植物挥发物对天敌的引诱作用,增强天敌对麦蚜田间控制作用,是有效开展害虫生态调控的基础。【方法】比较分析小麦受蚜虫取食对小麦挥发物的影响;检测异色瓢虫对未受损小麦、麦蚜危害小麦和顺-3-己烯乙酸酯的嗅觉反应;评估顺-3-己烯乙酸酯应用于田间后对异色瓢虫和麦蚜的影响。【结果】麦蚜取食提高了小麦挥发物顺-3-己烯乙酸酯的释放速率和相对含量;受麦蚜取食的小麦和单顺-3-己烯乙酸酯均对异色瓢虫有显著的引诱作用;顺-3-己烯乙酸酯投放到田间显著提高了异色瓢虫密度,降低了麦蚜密度。【结论】虫害诱导的植物挥发物(顺-3-己烯乙酸酯)能吸引天敌(异色瓢虫),可用于田间增强天敌对害虫的控制作用。     

三种捕食性瓢虫成虫对卵的种内自残及其集团内捕食作用

捕食性瓢虫是农田生态系中一类重要的天敌昆虫,种内自残和集团内捕食现象在捕食性瓢虫中普遍存在。本研究在室内通过选择性和非选择性试验比较分析了异色瓢虫、七星瓢虫及龟纹瓢虫成虫对卵的种内自残和集团内捕食作用以及卵表面的化学物质对集团内捕食作用的影响。结果表明:在非选择性试验中,3种捕食性瓢虫成虫对卵表现出相似的取食现象,即对龟纹瓢虫卵取食最多,其次为七星瓢虫卵,对异色瓢虫卵取食相对较少;在选择性试验中,七星瓢虫和龟纹瓢虫较偏好取食同种卵,对异色瓢虫卵取食均较少;而异色瓢虫喜欢取食异种卵,对同种卵取食相对较少。3种瓢虫卵经正己烷漂洗后,异色瓢虫、七星瓢虫和龟纹瓢虫成虫却未对卵表现出取食偏好性。本研究可为捕食性瓢虫组合释放与协调利用、田间集团内捕食作用评定及其在生物防治中的应用提供理论依据。     

不同虫态及虫龄大草蛉与七星瓢虫之间的集团内互作

【目的】为明确新疆棉田棉蚜 Aphis gossypii 捕食性天敌之间的集团内捕食效应及其对蚜虫数量的控制作用。【方法】本研究以优势天敌昆虫大草蛉 Chrysopa pallens 和七星瓢虫 Coccinella septempunctata 为对象,以棉蚜为猎物,在温室中利用盆栽棉花,首先观察了2种天敌昆虫之间各虫态及虫龄配对的19个处理在无蚜植株上共存24 h后的存活数,然后观察了2种天敌昆虫配对处理下棉苗上棉蚜数量随时间的变化趋势。【结果】在无蚜棉株上2种捕食性天敌昆虫共存24 h后的存活结果表明：（1）在发育阶段相同的配对组合中,若是成虫则均存活,若是１龄幼虫则大草蛉存活较多,若是末龄幼虫则七星瓢虫存活较多;（2）在有卵的组配中,除七星瓢虫卵不被大草蛉成虫所捕食外,其他5个组配处理中卵均被捕食;（3）在有蛹的配对组合中,除七星瓢虫蛹被大草蛉末龄幼虫捕食外,其他处理下蛹均不被捕食;（4）在成虫与幼虫的配对组合中,七星瓢虫成虫捕食较多的大草蛉1龄幼虫,但不捕食大草蛉末龄幼虫,而大草蛉成虫与七星瓢虫1龄或末龄幼虫之间不发生捕食;(5）在不同龄期幼虫的配对组合中,大草蛉末龄幼虫捕食七星瓢虫1龄幼虫,而七星瓢虫末龄幼虫捕食大草蛉1龄幼虫。在有蚜植株上2种捕食性天敌共存对棉蚜数量具有不同的控制作用：（1）2种捕食昆虫的幼虫各自单独存在（对照）下,蚜虫密度随时间而降低;（2）大草蛉幼虫与七星瓢虫幼虫或成虫配对处理下,棉蚜密度随时间而增大;（3）大草蛉成虫与七星瓢虫幼虫或成虫配对处理下,棉蚜密度随时间而减小。【结论】研究结果说明,大草蛉与七星瓢虫之间存在集团内捕食,但２种天敌共存对棉蚜的控制作用取决于大草蛉虫态, 若大草蛉为幼虫,可使蚜虫密度增大,若为成虫,则使蚜虫密度减小。     

红火蚁工蚁对棉蚜诱导的棉花挥发物的嗅觉和行为反应

【目的】红火蚁 Solenopsis invicta 与棉蚜 Aphis gossypii 存在兼性共生关系,红火蚁可能利用棉蚜危害诱导棉花释放的挥发物定位棉蚜。本研究将测试红火蚁工蚁对棉花挥发物的嗅觉和行为反应。【方法】使用Y型管实验测试红火蚁工蚁对棉花气味的行为反应;以红火蚁告警信息素2-乙基-3,5(6)-二甲基吡嗪为阳性对照,测试红火蚁工蚁对不同剂量(100, 10, 1 和0.1 μg)的9种棉花挥发物组分[α-蒎烯、β-蒎烯、β-石竹烯、( E, E )-4,8,12-三甲基-1,3,7,11-十三碳四烯(TMTT)、( E )-4,8-二甲基-1,3,7-壬三烯(DMNT)、辛醛、6-甲基-5-庚烯-2-酮、顺-3-己烯基乙酸酯和水杨酸甲酯]的触角电位反应;再利用Y型嗅觉仪测试这些挥发物对红火蚁工蚁的行为选择影响。【结果】结果表明,受棉蚜为害的棉花较健康棉花对红火蚁工蚁具有极显著的引诱效果。红火蚁对9种挥发物组分的EAG反应随着剂量升高而升高。各化合物在100 μg剂量时EAG反应值最大,其中,工蚁对水杨酸甲酯和6-甲基-5-庚烯-2-酮这两个化合物反应最强。在行为选择实验中,化合物水杨酸甲酯、6-甲基-5-庚烯-2-酮和DMNT对红火蚁工蚁均具有显著的引诱效果。【结论】棉蚜诱导的棉花挥发物中水杨酸甲酯和6-甲基-5-庚烯-2-酮对红火蚁有显著的引诱效果,这2种化合物可能在红火蚁定位棉蚜、建立共生关系中起着关键的作用。     

北疆棉田捕食性天敌昆虫应对棉蚜的数量反应

【目的】棉蚜Aphis gossypii是新疆棉田的主要害虫,近来的研究多集中于南疆棉区,较少关注北疆棉田在新种植模式下的天敌种群数量发生规律。本文研究了北疆棉田棉蚜的优势种捕食性昆虫数量发生规律。【方法】对五家渠地区棉田中棉蚜及其4种主要捕食性天敌昆虫(2种瓢虫和2种草蛉)的种群数量进行了持续2年的跟踪调查。【结果】不同种捕食性天敌昆虫对棉蚜种群数量变化具有不同的响应,具体表现为:七星瓢虫Cocinella septempunctata数量随蚜虫数量增大而显著增大,多异瓢虫Hippodamia verigata和普通草蛉Chrysopa carnea随蚜虫数量增大而逐渐增大,而大草蛉Ch.septempunctata种群数量与棉蚜数量无关;连续2年的大田调查均发现,这4种捕食性昆虫种群数量在7月底有一高峰,而且七星瓢虫和大草蛉数量大于多异瓢虫和普通草蛉。【结论】七星瓢虫和大草龄是北疆五家渠地区棉田棉蚜的优势天敌。     

无翅桃蚜对龟纹瓢虫的视觉和嗅觉识别反应

为探明桃蚜Myzus persicae是否可以识别来自其捕食性天敌的嗅觉和视觉信息,本研究采用桃蚜和龟纹瓢虫Propylaea japonica这一猎物-捕食者系统,在室内测定了无翅桃蚜对龟纹瓢虫成虫体色和挥发物的识别反应。选择反应试验结果表明,无翅桃蚜既能通过视觉信息识别瓢虫的存在,也能通过嗅觉信息识别瓢虫的存在,说明桃蚜对龟纹瓢虫体色和气味信息的识别存在一定的冗余现象。剂量反应试验结果表明,龟纹瓢虫粗提物的剂量与其对桃蚜的驱避率呈现良好的线性关系,识别反应剂量的临界值在0.3~0.6个瓢虫当量之间,1.2~1.5个瓢虫当量的粗提物的驱避作用与20头活体龟纹瓢虫的驱避作用相当。结论认为,桃蚜可以识别龟纹瓢虫的存在,并对其作出一定的躲避反应,从而降低被捕食的风险。     

植物源挥发物对玉米田天敌昆虫的诱集效果比较

【目的】比较7种植物源挥发物反式-β-法尼烯、橙花叔醇、6-甲基-5-庚烯-2-酮、顺-3-己烯乙酸酯、丁香酚、芳樟醇、顺式茉莉酮在玉米田中对天敌昆虫的诱集效果,为利用植物源挥发物对玉米田害虫进行生物防治提供参考。【方法】将7种植物源挥发物制作挥发物引诱球,利用水盆诱捕器、粘虫板和五点取样法调查百株虫量,比较7种植物源挥发物对捕食性和寄生性天敌昆虫的诱集效果。【结果】在7种植物源挥发物的筛选中,橙花叔醇对黄缘蜾蠃Anterhynchium flavomarginatum较其它6种化合物和对照的诱集效果有明显差异,顺式茉莉酮对黑带食蚜蝇Episyrphus balteatus较其它6种化合物和对照的诱集效果有明显差异,反式-β-法尼烯和顺式茉莉酮对龟纹瓢虫Propylaea japonica较其它5种化合物和对照的诱集效果有明显差异;在橙花叔醇和顺式茉莉酮的小区试验中,2种挥发物对龟纹瓢虫和异色瓢虫Harmonia axyridis的诱集效果明显优于对照,橙花叔醇对黑带食蚜蝇和虎斑食虫虻Astochia virgatipes的诱集效果明显优于对照。【结论】在7种植物源挥发物中,对玉米田天敌昆虫的诱集效果,橙花叔醇较好,顺式茉莉酮和反式-β-法尼烯次之。     

不同营养层次挥发物对燕麦蚜茧蜂寄主搜寻行为的影响

“Ｙ”型管嗅觉计及风洞测定试验明,小麦植株,麦长管蚜（Sitobion avenae),禾谷缢管蚜（Rhopalosiphum padi)对燕麦蚜蜂（Aphidius avenae)雌蜂的吸引作用较小,而有蚜植株及蚜害植株对其吸引作用较大,并以麦长管蚜有蚜植株的吸引作用最强,尽管该蜂对禾谷缢管蚜的寄生率极你,工作量 由其危害诱导产生的挥发性信息化僵物对该蜂仍具有较强的吸引作用,GC－MS鉴定结果表明,麦蚜取食诱导的挥发性信息化合物主要是2－莰烯,6－甲基－5－已烯－2－酮,顺－3－已酰酸酯有水杨酸甲酯,其中6－甲基－5－已烯－2－酮和6－甲基－5－已烯－2－醇对燕麦蚜划蜂的吸引作用最强,水杨酸酯无明显吸引作用。     

Semiochemicals associated to spacing behaviour of the bird cherry-oat aphid Rhopalosiphum padi L. (Hem., Aphididae) do not affect the olfactometric behaviour of the cereal aphid parasitoid Aphidius rhopalosiphi De Stephani-Pérez (Hym., Braconidae)

Volatiles produced by the interaction of Rhopalosiphum padi and wheat, and semiochemicals which elicit the spacing behaviour of R. padi on wheat and oat, were evaluated in an olfactometer against the cereal aphid parasitoid Aphidius rhopalosiphi . The parasitoid was attracted by volatiles produced by the R. padi -wheat interaction at high density of aphids, but not by the R. padi -wheat interaction at low density. Compounds produced by the interaction of wheat or oat that was infested with a high density of aphids (approximately 9 aphids/cm²), 6-methyl-5-hepten-2-one (MHO), 6-methyl-5-hepten-2-ol (MHOH), 2-tridecanone (2-T), and methyl salicylate (MS), neither attracted nor repelled A. rhopalosiphi as pure compounds or in the naturally occurring mixture. The results are discussed in terms of the use of semiochemicals and parasitoids in the integrated management of aphid pests.     

Development of lady beetle attractants from floral volatiles and other semiochemicals for the biological control of aphids

Aphids are among the most destructive phytophagous pests of host plants, because of their rapid reproduction, parthenogenesis, extensive crop damage, and the transmission of many plant viruses. Since lady beetles are important predatory natural enemies of aphids, developing lady beetle attractants to increase their field abundance is vital for aphid control. Floral volatiles and other semiochemicals are reportedly attractive to lady beetles. In this research, a total of 58 floral volatiles were tested by Y-tube olfactometer assays, among which 29 were highly attractive to both Harmonia axyridis (Coleoptera: Coccinellidae) and Coccinella septempunctata (Coleoptera: Coccinellidae). Meanwhile, the results of wind tunnel trials showed that only isoamyl acetate, α-humulene, trans-3-hexen-1-ol, methyl salicylate, and β-pinene lure these two species. Thereafter, 15 semiochemicals from pests, natural enemies, and pest-infested crops were mixed with the selected floral volatiles, to determine optimum formulations for attracting lady beetles through wind tunnels and further field trials. Eventually, formulas (1) α-humulene: β-pinene: methyl salicylate: trans-3-hexen-1-ol = 1:3:3:10; (5) α-humulene: β-pinene: methyl salicylate:1-nonanal = 1:3:3:10; (8) α-humulene: β-pinene: methyl salicylate: indole = 1:3:3:10 (1, 5, and 8 are labels used for the various formulations in field trials) were successfully verified to be attractive to lady beetles in both pumpkin and wheat fields. These formulations will be of great significance in developing integrated pest management strategies for aphid control.     

Lycopene accumulation affects the biosynthesis of some carotenoid-related volatiles independent of ethylene in tomato

For elucidating the regulatory mechanism of ethylene on carotenoid-related volatiles (open chain) compounds and the relationship between lycopene and carotenoid-related volatiles,transgenic tomato fruits in which ACC synthase was suppressed were used.The transgenic tomato fruit showed a significant reduction of lycopene and aroma volatiles with low ethylene production.6-methyl-5-hepten-2-one,6-methyl-5-hepten-2-ol and geranylacetone,which were suspected to be lycopene degradation products,were lower than those in wild type tomato fruits.In order to identify whether lycopene accumulation effects the biosynthesis of some carotenoid-related volatiles independent of ethylene in tomato or not,the capability of both wild type and transgenic tomato fruits discs to convert lycopene into carotenoid-related volatiles was evaluated.The data showed that external lycopene could convert into 6-methyl-5-hepten-2-one and 6-methyl-5-hepten-2-ol in vivo,Indicating that the strong inhibition of ethylene production had no effect on enzymes in the biosynthesis pathway of some carotenoid-related volatiles.Therefore,in ACS-suppression transgenic tomato fruits,the low levels of 6-methyl-5-hepten-2-one,6-methyl-5-hepten-2-ol was due to decreased lycopene accumulation,not ethylene production.Ethylene only affected the accumulation of lycopene,and then indirectly influenceed the level of lycopene-related volatiles.     

Plant response to touch affects the behaviour of aphids and ladybirds

Touching between leaves of the same plant and/or by neighbouring plants is one of the most common mechanical stimuli to which an individual plant has to respond on a daily basis. The possible ecological implications of a plant’s response to touch on plant–insect interactions have not been explicitly investigated. We examined whether plant response to 1 min daily touching over a period of 6 days affects host plant acceptance by the bird cherry-oat aphid Rhopalosiphum padi L. on maize and by the black bean aphid Aphis fabae Scop. on bean, as well as olfactory preference of an aphid predator, seven-spotted ladybird Coccinella septempunctata L. Maize plants responded to touch with significant reduction in plant height, total plant biomass, leaf weight, leaf surface, shoot/root ratio and specific leaf area (SLA), while bean plants responded with reduced stem height and reduced SLA. Both aphid species showed significantly reduced acceptance of touched plants compared with untouched plants. The two aphid species and male and female ladybirds preferred volatiles from untouched plants over those from touched plants. Volatiles in the headspace of touched and untouched plants were collected and identified. Stepwise discriminant analyses identified (E)-nerolidol and (E)-β-caryophyllene in maize and 6-methyl-5-hepten-2-one and an unidentified sesquiterpene in bean as the best discriminating compounds in the volatile profiles of touched plants. Our study suggests that touch-induced changes in plants can potentially affect host plant selection by aphids and habitat searching by ladybirds. Thus, touch-induced changes in plants may have significant effects at higher trophic levels.     

Continuous coenzyme dependent stereoselective synthesis of sulcatol by alcohol dehydrogenase

Summary 6-methyl-5-hepten-2-one was reduced to sulcatol ((+)-6-methyl-5-hepten-2-ol) by using alcohol dehydrogenase fromThermoanaerobium brockii in a continuous process. The cofactor NADP(H) was retained by a charged UF-membrane and regenerated by oxidation of isopropanol to acetone. Use of native NADP in a charged UF-membrane reactor proved to be superior to use of PEG coupled NADP in a uncharged UF-membrane reactor.     

小麦互益素对麦长管蚜及其天敌的影响

研究了在田间使用小麦互益素--水杨酸甲酯和6-甲基-5-庚烯-2-酮对麦长管蚜及其主要天敌--异色瓢虫和燕麦蚜茧蜂的影响.结果表明,小麦互益素虽然没有明显改变麦长管蚜的田间种群变动趋势,但显著降低了麦长管蚜的种群数量.使用小麦互益素能够恶化麦长管蚜的生存环境,使有翅蚜数量明显增加.尽管小麦互益素使天敌物种丰富度有所下降,天敌群落多样性和均匀度指数下降,但燕麦蚜茧蜂、异色瓢虫等优势天敌的种群数量不仅没有减少反而有所增加.因此,田间使用小麦互益素对控制麦长管蚜的危害具有重要作用.     

Stage and age-specific predation in four aphidophagous ladybird beetles

In the present study, stage- and age-specific predatory patterns and nutritional ecology attributes of four co-occurring aphidophagous ladybirds, namely, Coccinella septempunctata (L.), Coccinella transversalis F., Cheilomenes sexmaculata (F.) and Propylea dissecta (Mulsant) on pea aphid, Acyrthosiphon pisum (Harris) were investigated. Despite their lower consumption rates, smaller ladybirds (C. sexmaculata and P. dissecta) and earlier instars were efficient converters of aphid prey with higher relative growth rates, over the respective larger ladybirds (C. septempunctata and C. transversalis) and fourth instars. The consumption rates of pea aphids by the larvae increased with stage, but with a decline in the later part of the fourth instars, just prior to pupation. Adult females of early age groups (between 2 and 7 days) had higher consumption rates than later age groups in all the four species. Further in adult females, consumption rates decrease with increase in age, but without significant changes in conversion efficiencies and relative growth rates.