两种关键花香挥发物对棉铃虫的信息多义性

为了探明花香挥发物的信息多义性,作者测试了2种关键花香挥发物(苯乙醛和乙酸苯甲酯)对棉铃虫成虫产卵、性信息素诱捕和初孵幼虫趋向行为的影响。结果表明:在苯乙醛和乙酸苯甲酯组成的二元混剂与番茄、辣椒、棉花、烟草和玉米叶片共存条件下,花香挥发物上的落卵量与除了番茄外的其他寄主叶片气味源没有显著差异,证实其对雌成虫有较强引诱产卵作用;花香引诱剂能显著增加棉铃虫性信息素的野外捕获量,并且银纹夜蛾、小地老虎、甜菜夜蛾、亚洲玉米螟、稻纵卷叶螟和甜菜白带螟对花香引诱剂的趋向并不受棉铃虫性信息素存在的影响,说明花香引诱剂与棉铃虫性信息素具有良好兼容性。此外,花香挥发物还能增强棉铃虫初孵幼虫对烟草叶碟的识别能力。总之,花香挥发物对棉铃虫有多方面的生态学功能,这种信息化合物的多义性可能具有自然选择方面的优势。     

棉铃虫成虫对两种关键花香气味的联系性学习

为了明确棉铃虫对苯乙醛和乙酸苯甲酯两种关键花香气味的联系性学习行为,在室内分别测定了不同学习训练的棉铃虫雌雄成虫对两种关键花香气味的选择偏好性反应和雄成虫的触角电位反应。偏好性测定结果表明,无花香气味接触经历的棉铃虫对苯乙醛和乙酸苯甲酯的选择频次均无显著差异,且单纯的花香气味接触经历也不能诱导棉铃虫气味偏好性的显著改变,唯有花香气味接触经历伴随蔗糖溶液进行强化训练时,才能诱导气味偏好性的显著性改变。从对两种花香气味的联系性学习看,棉铃虫更容易将苯乙醛与蔗糖溶液进行联系性学习,而不容易将乙酸苯甲酯与蔗糖溶液进行联系性学习。从性别差异看,雌虫比雄虫具有更强的将花香气味与蔗糖溶液进行联系性学习的能力。触角电位测定结果表明,不同学习训练的棉铃虫雄成虫对两种花香气味和绿叶气味顺-3-己烯-1-醇的EAG反应值之间不存在显著性差异。总之,花香气味伴随食物资源的联系性学习经历,能够明显提高棉铃虫成虫对花香气味的选择偏好,可以此为基础进一步优化花香引诱剂的配方设计和应用技术。     

用替代寄主繁殖的川硬皮肿腿蜂的学习行为

采用Y型嗅觉仪进行双向选择实验,研究了用替代寄主黄粉虫蛹繁殖的川硬皮肿腿蜂寄主搜索过程中的学习行为。结果表明,川硬皮肿腿蜂羽化期和成虫初期经历松枝皮、松针、松节油、杉枝皮等的挥发物后,雌蜂对这些挥发物的选择性明显提高,但对杉叶挥发物无明显的学习行为。羽化期和成虫初期是否投放新鲜寄主,对雌蜂的气味选择性没有明显的影响。成蜂取食黄粉虫蛹和蜂蜜时均可联系性学习松枝和杉枝气味。取食并经历杉枝和松枝挥发物4天和8天的寄生蜂之间对相应气味的选择性无显著差异。     

与中红侧沟茧蜂生境与寄主定位相关的玉米及棉铃虫幼虫体表挥发性成分的提取与鉴定

【目的】鉴定玉米Zea mays L.和棉铃虫Helicoverpa armigera (Hübner)幼虫体表挥发性成分中对中红侧沟茧蜂 Microplitis mediator (Haliday)具有生境与寄主定位作用的信息化合物,从化学生态学的角度研究玉米-棉铃虫-中红侧沟茧蜂三重营养关系,解释中红侧沟茧蜂寻找寄主的过程中的信息识别机制,为害虫的综合防治的“推-拉”方法提供一定的理论基础。【方法】利用触角电位仪(EAG)、触角电位联用仪(GC-EAD)、气质联用仪(GC-MS)及“Y”型嗅觉仪确定玉米和棉铃虫幼虫体表提取物的信息化合物。在室内利用玉米以及棉铃虫幼虫体表挥发物标准品化合物以及模拟混合物,使用“Y”型嗅觉仪进行中红侧沟茧蜂成虫行为反应试验。【结果】玉米挥发物中有11种化学成分,棉铃虫幼虫体表挥发物中有6种化学成分对中红侧沟茧蜂的触角具有电生理活性,其中4种成分在两种挥发物中都存在。室内行为反应试验发现：与正己烷对照相比,玉米的模拟组分对雌、雄蜂均表现出显著（P<0.05）的诱引作用;棉铃虫1龄幼虫体表模拟组分对雌蜂具有极显著的诱引作用（P<0.01）,对雄蜂具有显著的诱引作用（P<0.05）;棉铃虫2龄幼虫体表模拟组分对雌蜂具有显著的诱引作用（P<0.05）。【结论】本研究证明了玉米以及棉铃虫幼虫体表挥发物中分别存在11种（庚醛、2-己醇、1-己醇、1-辛烯-3-醇、壬醛、葵醛、苯甲醛、反式-2-壬烯-1-醇、己酸、苯基乙醇、月桂醇）和6种（2-己醇、己酸乙酯、1-己醇、壬醛、辛酸乙酯、癸醛）中红侧沟茧蜂生境及寄主定位的化学信息物质。     

一种测定植物挥发物对棉铃虫引诱作用的无选择性风洞嗅觉仪(英文)

发展了一套测定棉铃虫Helicoverpaarmigera (H櫣ｂｎｅｒ)对植物挥发物的行为反应的生测系统。这套系统由嗅觉仪、风洞和风洞室组成。用这套系统测定了棉铃虫对萎蔫后的枫杨Pterocaryastenoptera叶、加拿大杨Populuscanadensis叶、香椿Toonasisnensis叶、新鲜的芹菜与胡萝卜花挥发物以及苯乙醛的行为反应。结果显示 ,萎蔫的枫杨叶、加拿大杨叶、香椿叶的挥发物均对棉铃虫处女雌蛾表现出显著的引诱作用 ,而对已交配过的雌蛾和雄蛾无明显的引诱作用 ;新鲜的芹菜与胡萝卜花挥发物对棉铃虫两性性成虫均不表现出显著的引诱作用 ;苯乙醛对棉铃虫处女雌、雄蛾有较强的引诱作用。讨论了杨树枝把引诱棉铃虫的原因。     

非嗜食寄主气味蛹期处理对不同寄主来源美洲斑潜蝇雌成虫嗅觉定向的影响

测定用菜豆和丝瓜饲养的美洲斑潜蝇Liriomyza sativae Blanchard蛹暴露于用正己烷稀释的番茄或南瓜叶片挥发性抽提物(TLE或PLE)72h后,羽化雌成虫在Y形嗅觉仪中对TLE或PLE的定向率、平均反应时间以及对正己烷的定向率和平均反应时间,比较幼虫寄主经历和寄主气味对美洲斑潜蝇成虫嗅觉记忆的影响。结果表明,蛹期使用非嗜食寄主植物气味处理,能增加美洲斑潜蝇羽化雌成虫对非嗜食寄主气味的定向;幼虫期的寄主经历对处理后的成虫嗅觉定向也产生影响,饲喂丝瓜的美洲斑潜蝇蛹期处理后,羽化雌成虫显著偏向选择处理气味而非正己烷,饲喂菜豆的美洲斑潜蝇对南瓜的气味也表现出同样的特点,但对番茄的气味则相反,即使处理后对番茄气味的选择比率增加,仍然偏向选择正己烷。     

甜菜夜蛾对不同寄主植物的产卵和取食选择

为了探讨甜菜夜蛾Spodoptera exigua对不同寄主植物的产卵选择及成虫产卵选择与幼虫取食选择间的关联度, 本研究选取玉米、豇豆、甘蓝、黄瓜、棉花、辣椒和番茄7种植物进行了选择性和非选择性实验研究, 并采用Y型嗅觉仪测定了成虫对其中3种寄主植物及其挥发物抽提物的趋性。结果表明：在田间非选择性实验中, 甜菜夜蛾在不同寄主植物上的落卵量依次为：玉米>辣椒>棉花>黄瓜、豇豆、番茄>甘蓝。Y型嗅觉仪的行为测定表明, 雌成虫对玉米及其挥发物抽提物的趋性最强, 黄瓜次之, 对甘蓝的趋性最弱, 这与雌虫的产卵选择性一致。不同龄期甜菜夜蛾幼虫对寄主植物的取食选择性有所不同, 且随观测时间的延长有所改变;低龄幼虫对豇豆、玉米和黄瓜的选择性较强, 对甘蓝、番茄、辣椒和棉花的取食选择性则较弱, 高龄幼虫对辣椒也具有较强的选择性;5龄幼虫对寄主植物的选择性不如低龄幼虫明显。结果显示, 甜菜夜蛾对不同寄主植物的产卵选择性显著不同, 植物抽提物在雌成虫的产卵选择中具有重要作用, 甜菜夜蛾对寄主植物的产卵选择性和幼虫取食选择性并不一致。     

亚麻荠对小菜蛾幼虫取食和成虫行为反应的影响

亚麻荠是一种很少有害虫危害的油料作物。用室内生测和Y 型嗅觉仪研究了亚麻荠对小菜蛾Plutella xylostella幼虫取食和成虫行 为反应的影响。以甘蓝作对照,用亚麻荠叶片喂养的小菜蛾初孵幼虫3天后校正死亡率为79 .2%,显示了较强的致死作用;喂养小菜蛾3龄幼虫至化蛹,其存活率、化蛹率、蛹重及成 虫寿命都显著降低,表明亚麻荠对小菜蛾幼虫的生长发育有不利影响。在幼虫的取食选择实 验中,有甘蓝叶供选择时,小菜蛾幼虫不取食亚麻荠;在无可选择的情况下,小菜蛾幼虫也 取 食亚麻荠叶片,但取食量很小,与取食甘蓝叶的量相比,差异极显著。行为反应测试表明, 小菜蛾成虫对甘蓝和亚麻荠植株的挥发物都有明显的趋性反应,与对照（净化空气）相比, 差异极显著,而在甘蓝和亚麻荠之间无选择性。说明小菜蛾成虫对亚麻荠植株的挥发物具有 较强的定向反应。     

柑橘大实蝇对不同颜色和糖类的偏好及对糖类的嗅觉反应

为探明影响柑橘大实蝇Bactrocera minax(Enderlein)成虫取食偏好的因素,本文研究了其对不同颜色和糖类物质的选择及其嗅觉反应。结果表明:柑橘大实蝇成虫明显偏好黄色和橙色基质的食物,对绿、白、蓝、黑、红色食物趋性较弱;对不同糖类的选择顺序是:红糖蜂蜜蔗糖和白糖;不同采集地间和不同性别间的柑橘大实蝇对颜色、糖类物质的选择差异不显著。嗅觉行为测试结果,柑橘大实蝇雌雄虫对所测试几种糖的气味均表现明显趋性,其中,雌虫对红糖和蜂蜜气味的嗅觉反应比雄虫更敏感。研究结果可以为柑橘大实蝇成虫食诱剂的研制和诱捕器的设计提供重要参考依据。     

草地贪夜蛾对2种豆科蔬菜的取食和产卵选择性及其适应性研究

草地贪夜蛾Spodoptera frugiperda是一种多食性昆虫,为明确该害虫对不同寄主的选择性和适生性,本文比较了草地贪夜蛾对玉米Zea mays、豇豆Vigna unguiculata和四季豆Phaseolus vulgaris等3种寄主的取食及产卵偏好性,并分析了取食不同寄主对其生长发育及繁殖的影响。结果表明：草地贪夜蛾低龄幼虫（初孵幼虫和2龄）对玉米叶和豇豆叶表现出取食偏好性,而高龄幼虫（3龄和5龄）对3种寄主不同组织的取食选择性无明显差异;草地贪夜蛾取食3种寄主植物均可以完成世代发育,但取食豇豆叶和四季豆叶的幼虫历期、蛹历期显著变短,化蛹率、羽化率显著降低;取食豇豆叶对其蛹重、成虫寿命无显著影响,但取食四季豆叶的蛹重显著变轻、雄成虫寿命显著变短;种群生命表参数显示,草地贪夜蛾在3种寄主上的繁殖力表现为玉米叶（1 138.29）>豇豆叶（1 179.00）>四季豆叶（585.50）,处理间差异显著;取食2种非嗜好寄主的种群内禀增长率（rm）和周限增长率（λ）均显著降低,平均世代历期（T）显著延长,取食豇豆叶的雌雄性比显著降低;草地贪夜蛾对寄主玉米具有明显的产卵偏好性,选择豇豆和四季豆的产卵量仅占植物着卵量的4.19%和18.23%,显著低于玉米着卵量。结果表明草地贪夜蛾偏好选择玉米进行取食和产卵,但在豇豆和四季豆寄主植物上可以实现种群繁衍,当其种群密度大时存在转移为害豇豆和四季豆的潜在风险。     

Polyphagy and primary host plants: oviposition preference versus larval performance in the lepidopteran pest Helicoverpa armigera

Oviposition preference and several measures of offspring performance of Helicoverpa armigera (Hübner) were investigated on a subset of its host plants that were selected for their reputed importance in the field in Australia. They included cotton, pigeon pea, sweet corn, mungbean, bean and common sowthistle. Plants were at their flowering stage when presented to gravid female moths. Flowering pigeon pea evoked far more oviposition than did the other plant species and was the most preferred plant for neonate larval feeding. It also supported development of the most robust larvae and pupae, and these produced the most fecund moths. Common sowthistle and cotton were equally suitable to pigeon pea for larval development, but these two species received far fewer H. armigera eggs than did pigeon pea. Mungbean also received relatively few eggs, but it did support intermediate measures of larval growth and survival. Fewest eggs were laid on bean and it was also the least beneficial in terms of larval growth. Among the host plant species tested, only flowering pigeon pea supported a good relationship between oviposition preference of H. armigera and its subsequent offspring performance. Australian H. armigera moths are thus consistent with Indian H. armigera moths in their ovipositional behaviour and larval performance relative to pigeon pea. The results suggest that the host recognition and acceptance behaviour of this species is fixed across its geographical distribution and they support the theory that pigeon pea might be one of the primary host plants of this insect. These insights, together with published results on the sensory responses of the females to volatiles derived from the different host plant species tested here, help to explain why some plant species are primary targets for the ovipositing moths whereas others are only secondary targets of this polyphagous pest, which has a notoriously broad host range. Handling Editor: Joseph Dickens     

Variation in flight response of the specialist parasitoidMacrocentrus grandii goidanich to odours from food plants of its European corn borer host

The specialist parasitoidMacrocentrus grandii Goidanich (Hymenoptera: Braconidae) appears to parasitize its polyphagous host, European corn borer (Ostrinia nubilalis (Hübner)) (Lepidoptera: Pyralidae), in only certain habitats. To determine whether it differed in its olfactory response to host-habitat odours, volatiles from four plants were isolated using Tenax. Wind tunnel bioassays of the extracts revealed that, besides corn which was tested in an earlier study, olfactory stimuli for attraction ofM. grandii females were present in potato and snap bean but not in pepper or soybean. To further characterize the response to pepper and soybean, these extracts were bioassayed in combination with an attractive extract. The results indicated that pepper volatiles evoked a neutral response inM. grandii while response to soybean volatiles appeared to be neutral or slightly negative. The innate response to soybean volatiles was altered to one of attraction after oviposition experience on soybean. Seven days after oviposition, experienced females continued to respond positively to soybean volatiles. Components of soybean volatiles responsible for the change in flight behaviour resulting from oviposition experience were eluted by nonpolar and slightly polar solvents. These results support the idea that plant odour may be a factor determining the range of plants on whichM. grandii parasitizes its host. The study indicates the occurrence of associative learning of plant-related volatiles during oviposition inM. grandii, and suggests the involvement of diverse plant compounds in the learning process.     

Host recognition by the specialist endoparasitoidMicroplitis croceipes (Hymenoptera: Braconidae): Role of host- and plant-related volatiles

The specialist parasitoidMicroplitis croceipes Cresson can parasitize only noctuid larvae in the generaHelicoverpa andHeliothis. To be successful in their search for hosts, the ability to distinguish hosts from nonhosts feeding on the same plant is beneficial. In flight tunnel experiments, we found that prior to landing on the odor sourceM. croceipes were able to distinguish volatiles released from frass of host larvae(Helicoverpa zea Boddie) and nonhost larvae (Spodoptera exigua Hübner andSpodoptera frugiperda J. E. Smith) fed on cotton. However, an initial contact experience with frass of cotton-fed host larvae appeared to be critical for this ability. Wasps that had antennated frass of host larvae fed pinto bean diet were equally attracted to frass of host and nonhost larvae fed on pinto bean diet. In short-range walking experiments, wasps located cotton-fed host larvae faster than diet-fed larvae, regardless of their experience. Wasps that had antennated frass of cotton-fed host larvae were less attracted to cotton-fed nonhost larvae, compared to host larvae, and preferred to sting host larvae. Plant-related volatiles in host frass and larvae appear to play a major role in the successful location of host larvae.     

Potential predation of non-webbuilding spider assemblage on cotton pests Helicoverpa armigera and Spodoptera littoralis (Lepidoptera: Noctuidae)

The relative feeding rates and preferences of a hunting-spider assemblage inhabiting southern Spanish cotton fields for two major cotton pests, Helicoverpa armigera (Hübner) and Spodoptera littoralis (Boisdubal) (Lepidoptera: Noctuidae), were analyzed under laboratory conditions. First, a no-choice feeding test was used to determine relative feeding rates for hunting-spider families and species, offering a fixed number of 10 neonate larvae of H. armigera or S. littoralis and observing predation after 2 h, 4 h, 8 h, and 24 h. In a second test, Drosophila melanogaster, a very palatable alternative prey, was used to determine the degree of preference for cotton pest larvae. The mean number of first-instar lepidoptera larvae consumed by hunting spiders after 24 h was 8.57±0.25. As expected, spiders showed no preference for either of the two cotton pest species H. armigera and S. littoralis over the other. Results also showed that cursorial spiders of the families Miturigidae (represented here by Cheiracanthium pelasgicum) and Philodromidae consumed significantly higher percentages of larvae than crab spiders belonging to the Thomisidae family after 2 h and 24 h, respectively. In the prey choice test, Cheiracantium pelasgicum displayed a strong preference for cotton pest larvae while Thomisidae and Oxyopidae showed no significant preference. In addition, as the attack sequence progressed, Ch. pelasgicum showed a clear tendency towards the alternation of prey while Thomisidae, and more irregularly Oxyopidae, maintained their preference for D. melanogaster. These findings confirmed both the considerable potential value of some cursorial spiders (e.g. Ch. pelasgicum) in the biological control of lepidopteran cotton pests and the relatively low impact of other hunting spiders, e.g. Thomisidae, on pests of this kind.     

The role of two plant-derived volatiles in the foraging movement of 1st instar Helicoverpa armigera (Hübner): time to stop and smell the flowers

Positive phototaxis and negative geotaxis are behaviours that 1st instar Helicoverpa armigera use to direct their foraging movement upward towards nutritious new plant growth and reproductive structures. Odours emitted by fruits or seeds can attract larvae directly via chemotaxis. In this study we clarify the effect of leaf and flower odours on foraging 1st instar H. armigera. Using a Y-tube olfactometer we tested for chemotaxis towards two plant volatiles and found larvae were not attracted. Bioassays for phototaxis towards UV, blue, green and white light showed that a green leaf volatile ((Z)-3-hexenyl acetate) and a flower volatile (phenylacetaldehyde) reduced larval phototaxis towards blue light. Feeding on a host plant reduced phototaxis towards blue and green light. We concluded that the upward movement of 1st instars on plants is largely due to phototaxis towards the blue wavelengths of skylight. Plant attributes such as volatile chemicals affect the expression of phototaxis and therefore, indirectly influence larval movement to locate food resources. Handling Editor: Anna-Karin Borg-Karlson     

Host preference of the facultative hyperparasitoidTetrastichus howardi (Hym.: Eulophidae)

Tetrastichus howardi (Olliff) preferred the lepidopteran hosts,Chilo partellus (Swinhoe) (Pyralidae) andHelicoverpa armigera (Hübner) (Noctuidae) to their parasitoids,Xanthopimpla stemmator (Thunberg) (Hymenoptera: Ichneumonidae) andPalexorista laxa (Curran) (Diptera: Tachinidae). IfT. howardi had previously experienced parasitising a certain host, its preference for that host increased, but not significantly. When reared on a certain host, the preference for that host increased.T. howardi showed no preference to any particular age of its hosts.T. howardi was able to discriminate between parasitised and unparasitised hosts, initially preferring parasitised hosts, but two days later preferring unparasitised hosts.     

The scale response ofTrichogramma [Hymenoptera: Trichogrammatidae]: Variation among species in host specificity and the effect of conditioning

Host specificity and the effect of conditioning on a behavioral response to lepidopteran scales varied among the females of 4Trichogramma spp. observed in laboratory experiments.Trichogramma species nrPretiosum Riley andT. exiguum Pinto & Platner responded weakly toOstrinia nubilalis (Hübner) scales relative toHeliothis zea (Boddie) andManduca sexta (L.).T. maltbyi Nagaraja & Nagarkatti andT. minutum Riley did not discriminate between scales from these 3 hosts. Conditioning with various combinations of host scales and eggs did not alter host specificity, but in some cases, changed general responsiveness to scales. These were attributed to habituation, loss of appetitive drive due to long oviposition bouts, and associative learning. In general, the scale response seems to be innate and fairly nonspecific.      

The chemosensory basis for behavioral divergence involved in sympatric host shifts II: olfactory receptor neuron sensitivity and temporal firing pattern to individual key host volatiles

The Rhagoletis species complex has been a key player in the sympatric speciation debate for much of the last 50 years. Studies indicate that differences in olfactory preference for host fruit volatiles could be important in reproductively isolating flies infesting each type of fruit via premating barriers to gene flow. Single sensillum electrophysiology was used to compare the response characteristics of olfactory receptor neurons from apple, hawthorn, and flowering dogwood-origin populations of R. pomonella, as well as from the blueberry maggot, R. mendax (an outgroup). Eleven volatiles were selected as stimuli from behavioral/electroantennographic studies of the three R. pomonella host populations. Previously, we reported that differences in preference for host fruit volatile blends are not a function of alterations in the general class of receptor neurons tuned to key host volatiles. In the present study, population comparisons involving dose–response trials with the key volatiles revealed significant variability in olfactory receptor neuron sensitivity and temporal firing pattern both within and among Rhagoletis populations. It is concluded that such variability in peripheral sensitivity and temporal firing pattern could influence host preference and contribute to host fidelity and sympatric host shifts in the Rhagoletis complex.     

Volatiles of two chemotypes of Majorana syriaca L. (Labiatae) as olfactory cues for the honeybee

Summary A study of olfactory discrimination by honeybee has been set up in order to understand the role of volatiles of the aromatic plant Majorana syriaca in attracting pollinating insects. The honeybee's response to volatiles from leaves and inflorescences of two M. syriaca chemotypes, which differ in the thymol carvacrol ratio of their volatiles, was tested using a bioessay method based on associative conditioning and recruitement techniques. Behavioural data show that a honeybee identifies and reacts selectively to olfactory signals from leaves and from inflorescences of the two chemotypes. Such data suggest that the volatiles from all parts of the aromatic plant M. syriaca may have a role in attracting pollinators. The vegetative parts produce a volatile emission which attracts the pollinators from a distance towards the whole plant. At close range these are directed by the flower signal which is amplified by the volatiles of bracts and leaves in the inflorescence.