Flight responses of Sitotroga cerealella (Lepidoptera: Gelechiidae) to corn kernel volatiles in a wind tunnel

The flight behavioral responses of males and females of Sitotroga cerealella (Lepidoptera: Gelechiidae) to corn kernel volatiles, in a wind tunnel, and the determination and identification of the active compounds of corn kernel volatiles were investigated. A wind tunnel bioassay was carried out to test the response of males and females to 15, 30, 60, and 120 g equivalents of corn kernel volatiles. Gas chromatography-electroantennography was used to determine which components in corn kernel volatiles elicited an EAD response using male and female antennae. Gas chromatography-mass spectrometry technique was used to identify the active compounds of corn kernel volatiles. A 60-g equivalent of corn kernel volatiles elicited attractant behavior of unmated males to landing near the source. Mated males and virgin females were not attracted to corn kernel volatiles. The number of mated females landing was significantly higher in 60- and 120-g equivalents of corn kernel volatiles, compared to the other concentrations and the control. The antennae of males and females responded to four active compounds of corn kernel volatiles. Three of these compounds were identified, namely nonanal, decanal, and geranyl acetone. It is suggested that host finding and selection by S. cerealella is associated with its host volatiles.     

Differential electroantennogram response of females and males of two parasitoid species to host-related green leaf volatiles and inducible compounds

Parasitoids employ different types of host-related volatile signals for foraging and host-location. Host-related volatile signals can be plant-based, originate from the herbivore host or produced from an interaction between herbivores and their plant host. In order to investigate potential sex- and species-related differences in the antennal response of parasitoids to different host-related volatiles, we compared the electroantennogram (EAG) responses of both sexes of the specialist parasitoid, Microplitis croceipes (Cresson), and the generalist, Cotesia marginiventris (Cresson), to varying doses of selected plant-based host-related volatiles: two green leaf volatiles (cis-3-hexenol and hexanal) and three inducible compounds (cis-3-hexenyl acetate, linalool, and (E,E)-alpha-farnesene). Mating had no significant effect on EAG response. Females of both species showed significantly greater EAG responses than conspecific males to green leaf volatiles, which are released immediately after initiation of herbivore feeding damage. In contrast, males showed greater responses than conspecific females to inducible compounds released much later after initial damage. Cotesia marginiventris females and males showed greater EAG responses than counterpart M. croceipes to the tested compounds at various doses, suggesting that the generalist parasitoid shows greater antennal sensitivity than the specialist to the tested host-plant volatiles. These results are discussed in relation to the possible roles of green leaf volatiles and inducible compounds in the ecology of female and male parasitoids.     

Behavioural and chemical evidence of a male‐produced aggregation pheromone in the flower thrips Frankliniella intonsa

The response of adult flower thrips Frankliniella intonsa (Trybom) (Thysanoptera: Thripidae) to conspecifics is investigated in Y‐tube olfactometer bioassays. The results show that both males and females are attracted to the odours of adult males, which indicates a male‐produced aggregation pheromone in this species. Gas chromatography‐mass spectroscopy analyses of headspace volatiles collected on solid‐phase microextraction fibres show that two major components and six minor components are present in volatiles from males but not in females. Further gas chromatography‐mass spectroscopy analyses reveal that the two major components in head‐space volatiles produced by F. intonsa males are the same compounds that are reported in volatiles of Frankliniella occidentalis males: (R)‐lavandulyl acetate and neryl (S)‐2‐methylbutanoate. However, the quantity of these two compounds in the volatiles differs between the species.     

华北大黑鳃金龟对桃树挥发物的电生理反应

【目的】华北大黑鳃金龟Holotrichia oblita是一种分布范围广,寄主种类多的农业害虫。本研究鉴定了桃树顶空挥发物中对华北大黑鳃金龟雌虫具有触角电生理活性的化合物,并探索桃树挥发物活性成分的剂量对华北大黑鳃金龟雌、雄虫触角电生理反应的影响。【方法】采用顶空吸附法收集桃树枝叶挥发物,用气相色谱 触角电位联用技术(GC-EAD)和气相色谱 质谱联用技术(GC-MS)鉴定有电生理活性的桃树挥发物成分,最后用触角电位(electroantennograph, EAG)技术测试这些挥发物在0.01,0.1, 1, 10和100 μg剂量下引起的华北大黑鳃金龟雌、雄成虫EAG反应。【结果】桃树挥发物中能引起华北大黑鳃金龟雌成虫触角电生理反应的成分有7种,包括Z-β-罗勒烯、顺-3-己烯乙酸酯、顺-3-己烯醇、壬醛、水杨酸甲酯以及2种未知化合物。所测试的对华北大黑鳃金龟雌成虫触角具有电生理活性的5种桃树挥发物成分在各剂量下都能引起雌、雄成虫明显的EAG反应。雌、雄虫对同种物质的EAG反应随着剂量的增加而有增大的趋势,并且雌虫的EAG反应显著高于雄虫。【结论】桃树挥发物中,罗勒烯、顺-3-己烯乙酸酯、顺-3-己烯醇、壬醛、水杨酸甲酯均能引起华北大黑鳃金龟雌、雄成虫的剂量依赖性的触角电生理反应,而且存在显著的性别差异。可利用这些化合物开展行为反应和田间诱集试验,进一步验证其对华北大黑鳃金龟的引诱活性。     

Volatile compounds emitted by Triatoma dimidiata,a vector of Chagas disease: chemical analysis and behavioural evaluation

In this study, we evaluated the responses of Triatoma dimidiata Latreille (Hemiptera: Reduviidae) to volatiles emitted by conspecific females, males, mating pairs and metasternal gland (MG) extracts with a Y‐tube olfactometer. The volatile compounds released by mating pairs and MGs of T. dimidiata were identified using solid‐phase microextraction and coupled gas chromatography‐mass spectrometry (GC‐MS). Females were not attracted to volatiles emitted by males or MG extracts; however, they preferred clean air to their own volatiles or those from mating pairs. Males were attracted to volatiles emitted by males, females, mating pairs, pairs in which the male had the MG orifices occluded or MG extracts of both sexes. However, males were not attracted to volatiles emitted by pairs in which the female had the MG orifices occluded. The chemical analyses showed that 14 and 15 compounds were detected in the headspace of mating pairs and MG, respectively. Most of the compounds identified from MG except for isobutyric acid were also detected in the headspace of mating pairs. Both females and males were attracted to octanal and 6‐methyl‐5‐hepten‐2‐one, and males were attracted to 3,5‐dimethyl‐2‐hexanol. Males but not females were attracted to a seven‐compound blend, formulated from compounds identified in attractive MG extracts.     

豆野螟成虫触角对植物挥发性和性信息素化合物的触角电位反应

以顺3-己烯乙酸酯为标准化合物,研究了豆野螟雌、雄成虫触角对不同浓度的植物挥发性和性信息素化合物组分的触角电位（EAG）反应.结果表明：豆野螟雌、雄成虫触角对植物挥发性气味具有强烈的EAG反应,但在大部分浓度下,雌、雄虫的反应没有显著差异.在测试的9种植物挥发性化合物中,雌、雄虫对高浓度反-2-己烯醛刺激的相对EAG反应的最大值分别达到250%和260%,且雌、雄虫触角对这种化合物的EAG反应的形状也有很大差异;但对豇豆花气味中的柏木烯和柏木脑没有明显的EAG反应.雌、雄蛾对性信息素都有明显反应,且雌、雄虫的反应存在显著差异,雄虫触角对性信息素化合物主要组分（反10,反12）-十六碳二烯醛的EAG反应的最大值达到250%,远超过雌虫反应的最大值(53%).雌、雄成虫这种神经感觉反应的差异反映了它们在感器结构、功能和行为上的差异.     

苹毛丽金龟对植物挥发物成分的触角电位及行为反应

为筛选适宜的苹毛丽金龟Proagopertha lucidula (Faldermann)引诱剂化学物质, 对已报道的金龟子科两性引诱剂单一组分进行了触角电位（EAG）和Y型嗅觉仪中的嗅觉反应测定。结果表明: 在10 μg刺激剂量下测试的11 种植物挥发物中, 只有顺-3-己烯-1-醇、香叶醇、茴香脑和丁香酚有明确的EAG反应值, 其他7种化合物具有弱反应值。剂量反应曲线表明, 具有明确的EAG活性的4种化合物激发的反应强度与化合物的剂量呈正相关。在Y型嗅觉仪中, 顺-3-己烯-1-醇、香叶醇、茴香脑和丁香酚4种化合物在1, 10, 100 μg剂量下的行为反应百分率都显著高于对照溶剂正己烷, 且雌雄之间无显著差异。该研究结果可为开发苹毛丽金龟田间引诱剂奠定基础。     

Electroantennogram responses of the carrot fly, Psila rosae, to volatile plant components

ABSTRACT. Electroantennogram (EAG) responses of male and female carrot flies, Psila rosae F. (Diptera: Psilidae), were recorded to thirty-six volatile plant constituents. The most distinct EAG responses were obtained to: (1) the general green leaf volatiles 1-hexanol, trans-2-hexen-1-ol and cis-3-hexen-1-ol, their isomers cis-2-hexen-1-ol and trans-3-hexen-1-ol, the alcohol 1-heptanol, the ester cis-3-hexenyl acetate and the leaf aldehydes hexanal and trans-2-hexenal, and (2) from four compounds associated with the umbelliferous host plants of this insect, namely trans-methyl-iso-eugenol, β-caryophyllene, linalool and trans-2-nonenal. Higher responses were elicited by the leaf aldehydes than by the corresponding alcohols. Although the absolute amplitude of the female response was over twice that of the male, there were no differences between the relative responses to the compounds tested in both sexes, with the exception of a much higher response to the leaf aldehydes in the male. The shape of the EAG evoked by the various compounds was consistently different, with the slowest recovery being recorded for trans-methyl-iso-eugenol. While the antennal olfactory receptors of the carrot fly are sensitive to the closely related general green leaf volatiles, they are most specifically tuned to the aldehyde component of this green odour complex. In addition, the ability of this insect to discriminate between different plants may be augmented by the perception of a group of more host specific volatiles. The conformity of the responses of males and females to the compounds tested may indicate that host plant volatiles plays an additional role as an aggregation cue for both sexes.     

Electroantennogram responses of Douglas-fir seed chalcids to plant volatiles

Douglas fir seed chalcids females oviposit specifically into Douglas cones which they locate using olfactory and visual cues. We have tested whether this specialization was correlated with a specialized sensitivity towards cone volatiles. Field collected adults were presented a series of pure volatile chemicals. Electroantennogram responses (EAG) were recorded to generally occurring terpenoids and straight chain alcohols and aldehydes found in flowers and plant leaves. Monoterpenes identified in Douglas cone headspaces (alpha-pinene, beta-pinene, 3-thujene, alpha- and beta-phellandrene, gamma-terpinene and myrcene) elicited lower EAG responses than fatty acid derivatives corresponding to green odours. The EAG response profile of females differed significantly from that of males. Females were very sensitive to hexanol-1, heptanal, (Z)-3 hexenol-1, terpineol and terpinen-4-ol. Male responses were significantly higher to humid air, nerolidol, thujan-4-ol, hexanal, carvacrol, piperitone and farnesol. Several compounds (Z- verbenol, carvone, jasminol, geraniol, nerol and eugenol) elicited long lasting electrophysiological responses (over 5 s) in both sexes.     

不同番茄品种挥发物对B型烟粉虱寄主选择行为的影响

采用顶空固相微萃取和气相色谱-质谱法鉴定了6个番茄品种(浙杂809、浙杂203、合作903、凯特一号、黄椭圆和金妃)植株挥发物的成分,并利用Y型嗅觉仪测定了烟粉虱对不同番茄品种植株及其挥发物的嗅觉反应.结果表明:从6个番茄品种中共鉴定出13种化合物,其主要成分为萜类化合物,品种间挥发物的组成成分和各成分所占比例存在差异.(+)-3-蒈烯和β-石竹烯对B型烟粉虱的驱避性较其他萜类强.烟粉虱对含萜类挥发物种类多、比例高的品种(如浙杂809和浙杂203)选择性较弱,而对含萜类挥发物种类少、比例低的品种(如黄椭圆和金妃)选择性较强.     

The Role of Chemical Cues in Host and Mate Location in the Pear Psylla Cacopsylla bidens (Homoptera: Psyllidae)

Chemical communication was shown to play a role in the pear psylla, Cacopsylla bidens. Electrophysiological (EAG) and behavioral responses were investigated in males and females pear psylla . Males were found to be attracted to females, and especially to those on host plants, but not to males, uninfested host plants, or plants infested with conspecific larvae. On the other hand, females were not attracted to males or females but displayed some attraction to host plants. Furthermore, females showed a preference for uninfested pear versus plants infested with conspecific larvae. The antennae of males gave highest electroantenographic response to volatiles from pears infested with females but not males, while females, responded also toward the volatiles of pear alone. These results indicate that females of C. bidens emit sex pheromones that are attractive to the males and suggest that, host volatiles may play a role in host selection by pear psylla females.     

Host odours enhance the responses of adult Rhyzopertha dominica to male-produced aggregation pheromone

The behavioural responses of adult male and female Rhyzopertha dominica (Coleoptera, Bostrichidae) to blends of host volatiles and male-produced aggregation pheromone were observed in a four-arm airflow olfactometer. The odour sources used were five pheromone-releasing males each on a single maize grain (lower maize-volatiles blend), five pheromone-releasing males on 500 g of maize (higher maize-volatiles blend) or the host volatiles emanating from 500g of maize (maize volatiles alone). Multiple-choice tests, in which volatiles from all three odour sources were presented in the exposure chamber at the same time, were used to study odour preferences of the males and females. Both sexes showed strongest attraction to the higher maize volatile blend but there were significant sex differences in response to the odour sources. Males spent significantly more time than females in the zone with only maize volatiles, and females spent significantly more time in the higher maize-volatiles zone. However, when odour sources were offered singly, females gave numerically greater responses than males to all sources although this difference was statistically significant for only the lower maize-volatiles blend. As males are more attracted than females to host odours alone it is suggested that they may be more highly adapted to seek out new hosts while females are more inclined to locate a food source by following the pheromone signals produced by males. However, both sexes responded most strongly to the odour source comprising aggregation pheromone with the higher proportion of maize volatiles.     

An omnivorous arthropod, <Emphasis Type="Italic">Nesidiocoris tenuis</Emphasis>, induces gender-specific plant volatiles to which conspecific males and females respond differently

Nesidiocoris tenuis Reuter (Heteroptera: Miridae) is an omnivorous mirid bug that preys on diverse generalist herbivorous arthropods. N. tenuis adults are attracted to volatiles from plants induced by their prey, such as tobacco cutworms (CCW) (Spodoptera litura larvae) and two-spotted spider mites (Tetranychus urticae). N. tenuis adults also induce volatiles when they infest plants. In this study, we focused on olfactory responses of N. tenuis males and females to volatiles from eggplants and sesame plants induced by conspecifics of the same or different gender by using a Y-tube olfactometer. Males were attracted to volatiles from plants of both species induced by either males or females. The male preference was biased to volatiles from plants of both species induced by females, probably because the biased response would facilitate their mate-finding. Females were attracted only to volatiles from plants of both species induced by females. Mating occurs multiple times in this species. Thus, the responses would indirectly affect mating of males and females. Slight but significant qualitative and quantitative differences were detected between the volatiles of plants of both species induced by N. tenuis females and those of the plants induced by conspecific males. N. tenuis might use such differences in their gender-specific responses.     

Concurrent modulation of neuronal and behavioural olfactory responses to sex and host plant cues in a male moth

Mating has profound effects on animal physiology and behaviour, not only in females but also in males, which we show here for olfactory responses. In cotton leafworm moths, Spodoptera littoralis, odour-mediated attraction to sex pheromone and plant volatiles are modulated after mating, producing a behavioural response that matches the physiological condition of the male insect. Unmated males are attracted by upwind flight to sex pheromone released by calling females, as well as to volatiles of lilac flowers and green leaves of the host plant cotton, signalling adult food and mating sites, respectively. Mating temporarily abolishes male attraction to females and host plant odour, but does not diminish attraction to flowers. This behavioural modulation is correlated with a response modulation in the olfactory system, as shown by electro-physiological recordings from antennae and by functional imaging of the antennal lobe, using natural odours and synthetic compounds. An effect of mating on the olfactory responses to pheromone and cotton plant volatiles but not to lilac flowers indicates the presence of functionally independent neural circuits within the olfactory system. Our results indicate that these circuits interconnect and weigh perception of social and habitat odour signals to generate appropriate behavioural responses according to mating state.     

Host plant volatiles induce oriented flight behaviour in male European grapevine moths, Lobesia botrana

The European grapevine moth Lobesia botrana relies on a female produced sex pheromone for long-distance mate finding. Grapevine moth males compete heavily during limited time windows for females. The aim of this study was to investigate the perception of host plant volatiles by grapevine moth males and whether such compounds elicit upwind oriented flights. We compared five host plant headspace extracts by means of gas chromatography linked electroantennogram (EAG) recording. We identified 12 common host plant volatiles (aliphatic esters, aldehydes, and alcohols, aromatic compounds and terpenes) that elicit EAG responses from grapevine moth males and that occur in at least three of the host plant volatile headspace extracts tested. Subsequently the behavioural response of grapevine moth males to four these compounds presented singly and in mixtures (1-hexanol, 1-octen-3-ol, (Z)-3-hexenyl acetate and (E)-β-caryophyllene) was recorded in a wind tunnel. Grapevine moth males engaged in upwind flights to all of four compounds when released singly at 10,000 pg/min and to all, except 1-octen-3-ol, when released at 100 pg/min. A blend of the four host plant volatiles released at 10,000 pg/min and mixed at a ratio based on the analysis of Vitis vinifera cv. Solaris volatile emissions attracted significantly more males than any single compound. Grapevine moth males perceive and respond to host plant volatiles at biologically relevant levels indicating that host plant volatiles figure as olfactory cues and that L. botrana males can discern places where the likelihood of encountering females is higher.     

Volatile organic compounds as signals in a plant-herbivore system: electrophysiological responses in olfactory sensilla of the moth Cactoblastis cactorum

The morphological sensillum types on the antennae of male and female Cactoblastis cactorum were visualized by scanning electron microscopy. Electrophysiological recordings were performed for the first time on single olfactory sensilla of C. cactorum. The male sensilla trichodea house a receptor cell responding to the putative pheromone component (9Z,12E)-tetradecadienyl acetate. The sensilla trichodea of the females were much shorter than those of the males and contained specialized receptor cells responding to certain terpenoids, the most frequent being the nerolidol-sensitive cell. The sensilla auricillica and sensilla basiconica of both sexes contained cells responding less specifically to terpenoid compounds as well as to green leaf volatiles. Cells of the sensilla coeloconica responded to aliphatic aldehydes and acids. Eight volatile organic compounds emitted by Opuntia stricta, a host plant of C. cactorum, were identified using gas chromatography-mass spectrometry, beta-caryophyllene being the major compound. Five compounds identified by gas chromatography in the headspace of O. stricta elicited responses in olfactory receptor cells of C. cactorum, nonanal being the most active compound and therefore a candidate attractant of C. cactorum.     

Identification of odoriferous compounds from adults of a swallowtail butterfly, Papilio machaon (Lepidoptera: Papilionidae)

Adults, particularly males, of a papilionid butterfly, Papilio machaon hippocrates, emit a fairly strong scent perceivable by humans. We have identified a variety of volatile compounds (hydrocarbons, alcohols, aldehydes, ketones, esters, and so on) from the wings and bodies of both sexes of the butterfly. Male wings secreted n-dodecane, linalool and geranylacetone as major components together with small amounts of camphene, limonene, p-cymene, 2-phenylethanol, n-hexanal, n-decanal, isoamyl acetate, p-allylanisole, 2-pyrrolidone and other characteristic volatiles. The overall profile of volatile compounds detected from male body was quite different from that of the wings. Male body was devoid of camphene, 2-phenylethanol, n-hexanal but instead contained limonene, acetoin, a sesquiterpene hydrocarbon (C15H24, methyl n-octanoate, (E,E)-hepta-2,4-dienal, and another isomer of heptadienal as principal components, of which the last four compounds were specific to the body. All these substances seem to concurrently characterize the male odor. The chemical patterns of compounds found from female wings and body were essentially the same in quality as those of male wings and body, respectively, although their quantities in females were generally smaller than in males. Females, however, had a larger amount of acetamide than males. The chemical compositions of volatiles from the fore and hind wings of males were not greatly different from each other, and every component was considered to be present on all parts of the wings. This suggests that the scent-producing organs or scent-emitting pores are widely distributed on the whole wings. EAG responses of both sexes to 12 selected compounds identified from the butterfly were not strong at a dose of 1 microg, while both sexes showed relatively stronger responses to n-nonanal, methyl n-octanoate, D-limonene and linalool at a higher dose (10 microg). Although sexual difference in EAG response was not prominent, females appeared a little more sensitive, and n-nonanal and acetoin evoked significantly higher responses from females at 1 microg.     

Electroantennogram responses of the potato tuber moth, <Emphasis Type="Italic">Phthorimaea operculella</Emphasis> (Lepidoptera; Gelichiidae) to plant volatiles

Electroantennograms (EAGs)were recorded from males and females of the potato tuber moth,Phthorimaea operculella in response to a broad range of plant volatile compounds belonging to diverse chemical classes.The responses to 27 compounds were evaluated,which indicated significant differences in EAGs between chemicals as well as between sexes.The fatty acid derivatives comprising essentially green leaf volatile components elicited significantly greater responses in females.The response profile of males was,in general,lower than that of females.EAG responses to the oxygenated and hydrocarbon monoterpenes were lower in both males and females.Dose -response studies indicate differences in response between the sexes and concentrations,suggesting the existence of sexual dimorphism. Compounds belonging to the fatty acid derivatives class appear to be important for an oligophagous pest such as the potato tuber moth and the findings are discussed in relation to host plant selection in this species.     

Electroantennogram responses of the three migratory forms of the damson-hop aphid, Phorodon humuli, to aphid pheromones and plant volatiles

Electroantennogram (EAG) responses were recorded from alate fundatrigeniae (spring migrants), gynoparae (the winged female form that produces sexual females) and males, the three migratory forms of the damson-hop aphid, Phorodon humuli (Schrank). EAG responses of gynoparae and males showed typical dose response characteristics to (E)-2-hexenal, (-)-R-carvone, hexanenitrile and (1RS,4aR,7S,7aS)-nepetalactol, the sex pheromone of this species. The 34 plant volatiles elicited broadly similar EAG response profiles in the three migratory forms. Green leaf volatiles produced large responses in all forms; however, the relative order of responsiveness varied. EAG responses to isomers of the monoterpene carvone differed between forms, with males being most, and spring migrants least, responsive. The hop-plant volatile and aphid alarm pheromone, (E)-beta-farnesene, evoked similar EAG responses in all forms. By contrast, males were most responsive to the three sex pheromone components, (-)-(4aS,7S,7aR)-nepetalactol, (+)-(4aS,7S,7aR)-nepetalactone and (1RS,4aR,7S,7aS)-nepetalactol. Males were no more responsive to their own sex pheromone, (1RS,4aR,7S,7aS)-nepetalactol, than to the other aphid sex pheromone components tested. Spring migrants and gynoparae also responded to the three sex pheromone components. This study indicates that migratory forms of P. humuli detect a wide range of volatile compounds, and that they are equally well-adapted for the detection of volatiles associated with host and non-host plants and with other species of aphid.     

Electroantennogram responses of Nilaparvata lugens (Homoptera: Delphacidae) to plant volatile compounds

Electroantennogram (EAG) recordings were made from the plaque organ receptors of the rice brown plant hopper, Nilaparvata lugens (St?l). The receptors of the distal plaque organ of both male and female hoppers responded to the air from above chopped rice plants, and those of females gave a larger response. Female hoppers, tested with 27 plant volatiles, gave dose-related responses to 16 of the compounds, including a range of green leaf volatiles. The aliphatic aldehydes hexanal and (E)-2-hexenal elicited a larger response than a range of green leaf alcohols. Of the remaining compounds, acetophenone, benzaldehyde, ethyl and methyl benzoate, and amyl and isoamyl acetate were among the most effective in eliciting responses. Receptor recovery times showed some variation between compounds. A comparison of the dose-related response of 16 compounds in paraffin oil and in pentane showed that considerably larger responses were recorded when the highly volatile solvent pentane was used.