Ultrastructure and potential role of integumentary glandular cells in adult male and female Callosobruchus subinnotatus (Pic) and C. maculatus (Fabricius) (Coleoptera : Bruchidae)

Transmission and scanning electron microscopy methods were used to study the ultrastructure of integumentary glandular cells that may be involved in the production of sex pheromones and other semiochemicals in Callosobruchus subinnotatus and C. maculatus (Coleoptera : Bruchidae). Additionally, we measured electroantennogram (EAG) responses of male and female antennae to solvent extracts and glassadsorbed volatiles from both sexes of C. maculatus in order to localize the source of the putative sex pheromone. Both species have numerous cuticular pores on the abdomen and thorax. These pores open via an epicuticular duct into a single type 3 secretory cell. Solvent extracts of the pygidium from the female elicit the highest EAG responses from male antennae, suggesting this area of the abdomen to be the source of the putative sex pheromone in C. maculatus.     

Olfactory attraction to aggregation pheromone is mediated by disti-flagellum of antennal segments in Riptortus pedestris

Riptortus pedestris (Hemiptera: Alydidae) is a serious pest of soybean and sweet persimmon and uses male produced aggregation pheromone, (E)-2-hexenyl (Z)-3-hexenoate, (E)-2-hexenyl (E)-2-hexenoate, and tetradecyl isobutyrate to facilitate food location and recognition by conspecifics. Using electroantennogram (EAG) and greenhouse bioassay, we determined which antennal segment is involved in the detection of their aggregation pheromone. In the first EAG test using individual antennal segments, significant EAG responses to 1:1:1 mixture of the aggregation pheromone were observed only from the disti-flagellum segments of both male and female antennae at both pheromone doses tested (1 µg and 100 µg). In the following EAG tests using gradually removed antennal segment(s), EAG response was still maintained when the distal half of a disti-flagellum was surgically removed, while EAG response was lost when whole segment of disti-flagellum or other whole segments were gradually removed from intact antenna of both sexes. In greenhouse experiment, removing one or both segment(s) of disti-flagellum from male or female antennae resulted in significant reduction in their attraction to the aggregation pheromone. Together, these findings support that the disti-flagellum of R. pedestris houses olfactory neurons associated with attraction to their aggregation pheromone.     

Electrophysiological correlates of attraction in Trichoplusia ni

A quantitative comparison was made between pheromone-induced electroantennogram (EAG) potentials and the attraction of male cabbage loopers, Trichoplusia ni. For this comparison, duplicate pheromone dispensers were used in both assays. The slope of the function of evoked EAG potentials was the same as the slope of the function of percentage attraction to different amounts of pheromone, but the EAG was calculated to be about 3 × 10⁴ times less sensitive than the attraction response. Thus, the EAG of T. ni was not a reliable indicator of relative attraction to various batches of synthetic pheromone, and no difference in the evoked EAG was observed between an inhibitor of the behavioural response to the pheromone and the pheromone itself.     

Antennal responses of Cydia pomonella (L.) exposed to surfaces treated with methoxyfenozide

Electroantennogram (EAG) measurements were recorded from the antennae of male and female codling moth, Cydia pomonella L., to determine whether adult moths exposed to surfaces treated with the ecdysteroid agonist methoxyfenozide experience a decline in their antennal reception and thus olfactory sensitivity. Such a phenomenon would offer a possible mechanism for the previously reported decreased responsiveness from moths treated with methoxyfenozide to pheromone‐ and plant volatile‐based monitoring lures. Mean EAG data revealed that the antennae from methoxyfenozide‐treated male moths appear to be just as sensitive to various doses of synthetic codlemone as the antennae from the control and surfactant‐treated moths, but they appeared to be less sensitive to the pheromone component 12OH (collected from female effluvia) than the control male antennae. Mean male EAG responses to the pheromone components E8,E10‐12Al and codlemone collected from methoxyfenozide‐treated females were significantly less than the responses towards those two pheromone components collected from the control and surfactant‐treated females. Female moth exposure to methoxyfenozide did not negatively impact the sensitivity of female antennae to the plant volatile pear ester, but it did towards the apple volatile butyl hexanoate. Data from this study show that adult C. pomonella exposure to methoxyfenozide‐treated surfaces does appear to negatively impact, in a minor way, the (i) olfactory sensitivity (or detection) of male antennae towards some components of the female sex pheromone, (ii) the female antennal sensitivity towards a key apple volatile and (iii) the attractiveness of female pheromone effluvia.     

Ontogeny of electroantennogram responses in the moth, Manduca sexta

The antennae of the moth, Manduca sexta, and the sensilla and sensory neurons they contain, develop during metamorphosis from pupa to adult. To determine when, during their development, antennae become capable of generating electrical responses to various stimuli, we recorded the electroantennogram (EAG), believed to be the summed extracellular record of receptor potentials, from developing and mature antennae. Antennae from male and female moths are similarly responsive to trans-2-hexenal, while only males respond to Manduca sex pheromone; these two odorants presumably stimulate separate receptors. Mechanical stimulation also elicits and EAG response. EAG responses to olfactory and mechanical stimuli are detectable several days before eclosion but not until the neurons are morphologically and biochemically quite mature. Responses increase in magnitude until the end of metamorphosis and then change little during the first 3 days after emergence of the adult. Responses to different stimuli do not develop synchronously.     

Electroantennogram responses of the male moth, Argyrotaenia velutinana to mixtures of sex pheromone components of the female

Electroantennogram (EAG) responses were recorded from male redbanded leafroller moth, Argyrotaenia velutinana, antennae using mixtures of the three female-produced sex pheromone components: cis-11-tetradecenyl acetate, trans-11-tetradecenyl acetate, and dodecyl acetate (12:Ac). Binary mixtures containing 3%, 8%, and 15% trans in cis elicited significantly higher amplitude responses than other isomeric mixtures as well as pure cis and trans alone. The higher responses to such mixtures were less than additive at high dosages and additive at lower dosages. Receptor adaptation studies using the two isomers support a previous single unit study demonstrating the presence of at least two functionally different receptor sites on male A. velutinana antennae; adaptation to an airstream containing one isomer did not eliminate response to the opposite isomer presented concurrently. An airstream containing the third component, 12:Ac, caused a significant slowing of the recovery rate during the entire recovery period of EAG responses to cis but not trans, suggesting that a possible temporal modulation of neuronal response by 12:Ac may be a means of coding for this component by antennal sensory neurons.     

Functional specialisation and polyphenism in aphid olfactory sensilla

Electroantennogram (EAG) responses to the aphid sex pheromone components, (1R,4aS,7S,7aR)-nepetalactol and (4aS,7S,7aR)-nepetalactone, and a plant volatile, (E)-2-hexenal, were investigated at three different positions (5/6th, 4/5th and 3/4th inter-segmental regions) along the antennae of four different morphs in two host-alternating aphid species, Aphis fabae Scopoli and Rhopalosiphum padi (L.). Position-dependent and morph-specific EAG responses were elicited in both species. The nepetalactol and nepetalactone isomers elicited large EAG responses at all three recording positions in males of both species, such that primary rhinaria as well as secondary rhinaria appeared to respond. Asexual female morphs showed relatively smaller EAG responses to these compounds. The secondary rhinaria, which have been reported as sex pheromone receptors in males, were not very different in their number and distribution between gynoparae and alate virginoparae, but the gynoparae showed significantly larger EAG responses to nepetalactol and nepetalactone. The alate virginoparae showed EAG responses that were similar to those of apterous virginoparae, which lack secondary rhinaria. Taking the EAG response profiles together with the distribution of the secondary rhinaria, it is suggested that the function of secondary rhinaria differs between the morphs. Secondary rhinaria appear to detect sex pheromone components in males and gynoparae but not in the alate virginoparae. If they are functional in the latter morph, they are likely to play a role in detecting specific, but as yet unknown, volatile compounds. Some 30 plant volatiles were tested but none evoked an EAG response that could be allocated to the secondary rhinaria. In contrast to the very different EAG response profiles to the pheromone compounds between morphs, EAG responses to (E)-2-hexenal were similar in all forms and both species. These findings suggest that this plant volatile was detected only by the two primary rhinaria, which are common to all morphs. The present study showed that EAG responses were not a simple summation of receptor potentials between recording and reference electrodes in aphids. The localised distribution pattern of olfactory receptor neurones around the recording electrode was also likely to contribute to the EAG responses.     

Investigation of a sex pheromone for the oriental cockroach,Blatta orientalis

A sex pheromone for adult male oriental cockroaches Blatta orientalis was isolated from the faeces of adult virgin female oriental cockroaches. It elicited a sexual response at 10 pg and 1 ng with B. orientalis and Periplaneta americana adult males, respectively. The site of production appers to be the crop, oesophagus, and proventriculus. Electroantennogram responses of male antennae toward the isolated pheromone were greater than those of the female antennae. The adult male oriental cockroach also responded to the American cockroach sex pheromone. The isolated pheromone with a mol. wt of 232 may be similar to one of the components of the American cockroach sex pheromone.     

Electroantennogram and behavioural responses of the gypsy moth to enantiomers of disparlure and its trans analogues

The attractive power of both enantiomers of disparlure and its trans analog was tested electrophysiologically (electroantennogram = EAG) and behaviourally (whole organism response). EAG responses correlated very well with the behaviourally determined effectiveness sequence: cis(+)-disparlure was the most effective substance; the authentic racemic disparlure came second; cis(?)-disparlure inhibited the activity of cis(+)-disparlure; and trans enantiomers were not significantly different from the control. These results allow us to conclude that cis(+)-disparlure is the natural sex pheromone of the gypsy moth, and that the male antennae have a chiral receptor system in the antenna for the reception of the sex pheromone.     

Reidentification of pheromone composition of Sparganothis sulfureana (Clemens) and evidence of geographic variation in male responses from two US states

GC-EAD analyses of pheromone gland extracts of calling female Sparganothis sulfureana revealed at least 6 compounds that consistently elicited antennal responses from male antennae. In addition to the major pheromone compound, (E)-11-tetradecenyl acetate (E11–14:OAc), which was previously reported, the other compounds were found to be (E)-9-dodecenyl acetate (E9–12:OAc), (Z)-9-dodecenyl acetate (Z9–12:OAc), (Z)-9-tetradecenyl acetate (Z9–14:OAc), (Z)-11-tetradecenyl acetate (Z11–14:OAc), and (E)-11-tetradecenol (E11–14:OH). Tetradecyl acetate, hexadecyl acetate and hexadecenyl acetates were also present in the extracts, but elicited no EAG response from male antennae. Wind tunnel tests demonstrated that males from New Jersey responded equally well to a blend containing five pheromone components in relative to the pheromone glands of calling females. Different male-response profiles from field-trapping tests conducted in the states of Wisconsin and New Jersey were observed, respectively. Significantly higher numbers of male S. sulfureana were caught in New Jersey in traps baited with the binary blend of E11–14:OAc (30 μg) with 1% of Z11–14:OAc, but males from Wisconsin responded equally well to traps containing blends of E11–14:OAc with 0–10% of Z11–14:OAc. The addition of more than 10% of Z11–14:OAc to the primary pheromone compound reduced male captures significantly in both states. Male catches were doubled by adding E9–12:OAc and E11–14:OH to the most attractive binary blend in both states. The trapping test with caged live virgin female moths showed that males in Wisconsin preferred females from the local population than those from New Jersey. The differences in male responses observed may indicate the existence of pheromone polymorphism in this species.     

Perception of volatiles associated with sex and food by different adult forms of the black bean aphid, Aphis fabae

Abstract. Electroantennograms (EAGs) were recorded from adult male and asexual forms (winged and wingless virginoparae and gynoparae) of the black bean aphid, Aphis fabae , during stimulation with two sex pheromone components, (+)-(4a S ,7 S ,7a R )-nepetalactone and (-)-(1 R ,4a S ,7 S ,7a R )-nepetalactol, as well as six plant volatiles, i.e. ( E )-2-hexenal, ( E )-2-hexenol-1, ( Z )-3-hexenol-1, ( Z )-3-hexenyl acetate, hexanal and allyl isothiocyanate. The male antennae are 1000-10,000 times more sensitive to nepetalactol and nepetalactone than to the plant compound ( E )-2-hexenal. Besides this marked difference of EAG peak responses in males, the EAG rise and decay are slower for the sex pheromone components. Males are also much more sensitive to the sex pheromone components than asexual females. This high sensitivity correlates with a predominance of antennal secondary rhinaria, the major sites of pheromone perception in the male. However, it is the primary rhinaria on the antennae of the wingless asexual females that are responsible for pheromone perception. Male antennae are as responsive as the asexual female antennae to the plant volatiles. The specialization of the male for mate location is discussed.     

棉铃虫齿唇姬蜂对植物挥发物和寄主性信息素腺体化合物的EAG反应

测试了棉铃虫齿唇姬蜂Campoletis chlorideae Uchida对58种植物挥发物和5种寄主性信息素腺体化合物的EAG反应。在100 μg的刺激剂量下,棉铃虫齿唇姬蜂对C₅～C₇脂肪醇的EAG反应最强,碳链延长或缩短都将导致反应的降低;对脂肪醛、酮、酸和酯都有一定的反应。棉铃虫齿唇姬蜂对萜烯的EAG反应很低,对氧化萜的反应普遍升高。3种芳香化合物均可激起棉铃虫齿唇姬蜂较强的EAG反应。剂量反应曲线表明,具有EAG活性的化合物激起的反应强度与化合物的剂量呈正相关,而2种萜烯——α-蒎烯和反式石竹烯,在测定的剂量范围内EAG活性都很低。棉铃虫齿唇姬蜂对寄主性信息素腺体化合物也有EAG反应,用100 μg和1 000 μg的寄主性信息素刺激,雄蜂的反应可比雌蜂的反应高出1倍。对植物挥发物在棉铃虫齿唇姬蜂寻找寄主中的作用进行了讨论。     

OLFACTORY RESPONSES OF COTTON BOLLWORM,HELICOVERPA ARMIGERA TO SEX PHEROMONE AND PLANT VOLATILE COMPONENTS*

Abstract Electroantennograms (EAGs) were recorded from unmated, laboratory-reared male and female Helicover pa armigera (Lepidoptera:Noctuidae) adults to two sex pheromone components and a range of plant volatile components, some of which are known volatiles from leaves and fruits. The female-produced sex pheromone was not detected by other female moths. The sex pheromone components to which male moths responded previously show to possess biological activity. As for plant volatile components, a large degree of EAG response uniformity between male and female moth was observed. The greatest EAG responses of all plant volatiles tested were elicited by monoenic C-6 alcohol and aldehyde. They are constituents of the “general green-leaf odor” that emanates from most plants. The potential adaptive benefit of selective perception to sex pheromone and green-leaf volatile components is discussed.     

小地老虎雄蛾对雌蛾性信息的EAG反应

利用触角电位记录（EAG）技术,测定了小地老虎Agrotis ypsilon (Rottemberg) 雄蛾对性信息素标准化合物Z7-12：Ac（A）、Z9-14：Ac（B）、Z11-16：Ac（C）、Z5-10：Ac（D）和Z8-12：Ac（E）的EAG反应。结果表明：这些标准化合物均能引起EAG反应,其中组分A（Z7-12：Ac）引起的反应最强,为5.65 mV,组分B（Z9-14：Ac）和C（Z11-16：Ac）居中; 组分D（Z5-10：Ac）的EAG反应值最小,为2.50 mV。二元混合物、三元混合物、四元混合物和全组分的EAG反应较高,其EAG反应值均显著高于单组分的反应值。三元混合物ABC的反应值最高,与5头雌蛾腺体的正己烷浸提液的EAG值相当。在使用剂量为0.01 ng～100 μg反应内,小地老虎雄蛾触角对性信息素各组分及其混合物的剂量反应曲线大致呈“S”形。从不同日龄雄蛾对标准化合物的反应中,发现在羽化后第3天达到最高值,之后则随日龄增加EAG反应降低。     

美洲大蠊对多种化合物的触角嗅觉电位反应

用多种化合物的气味制激美洲大蠊(Periplaneza americana)触角,诱导、记录触角电位(EAG)反应.试验了各类化合物154种,其中53%能诱发出明显的EAG反应.绝大多数EAG反应是负相慢波,波幅多数为0.5—2mV,时程1.5—3秒.苯等少数化合物能诱发正相EAG反应.剂量-反应曲线大致呈“S”形,还可见适应现象.萜类化合物和挥发性植物油类诱发EAG反应的作用最强,其次是酮、醇、酯、胺类化合物.化合物的含氧功能基团和空间构型与EAG反应的诱发有一定的关系.可能是同一种化合物对不同种的感受器都可能诱发EAG反应.一般性化合物诱发雌、雄、成、幼虫EAG反应的差异不大,但雌虫类提取物仅对雄性成虫触角诱发较强的EAG反应.一些已知的驱、诱、杀虫剂也能诱发EAG反应,但仅表现为对一般化合物的反应特征.     

Sex pheromone of the cabbage looper: Reactions with antennal proteins in vitro

In the presence of (Z)-7-dodecen-1-ol acetate, the sex attractant of the cabbage looper, Trichoplusia ni, soluble protein from male antennae showed a time-dependent difference spectral absorbance at 280 nm. The change was associated with the enzymatic conversion of the pheromone to (Z)-7-dodecen-1-ol, a potent inhibitor of behavioural responses to the pheromone. In contrast, the response obtained with the inhibitor was indicative of non-enzymatic binding to specific protein(s) in the fraction. GLC analyses of the relative rates of enzymatic hydrolysis of the pheromone by the antennae, haemolymph, and legs revealed 33·9, 10·1, and 6·5 per cent conversion per hour, respectively. These results may provide an insight into the fate of a pheromone in the olfactory process of this insect; however, the significance of the reaction with the inhibitor is not yet known.     

Quantitation of the insect electroantennogram: Measurement of sensillar contributions,elimination of background potentials,and relationship to olfactory sensation

A quantitative study of the electroantennogram (EAG) of Trichoplusia ni (Hübner) response to sex pheromone has provided new information about the physiological basis of the EAG and its relationship to behaviour. Procedures were developed that selectively stimulated defined numbers of sensilla and eliminated extraneous olfactory stimuli. The results show that the EAG is linearly proportional to the number of antennal sensilla stimulated and clarify interpretation of the blank response. Studies with calibrated dispensers indicate that the EAG is related to pheromone concentration by a power function frequently associated with quantitative measures of electrophysiological and behavioural responses in other animals. Based on correlations between the EAG, behaviour, and single-neurone responses, a model is presented that interrelates these three parameters as different indicators of a single quantitative process in the central nervous system.     

植物气味化合物对棉铃虫产卵及田间诱蛾的影响

利用触角电位技术（EAG）研究棉铃虫Helicoverpa armigera对17种植物气味物质的嗅觉反应,实验结果表明：棉铃虫雄蛾、雌蛾对所试各种植物气味物质均无明显的嗅觉反应差异,不同种类的气味物质能引起不同的EAG反应。对其中的几种植物气味物质进行了引诱产卵实验及田间诱蛾实验,结果表明：某些寄主植物的挥发性次生物质显示出较好的引诱产卵活性,且对棉铃虫性诱剂具有增效和协同作用。田间实验数据显示,增加了植物气味物质的棉铃虫性诱剂与单一的棉铃虫性诱剂相比差异显著。     

Autodetection and chemistry of female and male pheromone in both sexes of the tiger moth Panaxia quadripunctaria

Female moths of Panaxia quadripunctaria PODA (Lepidoptera, Arctiidae), produce (Z,Z)-6,9-heneicosadiene (I) as the major and (Z,Z)-6,9-eicosadiene (II) as the minor component of a putative pheromone. Related compounds occur in trace amounts. The abdominal scent glands contain 5–10 μg of (I) and 50–100 ng of (II). Recordings of electroantennogram (EAG) responses to (I), (II), and to female glands are of equal amplitude in both sexes. Females are thus capable of pheromone autodetection in contrast to the majority of moths where females are considered to be anosmic for their own attractant. The EAG threshold to (I) was below 1 ng at the odour source. The odour of the male scent gland (corema) elicited significant EAGs in both sexes. The chemical contents of coremata varied with the provenience of the moths. A variety of ethyl esters was always found, yet hydroxydanaidal (up to 20 μg/corema) and traces of danaidal, only in some samples. All these scents might be components of a male pheromone. Peculiar scent scales on the coremata are exposed during the extrusion. Antennae of both sexes have similar inventories of trichoid sensilla. Accepted: 11 July 1997     

The role of the androconia in the mating behaviour of the European skipper, Thymelicus lineola, and evidence for a male sex pheromone

Abstract. Laboratory experiments were carried out to determine the role and characteristics of male scent scales (androconia), located in patches (stigmata) on the forewings of Thymelicus lineola (Ochsenheimer) (Lepidoptera: Hesperiidae). In behavioural tests, there were 30—40% fewer matings of virgin females by males with the stigmata removed or where females had their antennal sensilla covered with nail polish, when compared to sham-treated controls. These reductions occurred despite a large increase in male courtship activity. No physical contact was observed between male wings and female antennae during mating. A scanning electron microscope study of male wings and female antennae showed that: (1) lysis zones form over time on the androconia and pieces (osmo-phores) distal to these zones break off; (2) while few of these zones are present at emergence they are numerous in-day-old males; (3) during a single episode of courtship and mating approximately two-thirds of the available osmophores break off, yet the commonly observed courtship between males does not appear to result in osmophore release; and (4) osmophores were never observed on the female antennae. Electroantennogram recordings (EAGs) indicated that: (1) female antennae responded strongly to odours from male forewings but not from other parts of either males or females; (2) female antennae responded more strongly to young field-collected males than to newly-emerged or old, field-collected males; (3) female antennal response to male forewings was reduced if the androconia were scraped off, and was eliminated if the stigmata were removed; (4) male antennae gave weak EAG responses to both male and female forewings. We conclude that males release pheromone via the breakage of osmophores during courtship. We propose that the frequently observed refusals by females of courting males are at least partially dependent on the quantity or quality of male pheromone released, which are in turn correlated with the male's age and mating status.