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 responses to the sex pheromone and other odours in the American cockroach

Electroantennogram responses of adult American cockroaches were recorded for the sex pheromone and 30 kinds of monoterpenoids. Strong responses to the sex pheromone were obtained from the antennae of male adults, but not from females. The compounds possessing a hydroxyl or carbonyl group produced significant EAG responses in the antennae. Bornyl acetate, however, was an exception and gave strong responses in both male and female antennae. There was basically no difference between the antennal responsiveness to monoterpenoids tested in both sexes.     

Gustatory adaptation affects sexual maturation in male German cockroaches,Blattella germanica

Adaptations to hazardous environmental factors are essential for survival, although they may be maladaptive in conditions where the hazard is absent. In German cockroach (Blattella germanica L.) populations, glucose aversion has evolved rapidly in response to glucose‐containing insecticidal baits, but little is known about the consequences of this behaviour in the absence of bait. In the present study, glucose‐averse (GA) and wild‐type (WT) male German cockroaches are restricted to a range of nutritionally defined diets containing either glucose or fructose as the sole carbohydrate source, and time to first expression of courtship is measured by stimulating the male antennae daily with isolated antennae from receptive, 6‐day‐old females. Glucose‐averse males that are restricted to glucose‐containing diets mature their courtship responses significantly later than GA males restricted to fructose‐containing diets, whereas there is no difference in maturation of courtship responses between GA males restricted to fructose‐containing diets and WT males restricted to diets containing either sugar type. Glucose‐averse males furthermore respond later to GA female antennae than to WT female antennae, all from 6‐day‐old females. This suggests that GA females are less sexually stimulating, and the results are also consistent with earlier findings showing that GA females contain less developed oocytes than WT females at this age. These findings demonstrate that an adaptive gustatory mutation conferring protection from a toxin may have comparatively detrimental effects under conditions where the toxin has vanished, both by delaying female sexual maturation and signalling and by delaying male sexual maturation and courtship under conditions where glucose is a major energy source.     

Communication in the courtship of a madagascan hissing cockroach. II. Effects of deantennation

The role of the antennae in courtship was studied by removing the antennae bilaterally from both male and female cockroaches, which were then paired with intact animals. These experimental pairings were compared with each other and with pairings of normal animals. Significant deviation from normal behaviour occurs in both the deantennated and the intact members of experimental pairs. When males are deantennated and paired with intact females the timing of courtship is prolonged and male cockroaches misdirect many of their copulation attempts. Under these conditions the intact female cockroaches perform some behaviours more frequently, in particular mounting and palpation. When deantennated females are paired with intact males, very little courtship ensues. The results suggest that information important to the progress of courtship is provided by both antennal inputs and antennal movements, and that the cockroaches are capable of some behavioural flexibility when deprived of this information.     

Contact chemoreceptive sex recognition in the male cricket, Teleogryllus commodus

ABSTRACT. A behavioural continuum ranging from extreme aggression to overt sexual behaviour was used to measure male crickets' reactions to being touched in a standardized manner on their antennae with freshly severed antennae of male and female conspecifics. Sexually receptive males responded primarily with the aggressive song to male antennae and with the courtship song to female antennae. The ontogeny of the antennal effectiveness and the males' reaction was also determined. Because the ability of the antennae to elicit a reaction could be eliminated by treating them with chloroform, and since there were no morphological differences between male and female antennae, separate male and female sex recognition pheromones must be implicated. The chemo-tactile nature of these substances is indicated by the inability to obtain either behavioural or EAG responses to air carrying the odour of males or females.     

Ethometric analysis of pheromone receptor function in cockroaches

Cockroach olfactory receptors were studied with respect to their rôle in mediating behavioural responses to aggregation pheromone and female sex pheromone by employing experimental cockroaches in bioassays for aggregation and courting activity.Using organ ablation and techniques combining ablation with colchicine treatment of antennae, the antennae were determined to be sensory organs for perception of both pheromones.Since proteins are thought to be implicated in the molecular mechanism of olfactory perception, chemicals known to affect proteins were applied to the antennae. Bathing antennae with saline, distilled water, vincristine, vinblastine, or colchicine resulted in no reduction in responses to aggregation pheromone, whereas responses to sex pheromone were reduced. Vinca alkaloids caused the greatest depression in responses, and of these, vincristine treatment required the longest time period for complete recovery. Full sexual display by vinca alkaloid-treated males was not apparent until 8 days after treatment.The effect of formaldehyde vapour treatment, habituation, or both produced differential results. Formaldehyde treatment reduced responses to aggregation pheromone, but did not affect responses to sex pheromone. Habituation alone had no effect on aggregation, but initially reduced responses to sex pheromone. Combined treatments did not affect responses to aggregation pheromone, but resulted in a complete loss of responses to sex pheromone requiring a recovery period of 8 days.The main conclusion drawn from this work is that although responses to sex and aggregation pheromone are mediated by antennal sensillae, their mechanisms must differ drastically.     

Behavioural responses to female sex pheromone components in Periplaneta americana

Female American cockroaches, Periplaneta americana, release two sex pheromones, periplanone-A and periplanone-B, each of which is perceived by a specialized receptor type on the male antennae. This study investigates whether male behavioural responses to both components may differ qualitatively or quantitatively. Running, upwind orientation and wing-raising were evoked by stimulation with either component. The intensity of running increased with stimulus concentration in much the same way for both substances. However, the relative effectiveness of periplanone-A was 30 times lower in behavioural assays than in the electroantennogram. Behavioural responses to periplanone-B declined faster and were more easily adapted by repeated stimulation than those to periplanone-A. It is hypothesized that periplanone-B is responsible for long distance attraction while periplanone-A influences male behaviour near the female.     

Sexual selection, antennae length and the mating advantage of large males in Asellus aquaticus

In crustacean species with precopulatory mate-guarding, sexual size dimorphism has most often been regarded as the consequence of a large male advantage in contest competition for access to females. However, large body size in males may also be favoured indirectly through scramble competition. This might partly be the case if the actual target of selection is a morphological character, closely correlated with body size, involved in the detection of receptive females. We studied sexual selection on body size and antennae length in natural populations of Asellus aquaticus, an isopod species with precopulatory mate guarding. In this species, males are larger than females and male pairing success is positively related to body size. However, males also have longer antennae, relative to body size, than females, suggesting that this character may also be favoured by sexual selection. We used multivariate analysis of selection to assess the relative influences of body size and antennae length in five different populations in the field. Selection gradients indicated that, overall, body size was a better predictor of male pairing success than antennae length, although some variation was observed between sites. We then manipulated male antennae length in a series of experiments conducted in the lab, and compared the pairing ability of males with short or long antennae. Males with short antennae were less likely to detect, orient to, and to pair with a receptive female compared with males with long antennae. We discuss the implications of our results for studies of male body size and sexual dimorphism in relation to sexual selection in crustaceans.     

Sexual selection, antennae length and the mating advantage of large males in Asellus aquaticus

In crustacean species with precopulatory mate-guarding, sexual size dimorphism has most often been regarded as the consequence of a large male advantage in contest competition for access to females. However, large body size in males may also be favoured indirectly through scramble competition. This might partly be the case if the actual target of selection is a morphological character, closely correlated with body size, involved in the detection of receptive females. We studied sexual selection on body size and antennae length in natural populations of Asellus aquaticus, an isopod species with precopulatory mate guarding. In this species, males are larger than females and male pairing success is positively related to body size. However, males also have longer antennae, relative to body size, than females, suggesting that this character may also be favoured by sexual selection. We used multivariate analysis of selection to assess the relative influences of body size and antennae length in five different populations in the field. Selection gradients indicated that overall body size was a better predictor of male pairing success than antennae length, although some variation was observed between sites. We then manipulated male antennae length in a series of experiments conducted in the laboratory, and compared the pairing ability of males with short or long antennae. Males with short antennae were less likely to detect, orient to and to pair with a receptive female compared to males with long antennae. We discuss the implications of our results for studies of male body size and sexual dimorphism in relation to sexual selection in crustaceans.     

Antennal and locomotor responses to attractive and aversive odors in the searching cockroach

The behavioral responses to attractive and aversive odors were examined in blinded adult male cockroaches under tethered-walking conditions. A sex pheromone-like stimulant derived from adult virgin females and artificially synthesized limonene were used as attractive and aversive odor sources, respectively. When a searching animal was stimulated with the attractive female-derived odor, the horizontal deflections of both the antennae were increased, and in most cases the vertical antennal positions were shifted downward. The stimulation also significantly decreased the walking speed of the animal. These behavioral changes imply a careful search in the immediate surroundings. The aftereffect of the sex pheromone was more pronounced on locomotion than on antennal movement. On the other hand, stimulation with the aversive odor (limonene) tended to suppress active antennal movement, and also increased the walking speed. Immediately after the withdrawal of the aversive odor, the active movement of the antennae was resumed, and the walking speed rapidly decreased to a level approximately the same as that of the control period. These results indicate that the responses to the qualitatively opposite types of odor are reciprocal to each other with regard to both antennal movement and locomotion.     

Volatiles from apple (Malus domestica) eliciting antennal responses in female codling moth Cydia pomonella (L.) (Lepidoptera: Tortricidae): effect of plant injury and sampling technique

The antennal responses of codling moth females, Cydia pomonella, to volatiles from apple branches with green fruits were recorded by electroantennography coupled to gas chromatography. The antennae strongly responded to 4,8-dimethyl-1,3(E),7-nonatriene, linalool, beta-caryophyllene, (E)-beta-farnesene, germacrene D, (Z,E)-alpha-farnesene, (E,E)-alpha-farnesene and methyl salicylate. These compounds were all present in volatile collections on Porapak Q from both living and cut branches. Analysis by the solid phase microextraction technique (SPME) showed that the emission of some electrophysiologically active compounds increased after branches had been cut, especially 4,8-dimethyl-1,3(E),7-nonatriene, linalool and (E,E)-alpha-farnesene. The identification of apple volatiles eliciting antennal responses is the first step towards the identification of compounds mediating host-finding and oviposition in codling moth females.     

Aggressiveness and size: a model and two tests

Individual variation in aggressive behavior in animals might be caused by adaptive covariation with body size. We developed a model that predicts the benefits of aggressiveness as a function of body size. The model indicated that individuals of intermediate sizes would derive the greatest benefits from being aggressive. If we assume that the cost of aggression is approximately uniform with respect to body size, selection should favor higher aggression in intermediate-sized individuals than in large or small individuals. This prediction was tested by stimulating male Madagascar hissing cockroaches, Gromphadorhina portentosa, with disembodied antennae and recording the males' aggressive responses. Antennae from larger males evoked weaker responses in subjects, suggesting that males obtained information about their opponents' size from the opponents' antennae alone. After accounting for this effect, we found support for the key prediction of our model: aggressiveness peaked at intermediate sizes. Data from actual male-male interactions validated that the antenna assay accurately measured aggressiveness. Analysis of an independent data set generated by staging male-male interactions also supported the prediction that intermediate-sized males were most aggressive. We conclude that adaptive covariation between body size and aggressiveness explains some interindividual variation in aggressiveness.     

Longer Antennae for Romeo: Assessing Effect of Antennae Length on Courtship and Mating Success in Male Crickets, Acheta domesticus (Orthoptera, Gryllidae)

Animals use a variety of chemosensory functions to coordinate behavioral actions, such as sexual recognition and courtship. In particular, many insects use antennae as a vital chemosensory organ to transmit and receive sexual signals that are believed to be crucial in mate recognition and mating in various species of insects. Crickets provide a usable model to test the significance of antennae in insects. The general importance of antennae in male crickets to initiate courtship, ensure copulation, and post-copulatory mate guarding has been documented in studies that performed full antennectomy. Our study is the first to perform partial antennectomy to test the hypothesis that even partial loss due to injury has negative effects on sexual behaviors. We found that partially antennectomized males are not slower than control males in mate recognition and courtship initiation. However, we found that partially antennectomized males take longer to achieve copulation than control males with normal uncut antennae. Our results suggest that male crickets require long, undamaged antennae to efficiently engage in mating behavior and may already incur fitness costs when they lose half of their antennae.     

Modification of cockroach behavior to environmental humidity change by dehydration (Dictyoptera: Blattidae)

Effects of dehydration on the behavioral response to humidity have been examined in the cockroach, Periplaneta americanaL. Under normal conditions cockroaches prefer lower humidity, but the preference is reversed by dehydration. Dehydrated cockroaches can distinguish smaller differences between two air streams compared with normal individuals. Cockroach behavioral responses to humidification include swing of antennae and locomotion. The period from onset of humidification to behavioral response decreases with increasing dehydration, indicating that the humidity threshold required for behavioral response decreases. Observed modulations of the behavioral response are discussed in relation to the contribution of the antennal hygroreceptors.     

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。     

Receptor neuron discrimination of the germacrene D enantiomers in the moth Helicoverpa armigera

Plants release complex mixtures of volatiles, including chiral constituents. In the search for the biologically relevant plant odorants, gas chromatography linked to electrophysiological recordings from single receptor neurons has been employed. In heliothine moths, including the females of the Eurasian cotton bollworm moth Helicoverpa armigera, a major type of receptor neurons is identified, showing high sensitivity and selectivity for the sesquiterpene germacrene D. In the present study, gas chromatography with a chiral column linked to single cell recordings were performed. It was found that all germacrene D neurons belonged to one type; all responded to both enantiomers, but (-)-germacrene D had approximately 10 times stronger effect than (+)-germacrene D. Parallel dose-response curves for the two enantiomers were obtained by direct stimulations. The enantiomeric composition of germacrene D, which differed in six plant species and in different individuals of one species, was determined on the basis of the neuron responses. The results, showing the presence of one neuron type for receiving the information about germacrene D in the various plants, suggests that the two enantiomers mediate the same kind of information to the moth, but with different intensity.     

Multisensory control of escape in the cockroach Periplaneta americana

1. All giant interneurons (GIs) were ablated from the nerve cord of cockroaches by electrocautery, and escape behavior was analyzed with high-speed videography. Animals with ablations retained the ability to produce wind-triggered escape, although response latency was increased (Table 1, Fig. 4). Subsequent lesions suggested that these non-GI responses depended in part on receptors associated with the antennae.
2. Antennal and cereal systems were compared by analyzing escape responses after amputating either cerci or antennae. With standard wind stimuli (high peak velocity) animals responded after either lesion. With lower intensity winds, animals lost their ability to respond after cereal removal (Fig. 6).
3. Removal of antennae did not cause significant changes in behavioral latency, but in the absence of cerci, animals responded at longer latencies than normal (Fig. 7).
4. The cercal-to-GI system can mediate short latency responses to high or low intensity winds, while the antennal system is responsive to high intensity winds only and operates at relatively longer latencies. These conclusions drawn from lesioned animals were confirmed in intact animals with restricted wind targeting the cerci or antennae only (Fig. 9).
5. The antennae do not represent a primary wind-sensory system, but may have a direct mechanosensory role in escape.

     

Dimorphic antennal systems in gynandromorphic honey bees,Apis Mellifera l. (Hymenoptera: Apidae)

Gynandromorphic honey bees, Apis mellifera (Hymenoptera: Apidae), were examined to determine characteristic morphological and anatomical features of the antennal system. The antennae of gynandromorphic individuals are predominantly worker or drone-like. Hybrid antennae, composed of female and male tissues, occur only rarely (7 out of 188 examined antennae). Depending on the mosaic pattern of the head, both antennae can be drone-like or worker-like, or one can be drone-like and the other worker-like. Examination of the antennal lobes of six characteristic specimens revealed that antennal lobes, which are innervated by drone-like antennae, always have drone-specific enlarged tracts and macroglomerular complexes, whereas antennal lobes innervated by worker-like antennae always are composed of normally sized glomeruli. Thus, there is a strict correlation between the sexual morphology of the antennae and the sexual organization of the antennal lobe neuropil. In one antennal lobe, innervated by a hybrid antenna, we found a hypertrophied glomerulus, certainly homologous to one of the macroglomerular complexes in drone-like antennal lobes.jy 1999 Elsevier Science Ltd. All rights reserved.     

Discrimination of conspecific individuals via cuticular pheromones by males of the cricket Gryllus bimaculatus

Cuticular substances on the body surface of crickets serve as pheromones that elicit a variety of different behaviors in male crickets. Antennal contact between males and females resulted in courtship behavior, and that between two males resulted in aggressive displays. As a first step in elucidating how crickets recognize and discriminate individuals, behavioral responses of male individuals to cuticular substances of conspecific males or females were investigated. The behavioral responses of males to antennal or palpal stimulation with an isolated antenna from a male or a female were recorded. To both antennal and palpal stimulation with female antennae, the majority of males responded with courtship behavior; to stimulation with male antennae, males responded with aggressive displays. To gain insight into the chemical nature of the behaviorally relevant components, isolated antennae were washed in either n-hexane, acetone or ethanol before behavior assays. Washed antennae no longer elicited courtship or aggressive responses in males. Next, polypropylene fibers were smeared with substances from the body surface of females and used for antennal stimulation. This experiment showed that the quality and quantity of cuticular substances appear to be highly age-dependent. Significantly more males responded with courtship behavior to cuticular substances from younger females. Isolated males generally showed higher levels of aggression than males reared in groups. Grouped males also were more likely to display courtship behavior towards antennae from younger females, and aggressive behavior towards antennae from older females. These results suggest that male discrimination of mating partners depends on the nature of female cuticular substances.     

(-)-Germacrene D increases attraction and oviposition by the tobacco budworm moth Heliothis virescens

The sesquiterpene germacrene D (GD) activates a major type of olfactory receptor neuron on the antennae of the heliothine moths. In Heliothis virescens females, 80% of the recordings have shown activity of one neuron type responding with high sensitivity and selectivity to GD. With the aim of determining the behavioural significance of this sesquiterpene, we have used a two-choice wind-tunnel to study the preference of mated H. virescens females for host plants with and without (-)-GD added. Tobacco plants containing dispensers with low release rate of (-)-GD had a greater attractiveness than tobacco plants without this substance. In addition, a significant increase of oviposition was found on the plants with (-)-GD.