Role of Volatile Semiochemicals in the Host and Mate Location Behavior of Mallodon dasystomus (Coleoptera: Cerambycidae)

Little is known of the role semiochemicals play in the mating systems of longhorned beetles (Coleoptera: Cerambycidae) in the primitive subfamily Prioninae. Mallodon dasystomus (Say), the hardwood stump borer, is a widely distributed prionine native to the southern US. Preferred hosts of M. dasystomus include oak, sweetgum, sugarberry and hackberry; although they also colonize a variety of other hardwoods. Here, we study the mate location behavior of M. dasystomus by testing the hypotheses that the sexes are mutually attracted to volatiles emanating from the larval host and that females release a volatile pheromone that is attractive to males alone. In a Y-tube olfactometer, male and female M. dasystomus responded to volatiles from host material (i.e., sweetgum and sugarberry). However, only males responded to females in the olfactometer, suggesting that females release a volatile sex pheromone. In choice experiments conducted in a greenhouse, we determined that both males and females prefer host over non-host material. In further bioassays in the greenhouse, males chose host material containing a live female over that containing a live male or host material alone. These findings are further evidence of the critical role host volatiles and pheromones play in mating systems of longhorned beetles.     

松墨天牛是否存在雌性接触信息素?

将松墨天牛MonochamusalternatusHope的身体不同部位切除之后的交配试验显示,分别剪去头部、鞘翅以及前胸部后仍然可以正常交配,用雄虫的腹部代替雌虫的腹部后,仍然能够引起雄虫的交配趋势动作,但不能完成真正交配,因此推测雌性接触信息素如果存在,主要集中在雌虫身体后半部,尤其是中后胸部位。但是冻死后的雌虫不再引起雄虫的交配行为,而且冻死的雌虫与活雌虫同时放入培养皿中,雄虫喜欢与活雌虫交配,不选择冻死的雌虫,因此推测视觉在其松墨天牛的交配过程中扮演着重要的角色,而接触性信息素有可能并不存在。将雄虫的触角分别从第5~6节和第1节剪去的试验结果显示,雄虫仍然可以很快地找到雌虫,发生交配行为。这有2种可能的解释一是雄虫不仅仅靠触角来感受雌虫的接触信息素,头部下颚须和下唇须上或者足上也有可以感受信息素的感受器;二是雌虫不存在接触信息素,雄虫通过视觉就可以找到对方,完成交配过程。浸泡致死的雌虫不再引起雄虫的交配行为,并且将正己烷和乙醚的浓缩液滴加在浸泡致死的雌虫以及玻璃棒和鹅卵石的生测试验结果显示,都没有引起雄虫的交配行为。这进一步说明,松墨天牛可能并不存在体表接触信息素。性成熟后的松墨天牛雌雄成虫是靠衰弱寄主的强烈的挥发性气味聚集到寄主树干上,在树干这个较为狭小的环境里,有可能是通过视觉找到配偶,完成交配过程。     

Intimate Rendezvous in a Tritrophic Context? Nothing but the Girls for Male Lysiphlebus testaceipes

In insects, mating often occurs after natal dispersal, and hence relies on a coevolved combination of sexual communication and movement allowing mate encounter. Volatile sex pheromones are widespread, generally emitted by females and triggering in‐flight orientation of conspecific males. In parasitoid wasps, unmated females can start laying unfertilized eggs via parthenogenesis so that host patches could serve as sites of rendezvous for mating. Males could therefore use cues associated with host patches to focus their search on females that have successfully found oviposition sites. We hypothesized that in parasitoids exploiting herbivorous hosts, sex pheromones, and herbivore‐induced plant volatiles (HIPV) should act in synergy, triggering male orientation toward ovipositing females. We tested this hypothesis with the aphid parasitoid Lysiphlebus testaceipes. Results from both field and laboratory experiments show that males are strongly attracted to virgin females, but that volatiles from aphid‐infested plants have no effect on male orientation, neither has a cue, nor in interaction with the female sex pheromone. The absence of synergy between sex pheromones and HIPV contrasts with results on other species and raises interesting questions on mating systems and sexual selection in parasitoid wasps.     

Courtship behaviour of the African Maize Stem Borer: Busseola fusca (Fuller) (Lepidoptera: Noctuidae) under laboratory conditions

Busseola fusca (Fuller) (Lepidoptera: Noctuidae) is the most important African stem borer damaging maize and sorghum. Chemical mediators play an essential role in all life cycle of this moth, especially for mating recognition and host plant choice. The female sex pheromone, courtship and mating behaviours act on the reproductive isolation within insect populations. B. fusca courtship behaviour was studied to decipher each step that could account as a process for reproductive isolation. B. fusca males and females presented a very simple and fast courtship behaviour, without any particular events or male pheromone emission.     

Pheromone Blend Does not Explain Old Male Mating Advantage in a Butterfly

In several insect species, male mating success is higher in older than in younger males, although condition diminishes dramatically with age. Two hypotheses are under debate to explain the counterintuitive pattern of old male mating advantage: first, an increased eagerness of older males to mate, driven by their low residual reproductive value, and second female preference for older males based on chemical cues such as sex pheromones (female choice hypothesis). In a series of experiments, we manipulated female olfaction, male pheromone blend and female age to test whether old male mating advantage prevails when the influence of male sex pheromones is controlled for, using the tropical butterfly Bicyclus anynana as model. We found that older males had a higher mating success than younger ones irrespective of female scent‐sensitivity and irrespective of male pheromone blend. Interestingly, older males were found to court more often and for longer time bouts than younger males. These results were independent of female age, although younger males courted younger females more often and for longer bouts than older females. Taken together, our results indicate that male courtship activity (1) is higher in older compared to younger males and (2) increases the mating success of older males. Olfaction and sensing pheromones, in contrast, were not a necessary prerequisite for old male mating advantage to occur and may use other cues than pheromones to assess male quality.     

豆野螟成虫行为学特征及性信息素产生与释放节律

豆野螟Maruca vitrata (Fabricius)是一种严重的泛热带豆类蔬菜害虫。本文在（29±1）℃、相对湿度75%～80%、光周期14L∶10D条件下研究了豆野螟成虫的羽化、交尾行为以及雌蛾性信息素的释放节律。结果表明：其羽化行为全天可见,在雌蛾中,86%于暗期羽化; 在雄蛾中,73%于暗期羽化。雌雄蛾羽化行为在暗期第4、5和8 h差异达到显著 (t>4; P<0.05)。交尾活动发生在暗期19：00到5：00之间,交尾持续时间最短约为20 min,最长约为90 min,3日龄进入暗期第5 h具有最高的交尾率。1、6和7日龄成虫具有单个交尾高峰,2到5日龄成虫具有两个交尾高峰。同一日龄成虫交尾在暗期前半段平均花费的时间要明显高于在后半段花费的时间。低龄和高龄的成虫用于交尾的时间明显高于中龄的性成熟成虫。成虫的开始交尾时间随着日龄的增加逐渐前移。雄蛾对进入暗期后第5 h和第9 h处女雌蛾的性腺提取物和空气收集性信息素的触角电位反应最强,对 3日龄处女雌蛾的性腺提取物和空气收集性信息素的触角电位反应最强。处女雌蛾田间诱蛾试验表明：23：00-01：00为诱蛾高峰期,3日龄处女雌蛾的诱蛾效果最好。该蛾的羽化、交尾及性信息素产生与释放均存在节律上的一致性。雌蛾的性信息素释放的时间较长,见于整个暗期,然而交尾行为发生时间较短,主要发生于两个交尾高峰之间。     

雌性信息素在麻点豹天牛成虫交尾行为中的作用

通过对麻点豹天牛Coscinesthes salicisGressitt成虫交尾行为的观察,发现雌、雄成虫间明显存在着性引诱物质的诱导现象,作者采用溶剂从雌虫体上提取出该物质,并对其生物活性及雄虫的感应方式进行检测,结果证明该信息素提取物在成虫的交尾行为中起着较为关键的作用,雄虫依靠此信息物来寻找和识别雌虫。应用提取物对雄虫所诱发的交尾行为反应与正常状态下的行为相似,经测定雄虫对该性信息素提取物的感应方式主要是接触感应。     

Male territoriality and mating system in the European beewolf Philanthus triangulum F. (Hymenoptera: Crabronidae): evidence for a “hotspot” lek polygyny

The evolution of the mating system of a species is strongly influenced by the spatial and temporal distribution of females and/or resources. Here, we describe aspects of the territorial behavior of males of a solitary digger wasp, the European beewolf (Philanthus triangulum) and characterize the mating system. We show that beewolf males establish small territories that do not contain any resources essential to females. These territories are intensively scent-marked with a pheromone from a cephalic gland and are defended against intruders in combat flights. We provide evidence that scent-marking constitutes a chemical display and that the pheromone serves to attract receptive females and, thus, represents a sex pheromone. Using spatial statistics, we show that beewolf territories are clumped in space both with respect to other male territories and, more importantly, with respect to female nesting sites. Additionally, the proportion of days a territory is occupied by a male is correlated with the number of female nests in the vicinity. Taking into account that beewolf males do not defend or provide resources essential to females, but merely display chemically to attract females for mating in an aggregation of territories close to female nesting sites, we conclude that the European beewolf exhibits a hotspot lek polygyny with female nesting sites constituting “hotspots” for lek formation.     

Mating behavior ofXylotrechus pyrrhoderus Bates (Coleoptera: Cerambycidae) V. Female mounting behavior

Female mounting behavior was observed in the grape borerXylotrechus pyrrhoderus Bates (Coleoptera: Cerambycidae) under laboratory conditions. This behavior was directed towards either females (i.e., female homosexual mounting) or males. The female homosexual mounting was strongly elicited in females which had previously been allowed to fly. The frequency of this behavior was not related to the experience of mating. The investigation of the daily temporal pattern in female homosexual mounting activity indicated that the behavior most frequently occurred between 12∶00 and 16∶00, i.e., when females were searching for the pheromone-releasing males. Oviposition was also observed during this time interval. A detailed analysis revealed female mounting behaviors which are characteristic of male mounting behaviors, such as chasing conspecifics and synchronism of licking and abdominal bending. On the other hand, the frequency of male homosexual mounting was lower than that of females. Taken together with cases of other species previously reported, the expression of mounting behavior in females may be related to the evolution of the reproductive system, in which females approach their mates.     

Emergence, Mating, and Postmating Behaviors of the Oriental Beetle (Coleoptera: Scarabaeidae)

In a previous field-trapping study of the oriental beetle, Exomala orientalis (Waterhouse), by using synthetic sex pheromone on golf course fairways, numerous males were observed and trapped during the hours of peak mating activity. However, very few beetles were observed in the same areas when synthetic pheromone was absent. To investigate the hypothesis that mating in nature occurs cryptically within vegetation at the soil surface, laboratory studies on female emergence and pheromone release, male emergence and mate-locating, and female and male mating behaviors were conducted. Mate acquisition and copulation occurred on the soil surface near the female emergence site, with both sexes engaging in pheromone-mediated behaviors after having emerged from the soil. A highly stereotyped female pheromone release, or calling, behavior was observed, consisting of insertion of the female's head into the soil and elevation of the tip of her abdomen into the air. Bioassays conducted in a wind tunnel that simulated a turf fairway environment showed that walking and flying were both important in the upwind response of males to females. Mating and copulation occurred without an obvious complex courtship, but observations of postmating behaviors suggested that mate guarding occurs.     

Modeling intra-sexual competition in a sex pheromone system: how much can female movement affect female mating success?

Mating disruption theory predicts that high concentrations of female pheromone, and/or large numbers of release sites, should confuse males orienting to "calling" females, reduce the number of successful matings, and decrease the reproductive potential of the population. In this scenario, females are regarded as stationary point sources of pheromone. Past behavioral observations, however, have shown virgin female grape root borers, Vitacea polistiformis Harris, significantly alter their behavior in mating disruption treatments. Treated females call at different heights, move less before call initiation, and move more after call initiation than control females. Pheromone gland dragging and wing fanning also increase significantly during pheromone treatments. These behavioral differences are significant only if they alter the mating success of females. Because long-term field studies are impractical, we used known behavior of male and female GRB to build a Fortran language time step model, adding the effects of female movement to past models of male pheromone plume following. Females were distributed randomly, and then assigned a conditional movement strategy. If females were within the competitive portion of another female's plume, the downwind female moved. Except in the lowest population density tested, females moving upwind and crosswind when in a competing female's pheromone plume mated significantly more often than females remaining stationary. In all population simulations, mating success was significantly reduced when females moved downwind. These field and simulation studies provide strong evidence for female movement as a previously overlooked potential mechanism for resistance to mating disruption treatments, as well as a shaping behavior in the evolution of pheromone communication systems.     

同种雄性竞争对手的存在对星豹蛛雄蛛求偶和交配行为的影响

越来越多的研究发现,雄性产生精子(精液)也需付出代价。雄性除了依据配偶质量和竞争对手的竞争强度适应性调整生殖投入外,雄性在求偶和交配行为上也相应产生适应性反应,求偶和交配行为具有可塑性。目前雄性求偶和交配行为可塑性研究主要集中于雌性多次交配的类群中,在雌性单次交配的类群中研究甚少。以雌蛛一生只交配一次而雄蛛可多次交配的星豹蛛为研究对象,比较:(1)前一雄性拖丝上信息物质对后续雄蛛求偶和交配行为的影响,(2)雌雄不同性比对雄蛛求偶和交配行为的影响。研究结果表明,星豹蛛前一雄蛛拖丝上的信息物质对后续雄蛛求偶潜伏期、求偶持续时间和交配持续时间都没有显著影响,但前一雄蛛拖丝上的信息物质对后续雄蛛求偶强度有显著抑制作用。同时,性比对星豹蛛雄蛛求偶和交配行为都没有显著影响。可见,星豹蛛雄蛛对同种雄性拖丝上的化学信息可产生求偶行为的适应性调整,而对性比不产生适应性反应。     

Pheromone detection by a pheromone emitter: a small sex pheromone-specific processing system in the female American cockroach

Many animals depend on pheromone communication for successful mating. Sex pheromone in insects is usually released by females to attract males. In American cockroaches, the largest glomerulus (B-glomerulus) in the male antennal lobe (first-order olfactory center) processes the major component of sex pheromone. Using intracellular recordings combined with fine neuroanatomical techniques, we provide evidence that the female homolog of the male B-glomerulus also acts as a sex pheromone-specific detector. Whereas ordinary glomeruli that process normal environmental odors are innervated by single projection neurons (PNs), the B-glomerulus in both sexes is innervated by multiple PNs, one of which possesses a thicker axon, termed here B-PN. Both soma size and axon diameter were smaller on B-PNs from females compared with B-PNs from males. The female B-PNs also produce fewer terminal arborizations in the protocerebrum than male B-PNs. Termination fields in the lateral protocerebrum of the female B-PN are mostly segregated from those formed by other uniglomerular PNs innervating ordinary glomeruli. Female B-PN activity was greatest in response to sex pheromone but lower than that in the male B-PN. This specific detection system suggests that sex pheromone affects the behavior and/or endocrine system of female cockroaches.     

Male Aggression,Female Mimicry and Female Choice in the Rove Beetle,Aleochara curtula (Coleoptera,Staphylinidae)

Causes, consequences and pheromonal regulation of male contest and female choice in the staphylinid beetle, Aleochara curtula (Goeze), have been investigated in the field and in the laboratory. At the feeding and mating site (carcass) the sex ratio is male biased. Polyandry is affected by prolonged copulations, spermatophore plugs and anti-aphrodisiac pheromones transferred from the male, and by female repulse behaviour as well. Aggression of competing males leads to expulsion of inferior males from the carcass. Young, starved and multiply mated males, which need access to the food resource, produce the female sex pheromone. They release homosexual responses, but also avoid intrasexual aggression. On the other hand, females behave aggressively towards individuals bearing the female sex pheromone or repulse their copulatory attempts. Those males of insufficient physiological condition produce a lighter spermatophore and fertilize less eggs. The adaptive significance of female mimicry, male mating tactics, and female choice is discussed.     

Production and perception of pheromones by the beetle Tribolium confusum

Adults of Tribolium confusum secrete two pheromones. The first, produced by the male, is attractive to both sexes and the second, produced by the female, is attractive to the male only. Pheromone production and perception was studied in relation to habituation, beetle age, time of day and previous mating. A living source of each pheromone habituates the responding beetles, the male pheromone habituating more strongly; female pheromone habituates only in the absence of the male pheromone. Habituation to one pheromone was always accompanied by an enhanced response to the other.Five days after emergence, production of male pheromone reaches a peak that is maintained. Production of female pheromone peaks after 3 days. Both sexes are responsive to male pheromone immediately upon eclosion, males reaching maximum response at 14 days, females at 8 days. Males are also responsive to female pheromone upon eclosion reaching maximum response at 8 days; female response to female pheromone is imperceptible. Males but not females display a 24 hr rhythm in pheromone production. Mated beetles did not differ significantly from unmated beetles in their ability to perceive pheromones. Alteration in male pheromone production after mating was detected by females but not males; this pheromone may, therefore, act as both a sex and aggregation pheromone.     

Mating Effect on Sex Pheromone Production of the Oriental tobacco budworm,Helicoverpa assulta

This study was undertaken to clarify the suppression phenomenon of sex pheromone production after mating and its relationship to the physiological mechanism in adult females of Helicoverpa assulta, and determine the mating factor from males causing depletion of sex pheromonc production. Sex pheromone production of H. assulta females was mostly terminated in 3 hours after mating. Mated females maintained with a low titer of sex pheromone until 3 days when it started to increase again, which showed a characteristic of species mating more than once. The mated female again produced pheromone upon injection of pheromone biosynthesis activating neuropeptide (PBAN) or extracts of brain-suboesophageal ganglion complexes (Br-Sg) of mated female, which were shown similar pheromonotropic activities as compared with virgin females. These results indicated that the mating did not inhibit the receptivity of pheromone gland itself and PBAN biosynthesis in suboesophageal ganglion of the mated females. And it seems to support that the depletion of sex pheromone production is responsible for blocking of PBAN release from head. To investigate the mating factor from adult males, when extracts of reproductive organs of male were injected into hemocoel of virgin females evoking depletion of sex pheromone production as shown in mated female. The results suggest that a chemical substance(s) from the male reproductive organs could be responsible for the loss of sex pheromone biosynthesis in H. assulta.     

褛裳夜蛾的交配行为及雄蛾对性腺提取物的反应节律

详细观察了褛裳夜蛾成虫的交配行为,利用风洞、触角电位技术研究了雄蛾对性腺提取物的反应节律,通过林间诱蛾试验进行了验证,旨在为褛裳夜蛾性信息素的精确提取及性信息素组份分离、鉴定提供依据。研究结果表明:成虫的求偶、交配行为均发生在暗期,有一定的节律性:雌蛾在羽化3d以后开始求偶,1周左右表现最为强烈,3-4日龄雌蛾在暗期4-6h开始求偶,最大求偶率在暗期6-8h;5-9日龄在进入暗期就开始求偶,最大求偶率出现在暗期4-6h。风洞试验表明,3-7日龄的雄蛾对性腺提取物均有明显的性行为反应,5日龄雄蛾在暗期4-6h对性腺提取物的反应最为强烈。3-6日龄的成虫在暗期4-6h开始交配,而7-8日龄的成虫于暗期2-4h开始交配,6日龄的成虫交配率最高,交配高峰在暗期4-8h。雄蛾对性腺提取物的触角电位反应也有一定的节律性:雄蛾对4日龄雌蛾性腺提取物开始有电生理反应,对6-7日龄暗期5h性腺提取物反应最为强烈。林间诱蛾试验测定了性腺提取物的引诱活性,7日龄雌蛾性腺提取物林间诱蛾量最高,引诱高峰在暗期4-6h,该结果也验证了褛裳夜蛾雄蛾对性腺提取物的反应节律。     

Sex pheromone titre in the glands of Spodoptera litura females: circadian rhythm and the effects of age and mating

The present study investigates the effects of age and mating status on the circadian variations of gland sex pheromone titre in female Spodoptera litura Fabricius. Similar to other nocturnal moths, S. litura females exhibit circadian variations of gland sex pheromone contents, with higher levels during scotophase and lower levels during photophase. The sex pheromone titre in the glands peaks during the first scotophase after eclosion and sharply declines afterwards. Higher pheromone contents during scotophase may facilitate female reproductive activities, and the negative relationship between pheromone titre and female calling is likely the result of pheromone release during female calling. Interestingly, the present study demonstrates that mated S. litura females have significantly higher sex pheromone titre in their pheromone glands (PGs) than virgin females. This finding contrasts with all previous studies of other insect species, in which mating generally reduces the sex pheromone titre in female PGs. In S. litura, mating and male accessory gland fluids can suppress female calling behaviours and re‐matings. These results suggest that the suppression of female calling behaviours by mating and male accessory gland fluids may significantly reduce the release of sex pheromones and thus result in higher sex pheromone titre in the PGs of mated females.     

Observations on the mating behavior of the alfalfa blotch leafminer,Agromyza frontella (Rondani) (Diptera: Agromyzidae), and evidence of a female sex pheromone

The mating behavior of Agromyza frontella was studied under laboratory conditions. Adults were able to mate on the day of emergence, with no evident periodicity throughout the photophase. The host plant was essential for mating to occur, its presence affecting female receptivity rather than male copulatory behavior. Males generally entered a stationary phase once in the proximity of a female, before undertaking a final approach. This stationary behavior frequently resulted in male aggregations around a female, and under such conditions males exhibited a characteristic wing vibrating behavior. As male wing vibration was not an essential behavior for successful mating, and rarely occurred during male encounters in the absence of females or when only one male was near a female, it was considered as being primarily a male-male signal. The majority of females that mated exhibited an ovipositor pumping behavior that stimulated the male approach. However, such behavior was not essential to attract mates, as dead females elicited the entire sequence of male mating behavior. This suggested the presence of a cuticular sex pheromone, as reported for other species of higher Diptera. Whole virgin female (<24- h or 3- day-old) hexane extracts applied to male cadavers increased the time males spent on the plant, the number of contacts with the treated cadavers, the incidence of attempted copulations, and the wing vibrating behavior between males compared with controls using untreated cadavers. The results obtained indicate that females control copulation in A. frontella and that both semiochemical and visual cues are important in eliciting male mating behavior.     

小木蠹蛾性行为和性信息素产生与释放的时辰节律

观察了小木蠹蛾Holcocerus insularis的性行为反应,并采用腺体提取、空气收集 、触角电位和田间试验等方法对雌蛾产生和释放性信息素的时辰节律进行了研究。结果表明： (1) 该虫羽化24 h后性成熟,婚飞和交配活动主要在1：00～4：00,交配历时15～45 min;(2) 大部分雌蛾一生交配1～3次,雄蛾多数一生只交配1次,雌雄比为1∶0.89; (3) 雌蛾腺体提取物中性信息素含量同蛾龄有关,2日龄雌蛾腺体性信息素含量最高;(4) 雌蛾腺体中性信息素含量在1：00时最高,而性信息素释放高峰在2：30。