Relationships among pheromone titre,calling and age in the omnivorous leafroller moth (Platynota stultana)

Temperature modified the expression of female calling in Platynota stultana. Absolute temperature levels and not necessarily a decrease in temperature appear to modulate the timing of calling by delimiting a specific time interval for calling at each temperature. Calling began earlier in the photoperiod at lower temperatures than at higher temperatures. As females aged they initiated calling at an earlier time. Pheromone production (at 24°C) was rhythmical with maximal titre being reached near to the onset of the calling period at 14°C and about 5 hr prior to the onset of calling at 24°C. Females thus appear to be capable of emitting pheromone at an appropriate rate any time during calling intervals delimited by temperatures between 14 and 24°C. Pheromone titre appears to reflect a time-dependent readiness to respond to a decrease in temperature.     

DIEL RHYTHMS OF CALLING BEHAVIOR AND SEX PHEROMONE PRODUCTION OF BEET ARMYWORM,SPODOPTERA EXIGUA (LEPIDOPTERA:NOCTUIDAE)*

Abstract Beet armyworm (BAW), Spodoptera exigua, is becoming one of more and more serious pests in China in recent years. As a part of research program of sex pheromone and its application of BAW in China, the hourly and daily variation of calling behavior and pheromone production of BAW females were investigated. Both calling behavior and titers of 4 sex pheromone components showed distinct diel rhythms, and the two peak periods were synchronous. In comparison, the calling activity lasted shorter period of time with a longer peak time, whereas the production of the sex pheromone lasted throughout the whole scotophase and part of the photophase with a very short peak time. The calling behavior began at the middle scotophase, reached the maximum at the middle‐later scotophase, and continued the maximal calling activity until the end of the scotophase. When the light was on, the calling percentage reduced sharply, and all females stopped calling 1 hour later. The variation patterns of the 4 pheromone components in the glands of the 3 day old moths were similar from one to another. From 0.5 h before to 4.5 h into scotophase, the titers increased slightly, but at 6.5 h they showed a significant increase up to the peak values of the scotophase. Soon at 8.5 h into the scotophase, they decreased significantly and thereafter gradually to undetectable level at 4.5 h into the next photophase. The daily change experiment showed that BAW females began calling at 0 scotophase, became fully active in calling at 3rd scotophase, and maintained the calling activity to 7th scotophase. There was no significant difference in pheromone titers among different day‐old moths.     

Electrophysiological and Behavioral Responses of Female Beet Armyworm Spodoptera exigua (Hübner) to the Conspecific Female Sex Pheromone

Electroantennogram (EAG) recordings showed that female Spodoptera exigua can detect their own sex pheromones (two single components and their mixture), displaying a similar dose–response pattern to that of males, although intensities of female responses were much less at all doses compared with males. Furthermore, the female calling behavior was inhibited and late-shifted by the presence of the female sex pheromone. When the pheromone components were presented, the calling female proportion in the peak calling period was significantly reduced and the calling peak time and calling termination time postponed, compared with controls. Although the calling behavior was inhibited, the pheromone titer of treated females was not different to the control, implying a reduced pheromone biosynthesis in the pheromone glands of treated moths. However, observations during the olfactometer experiments revealed that there were no obvious behavioral responses of females exposed to sex pheromone stimuli including whole gland extracts, 0.1, 1 or 10 μg binary pheromone mixtures.     

甜菜夜蛾雌蛾求偶行为及性信息素产生的时间节律(英文)

研究了甜菜夜蛾雌蛾求偶行为和腺体中性信息素滴度时日变化的规律。结果表明 ,雌蛾求偶行为和性信息素滴度均呈明显的昼夜节律 ,且均在暗期的中后期达到高峰。比较而言 ,雌蛾的求偶活动期较短 ,在暗期中期开始 ,暗期结束后很快停止 ;但峰期较长 ,从中后期达到高峰后一直保持到暗期结束。而腺体内 4种性信息素组份从暗期前 0 .5h到下一个光期 4.5h均有产生 ;但峰期很短 ,暗期 6.5h显著增加达到高峰后 ,在 8.5h又迅速回落。日变化研究表明 ,甜菜夜蛾当日龄即可求偶 ,3日龄起进入求偶盛期 ,至 7日龄末有明显减退。 0～ 3日龄雌蛾的平均初始求偶时间逐日显著提前 ,以后则稳定在暗期 5h左右。不同日龄间性信息素滴度的变化较小     

Endogenous and exogenous factors affecting periodicities of female calling and male sex pheromone response in Grapholitha molesta (Busck)

In Grapholitha molesta periodicities of both female calling and male response to sex pheromone by wing fanning while walking were determined in part by circadian rhythms. The lights-on photoperiodic cue was at least partly responsible for setting the phase of the female calling rhythm. Absolute temperature levels and not necessarily a decrease in temperature modified the timing of calling; there were both high and low thresholds of temperature and, at particular photoperiod times, a temperature range optimal for calling. When the previous performance of calling was prevented by subthreshold temperatures, calling during the next period commenced earlier if temperatures were favourable. Thus, the previous performance of calling may establish a refractory period, or temperature decrease may act as a cue resetting the phase of the calling rhythm. The ability to use both an endogenous clock and exogenous temperature cues to synchronize sexual activity appears adaptive for a temperate zone insect whose multiple generations are exposed to both long periods of favourable climatic conditions in summer and harsh, unpredictable conditions in spring or fall.     

Circadian rhythm of sex pheromone-releasing behaviour in females of the dermestid beetle,Trogoderma glabrum: Regulation by photoperiod

The effects on sex pheromone-releasing, or calling behaviour, of diel photoperiods of varying daylength, of light cycle phase shifts, and of continuous illumination were investigated in Trogoderma glabrum females. On light régimes with 8 to 20 hr daylengths, calling maxima tended to centre close to photophase midpoints. Although influencing the time of day at which calling occurred, daylength had little effect on the amount of activity or the length of the calling period. When 16 : 8 LD light cycles were advanced or delayed by 4 hr, the time of day at which calling peaks were observed shifted within 2 to 4 cycles so that a constant phase relationship with photoperiod was maintained. Daily calling peaks were evident in groups of females exposed to between 1 and 5 days of continuous illumination, but mean calling time occurred earlier in the day as light exposures were lengthened. It was concluded that a circadian rhythm of calling behaviour exists in T. glabrum females. and that the rhythm can be entrained to 24 hr periodicity by photoperiod.     

Diel periodicity and influence of age and mating on female sex pheromone titre in Estigmene acrea (Lep., Arctiidae)

Abstract:  Calling behaviour, diel periodicity, and effect of age and mating on female sex pheromone titre in Estigmene acrea (Drury) were studied under laboratory conditions. Forty-five per cent of females started calling during the first scotophase, but the highest number of calling females was observed during the second, third and fourth scotophases. Calling behaviour occurred from the third hour after dark until just before the end of the scotophase. However, females exhibited a bimodal pattern of calling with the first peak occurring between 4 and 6 h and a second peak at 10 h after the onset of scotophase. The mean onset of calling time differed significantly with age. Older females showed a tendency to call longer, but there was no significant difference. The amount of (Z,Z)-3,6-cis-9, 10-epoxyheneicosadiene in females was quantified from the first scotophase following emergence, until the fifth scotophase. Glands of 0-day-old females presented a higher content of pheromone compared with that found in glands of 1-, 2-, 3- and 4-day-old females. Pheromone titre was determined at 2-h intervals throughout the third scotophase and photophase. (Z,Z)-3,6-cis-9,10-epoxyheneicosadiene was found in the gland during the scotophase as well as the photophase. However, there was no consistent pattern of pheromone production throughout the scotophase or photophase. Mated females of E. acrea produced significantly less pheromone than virgin females.     

Rate and diel periodicity of pheromone emission from female gypsy moths, (Lymantria dispar) determined with a glass-adsorption collection system

The rate of pheromone emission from wild and laboratory-reared gypsy moth (Lymantria dispar) (Lepidoptera: Lymantriidae) virgin females was determined with an all-glass aeration apparatus. This device incorporated a bed of 1-mm glass beads to extract entrained pheromone from the air flowing over the protruded gland. The temporal pattern of emission was established by monitoring individual females after eclosion for 24 consecutive 2-hr intervals.At a constant 24°C, both wild and laboratory females exhibited a similar diel periodicity of pheromone emission. The mean release rate increased after onset of photophase, generally attained maximal levels between 1600 and 2200 hr and declined during scotophase. Pheromone was released continuously and the mean daily emission increased with age for both wild and laboratory moths. The mean emission rate over the 48-hr monitoring interval was $\text{15.4 ng}\text{2 hr}$ for wild females vs $\text{14.7 ng}\text{2 hr}$ for laboratory moths. The peak emission from 2-day-old laboratory moths was ca.$\text{28 ng}\text{2 hr}$ compared with the ca.$\text{25 ng}\text{2 hr}$ released by their wild counterparts.The calling periodicity of laboratory females was determined at a constant 24°C and under a natural temperature rhythm. At 24°C, the proportion of females calling exceeded 45% throughout the diel period, whereas under the temperature rhythm, calling was virtually eliminated by temperatures below 15°C, indicating that temperature acts as an exogenous cue to modify the expression of the calling rhythm and thus potentially the periodicity of pheromone emission.     

Modulation of the temporal pattern of calling behavior of female Spodoptera littoralis by exposure to sex pheromone

We have examined the timing of calling behavior in the female Egyptian cotton leafworm, Spodoptera littoralis and its modification by exposure to sex pheromone. The calling rhythm of the female moth was found to be circadian, persistent for at least 4 days once it has been entrained, and could be phase shifted by altering the light:dark regime. We also found that female exposure to pheromone affected the rate and duration of calling. A brief exposure to pheromone gland extract increased the proportion of females calling in a constant dim light and this effect persisted for at least 2 days. In response to pheromone exposure, significantly more females also called late into scotophase when most unexposed control females had ceased calling. The adaptive significance of responding to conspecific sex pheromone is discussed.     

蜀柏毒蛾生殖行为及性信息素产生与释放节律

为了探索蜀柏毒蛾Parocneria orienta Chao性信息素产生和释放规律, 为利用性信息素监测和防治蜀柏毒蛾奠定基础, 本研究在野外及室内温度22±1℃、 相对湿度75%~80%、 光周期14L∶10D条件下观察研究了蜀柏毒蛾成虫的羽化、 求偶、 交尾、 产卵行为, 触角电位反应测定处女雌蛾性信息素产生与释放的时辰节律。结果表明： 蜀柏毒蛾羽化行为全天可见, 主要集中在1:00-5:00, 占总羽化量的44.94%, 7:30-11:00进行婚飞和交尾, 交尾高峰期出现在8:30左右, 交配时间少则2 h, 多则8 h, 求偶、 交配均发生在光期。随着日龄的增加, 召唤时间前移并且延长, 1日龄的处女雌蛾交尾时间较短; 雌蛾羽化当天就可交尾, 2日龄雌蛾交尾率最高, 达36.67%。雌蛾分多处产卵, 雌蛾一生最高产卵量达402粒, 最低产卵量为78粒。羽化当天的雌蛾体内性信息素含量较低, 第2天最高, 以后逐日下降; 2日龄蜀柏毒蛾处女雌蛾性信息素的产生量从7:00起逐渐增加, 8:30-9:30时最高, 9:30后逐渐减小。雄蛾对处女雌蛾腺体提取物的触角电位反应在8:30-9:00最强, 说明8:30-9:00是雌蛾产生和释放性信息素的高峰期。蜀柏毒蛾的羽化、 求偶、 交尾及性信息素的产生与释放存在一定的时辰节律, 野外处女雌蛾诱蛾试验证实了性信息素释放与交配行为在时辰节律上的一致性。     

The effects of photoperiod and temperature on calling behaviour and egg development of the bertha armyworm,Mamestra configurata (Lepidoptera: Noctuidae)

The effects of photoperiod and temperature on calling behaviour and the effects of temperature on the relationship between egg development and calling of virgin females of Mamestra configurata Walker were examined at 3 photoperiodic regimes and seven constant temperatures. Photoperiod affected the diel periodicity of calling and length of the daily calling period. The mean onset calling times were similar if the preceding scotophase(s) was 6–10 h long, but the onset of calling was delayed by 1–5 h if the preceding scotophase(s) was 12–18 h long. Long-term, constant temperature (from emergence until death) affected 4 aspects of calling: age at first calling, diel periodicity, length of the daily calling period, and percentage of females calling. Short-term temperature changes (during a single scotophase) affected calling in 3 ways: diel periodicity, length of the daily calling period, and percentage of females calling. The optimal temperature range for calling was, at least, 10–25°C; the upper limit and threshold were near 35 and < 5°C. The time of first calling was synchronized closely with the appearance of the first chorionated eggs in the ovaries at 10–35°C. Egg development and calling were adversely affected at 30 and 35°C. The physiological and ecological significance of the data are discussed.     

Temporal distribution of PBAN‐like immunoreactivity in the hemolymph of Mamestra brassicae females in relation to sex pheromone production and calling behavior

A direct enzyme‐linked immunosorbent assay has been developed and applied to the analysis of PBAN immunoreactivity in female hemolymph of the cabbage armyworm, Mamestra brassicae. PBAN‐IR determinations have been carried out with third scotophase insects at different times of the photoperiod. The rhythm of calling and the pattern of pheromone production by third scotophase females at different times of the photoperiod have also been determined. PBAN‐IR and calling are well correlated. However, whereas pheromone titers decrease, both PBAN‐IR levels and percentage of calling females remain high in the last hours of the scotophase. These results are discussed in the context of the regulation of sex pheromone biosynthesis in M. brassicae. Arch. Insect Biochem. Physiol. 40:80–87, 1999. © 1999 Wiley‐Liss, Inc.     

Copulation behaviour of Lygocoris pabulinus under laboratory conditions

As a prerequisite to the elucidation of the sex pheromone of the green capsid bug Lygocoris pabulinus (L.), we studied the bug's reproductive development and behaviour. When kept under long-day conditions (L18:D6) at 25 °C, both males and females start to copulate 4 days after the final moult. Second matings occur in some females, even on consecutive days. The premating period is 10 min on average and copulation lasts 1 to 2 min. At long range, when males are attracted to traps baited with live females, we did not observe a specific calling position of the females. At short range, a characteristic courtship behaviour of the females was not observed either. Males showed a characteristic vibration of the abdomen, which was repeated several times before copulation. This behaviour can be used as a bioassay to test potential sex pheromone compounds.     

Mechanisms of premating isolation between Helicoverpa armigera (Hübner) and Helicoverpa assulta (Guenée) (Lepidoptera: Noctuidae)

Helicoverpa armigera and Helicoverpa assulta are sympatric sibling species, and in the laboratory they can interbreed and produce viable offspring. To assess the contributions of temporal barriers and sexual barriers to premating isolation, we investigated both the temporal rhythms of calling behavior and pheromone titers of H. armigera and H. assulta females and the behavioral responses of males to conspecific and heterospecific calling females in a wind tunnel. Both H. armigera and H. assulta females called throughout the scotophase, and there was more calling during the second half of the scotophase than during the first half. Maximal pheromone titer and maximal calling activity in H. armigera synchronously occurred at the sixth hour into the scotophase, whereas, in H. assulta, the maximal pheromone titer occurred 2 h before the peak of calling. Pheromone blend ratios of the two species were opposite and, within each species, changes in the ratio within the scotophase and at different ages were relatively small. Males of both H. armigera and H. assulta responded strongly to their conspecific calling females in the wind tunnel and completed the whole courtship sequence. In contrast, they did not land and had no copulation attempts in response to heterospecific calling females. These results show that the two species do not have obvious temporal differences in calling behavior and pheromone production, and the specificity of sex pheromone blend emitted by females plays a key role in their premating isolation. In addition, we summarized the potential isolation mechanisms of H. armigera and H. assulta.     

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.     

The behavioural basis of a pheromone monitoring system for pea moth, Cydia nigricana

The flight and mating behaviour of the pea moth (Cydia nigricana) was studied at overwintering sites and in pea fields to see whether it could be exploited to provide early warning of adult immigration into pea crops. The field threshold temperature for take-off is 18 ^CC. Most flight activity-occurred in June and July between 16.00 and 18.00 B.S.T. with peak activity at 17.04 h. Moths were not caught in suction traps at heights above 0–4 m, but they can probably travel several km by fluttering above vegetation in winds of up to 10 km/h. Female moths produce a sex pheromone(s) highly attractive to males; ‘calling’ by females and mating occur during the period of maximum flight activity. Suction traps and egg counts detected the presence of moths in crops at about the same time. On average, sticky and water traps containing live virgin females as a lure caught respectively 17 and 130 times more males than suction traps and, on occasions, 25 and 300 times more; these attractive traps should detect the arrival of immigrants sooner than suction traps or egg counts. Extracts of virgin females dispensed from filter paper at doses of one and five female-equivalents (FE) attracted males rapidly but temporarily. Rubber dispensers with extracts of twenty FE remained attractive for 6 days. Several synthetic attractants were screened using doses of o-i mg on rubber dispensers in sticky traps. CYs-8-dodecenyl acetate and erans-8, frans-io-dodeca-dienol at doses of o-i mg were slightly attractive; the latter at doses of 1 -o mg was more attractive than twenty FE doses of extract and could be used for experimental monitoring of pea moth until its own synthetic sex pheromone(s) is available.     

Effect of age and mating on pheromone production in the female olive fruit fly, Dacus oleae (Gmel.)

Virgin female olive fruit flies began producing sex pheromone on the third day after emergence. Production of sex pheromone appears to be cyclical with peaks of production recurring at about 10-day intervals, each peak lasting 2–3 days. As the female ages, the quantity of sex pheromone produced during the period of high pheromone production decreases, but it is always higher than the quantity present in the pheromone gland during the rest of female life.Mated females produced less sex pheromone the first 10 days after mating which then increased to near the same level of that in virgin females.     

Calling Behavior and Rhythms of Sex Pheromone Production in the Black Cutworm Moth in China

The hourly and daily variation of calling behavior and sex pheromone production by the female black cutworm moth, Agrotis ypsilon (Rottemberg), were investigated. Both calling behavior and titers of five sex pheromone components showed distinct diel rhythms, and peak periods of calling and pheromone titer were synchronous. Females began to call on the first night after eclosion and called mainly during the second half of the scotophase. The percentage of females calling increased in 1 to 3-d-old females and decreased in 3 to 7-d-old females. Females advanced their calling time with increasing age (1 to 7 d). GC-MS analysis of hexane extracts of pheromone glands revealed that the titers of the five sex pheromone components were very low on the first night after eclosion, but increased sharply and peaked on the third night. Titers decreased greatly with increasing age (3 to 7 d), but from the onset of the scotophase to 4.5 h into scotophase, titers remained invariate. However, from 4.5 to 7 h, pheromone titers, especially that of the primary component Z7-12:Ac, increased sharply and peaked. After the peak, the titers decreased greatly at 8 h, and thereafter decreased gradually to the level before 4.5 h. The quantity of each component almost reached zero after lights-on.     

Hormone-pheromone relationships of male Tenebrio molitor

Males of the beetle Tenebrio molitor produce a volatile sex pheromone which attracts females of the same species. The pheromone level peaks 8 days after emergence and then reaches a plateau. Elimination of endocrine centers by decapitating male adults 24 hr following adult ecdysis did not impair pheromone production. Treatment of decapitated males with juvenile hormone analogues did not make any detectable difference in the levels of pheromone activity. However, undecapitated males treated with juvenile hormone analogue showed a significant increase in pheromone activity when compared with those that had been decapitated and subsequently treated with juvenile hormone analogue. This observation is discussed in the light of published research on the effect of juvenile hormone on pheromone activity of females of T. molitor.     

光强度对棉铃虫交配行为的影响

【目的】为阐明光强度对棉铃虫Helicoverpa armigera (Hübner)交配行为的影响。【方法】本实验设置4个光照强度(0,0.5,5.0和50.0 lx),观察记录不同光照强度下棉铃虫雌蛾的求偶行为;分别通过单个腺体性信息素提取法和解剖雌虫受精囊的方式,检测不同光照强度下棉铃虫的雌蛾性信息素滴度和交配率。【结果】在强光(50.0 lx)下,棉铃虫雌蛾求偶起始时间最长,求偶持续时间最短,求偶次数最少,雌蛾性信息素滴度始终处于较低水平,交配率也属于最低。在微光(0.5 lx)下,雌蛾求偶起始时间最短,求偶持续时间最长,求偶次数最多;雌蛾性信息素始终处于较低水平,但暗期后段求偶率高达40%。【结论】强光(50.0 lx)可以抑制棉铃虫雌蛾的求偶行为、性信息素的合成及交配;微光(0.5 lx)可以促进棉铃虫雌蛾的求偶行为;相对黑暗环境(0 lx),微光(0.5 lx)还可以促进棉铃虫快速(1 h)完成交配,微光(0.5 lx)对棉铃虫的交配行为具有重要意义;求偶和性信息素的合成没有必然联系。本研究可为探讨光对夜蛾交配行为的影响提供一定的理论基础,也可为利用物理、化学通讯信息调控夜蛾行为提供一定的参考。