Location,morphology and histology of sex pheromone glands of the female gypsy moth, Lymantria dispar (L.)

Scanning electron microscopy, histology and a male wing fanning bioassay were used in this study to locate the sex pheromone-producing glands of the female gypsy moth, Lymantria dispar. When exposed to female sex pheromone, adult males exhibit a strong wing fanning behaviour prior to take off. We found that adult males showed positive response to calling females and to tissue extract from both dorsal and ventral portions of the intersegmental membrane between 8th and 9th-abdominal segments. A typical male response usually starts with elevation of antennae, movement of head in different directions, walking, wing fanning and onset of search flight. Histological and scanning electron microscopic studies suggested that the sex pheromone glands are located on the dorsal and ventral aspects of the intersegmental membrane. The glands appear as two highly convoluted integumentary areas with hypertrophied glandular epidermal cells.     

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.     

Orientation of male gypsy moths,Lymantria Dispar (L.), to pheromone sources: The role of olfactory and visual cues

The role of olfaction and vision in the close-ranging flying and walking orientation of male gypsy moths, Lymantria dispar(L.), to females was studied in the forest and in the laboratory. In the forest, feral males found an isolated pheromone source as readily as one supplemented with female visual cues; dead, acetonerinsed females deployed without pheromone received virtually no visitations. In flight tunnel choice experiments using cylinders as surrogate trees and pheromone in different spatial configurations, visual attributes of the female did not influence either the males' choice of landing site or the efficiency with which they located the female. Rather, the presence of pheromone on the cylinder was necessary to elicit orientation as well as landing and walking on the cylinder. When a female visual model was placed in various positions around a pheromone source, walking males oriented primarily to the chemical stimulus. There were, however, indications that males would alter their walking paths in response to female visual cues over short distances (<5 cm), but only if they continued to receive pheromone stimulation. When visual and chemical cues were abruptly uncoupled by altering the trajectory of the pheromone plume, most males responded to the loss of the odor cue rather than to visual cues from the female. Temporal pheromone stimulation patterns affected male walking orientation. When stimulated by pheromone, males oriented toward the source; loss of the odor cue prompted an arearestricted local search characterized by primarily vertical and oblique movements with frequent reversals in direction. Presumably these maneuvers enhance the likelihood of recontacting the plume or serendipitously encountering the female. The apparent lack of visual response to the female is discussed in light of morphological and behavioral evidence suggesting that gypsy moths were formerly nocturnal.     

Determination of the site of pheromone emission in the virgin females Culicoides nubeculosus Meigen (Diptera: Ceratopogonidae)

The zone of emission of the sex pheromone from the body of Culicoides nubeculosus was investigated. The amount of pheromone emitted was evaluated by counting the number of matings between males and females exposed to a flow of air coming from a chamber containing virgin females. The number of matings is higher than that recorded when the air flow comes from an empty chamber (control). Three parts of the body were examined: head, thorax and abdomen. Each part was studied by neutralizing the effect of the others. The head was neutralized by decapitation and the females continued to emit pheromone. The head is, therefore, not indispensible for pheromone emission. The roles of the thorax and abdomen were studied by coating these with paraffin wax. When the thorax is coated, pheromone emission continues, but when the abdomen is coated, it stops. It appears that the abdomen alone is responsible for emission of the sex pheromone.     

Effectiveness of gypsy moth mating disruption from aerial applications of plastic laminate flakes with and without a sticking agent

1 The plastic laminate flake formulation, Disparlure II, is currently the only gypsy moth mating disruption product available for aerial application. The elimination of a sticking agent from the formulation would reduce costs, simplify application, and make it possible to apply the product without specialized equipment. 2 A test was conducted in wooded plots in Virginia during 1997 and 1998 to determine whether a sticking agent is necessary. Treatment effectiveness was assessed from the rates of male moth capture in pheromone‐baited traps and mating success of both laboratory‐reared and wild females. 3 Male moth capture was reduced 75.6 and 92.9% in plots treated with flakes without and with a sticking agent, respectively. The percentage of mated females that produced egg masses with more than 5% fertile eggs was reduced by 86.3 and 99.5% in plots treated with flakes without and with a sticking agent, respectively. 4 Moth capture and mating success of laboratory‐reared females did not differ significantly between plots treated with flakes with and without a sticking agent. However, the consistently greater reduction in mating success in both years provides strong evidence that mating disruption is less effective when flakes are applied without a sticking agent. The proportion of wild egg masses collected in 1998 with more than 5% fertile eggs was significantly higher under the no‐sticking agent treatment. 5 In special situations where the use of a sticking agent may be problematic, such as in residential areas, the data indicate that a high level of mating disruption is likely to occur even without the use of a sticking agent.     

Influence of pheromone concentration and ambient temperature on flight of the gypsy moth, Lymantria dispar (L), in a sustained-flight wind tunnel

Abstract. The effects of pheromone concentration and ambient temperature on male gypsy moth, Lymantria dispar (L.) (Lepidoptera), flight responses to pheromone were investigated in a wind tunnel. As the pheromone dose increased from 10 ng to 1000 ng, males flew at progressively slower airspeeds and ground speeds, and reduced their wingbeat frequencies. Furthermore, the moths steered significantly smaller course angles as the pheromone concentration increased, indicating that they were adopting a more upwind heading. The overall width of the flight tracks also decreased when males flew in more concentrated pheromone plumes. Estimation of plume dimensions using a male wing-fanning assay showed that as pheromone dosage increased, the resultant active spaces became wider, indicating that an inverse relationship existed between the dimensions of the time-averaged plume and the width of track reversals and that most turns were initiated within the plume. When males were flown at cool (20°C) and warm (26°C) ambient temperatures but to equivalent pheromone emission rates, they exhibited higher airspeeds and ground speeds at the higher temperature but steered larger course angles. Track widths, and length of track legs were, however, similar at the two temperatures. The mean turning frequency was nearly the same (c. 4 turns/s) across all the concentrations and temperatures tested even though the moths' thoracic temperature differed by 5°C when the ambient temperature was varied.     

Lack of humoral control in calling and pheromone release by brain,corpora cardiaca,corpora allata and ovaries of the female gypsy moth, Lymantria dispar (L.)

Investigations into the physiological regulation of calling behaviour and pheromone release by the adult female gypsy moth, Lymantria dispar, showed that the brain, corpora cardiaca, corpora allata and ovaries play no significant endocrine role for either calling behaviour or pheromone release. Removal of corpora allata, corpora cardiaca-corpora allata complex and ovaries from last-instar larvae had no effect on calling behaviour nor on the pheromone release in the resulting moths. Severing the suboesophageal connectives had no effect on calling, but effectively eliminated pheromone release. Since severing nerves should not remove humoral output from the brain, the regulation on pheromone release appears neural.     

六星黑点豹蠹蛾求偶行为与性信息素产生和释放的时辰节律

六星黑点豹蠹蛾Zeuzera leuconotum Butler(Lepidoptera:Cossidae)是一种重要的园林害虫。为研究利用其性信息素防控六星黑点豹蠹蛾,在光周期L∶D=14∶10、温度19—32℃、相对湿度75%—85%条件下,对雌蛾求偶行为进行了观察;采用腺体提取法和瓶内收集法分别制备了不同日龄在同一时辰、同日龄在不同时辰的雌蛾性信息素粗提物,然后测定雄蛾触角对各种性信息素提取物的触角电位反应;以雄蛾对腺体提取物的EAG值表示性信息素的产生量,对瓶内收集物的EAG值表示释放量,检测性信息素产生与释放的时辰节律。结果表明:雌蛾求偶均发生在暗期;雌蛾求偶率与日龄有关,其中2日龄雌蛾求偶率最高,平均为86.7%;不同日龄雌蛾求偶高峰期均在进入暗期4—6h期间;随着虫龄的增加,求偶高峰期前移。雌蛾羽化当晚体内即可产生性信息素,并且向体外释放,但量较少;2日龄雌蛾产生和释放的性信息素量最大;雌蛾腺体中性信息素含量从进入暗期后逐渐增加,在暗期5h含量最高,随后逐渐减少;雌蛾释放性信息素从暗期4h开始,至暗期6h释放量最大。通过林间处女雌蛾诱捕试验证明了六星黑点豹蠹蛾的求偶行为与性信息素产生和释放在时辰节律上具有一致性。     

Oddity in diel periodicity of Ditula angustiorana (Haw.) (Lepidoptera: Torticidae) female calling behaviour,pheromone titre and reproductive activity

The diel periodicity of female calling behaviour in Ditula angustiorana (Haw.) was studied under laboratory conditions. Observations throughout photophases and scotophases showed that D. angustiorana females presented a rare diurnal calling behaviour with two distinct calling periods, one at the first part of the photophase (L+5) and another one at the end (L+14). Mating only occurred during the second calling period (L+14). Five components were identified in extracts of the pheromone glands: Z10–14:Ac, 14:Ac, Z10–14:OH, Z8–14:Ac, Z8–14:OH in the average ratio of 74.1/18.2/4.8/2.2/0.6 respectively. The blend ratio remains similar throughout the photoperiod, whilst the total quantity of pheromone components reached a maximum during the calling period overlapping the mating period (L+14). Wind tunnel experiment confirms that the synthetic blend baited with the identified pheromone components was as attractive as calling females for males. The particular chemical structure of the components within Tortricidae and the particular occurrence of the two calling periods, one not matching any reproductive behaviour are discussed in terms of phylogeny and sexual selection.     

The effects of mating,exogenous juvenile hormone and a juvenile hormone analogue on pheromone titre,calling and oviposition in the omnivorous leafroller moth (Platynota stultana)

Mating in Platynota stultana resulted in the termination of calling, the gradual reduction of pheromone in the pheromone glands to non-detectable levels (<0.1 ng/♀) within 14 h, and oviposition of the first batch of eggs 20–24 h after copulation. Decapitation of virgin females resulted in a similar decline in pheromone titre, and also eliminated oviposition and calling. Pheromone production appears to be controlled via the head. Mating probably terminates neural or hormonal input required for pheromone production and/or removes neural or hormonal inhibition of pheromone degradation. A juvenile hormone analogue (ZR-512) and juvenile hormones I, II and III applied exogenously to virgin females elicited oviposition comparable to mated females and terminated calling within 48 h. The juvenile hormone analogue also appeared to block pheromone production in virgin females. These results suggest that juvenile hormone may be involved in the switch from virgin to mated behaviour in this species.     

Effects of increased atmospheric CO2 on nutritional contents in poplar (Populus pseudo-simonii [Kitag.]) tissues and larval growth of gypsy moth (Lymantria dispar)

Changes in the concentrations of phytochemical compounds usually occur when plants are grown under elevated atmospheric CO₂. CO₂-induced changes in foliar chemistry tend to reduce leaf quality and may further affect insect herbivores. Increased atmospheric CO₂ also has a potential influence on decomposition because it causes variations in chemical components of plant tissues. To investigate the effects of increased atmospheric CO₂ on the nutritional contents of tree tissues and the activities of leaf-chewing forest insects, samples of Populus pseudo-simonii [Kitag.] grown in open-top chambers under ambient and elevated CO₂ (650 μmol mol^-1) conditions were collected for measuring concentrations of carbon, nitrogen, C : N ratio, soluble sugar and starch in leaves, barks, coarse roots (>2 mm in diameter) and fine roots (<2 mm in diameter). Gypsy moth (Lymantria dispar) larvae were reared on a single branch of experimental trees in a nylon bag with 1 mm 1 mm grid. The response of larval growth was observed in situ. Elevated CO₂ resulted in significant reduction in nitrogen concentration and increase in C : N ratio of all poplar tissues. In all tissues, total carbon contents were not affected by CO₂ treatments. Soluble sugar and nonstructural carbohydrate (TNC) in the poplar leaves significantly increased with CO₂ enrichment, whereas starch concentration increased only on partial sampling dates. Carbohydrate concentration in roots and barks was generally not affected by elevated CO₂, whereas soluble sugar contents in fine roots decreased in response to elevated CO₂. When second instar gypsy moth larvae consuming poplars grew under elevated CO₂ for the first 13 days, their body weight was 30.95% lower than that of larvae grown at ambient CO₂, but no significant difference was found when larvae were fed in the same treatment for the next 11 days. Elevated atmospheric CO₂ had adverse effects on the nutritional quality of Populus pseudo-simonii [Kitag.] tissues and the resultant variations in foliar chemical components had a significant but negative effect on the growth of early instar gypsy moth larvae.     

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.     

Behavioral responses of maleHeliothis armigera (Lepidoptera: Noctuidae) moths in a flight tunnel to combinations of components identified from female sex pheromone glands

Six compounds were identified from gland extracts of the cotton bollworm, Heliothis armigera(Hubner): (Z)-11-hexadecenal (Z11-16:Ald), (Z)-9-hexa-decenal (Z9-16:Ald), hexadecanal, (Z)-11-hexadecenol (Z11-16:OH), (Z)-7-hexadecenal (Z7-16:Ald), and (Z)-9-tetradecenal (Z9-14:Ald). Each of the compounds that were identified was examined for its ability to elicit sexual responses from male moths in a flight tunnel. Males flew upwind to Z11-16:Ald alone, but greater levels of copulatory responses were evoked with the addition of 2.5% Z9-16:Ald to the Z11-16:Ald. Addition of hexadecanal to the binary mixture had no effect in raising the behavioral response of the males in the flight tunnel. The effect of Z7-16:Ald on male flight depended on the loading. The addition of 1% of this component to 2 mg of the binary mixture reduced levels of copulatory response, but the same addition (1 %) to 10 g of the binary mixture increased copulatory response. The addition of 79-14:Ald or Z11-16:OH to the binary mixture reduced behavioral responses of males. High loadings of the binary mixture (200–2000 g) were better than a low loading (10 g) in eliciting response of males.Contribution from the Agricultural Research Organization, The Volcani Center, Bet Dagan, Israel. No. 2455-E, 1988 series.     

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.     

Cloning and functional characterization of a fatty acid transport protein (FATP) from the pheromone gland of a lichen moth, Eilema japonica, which secretes an alkenyl sex pheromone

Sex pheromones of moths are largely classified into two types based on the presence (Type I) or absence (Type II) of a terminal functional group. While Type-I sex pheromones are synthesized from common fatty acids in the pheromone gland (PG), Type-II sex pheromones are derived from hydrocarbons produced presumably in the oenocytes and transported to the PG via the hemolymph. Recently, a fatty acid transport protein (BmFATP) was identified from the PG of the silkworm Bombyx mori, which produces a Type-I sex pheromone (bombykol). BmFATP was shown to facilitate the uptake of extracellular fatty acids into PG cells for the synthesis of bombykol. To elucidate the presence and function of FATP in the PG of moths that produce Type-II sex pheromones, we explored fatp homologues expressed in the PG of a lichen moth, Eilema japonica, which secretes an alkenyl sex pheromone (Type II). A fatp homologue cloned from E. japonica (Ejfatp) was predominantly expressed in the PG, and its expression is upregulated shortly after eclosion. Functional expression of EjFATP in Escherichia coli enhanced the uptake of long chain fatty acids (C₁₈ and C₂₀), but not pheromone precursor hydrocarbons. To the best of our knowledge, this is the first report of the cloning and functional characterization of a FATP in the PG of a moth producing a Type-II sex pheromone. Although EjFATP is not likely to be involved in the uptake of pheromone precursors in E. japonica, the expression pattern of Ejfatp suggests a role for EjFATP in the PG not directly linked to pheromone biosynthesis.     

Female sex pheromone of a lichen moth Eilema japonica (Arctiidae, Lithosiinae): Components and control of production

Seven candidates for components of the female sex pheromone of Eilema japonica (Arctiidae, Lithosiinae) were detected in an extract of pheromone glands with a gas chromatograph-electroantennographic detector. The compounds were identified as (Z,Z)-6,9-icosadiene (D20), (Z,Z)-6,9-henicosadiene (D21), (Z,Z,Z)-3,6,9-henicosatriene (T21), (Z,Z)-6,9-docosadiene (D22), (Z,Z,Z)-3,6,9-docosatriene (T22), (Z,Z)-6,9-tricosadiene (D23), and (Z,Z,Z)-3,6,9-tricosatriene (T23). Assays using synthetic lures in a wind tunnel showed that D21 (proportion, 0.39), T21 (0.08), D22 (0.27), and T22 (0.26) are important for evoking full behavioral responses from the males. Titers of the pheromone components did not show clear temporal fluctuations. Moreover, decapitation of the female moth had no effect on the titers of pheromone components in the pheromone gland, suggesting that cephalic endocrine factors such as pheromone biosynthesis activating neuropeptide (PBAN) are not involved in the control of pheromone biosynthesis in this species.     

Catches of vine bud moth Theresimima ampellophaga (Lep., Zygaenidae: Procridinae) males in pheromone traps: effect of the purity and age of baits, design, colour and height of the traps, and daily sexual activity of males

Pure (2R)‐butyl (7Z)‐tetradecenoate, as well as racemic 2‐butyl (7Z)‐tetradecenoate, in a dose of 100 μg (calculated for the active (2R)‐enantiomer) applied onto serum bottle caps of grey rubber, were an effective pheromone bait for Theresimima ampellophaga (Bayle‐Barelle, 1808) (Lepidoptera: Zygaenidae: Procridinae). This bait remained active for longer than one full flight of the pest in the regions with one generation per year. Colourless transparent as well as red and yellow sticky traps were the cheapest and most simple design for trapping T. ampellophaga, while green and blue traps performed worse. Among the traps tested, VARL (CSALOMON^®) funnel traps had the highest capture ability for the pest. Traps had to be mounted at least 1.0–2.0 m above ground level. T. ampellophaga males flew to a source of sex pheromone all day long with a main peak between 07.00 and 09.00 hours and a much smaller one between 19.00 and 21.00 hours.     

Vaccination with a genetically modified Brugia malayi cysteine protease inhibitor-2 reduces adult parasite numbers and affects the fertility of female worms following a subcutaneous challenge of Mongolian gerbils (Meriones unguiculatus) with B. malayi infective larvae

Vaccination of Mongolian gerbils with Brugia malayi cysteine protease inhibitor-2 in which the amino acid Asn66 was mutated to Lys66 (Bm-CPI-2M) resulted in reduced parasite numbers of 48.6% and 48.0% at 42 and 90 days p.i. with B. malayi L3s. Fertility of female worms was also affected at 90 days p.i. In vitro killing of L3s observed in the presence of gerbil peritoneal exudate cells and anti-Bm-CPI-2M sera suggests antibody-dependent cell-mediated cytotoxicity as a putative protective mechanism. These observations suggest that Bm-CPI-2M is a promising prophylactic and anti-fecundity vaccine candidate.     

Coincident isolation of a novel homoisoflavonoid from Resnova humifusa and Eucomis montana (Hyacinthoideae: Hyacinthaceae)

We report on the first phytochemical investigation of a member of the African genus Resnova (Hyacinthoideae: Hyacinthaceae). From the dichloromethane extract of the bulbs of both Resnova humifusa and Eucomis montana (Hyacinthoideae: Hyacinthaceae) a novel 3-benzyl-4-chromanone homoisoflavonoid, 5,6-dimethoxy-7-hydroxy-3-(4′-hydroxybenzyl)-4-chromanone, was isolated. A further 11 known homoisoflavonoids were also identified, the 12 in total presenting a clear biosynthetic sequence. Eight of the 12 compounds found were common to both species.