Moth Sex Research Articles

A multifunctional desaturase involved in the biosynthesis of the processionary moth sex pheromone.

The sex pheromone of the female processionary moth, Thaumetopoea pityocampa, is a unique C16 enyne acetate that is biosynthesized from palmitic acid. Three consecutive desaturation reactions transform this saturated precursor into the triunsaturated fatty acyl intermediate: formation of (Z)-11-hexadecenoic acid, acetylenation to 11-hexadecynoic acid, and final Delta(13) desaturation to (Z)-13-hexadecen-11-ynoic acid. By using degenerate primers common to all reported insect desaturases, a single cDNA sequence was isolated from total RNA of T. pityocampa female pheromone glands. The full-length transcript of this putative desaturase was expressed in elo1Delta/ole1Delta yeast mutants (both elongase 1 and Delta(9) desaturase-deficient) for functional assays. The construct fully rescued the Deltaole1 yeast phenotype, confirming its desaturase activity. Analysis of the unsaturated products from transformed yeast extracts demonstrated that the cloned enzyme showed Delta(11) desaturase, Delta(11) acetylenase, and Delta(13) desaturase activities. Therefore, this single desaturase may account for the three desaturation steps involved in the sex pheromone biosynthetic pathway of the processionary moth.

Occurrence and effects of Nosema fumiferanae infections on adult spruce budworm caught above and within the forest canopy

Abstract1 Nosema fumiferanae infections in populations of both sexes of spruce budworm Choristoneura fumiferana moths, collected live above the forest canopy (canopy moths), within the tree crown (crown moths) and in drop trays (dead moths), were examined over a 5‐year period in New Brunswick, Canada.2 The incidence of infection and of moderate–heavy infections in canopy and crown moths of both sexes increased concomitantly with moth eclosion, indicating that N. fumiferanae retards larval/pupal development, with infected moths, particularly those having higher disease loads, emerging later in the season.3 Infection rates differed among canopy, crown, and dead female, but not male, moths. Canopy (i.e. emigrating) females had a lower incidence of infection, lower incidence of moderate–heavy infections, and had longer forewings and higher dry weights, than crown females. These results suggest that N. fumiferanae infections negatively affect aspects of female, but not male, flight performance. Regardless of infection, forewing length and dry weight of both canopy and crown females declined over the moth flight period, but infected females in both moth types were smaller than their uninfected counterparts. Forewing lengths and dry weights of moderately–heavily infected females were most severely affected.4 Despite high annual infection rates in parents, only a small percentage of offspring (second‐instar larvae) that established feeding sites each spring were infected, indicating that high rates of horizontal transmission occurred annually throughout the larval period.5 The present study indicates that whether N. fumiferanae infections are a debilitating sublethal factor in spruce budworm populations depends more on the disease load than on the overall incidence of infection. The potential importance of N. fumiferanae infections on various fitness parameters related to host dispersal is discussed.

Synthesis of 4E,7Z-tridecadien-1-ylacetate, a component of the Phthorimaea opercucella sex pheromone

A new synthetic approach to 4E,7Z-tridecadien-1-ylacetate, a component of the Phthorimaea opercucella (Zeller) potato moth sex pheromone, was developed using a highly stereoselective Claisen rearrangement and Wittig reaction.

Support for (Z)-11-Hexadecanal as a Pheromone Antagonist in Ostrinia nubilalis: Flight Tunnel and Single Sensillum Studies with a New York Population

The flight-tunnel response of male Z-strain European corn borer moths (ECB), Ostrinia nubilalis, from a population in New York State (USA), was significantly antagonized by addition of 1% (Z)-11-hexadecanal (Z11-16:Ald) to their sex pheromone (a 97:3 mix of (Z)- and (E)-11-tetradecenyl acetate [Z/E11-14:OAc]). The level of antagonism was equivalent to that observed for the previously identified ECB antagonist, (Z)-9-tetradecenyl acetate (Z9-14:OAc), and supports a recent report showing that Z11-16:Ald, a minor pheromone component of the Noctuid moth, Sesamia nonagrioides, caused antagonism of ECB pheromone communication in sympatric populations in the Iberian Peninsula. Single-sensillum recordings from ECB antennae, which included cross-adaptation experiments, showed that the same olfactory receptor neuron processing Z9-14:OAc inputs was responsible for detecting Z11-16:Ald, and that this neuron was not responsive to two other aldehydes, (Z)-9-tetradecanal (Z9-14:Ald) and (Z)-9-hexadecanal (Z9-16:Ald), found in other moth sex pheromones. Our results show that the antagonism is not confined to one geographic region, is specific for Z11-16:Ald, and that antagonist pathways might have the potential for processing a number of structurally similar compounds.

Novel sex pheromone desaturases in the genomes of corn borers generated through gene duplication and retroposon fusion.

The biosynthesis of female moth sex pheromone blends is controlled by a number of different enzymes, many of which are encoded by members of multigene families. One such multigene family, the acyl-CoA desaturases, is composed of certain genes that function as key players in moth sex pheromone biosynthesis. Although much is known regarding the function of some of these genes, very little is known regarding how novel genes have evolved within this family and how this might impact the establishment of new sex pheromone blends within a species. We have discovered that several cryptic Delta11 and Delta14 desaturase genes exist in the genomes of the European and Asian corn borers (Ostrinia nubilalis and Ostrinia furnacalis, respectively). Furthermore, an entirely novel class of desaturase gene has arisen in the Ostrinia lineage and is derived from duplication of the Delta11 desaturase gene and subsequent fusion with a retroposon. Interestingly, the genes have been maintained over relatively long evolutionary time periods in corn borer genomes, and they have not been recognizably pseudogenized, suggesting that they maintain functional integrity. The existence of cryptic desaturase genes in moth genomes indicates that the evolution of moth sex pheromone desaturases in general is much more complex than previously recognized.

Detection versus perception: Physiological and behavioral analysis of olfactory sensitivity in the moth (Manduca sexta).

The precise relationship between olfactory transduction sensitivity and sensitivity at the level of sensory perception is poorly understood. The goal of this work was to correlate neurophysiological measures of sensory transduction and psychophysical measures of salient odor perception using the moth (Manduca sexta). Moths were conditioned to respond to a single monomolecular odor and then tested across a dilution series. Resulting concentration-response functions were dependent on the conditioning odor and its concentration but not on the moth's sex. Comparison of responsiveness to odor versus an odorless blank provided a statistical indicator of detection threshold. Separate control experiments revealed that conditioned responsiveness to odor was a function of test concentration and independent of the conditioning concentration. Next, electroantennogram (EAG) responses to these odorants and concentrations were recorded. EAG responses were highly correlated with the behavioral results but typically identified lower detection thresholds. Furthermore, significant effects of sex, Sex x Odor, and Sex x Odor x Concentration were observed only within the EAG data, suggesting a mismatch across methods. Possible reasons for and implications of this mismatch are discussed.

Differentiation of Competitive vs. Non-competitive Mechanisms Mediating Disruption of Moth Sexual Communication by Point Sources of Sex Pheromone (Part 2): Case Studies

Eleven out of 13 disruption profiles (plots of dispenser density vs. male catch) from moth sex pheromone literature were consistent with a competitive-attraction mechanism, in which dispensers attract males and thereby divert them from females. Mean dispenser activity (D(a)) across all competitive-attraction cases was 0.04 +/- 0.06 (SD); values ranged from 0.0005 for a tiny laminated flake dispenser of racemic disparlure targeting gypsy moth to 0.2 for polyethylene tube dispensers used against lightbrown apple moth. A dispenser application activity (D(Aa)) can be calculated by multiplying D(a) by the number of such dispensers applied per hectare of crop. The highest dispenser application activity (D(Aa)) values approached 200 and corresponded to >99% inhibition of catches of male moths in monitoring traps. Relative to the D(Aa) scale, % inhibition of catches of male moths compressed and obscured large differences in D(Aa) when % disruption exceeded 90%. For cases of competitive attraction, these two efficacy scales can be interconverted by using the formula: D(Aa) approximately = 100/(100 minus % disruption). When disruptive point sources of pheromone were directly observed, male moths were seen approaching pheromone dispensers whose disruption profiles matched competitive attraction. Two cases fit non-competitive disruption mechanisms, which include camouflage, desensitization (adaptation and/or habituation), and sensory imbalance. In these cases, pheromone was released at rates higher than for cases of disruption by competitive attraction. Practical ramifications of the finding that competitive attraction appears to be the prevalent mechanism for moth mating disruption by pheromone point sources are listed. We believe that the congruence of diverse sets of mating disruption field data with explicit a priori predictions validates competitive-attraction theory. The analytical tools and principles governing competitive attraction that were uncovered during this study of mating disruption of moths should be generally applicable to competitive-attraction phenomena.

Field Response of Alfalfa Looper and Cabbage Looper Moths (Lepidoptera: Noctuidae, Plusiinae) to Single and Binary Blends of Floral Odorants

In field tests of floral chemicals dispensed singly, alfalfa looper moths, Autographa californica (Speyer), were captured in traps baited with phenylacetaldehyde, &bgr;-myrcene, or benzyl acetate. Cabbage looper moths, Trichoplusia ni (Hübner) were also captured in traps baited with phenylacetaldehyde, methyl salicylate, or methyl-2-methoxy benzoate. In evaluations of binary blends of those same compounds, generally more alfalfa looper moths were trapped when &bgr;-myrcene was presented with phenylacetaldehyde or with benzyl acetate compared with phenylacetaldehyde alone or benzyl acetate alone. Similarly, more cabbage looper moths were trapped with &bgr;-myrcene with phenylacetaldehyde compared with phenylacetaldehyde alone. These findings provide new chemical blends for luring and trapping both sexes of alfalfa looper and cabbage looper moths and suggest differences in preferences of these two moth species for floral odorants.

Pheromone component patterns of moth evolution revealed by computer analysis of the Pherolist

1. The Pherolist internet site listing moth sex pheromone components reported in the literature was downloaded and processed by a basic program into a database with 2931 combinations of 377 unique chemical names of sex pheromone attractants used by 1572 moth species in 619 genera and 49 families. Names of pheromone compounds were analysed for aliphatic chain length, unsaturation position, geometric configuration, functional group (aldehyde, alcohol, acetate, epoxide, methyl-branched and hydrocarbon) and number of instances such combinations are used by species and families. 2. The analyses revealed pheromone blends of species ranged from one to eight components (45% species with one component, 36% two, 12% three, 5% four, 1% five, < or = 0.5% for > or = six). The numbers of different components of various chain lengths and functional groups, the numbers of instances such compounds are used by species and the numbers of species using such compounds are presented. 3. The average number of pheromone components per species increased as the number of species in a family increased based on linear regression of components in the 10 largest families, with species numbers ranging from 19 to 461. Pooling the four largest families gave a mean of 1.96 components per species that was significantly greater than the mean of the next 14 smaller families (1.63). Because related species in a large family would need more communication channels, this suggests that these species on average evolved to produce and detect more components in their pheromone blends to achieve a unique communication channel than was needed by species in smaller families. 4. Speciation in moths would entail evolutionary changes in both pheromone biosynthetic and sensory systems that avoided competition for communication channels of existing species. Regression analysis indicated that the more species in a family the more unique pheromone components, but the increase diminishes progressively. This suggests that, as the number of components increases with species number in a family, new species are more likely to evolve a unique blend comprising a communication channel from among existing components of the family.

Effects of intentional gaps in spray coverage on the efficacy of gypsy moth mating disruption

Abstract: The study was conducted during 2001 and 2002 in forested areas in Virginia, US to examine the effects of gaps in coverage of pheromone on gypsy moth, Lymantria dispar (L.) (Lep., Lymantriidae), mating disruption. Gypsy moth male moth catches in pheromone‐baited traps were significantly reduced in plots treated with the gypsy moth sex pheromone, disparlure, at an overall application rate of 37.5 g of active ingredient (AI)/ha but with untreated gaps of 30 or 90 m between 30‐m wide treated swaths. In one of the two plots with 90 m gaps, significantly more males were captured in traps in the untreated areas compared with the treated areas within the plot. However, in another plot, significant differences in trap catches between treated and untreated areas were not observed. No difference in male moth catches in the pheromone‐baited traps was observed between treated and untreated areas within the plots treated with 30 m gaps. Female mating success did not differ significantly between treated and untreated areas within the one plot in which it was measured. These results suggest that it may be possible to lower costs associated with gypsy moth mating disruption applications by alternating treated and untreated swaths, which would reduce flight time and fuel costs, without a reduction in efficacy.

A short and efficient synthesis of (+)-disparlure and its enantiomer

A short and highly efficient approach was applied for the total synthesis of the gypsy moth sex pheromone (+)-disparlure and its enantiomer from isopropylidene D- and L-erythrose, using a common strategy.

Evaluation of Pheromone Release from Commercial Mating Disruption Dispensers

Pome fruit growers and crop consultants have expressed concerns about the seasonal release performance of commercial codling moth mating disruption dispenser products. Because of these concerns, we developed a laboratory flow-through volatile collection system (VCS) for measuring the volatile release of the codling moth sex pheromone, codlemone, from commercially available hand-applied dispensers. Under controlled air-flow and temperature conditions, the released vapor was trapped onto a polyurethane foam adsorbent followed by solvent extraction, solvent reduction, and GC/MS determination. Method recovery and breakthrough validations were performed to demonstrate system reliability before determining codlemone release from commercial dispensers field-aged over 140 days. The volatile collection was carried out in a consistent manner among five dispenser types most commonly used by growers, so that direct comparison of performance could be made. The comparison showed differences in the amount of pheromone released and in the patterns of release throughout the season between dispenser types. The variation in release performance demonstrates the need for routine evaluation of commercially marketed mating disruption dispensers. We believe that the simple and cost-effective volatile collection system can assist pheromone dispenser manufacturers in determining seasonal dispenser performance before new products are introduced into the commercial market and in rapidly verifying dispenser release when field-aged dispenser efficacy is in question.

Expression and evolution of Δ 9 and Δ 11 desaturase genes in the moth Spodoptera littoralis

Desaturation of fatty acids is a key reaction in the biosynthesis of moth sex pheromones. The main component of Spodoptera littoralis sex pheromone blend is produced by the action of Δ 11 and Δ 9 desaturases. In this article, we report on the cloning of four desaturase-like genes in this species: one from the fat body (Sls-FL1) and three (Sls-FL2, Sls-FL3 and Sls-FL4) from the pheromone gland. By means of a computational/phylogenetic method, as well as functional assays, the desaturase gene products have been characterized. The fat body gene expressed a Δ 9 desaturase that produced ( Z)-9-hexadecenoic and ( Z)-9-octadecenoic acids in a (1:4.5) ratio, whereas the pheromone gland Sls-FL2 expressed a Δ 9 desaturase that produced ( Z)-9-hexadecenoic and ( Z)-9-octadecenoic acids in a (1.5:1) ratio. Although both Δ 9 desaturases produced ( Z)-9-tetradecenoic acid from myristic acid, transformed yeast grown in the presence of a mixture of myristic and ( E)-11-tetradecenoic acids produced ( Z, E)-9,11-tetradecadienoic acid, but not ( Z)-9-tetradecenoic acid. The Sls-FL3 gene expressed a protein that produced a mixture of ( E)-11-tetradecenoic, ( Z)-11-tetradecenoic, ( Z)-11-hexadecenoic and ( Z)-11-octadecenoic acids in a 5:4:60:31 ratio. Despite having all the characteristics of a desaturase gene, no function could be found for Sls-FL4.

Desaturases from the spotted fireworm moth ( Choristoneura parallela) shed light on the evolutionary origins of novel moth sex pheromone desaturases

Six acyl-CoA desaturase-encoding cDNAs from mRNA isolated from the spotted fireworm moth, Choristoneura parallela (Lepidoptera: Tortricidae) were characterized and assayed for functionality. The expression levels of these cDNAs were determined in the pheromone gland and fat body by real-time PCR and the resulting patterns are in line with results from published studies on other moth sex pheromone desaturases. The cDNAs were found to correspond to six genes. Using both biochemical and phylogenetic analyses, four of these were found to belong to previously characterized desaturase functional groups [the Δ10,11, the Δ9 (16>18) and the Δ9 (18>16) groups]. A desaturase highly expressed in the pheromone gland was a novel E11 desaturase that was specific to 14-carbon precursor acids. The fifth gene [CpaZ9(14–26)] was found to display a novel Z9 activity indicating that it belongs to a new Δ9 functional group, whereas the sixth gene was determined to be nonfunctional with respect to desaturase activity. In accordance with previous studies, we find that desaturases of the Δ10,11 and Δ14 groups, which are the fastest evolving desaturases and possess the novel pheromone biosynthetic function, are expressed primarily in the pheromone gland whereas all other desaturases, which do not possess the novel reproductive function, evolve more slowly and display the ancestral metabolic function and pattern of gene expression.

Sublethal effects of larval treatment with deltamethrin on moth sex pheromone communication system of the Asian corn borer, Ostrinia furnacalis

The first, third, and fifth instar larvae of Asian corn borer, Ostrinia furnacalis (Guenée) (Lepidoptera: Pyralidae), were treated with a lethal dose 30% of deltamethrin to determine its sublethal effects on chemical communication of the adult survivors. The capability of all males surviving deltamethrin to contact the pheromone source in a wind tunnel was significantly reduced, but those treated as the first and third instars also exhibited lower percentages of `orientation,' `up-wind flight,' and `approaching' behaviors than the control males. Female moths from the deltamethrin treatment exhibited similar calling periodicity and percentages to the control moths during 10-h scotophase. However, approximately 20% of the females that survived the pyrethroid in the first and third instars contained significantly higher amounts of sex pheromone and wider coefficients of variation of the ratio of E12-tetradecenyl acetate to its Z isomer in those female survivors. There was no significant difference in the pheromone titers and coefficients of variation in control females and the females treated in the fifth instars. The present study indicates that the Asian corn borer may possess a compensation system by which the males that survived treatment at larval stage present a lower response to the pheromone, while the female survivors produce and release more pheromone.

First semi-synthetic preparation of sex pheromones

Here we describe the first construction of a genetically modified plant (GMP) with the ability to produce moth sex pheromone precursors. Previously prepared (Svatos et al., Czech Patent Appl. 2000/0125) N. tabacum GMP transformed with a plasmid encoding cabbage looper moth (Trichoplusia ni, Hubner, Lepidoptera, Noctuidae) acyl-CoA Δ11-(Z)-desaturase (Knipple et al., Proc. Natl. Acad. Sci. USA, 1998, 95, 15287) showed a substantial presence (ca. 6%) of the potential pheromone precursor, methyl (11Z)-hexadec-11-enoate (1). The ester 1 was isolated in bulk (6.5% of extracted lipids) from a greenhouse cultivated transgenic tobacco and the corresponding acetate, which are principal components of a large number of sex pheromones, was semi-synthetically prepared from the in planta produced pheromone precursor. The attractiveness of the prepared blends for moth, Mamestra brassica was proved in field trials.

Evolution of moth sex pheromones via ancestral genes.

Mate finding in most moth species involves long-distance signaling via female-emitted sex pheromones. There is a great diversity of pheromone structures used throughout the Lepidoptera, even among closely related species. The conundrum is how signal divergence has occurred. With strong normalizing selection pressure on blend composition and response preferences, it is improbable that shifts to pheromones of diverse structures occur through adaptive changes in small steps. Here, we present data supporting the hypothesis that a major shift in the pheromone of an Ostrinia species occurred by activation of a nonfunctional desaturase gene transcript present in the pheromone gland. We also demonstrate the existence of rare males that respond to the new pheromone blend. Their presence would allow for asymmetric tracking of male response to the new blend and, thus, evolution of an Ostrinia species with structurally different sex pheromone components.

Aggressive chemical mimicry of moth pheromones by a bolas spider: how does this specialist predator attract more than one species of prey?

The bolas spider, Mastophora hutchinsoni, attracts Lacinipolia renigera and Tetanolita mynesalis males by mimicking the female moth sex pheromones. However, as the prey species use completely different pheromone blends we conducted experiments to determine how this is accomplished by the predator. The periodicity of L. renigera mate-seeking activities occurs early in the scotophase, whereas male T. mynesalis are active late at night, corresponding with periods when these moths are captured by the spider. The pheromone blend of early-flying L. renigera interferes with attraction of late-flying T. mynesalis to its pheromone in a dose-dependent manner, suggesting the spider must always produce a single sub-optimal “compromise” blend for both species or that it adjusts its allomonal blend to optimize capture of the respective prey species at different times during the night. We delayed (L. renigera) or advanced (T. mynesalis) the periodicity of male activity through photoperiodic manipulation and found that the bolas spider attracted both prey species outside their normal activity windows. These results support the idea that bolas spiders produce components of both species at all times rather than producing the pheromone of each prey species at different times of the night. However, using coupled gas chromatography-electroantennography, we also demonstrated that the spider decreases its emission of the L. renigera pheromone over the course of the night. This modification should reduce the behavioral antagonism of the L. renigera pheromone on T. mynesalis males and increase the predator's success of attracting T. mynesalis during this prey's normal activity window late at night.

Field and Laboratory Responses of Male Codling Moth (Lepidoptera: Tortricidae) to a Pheromone-Based Attract-and-Kill Strategy

A case study of a pheromone-based attract-and-kill management strategy for codling moth, Cydia pomonella (L.), was conducted to examine key insect behavioral factors mitigating the possible effectiveness of this strategy. Last Call CM is a newly registered attracticide product that combines the primary component of codling moth sex pheromone with the insecticide permethrin. Studies of competition between pheromone point sources within caged trees showed individual attracticide droplets were significantly more attractive to male moths than calling females. In commercial orchard blocks, marked male moths were recaptured after visiting attracticide droplets applied at rates of 50, 100, and 200 droplets/ha, although no marked moths were recaptured in plots with 500 droplets/ha. This experiment also revealed no significant differences among 0, 50, 100, and 200 droplets/ha in suppressing total catch in female-baited traps, nor were total numbers of females attracting at least one male reduced significantly. In plots with 500 droplets/ha applied, male moth catch was suppressed significantly compared with catches in untreated control plots, and the number of females attracting at least one male was reduced significantly as well. Experiments investigating sublethal physiological effects of attracticide exposure upon mating competency of male codling moths demonstrated male leg autotomy at 1, 24, 48, and 72 h after exposure. Male codling moth at 1, 24, 48, and 72 h after exposure placed near calling virgin females exhibited significant behavioral differences from sham-treated males in courtship and mating. These results clarify some of the possible mechanisms, and strengths and weaknesses of this attract-and-kill management strategy for codling moth.

Internet programs for drawing moth pheromone analogs and searching literature database.

An Internet web page is described for organizing and analyzing information about lepidopteran sex pheromone components. Hypertext markup language (HTML) with JavaScript program code is used to draw moth pheromone analogs by combining GIF bitmap images for viewing by web browsers such as Netscape or Microsoft Intemet Explorer. Straight-chain hydrocarbons of 5-22 carbons with epoxides or unsaturated positions of E or Z geometrical configuration with several altemative functional groups can be drawn by simply checking menu bars or checkboxes representing chain length, E/Z unsaturation points, epoxide position and chirality, and optional functional groups. The functional group can be an aldehyde, alcohol, or ester of formate, acetate, propionate, or butyrate. The program is capable of drawing several million structures and naming them [e.g., (E,E)-8,10-dodecadien-1-ol and abbreviated as E8E10-12:OH]. A Java applet program run from the same page searches forthe presently drawn structure in an intemal database compiled from the Pherolist, and if the component is found, provides a textarea display of the families and species using the component. Links are automatically specified for drawn components if found in the Pherolist web site (maintained by H. Am). Windowed links can also be made to two other JavaScript programs that allow searches of a web site database with over 5900 research citations on lepidopteran semiochemicals and a calculator of vapor pressures of some moth sex pheromone analogs at a specified temperature. Various evolutionary and biosynthetic aspects are discussed in regard to the diversity of moth sex pheromone components.