Attraction ofCacoecimorpha pronubana male moths to synthetic sex pheromone blends in the wind tunnel

Attraction ofCacoecimorpha pronubana male moths to blends of four sex pheromone components was studied in the wind tunnel.Z11–14Ac alone did not elicit upwind flight, admixture of 10%Z11–14OH or more led to successful attraction of males to the source. Attractivity of these binary blends was further enhanced by addition ofE11–14Ac orZ9–14Ac; the optimum was a blend ofZ11–14Ac,Z11–14OH,E11–14Ac, andZ9–14Ac at the proportion of 1003033. In ternary and quaternary blends, the effect ofZ11–14OH andE11–14Ac was strongest at 30% and 3%, respectively. By contrast,Z9–14Ac increased behavioral responses over a wide range.     

Disruption of male spruce budworm orientation to calling females in a wind tunnel by synthetic pheromone

Male spruce budworm [Chorisloneura fumiferana (Clem.)] moths were held for 3 hr in a wind tunnel and subjected to various concentrations of background synthetic pheromone. They were then exposed to calling females and their response was recorded. The background pheromone was presented either as discrete turbulent plumes or as a uniform permeation throughout the tunnel. The numbers of males wing-fanning and flying in response to the calling females decreased as the concentration of background pheromone increased. Of the males which flew, a higher proportion progressed upwind in the discrete plumes than in the uniform permeation, an indication that structure in the pheromone cloud is necessary for upwind progression. In both discrete plumes and uniform permeation fewer males were able to locate the females (i.e., disruption was greater) as the concentration of synthetic pheromone increased, but for the same total release rates, disruption was greater when the synthetic pheromone was released in discrete plumes rather than in a uniform permeation. This implies that disruption which involves luring males to sources of synthetic pheromone is more effective than masking female plumes by uniform permeation and suggests that it is more efficient to release pheromone from a few potent sources than from numerous low-potency sources.     

Disruption of male oriental fruit moth to calling females in a wind tunnel by different concentrations of synthetic pheromone

Disruption of male Oriental fruit moth orientation to calling females was studied in a wind tunnel by surrounding calling female moths with septa loaded with synthetic pheromone. At the lowest loadings, 0.01 and 0.1µg, which produced release rates well below those of calling females, some males flew to septa instead of the females. At loadings of 1 and 10µg, which produced release rates close to those of a calling female, more than half the males flew to septa instead of the females, but there was little evidence of habituation at any of these loadings. At higher loadings, 100 and 1000µg, upwind flight of males was arrested, and many males remained inactive, indicating habituation. Preexposure of the males for 3 hr to ambient pheromone concentrations in the tunnel had no significant effect on numbers of disrupted males. However, at the 1000-µg loading, most of the males that had been preexposed to the synthetic pheromone remained inactive. This may indicate a higher level of habituation than among males that had not been preexposed, most of which flew, although they subsequently showed flight arrestment. Levels of disruption were similar to those found for the spruce budworm in comparable experiments. In both species, less than 1% of the males were able to locate females when time-averaged concentrations of synthetic pheromone were above 20 ng/m³. However, levels of inactivity and flight arrestment were higher among male Oriental fruit moths than among male spruce budworms, which may explain why Oriental fruit moths are more susceptible to disruption than are spruce budworms.     

Identification of male cabbage looper sex pheromone attractive to females

A multicomponent pheromone produced by male cabbage looper moths that is attractive to female moths in a flight tunnel bioassay was isolated and identified. Based on analyses of hairpencil extracts of male cabbage loopers and volatiles emitted by males, the pheromone has been identified as a blend consisting of (S)-(+)-linalool,p-cresol, andm-cresol. The chirality of the major component, (S)-(+)-linalool, is important for behavioral response of females. These pheromonal compounds were also identified as volatiles released by males when males were exposed to the principal pheromone component of female cabbage loopers, (Z)-7-dodecen-1-ol acetate. The amount of male pheromone released was increased significantly when males were exposed to a combination of (Z)-7-dodecen-1-ol acetate and the odor from cabbage. Neither linalool nor the cresols were detected in volatiles from cabbage or from males exposed to cabbage odor.     

Behavioral responses of maleHeliothis zea moths in sustained-flight tunnel to combinations of 4 compounds identified from female sex pheromone gland

Each of the four compounds that have been identified from sex pheromone glands ofHeliothis zea female moths was examined for its ability to elicit sexual responses from male moths in a flight tunnel. Males flew upwind to (Z)-11-hexadecenal alone, but greater levels of behavioral activity were evoked with the addition of (Z)-9-hexadecenal to the treatment. Addition of hexadecanal or (Z)-7-hexadecenal to the initial two components had no effect in raising the behavioral response of the males in the flight tunnel whether added singularly at both the normal gland-emission ratio or at varying ratios or in combination at the normal ratio. Live, calling females elicited levels of sexual activity from males not significantly different from that elicited by the mixture of (Z)-11- and (Z)-9-hexadecenal on cotton wicks.Lepidoptera: Noctuidae.     

Effect of release rate and ratio of (Z)-11-hexadecen-1-ol from synthetic pheromone blends on trap capture ofHeliothis subflexa (Lepidoptera: Noctuidae)

Response of maleHeliothis subflexa to pheromone-baited traps containing blends of tetradecanal, (Z)-9-tetradecanal, hexadecanal, (Z)-7-hexadecenal, (Z)-9-hexadecenal, (Z)-11-hexadecenal, hexadecan-1-ol acetate, (Z)-7-hexadecen-1-ol acetate, (Z)-9-hexadecen-1-ol acetate, (Z)-11-hexadecen-1-ol acetate, (Z)-9-hexadecen-1-ol, and (Z)-11-hexadecen-1-ol was evaluated. Analysis of trap capture data indicated that (Z)-11-hexadecen-1-ol was a critical component of the pheromone blend. It was determined from emission rate data and measurements of the ratio of pheromone components emitted from rubber septa tested that a significant increase in trap capture of maleH. subflexa occurred when the blends investigated released the alcohol in a narrow range relative to the total amount of pheromone emitted. The optimum range of release ratio of the alcohol for the capture of males in sticky traps was determined to be 0.9–3.5% of the pheromone blend. This release ratio range was reduced to 0.9–1.6% when bucket traps were used.     

Identification of a sex pheromone ofHeliothis subflexa (GN.) (Lepidoptera: Noctuidae) and field trapping studies using different blends of components

Eight compounds were isolated from the sex pheromone gland ofHeliothis subflexa (Gn.) and identified as hexadecanal, (Z)-9-hexadecenal, (Z)-11-hexadecenal, (Z)-7-hexadecen-1-ol acetate, (Z)-9-hexadecen-1-ol acetate, (Z)-11-hexadecen-1-ol acetate, (Z)-9-hexadecen-1-ol, and (Z)-11-hexadecen-1-ol. Although the whole blend was found to be an effective male attractant, the deletion of alcohols from the blend increased trap captures considerably. Further, although the binary mixture of (Z)-9-hexadecenal and (Z)-11-hexadecenal caught some maleH. subflexa, significant increases in captures were noted when the three acetate components were included in the blend.Mention of a commercial or proprietary product in this paper does not constitute an endorsement of that product by the USDA or the State of Florida.     

Behavioral responses ofSpodoptera littoralis males to sex pheromone components and virgin females in wind tunnel

The major component of the sex pheromone of femaleSpodoptera littoralis, (Z,E)-9,11-tetradecadienyl acetate (1), elicited all steps of the male behavioral sequence, i.e., wing fanning and taking flight, oriented upwind flight and arrival to the middle of the tunnel, close approach and contact with the source. The activity was equivalent to that elicited by virgin females. In the range of doses tested, the dosage of1 had no significant effect on the number of source contacts. Male response was significantly affected by light intensity, being optimum at 3 lux. Activity of the minor components (Z)-9-tetradecenyl acetate (2), (E)-11-tetradecenyl acetate (3), tetradecyl acetate (4), (Z)-11-tetradecenyl acetate (5), and (Z,E)-9,12-tetradecadienyl acetate (6) was significantly lower than that of the major component when assayed individually. In multicomponent blends compound4 appeared to strongly decrease the number of males arrested at the source, the effect being particularly important when compound5 was present in the blend. Results of single sensillum experiments confirmed the existence of two main physiologically distinct sensillar types. The most common type of sensilla contained a neuron that responded specifically to compound1. A second type of sensilla, located laterally on the ventral sensory surface, contained two receptor neurons responding to compound6 and to (Z)-9-tetradecenol. Among short sensilla, one hair responded to compound4 and could represent a minor sensillar type. No sensory neuron was found to detect the other minor pheromone compounds2, 3, and5.Dedicated to the memory of the late Prof. Félix Serratosa (1925–1995).     

Sex pheromone ofEupoecilia ambiguella female: Analysis and male response to ternary blend

Sex gland extracts and washes ofEupoecilia ambiguella contain 10–20 ng/female of the primary sex pheromone componentZ-9-dodecenyl acetate (Z9–12Ac), accompanied by a number of related compounds. These areE-9-dodecenyl acetate (E9–12Ac),Z-9-dodecen-1-ol (Z9–12OH), saturated acetates of 12, 16, 18, and 20 carbons, and traces of a doubly unsaturated acetate, tentatively identified as a 9,11-dodecadienyl acetate. Octadecyl acetate predominates among the pheromone-related components, making up 1–2, occasionally 20–30 times the amount ofZ9–12Ac. The same compounds were also found in field-collected females and in effluvia.Z-9-Undecenyl acetate, which is a male attractant on its own, was also found in a sample of female effluvia. A hierarchy is observed in the ethological function of the pheromone components.Z9–12Ac is an attractant forE. ambiguella males. Dodecyl acetate (12Ac) is not attractive on its own but augments male catch when added to the main attractant. Addition of 18Ac augments attraction only when bothZ9–12Ac and 12Ac are present. Windtunnel tests demonstrate that 18Ac also raises the disorientation threshold, as previously shown for 12Ac. Other compounds, with the possible exception of additional saturated acetates, had either no effect on trap catch or, in the case ofE9–12Ac,Z9–12OH, andE-9,11-dodecadienyl acetate, were inhibitory above a certain level. A blend of roughly equal parts ofZ9–12Ac, 12Ac, and 18Ac provides the best attractant blend forE. ambiguella known to date.     

Evolution of behavioral responses to sex pheromone in mutant laboratory colonies ofTrichoplusia ni

Male cabbage looper moths,Trichoplusia ni, from two colonies in which all females express an abnormal sex pheromone production phenotype were evaluated in a laboratory wind tunnel for upwind flight responses to the normal and abnormal sex pheromones. The abnormal sex pheromone blend consisted of 20 times as much (Z)-9-tetradecenyl acetate and 30-fold less (Z)-5-dodecenyl acetate compared to the normal pheromone blend. Initially, these males exhibited poor behavioral responses to the abnormal sex pheromone and maximum responses to the normal pheromone blend, indicating that there was no linkage between signal production and response. After 49 generations of laboratory rearing, males from the mutant colonies maintained good responses to the normal pheromone and increased their behavioral response to the abnormal sex pheromone to the same levels as for the normal pheromone. Over the same period, normal males maintained their preference for the normal pheromone. These results indicated that evolution had occurred in mutant colonies in favor of greater male responsiveness to the abnormal sex pheromone, resulting in the broadening of the response spectrum to pheromone blend ratios. This evolution presumably resulted from a mating advantage to those males that did not discriminate against mutant-type females in the mutant colonies.     

Genetic aspects of interpopulational differences in pheromone blend of cabbage looper moth,Trichoplusia ni

The genetic basis of interpopulational differences in the pheromone blend emitted by the cabbage looper moth,Trichoplusia ni (Hübner), was examined by crossing individuals from a field-derived population (P₁) with individuals from a long-maintained laboratory colony (P₂). These colonies differed in the emission rate and relative proportions of four of the five known minor pheromone components, but not in the emission rate of the major component, (Z)-7-dodecenyl acetate (Z7-12Ac). These differences in pheromone blend were quantitatively small but biologically significant, because in the field, males responded preferentially to traps baited with a pheromone blend that is similar to that emitted by P₁ females relative to a blend similar to that emitted by P₂ females. In initial crosses, variation in the quantity and quality of pheromone blends among families of P₁, P₂, and F₁ hybrid females was examined. In F₁ females the relative proportions (quantity relative to the major component) of (Z)-5-dodecenyl acetate (Z5-12Ac) and (Z)-7-tetradecenyl acetate (Z7-14Ac) were intermediate to parental lines. In a second more extensive set of crosses, analyses included P₁, P₂, F₁, F₂, and selected backcrosses. The relative proportion of Z5-12Ac, Z7-14Ac, and Z9-14Ac emitted by F₁ females were intermediate to parental lines. The frequency distributions of relative proportions of these components emitted by females were not consistent with those expected under a single autosomal or sex-linked gene hypothesis, suggesting that more than one gene is involved in the quantitative differences in the pheromone blend.     

Behavioral responses of male epiphyasPostvittana (walker) to sex pheromone-baited delta trap in a wind tunnel

The effects of parameters associated with a Delta sticky trap on the sex pheromone-mediated responses of maleEpiphyas postvittana (Walker) were tested in a wind tunnel. Males flying to a pheromone source landed closer to the source when other males were stuck on the base, suggesting the importance of visual cues in the landing behavior of males of this species. With an increase in time (numerical order of the male in the experiment), males became stuck on the base farther from the source whether or not other males were stuck on the base. The alignment of the trap to the wind or the location of the pheromone source within the trap did not significantly affect the percentages of males that entered the trap, but both significantly affected the position at which males entered the trap. When these data were corrected for the probability of catching males, a treatment with the source to the side of the trap was predicted to catch more moths than the other treatments tested, although this difference was not significant. However, in a field-trapping experiment the treatment with the source to the side caught significantly more moths than treatments with the source either in the middle or near the top of the trap. This latter result is probably due to the greater efficiency of the trap when the source is in this position, as indicated in the wind-tunnel experiment, rather than an increase in the numberof males entering the trap. Finally, the pheromone-mediated responses of malePlanotortrix octo were tested to the various trap alignments. As the angle of the trap to the wind increased, significantly fewerP. octo males entered the trap, due principally to both fewer males orienting to the source and proceeding to enter the trap after having landed on it. This difference between the responses ofP. octo andE. postvittana males is, we believe, due to the breakdown in plume structure from the source as the trap angle to the wind increases and to a greater sensitivity ofP. octo males to a more structured pheromone plume. This accounts, at least to some extent, for the consistently greater field catches ofE. postvittana overP. octo (and possibly other New Zealand leafroller moths) in many locations throughout New Zealand.     

Redundancy in a chemical signal: Behavioral responses of maleTrichoplusia ni to a 6-Component sex pheromone blend

The flight response of maleTrichoplusia ni was observed in a flight tunnel to a sex pheromone blend composed of six components:Z7–12Ac, 12Ac,Z5-12Ac, 11-12Ac,Z7-14Ac, and Z9-14Ac. The number of males reaching a 3000-g source of this blend was > 95%, equal to that observed to female glands and significantly greater than with the previously identified two-component blend (Z7-12Ac + 12Ac). In subtraction tests, all five-component blends, with the exception of the blend lacking the primary componentZ7-12Ac, and several four-component blends elicited similar peak levels of upwind flight, source contacts, and hairpencil displays to that observed with the six-component blend. We characterize the substitution of certain minor components for one another as a form of redundancy in the chemical signal and suggest that it contributes to response specificity and signal recognition in males. The results also support the concept that the full blend of components acts as a unit to influence male behavior at all phases of the response. Individual minor components were not responsible for eliciting specific behaviors in the sequence.     

Influence ofHeliothis virescens sex pheromone dispensers on captures ofH. zea males in pheromone traps relative to distance and wind direction

Evaluations conducted by placingHeliothis virescens (F.) sex pheromone (virelure) dispensers at different distances in the predominant downwind and upwind directions fromHeliothis zea (Boddie) pheromone traps indicated that reductions inH. zea male captures were greatest relative to distance when theH. zea traps were located downwind from the virelure dispensers than when the traps were located upwind. When operating traps for both species at the same site, the influence of virelure dispensers on captures inH. zea pheromone traps would be minimized by placing theH. zea traps upwind of theH. virescens traps and, if wind direction is variable, the traps should be spaced at least 75 m apart.Lepidoptera: Noctuidae.In cooperation with the Texas Agricultural Experiment Station, Texas A&M University, College Station, Texas 77843. This paper reports the results of research only. Mention of a commercial or proprietary product in this paper does not constitute an endorsement of this product by USDA.     

Dodecyl acetate,a second pheromone component of the cabbage looper moth,Trichoplusia ni

Dodecyl acetate was identified as a second component of the sex pheromone ofTrichoplusia ni (Hübner). Dodecyl acetate comprised 9.6% by weight of the total pheromone [(Z)-7-dodecenyl acetate plus dodecyl acetate] extracted from glands and 7.3% by weight of the total pheromone evaporated from the surfaces of glands. Dodecyl acetate appears to function as a short-range pheromone component. Evaporation at female release rates of a 1090 mixture of dodecyl acetate and (Z)-7-dodecenyl acetate in the field caused a significantly greater percentage of males to land on the pheromone source, increased significantly the time they spent on the source, but decreased significantly the time they spent searching for the source when within 50 cm, as compared to (Z)-7-dodecenyl acetate alone.Lepidoptera: Noctuidae.     

Behavior of processionary males (Thaumetopoea pityocampa) induced by sex pheromone and analogs in a wind tunnel

The behavioral response of processionary males (Thaumetopoea pityocampa) to the natural pheromone (Z)-13-hexadecen-11-ynyl acetate (1) and structurally related analogs in a wind tunnel is presented. Stereomerically pureZ-1 and a mixture with theE isomer in 80:20 ratio elicited similar attraction responses at 1 µg and higher. The activity was dose-dependent, being optimum at 1 µg with 90% and 80% of males contacting with the source in the presence of theZ-1 andZ/E-1, respectively. 11-Hexadecynyl acetate (2) functioned as a pheromone mimic, being able to induce the complete mate-finding behavioral sequence, although its activity was much lower than that of the pheromone. (Z)-13-Hexadecen-11-ynyl alcohol (3) and, particularly, (Z)-13-hexadecen-11-ynal (4) were potent inhibitors of the upwind flight response in mixtures withZ-1 in 99:1, 95:5, and 91:9 ratios. (Z)-1,1,1-Trifluoro-16-nonadecen-14-yn-2-one (5) also inhibited the response of males to pheromone, particularly in the source contact behavior. Comparison with activity displayed by analogs in field tests is also reported.     

Responsiveness ofPseudaletia unipuncta (Lepidoptera: Noctuidae) males,maintained as adults under different temperature and photoperiodic conditions,to female sex pheromone

Different-agedPseudaletia unipuncta (Haworth) males, maintained as adults at 10 and 25°C under 16∶8 and 12∶12 light-dark photoperiodic regimes, were flown to a 30-μg pheromone source in a wind tunnel at 20°C. While the responsiveness of individuals reared under both photoperiodic conditions at 25 °C was similar by day 5 (65–75%), response levels of younger males showed that those reared at 16∶8 light-dark matured more rapidly than those under 12∶12 light-dark. A significant delay in the onset of responsiveness was observed for males reared under 10°C with less than 25% of individuals responding to the pheromone, even at 25 days old. At this temperature, photoperiodic conditions had no significant effect on male receptivity. When males are transferred from 10°C to 25°C 16∶ 8 light-dark, their level of responsiveness after five days was similar to control 5-day-old males reared at 25°C, 16∶8 light-dark. These results are discussed relative to the hypothesis that this species migrates in response to seasonal cues that indicate a predictable habitat deterioration.     

Female sex pheromone of the melonworm,Diaphania hyalinata (Lepidoptera: Pyralidae), and analysis of male responses to pheromone in a flight tunnel

Ten C₁₆ chain-length compounds were identified from heptane extracts of ovipositors of female melonworm,Diaphania hyalinata (L.). The major constituents of the extracts were (E)-11-hexadecenal and (E,E)-10,12-hexadecadienal [(E,E)-10,12–16:Ald] and the alcohols and acetates of these olefins were found in trace amounts (<2%). Extracts also contained traces of (E,Z)- and (Z,Z)-10,12-16:Ald, hexadecanal, and 1-hexadecanol. Analysis of the behavioral responses of males to synthetic mixtures of these compounds and responses to ovipositor extracts in a flight tunnel showed that a synthetic mixture of the 10 compounds elicited a behavioral repertoire from males that was indistinguishable from that elicited by ovipositor extract. Flight tunnel studies also indicated that six of the 10 compounds probably represent the essential components of the female's sex pheromone.Supported in part by USDA Cooperative Agreement No. 58-32U4-1-299. Scientific Article No. A-4073, Contribution No. 7058 of the Maryland Agricultural Experiment Station. Mention of a commercial product in this paper does not constitute a recommendation by the U.S. Department of Agriculture.     

Spruce budworm (Choristoneura fumiferana) pheromone chemistry and behavioral responses to pheromone components and analogs

This paper reviews the sex pheromone chemistry and pheromone-mediated behavior of the spruce budworm and related coniferophagous (Choristoneura) budworms. InC. fumiferana, temporal changes in pheromone-gland monounsaturated fatty acids (pheromone precursors) enable the prediction of the primary sex pheromone components. This technique may also be applicable for predicting additional pheromone components. Tetradecanal (14 Ald), previously shown to enhance close-range precopulatory behavior, lowers the threshold of response by males for upwind flight to a pheromone-component source. Spruce budworm males maintain upwind flight to 955 (E/Z)-1,12-pentadecadiene (diolefin analog) after initiating upwind flight to a primary-component pheromone source (955E/Z11-14Ald). This is the first demonstration of apparently normal male flight responses to a pheromone analog.Lepidoptera: Tortricidae     

Identification of a male-produced pheromone ofAnticarsia gemmatalis (Hübner) (Lepidoptera; Noctuidae) attractive to conspecific males

Observations in the laboratory and in the field indicated that maleAnticarsia gemmatalis (Hübner), the velvetbean caterpillar (VBC), are attracted to conspecific courting males. Male VBC subsequently were found to be attracted to extracts of male abdominal tips including the extrudable hairpencils. The active chemical in these extracts was identified as (Z,Z,Z)-3,6,9-heneicosatriene, which is also one of the major components of the female VBC sex pheromone. Male VBC in a wind tunnel and in the field exhibited a bimodal response distribution to a range of ratios of the (Z,Z,Z)-3,6,9-heneicosatriene and (Z,Z,Z)-3,6,9-eicosatriene, with one maximum at the pure heneicosatriene alone and the other at the 6040 female blend. This demonstrates that the male response to the male hairpencil component is distinct from that to the female sex pheromone.This article reports the results of research only. Mention of a proprietary product does not constitute an endorsement or the recommendation for its use by USDA.