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.     

Inhibitory pheromonal activity promoted by sulfur analogs of the sex pheromone of the female processionary mothThaumetopoea pityocampa (Denis and schiff)

New sulfur analogs of the sex pheromone of the female processionary mothThaumetopoea pityocampa have been found to be effective inhibitors of the natural pheromone activity both in EAG bioassays and field tests. The structures of these analogs have been derived from replacement of the oxygen atom(s) of the acetate group by sulfur (compounds 3-5) and the olefinic moiety of the enyne function by the isosteric SCH₂ group (compounds 6 and 7). The synthesis and biological activity of 3-[(Z)-12-pentadecen-10-ynylthio]-1,1,1-trifluoropropan-2-one (8), a closely related structure to the pheromone is also described.     

Role of trail pheromone in foraging and processionary behavior of pine processionary caterpillars Thaumetopoea pityocampa

Although caterpillars of Thaumetopoea pityocampa may mark their pathways with silk, this study shows that the material is essential to neither the elicitation nor maintenance of trail-following or processionary behavior. Trail following is dependent upon a pheromone the caterpillars deposit by brushing the ventral surfaces of the tips of their abdomens against the substrate. Earlier instars are strongly bound to their trail system; in the laboratory, caterpillars followed circular trails continuously for as long as 12 hr before breaking away from them. The trail pheromone is long-lived and soluble in nonpolar solvents, but its volatilization or degradation allows the caterpillars to distinguish new from aged trails. In contrast to trail following, processionary behavior, the head-to-tail, single-file movement of the caterpillars is dependent on neither silk nor the trail pheromone. Stimuli associated with setae found on the tip of the abdomen of the precedent caterpillar serve to hold processions together, and such stimuli take priority over those associated with either the trail pheromone or silk. Although the caterpillars discern trail strength and choose stronger over weaker trails, the trail marking system of the processionary caterpillar appears less sophisticated than those of other, previously studied species of social caterpillars, and colonies are relatively inefficient in abandoning exhausted feeding sites in favor of new food finds. In laboratory studies, females were more likely to lead processions than males, and leaders, regardless of gender, expended more energy in locomotion than followers.     

Reinvestigation of Female Sex Pheromone of Processionary Moth (Thaumetopoea pityocampa): No Evidence for Minor Components

The female sex pheromone of the processionary moth Thaumetopoea pityocampa has been reinvestigated to look for possible minor components. Examination by GC-MS and GC-EAD of the contents of virgin female glands, after stimulation with PBAN (pheromone-biosynthesis-activating neuropeptide), showed that the major component, (Z)-13-hexadecen-11-ynyl acetate (1), appears to be the only pheromone compound present in the gland. Comparison of female attractivity with that of the natural extract and synthetic (Z)-13-hexadecen-11-ynyl acetate showed that this chemical is able to elicit a similar activity to that displayed by virgin females in a wind tunnel. In single cell recording experiments, two specialist receptor cell types were found in the trichoid sensilla. One cell type was tuned to enyne acetate 1. The other one was tuned to (Z,Z)-11,13- hexadecadienal and (Z)-13-hexadecen-11-ynal, the major components of the pheromone blend of other Thaumetopoea spp., and constitutes a further example of interspecific inhibitor receptor cells. Our results show that the processionary moth may not need minor components for successful mate recognition.     

Field Trials with the Synthetic Sex Pheromone of the Oak Processionary Moth Thaumetopoea processionea

The biological activity of synthetic (Z,Z)-11,13-hexadecadienyl ace- tate, the major pheromone component found in female gland extracts of the oak processionary moth Thaumetopoea processionea, was evaluated in field trials. Traps baited with 10 mg of the chemical efficiently attracted a large number of males provided they were placed in the upper crown region of the oaks. Devices positioned 10–15 m high in the trees attracted significantly more males than those traps installed at 2 or 6–8 m above the ground. Pherocon traps were slightly more efficient than Delta traps, and lower or higher amounts of the attractant in the baits did not significantly influence the number of moths caught. The importance of the stereomeric purity of the lure and the easy isomerization of the (Z,Z)-acetate to other isomers, particularly to the E,E isomer, should be considered for the development of efficient formulations in the field.     

Biosynthesis of sex pheromone components and glycerolipid precursors from sodium [1-14C]acetate in redbanded leafroller moth

Sodium [1-¹⁴C]acetate in water-dimethyl sulfoxide (11) was applied topically to sex pheromone glands ofArgyrolaenia velutinana. Radiolabel was incorporated into the pheromone components (Z)-11-tetradecenyl acetate and (E)-11-tetradecenyl acetate, and also into triacylglycerols, diacylglycerols, ethanolamine phosphatides, and choline phosphatides. In the triacylglycerols, radiolabel appeared in (Z)-11-tetradecenoate, (E)-11-tetradecenoate, tetradecanoate, hexadecanoate, and octadecanoate. In the choline phosphatides, the same acyl moieties incorporated radiolabel but at lower levels. In the diacylglycerols and ethanolamine phosphatides, only the radiolabel in hexadecanoate and octadecanoate was above the limit of detection. At different times following application of sodium [1-¹⁴C]acetate, the relative proportions of labeled (Z)-11-tetradecenyl acetate and (E)-11-tetradecenyl acetate changed very little, but the relative proportions of labeled fatty acyl moieties in the triacylglycerols and choline phosphatides changed markedly. After 8 min, triacylglycerols had incorporated about equal amounts of radiolabel into (Z)-11-tetradecenoate, (E)-11-tetradecenoate, and tetradecanoate. As the incubation time was increased, triacylglycerols accumulated proportionately more radiolabeled (E)-11-tetradecenoate than (Z)-11-tetradecenoate, and accumulated proportionately less radiolabeled tetradecanoate. In the choline phosphatides, at all times of incubation the amount of radiolabel incorporated into (Z)-11-tetradecenoate was small but above the limit of detection, and the amounts of radiolabel in (E)-11-tetradecenoate and tetradecanoate were smaller and often below the limit of detection. In both the triacylglycerols and the choline phosphatides, the relative proportion of radiolabeled hexadecanoate decreased with time, and that of octadecanoate increased.     

Individual variation in sex pheromone of smaller tea tortrix moth,Adoxophyes sp. (Lepidoptera: Tortricidae)

Female smaller tea tortrix mothsAdoxophyes sp. (Lepidoptera: Tortricidae), which initiated calling at 1, 2, or 3 days old, respectively, were analyzed individually for (Z)-11-tetradecenyl acetate (Z11-14:OAc) and (Z)-9-tetradecenyl acetate (Z9–14: OAc) in the pheromone gland via GLC. Among different age groups, broad and similar distributions were found for pheromone quantity (¯X=58.6±52.9 ng/female; range 1.3–219.8 ng/female). The ratio of the two pheromone components averaged 6535 but ranged from 8416 to 4060. The significance of the pheromone blend variation to the attraction of males was tested in a field experiment. The ratio of males trapped by the most attractive blend versus the least attractive one was 2.2.     

Identification of a minor component of the sex pheromone ofLeucoptera malifoliella (Lepidoptera,lyonetiidae)

A new minor component in the female volatile extract ofLeucoptera malifoliella (Costa) (Lepidoptera, Lyonetiidae) has been identified as 5,9-dimethyloctadecane (2). The amount detected of the minor compound2 ranged from 4 to 8% in comparison with the major component 5,9-dimethylheptadecane (1). Neither compound has been found in the male volatile extract. The identification has been based on its spectroscopic properties and Chromatographic behavior in comparison with an authentic synthetic sample. The synthesis has been carried out through a short route from 2,6-dimethylcyclohexanone (3). In field tests, compound2 appears to act as a Synergist of the major component1 when mixed with the latter in a 1000.1– 5 ratio.     

Effect of temperature on biosynthesis of sex pheromone components in potato tuberworm moth,Phthorimaea operculella (Lepidoptera: Gelechiidae)

Rearing temperature modified the sex pheromone component ratio in the potato tuberworm moth,Phthorimaea operculella. This phenomenon seemed to be induced with ambient temperature by differences in timing and speed of biosynthesis between two pheromone components. (E,Z,Z)-4,7,10-Tridecatrienyl acetate (triene) was mainly synthesized during the pupal period, while most of (E,Z)-4,7-tridecadienyl acetate (diene) was synthesized during a short period just after emergence. Therefore, the ratio of triene in a newly emerging adult was relatively high at all temperatures although the amount of triene was relatively low at 35°C. On the other hand, the synthetic rate of accumulation of diene was clearly modified by ambient temperature. Biosynthesis of diene at 15°C was very low in the first two days and high in the third day. Consequently, a titer of the diene component at 15°C became approximately equivalent to that at 25°C one day later.     

Study of female sex pheromone of leopard moth,Zeuzera pyrina L. Isolation and identification of three components

Three compounds have been identified in the abdominal tip extracts from the female leopard moth,Zeuzera pyrina L. Gas-liquid chromatography and mass spectroscopy data showed that (E, Z)-2, 13-octadecadien-1-ol acetate was the main component and that (Z)-13-octadecen-1-ol acetate and octadecan-1-ol acetate were secondary components. The electroanten-nographic responses of maleZ. pyrina to nanogram amounts of all four 2, 13-octadecadien-1-ol acetate isomers indicated that theE, Z isomer had the maximum activity. A strong EAG response was also recorded for (Z)-7-do-decen-1-ol acetate, which was not detected in the female extracts.     

Codling moth,Cydia pomonella, (Lepidoptera: Tortricidae): Is its sex pheromone multicomponent?

When the nine identified components in the effluvium of calling female codling moths were compared to pure synthetic (E,E)-8,10-dodecadien-1-ol in flight-tunnel tests, equal responses were obtained over a concentration range of 300-fold. When synthetic (E,E)-8,10-dodecadien-1-ol was compared to extract of female sex pheromone glands by a male wing-flutter bioassay, or in flight-tunnel tests, equal responses were obtained over a concentration range of 1000-fold. The sum total of these and previous studies indicate that the codling moth sex pheromone consists of only one component.     

Identification of a sex pheromone produced by female velvetbean caterpillar moth

A sex pheromone produced by female velvetbean caterpillar moths,Anticarsia gemmatalis Hübner, that attracts conspecific males was isolated and identified as a blend of (Z,Z,Z)-3,6,9-eicosatriene and (Z,Z,Z)-3,6,9-heneicosatriene in a ratio of ca. 53, respectively, when combined. The synthesized compounds elicited responses by velvetbean caterpillar moth males equivalent to those elicited by females in both laboratory wind tunnel bioassays and field trapping experiments.Lepidoptera: Noctuidae.Mention of a commercial or proprietary product does not constitute an endorsement by the USDA.Employed through a cooperative agreement between the Department of Entomology & Nematology, University of Florida, and the Insect Attractants, Behavior, and Basic Biology Research Laboratory, Gainesville, Florida 32604.     

Nantucket pine tip moth,Rhyacionia frustrana: Identification of two sex pheromone components

Two compounds identified as components of the sex pheromone system ofRhyacionia frustrana are (E)-9-dodecen-1-yl acetate (I) and (E)-9,11-dodecadien-1-yl acetate (II), which were found in female gland extracts in the ratio of 964, respectively. The identifications were based on chemical and instrumental analyses, electroantennogram studies, and field trapping tests. The optimum ratio for trapping maleR. frustrana is the range of 955 to 97.52.5 (III), when dispensed from rubber septa at a loading of ca. 1000/g/lure. In addition to these two compounds, evidence was obtained for the presence of dodecan-1-ol and (E)-9-dodecen-1-ol in female tip extracts and in female effluvium, and for dodecan-1-yl acetate in female tip extracts.Lepidoptera: Tortricidae: Olethreutinae.Supported in part by the Rockefeller Foundation and by National Science Foundation grants GB-38020 and PCM 78-13241.     

Anemotactic response threshold of the Indian meal moth,Plodia interpunctella (Hübner) (Lepidoptera: Pyralidae), to its sex pheromone

The effect of different concentrations of the sex pheromone (Z,E)-9,12-tetradecadien-1-ol acetate on the upwind anemotactic behavior of the malePlodia interpunctella (Hübner) was measured at 23 ± 1 ° C and 34 ± 1 ° C. The stimulus-response regression lines were analyzed by a new procedure that accounts both for control responses in the absence of pheromone and also for peak responses below 100% in the presence of concentrations considerably above the normal physiological levels. From the regression line for each temperature, the upwind anemotactic thresholds were calculated to be 1.34 × 10⁶ molecules/cm³ at 23 ° C and 1.65 × 10⁴ molecules/cm³ at 34 ° C, similar to other thresholds reported in the literature. Since departures from the two lines occurred at the highest concentrations tested, near 10⁸ molecules/cm³, the upwind anemotactic behavior may change qualitatively above an altered-behavior threshold that is about two orders of magnitude higher than the upwind anemotactic threshold. The lower response at 23 ° C suggests that cool temperatures inhibit flight in response to pheromonal stimulation.Mention of a commercial or proprietary product in this paper does not constitute an endorsement of that product by the USDA.     

Temporal patterns of sex pheromone titers and release rates inHolomelina lamae (Lepidoptera: Arctiidae)

Six hydrocarbon components (2-methylhexadecane,n-heptadecane, 2-methylheptadecane, 2-methyloctadecane,n-nonadecane, and 2-methylnonadecane) were identified in sex-pheromone gland extracts and in airborne collections ofHolomelina lamae. Low variability in the ratio of components among individuals indicates tight regulation of blend composition. Minor changes were evident in the quantity and ratio of the blend as a function of time of day. Based on gland extracts, the total quantity of the six components increased from day 1 (X = 6299 ng) to day 4 (X = 7498 ng) and subsequently decreased. No significant correlations were found between total gland contents and wet or dry weights of moths. Emission rates ofH. lamae females were determined from pheromone adsorbed onto Porapak Q. Quantities released peaked shortly after the onset of calling and decreased rapidly as calling continued. Peak release rates ranged from 13 to 350 ng/10 min, and from 37 to 835 ng/60 min. Noncalling females did not emit detectable quantities of pheromone. Based on release rates and the rate of pulsation of the abdominal tip, the average amount released per pulse is not constant. The mean ratio of components released (0.787.45 84.802.842.591.53) was not very different from the ratio of components in gland extracts of 2-day-old females (0.704.1990.12 1.651.911.42). We propose that the blend is atomized rather than volatilized from the gland, thus retaining nearly the same ratios in the female's effluvium as in her gland.     

Variability in pheromone composition and periodicity of pheromone titer in potato tuberworm moth,Phthorimaea operculella (Lepidoptera: Gelechiidae)

The ratios and quantities of the pheromone components, (E,Z)-4,7-tridecadien-1-yl acetate (diene) and (E,Z,Z)-4,7.10-tridecatrien-1-yl acetate (triene), in the glands of individual female potato tuberworm moths (Phthorimaea operculella) originating from the United States (California) and Japan (Nagoya) were analyzed by gas chromatography. Quantities of glandextracted pheromone components of Nagoya females fluctuated in a periodic fashion during the photoperiod. Maximal titers coincided with the onset of scotophase (and calling), then gradually declined to minimal levels soon after lights-on. The average daily pheromone quantities decreased significantly as females aged. Both populations exhibited considerable variation in the ratio of the two components. The proportions of triene in the blend ranged from 27% to 88% (triene –X = 56 ± 13% SD; CV = 23%) for California females and from 16% to 71% (42 ± 13%; CV = 31%) for Nagoya females. Nagoya females also stored significantly higher amounts of pheromone in their glands (8.6 ± 3.9 ng) than did California females (2.7 ± 1.4). The differences between the populations, while substantial, would probably not be sufficient to impart a barrier to panmixis, given the wide range of component ratios favored by the males.     

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.     

Heritable variation of sex pheromone composition and the potential for evolution of resistance to pheromone-based control of the Indian meal moth,Plodia interpunctella

The short-term evolutionary effect of pheromone-based mating disruption on the mating ability of the Indian meal moth, Plodia interpunctella, was investigated. Three independent selection lines were established, and the mating ability of moths in plastic tents treated with high doses of pheromone and in control tents was compared for two consecutive generations. In addition, the heritability of the sex pheromone blend, measured as the ratio of two major pheromone components (Z,E)-9,12-tetradecadienyl acetate and (Z,E)-9,12-tetradecadienol, was estimated. Based on a mother–daughter regression analysis including 21 families, the heritability of the pheromone blend was 0.65 ± 0.14, indicating a potential for evolutionary change of the character. However, no increase in mating ability of females in pheromone-treated tents or alteration of the pheromone blend was observed in any selection line when compared with control lines, indicating no or weak selection on the pheromone blend as well as other traits influencing mating ability of this species under the created mating disruption conditions. Factors contributing to the lack of selection effects are discussed.     

Effect of rearing temperature on pheromone component ratio in potato tuberworm moth,Phthorimaea operculella, (Lepidoptera: Gelechiidae)

The ratio of two components in the sex pheromone of the potato tuberworm moth,Phthorimaea operculella, was influenced by the rearing temperature. The percentage of the (E,Z,Z)-4,7,10-tridecatrienyl acetate dropped as the rearing temperature was raised. The total amount of the pheromone did not change parallel with the change of ratio. The critical period sensitive to temperature seemed to be the pupal stage. Temperature in the larval stage may also influence the ratio slightly. The biological significance of the phenomenon was also discussed.     

Components of female sex pheromone of cocoa pod borer moth,Conopomorpha cramerella

The cocoa pod borer,Conopomorpha cramerella (Snellen) (Lepidoptera: Gracillariidae), is the most serious pest of cocoa in Southeast Asia. Analyses of ovipositor washings and entrained volatiles from virgin female moths by gas chromatography (GC) linked to electroantennography (EAG), and comparison of EAG responses from the male moth to synthetic compounds indicated the presence of theE,Z,Z andE,E,Z isomers of 4,6,10-hexadecatrienyl acetate and the corresponding alcohols, and of hexadecyl alcohol. Amounts of pheromone produced were less than 0.1 ng/female, and no peaks for the unsaturated components were observed on GC analysis. Extensive field testing of synthetic mixtures in Sabah, East Malaysia, showed that traps baited with a polyethylene vial impregnated with 1.2 mg of a mixture of the above five components in 40604610 ratio caught more maleC. cramerella moths than traps baited with a virgin female moth.