Phenotypic plasticity of Rhyzopertha dominica pheromone signaling: the effects of different hosts and presence of conspecific females on male produced aggregation pheromone

Male Rhyzopertha dominica (F.) (Coleoptera: Bostrichidae) release an aggregation pheromone consisting of a blend of two components, dominicalure 1 (D1) and Dominicalure 2 (D2). Pheromone from single insects, in different contexts, was collected and measured to determine if this signal is phenotypically plastic. Release rates were lowered when males were moved from maize grains to groundnut kernels or when moved from solitary occupation of maize grain to grain occupied by seven females. The pheromone release was increased again once these moves were reversed. The release of D1 was more affected than D2: thus, on groundnuts or in the presence of females, less pheromone was released and the proportion of D1 in the blend was lowered. Possible reasons for the modifications of the signal are discussed.     

Rate of release of spruce budworm pheromone from virgin females and synthetic lures

The rate of pheromone [(E)- and (Z)-11-tetradecenal] release from calling virginChoristoneura fumiferana females and synthetic lures was determined in both static and aerated atmospheres. In a static system ca. 2 ng/hr was recovered per female. Owing to the > 75% adsorption onto the females' bodies in static atmospheres, the actual release rate has to be corrected to roughly 9–27 ng/hr, depending on the percentage adsorbed. In the air-flow system, females were found to release between 4 and 20 ng/hr. On a 168 light-dark cycle, calling began 1–2 hr before lights-off and continued nonstop until lights-on. Pheromone was emitted throughout calling, while no pheromone was detected during the noncalling periods.Lepidoptera: Tortricidae.Published as Journal Article No. 10258 of the Michigan Agricultural Experiment Station.     

Patterns of sex pheromone release from adult females,and effects of air velocity and pheromone release rates on theoretical communication distances inTrogoderma glabrutm

By means of olfactory communication models, theoretical maximum communication distances for dispensers releasing synthetic (E)-14-methyl-8-hexadecenal (trogodermal) were confirmed in windtunnel tests withTrogoderma glabrum males. Pheromone release rates ofT. glabrum females are at least 10⁴ greater during than before calling, and are gradually reduced after calling. The models predict that, even under ideal conditions, females may attract males from only several meters. The models are used to estimate active space lengths for female and synthetic pheromone sources, as a function of realistic release rates and wind velocities.Coleoptera: Dermestidae.     

Aggregation pheromone ofCarpophilus antiquus (Coleoptera: Nitidulidae) and kairomonal use ofC. lugubris pheromone byC. antiquus

Males ofCarpophilus antiquus Melsheimer (Coleoptera: Nitidulidae) emit an aggregation pheromone that was found to be a novel hydrocarbon, (3E,5E,7E,9E)-6,8-diethyl-4-methyl-3,5,7,9-dodecatetraene. A synthetic scheme and spectra (mass and proton NMR) are given for the compound. Beetles produced the pheromone when feeding on a variety of media, including the brewer's yeast-based artificial diet, fermenting whole-wheat bread dough, corn, and prunes; live baker's yeast was generally added to the food media. Males held individually produced, on average, 25 × more pheromone per beetle than males held in groups of 10 or more. Pheromone was not produced until males were at least 5 days old but was still detected from the oldest beetles tested (47 days). In field tests, the pheromone was attractive to both sexes ofC. antiquus, and it was synergized by food volatiles: A combination of pheromone and fermenting whole wheat dough attracted 2.5× more beetles than pheromone alone, but dough by itself was not significantly more attractive than the control. Semiochemical interactions were studied amongC. antiquus and two other sympatric species for which pheromones are known,C. lugubris Murray andC. freemani Dobson.C. antiquus responded readily to the pheromone ofC. lugubris, but all other interspecific responses to the pheromones were weak. In a sample of naturally infested corn ears, the presence ofC. antiquus was strongly associated with the presence ofC. lugubris, as would be expected if the pheromone ofC. lugubris serves as a kairomone forC. antiquus.     

Male-Produced Sex Pheromone of the Cerambycid Beetle <Emphasis Type="Italic">Hedypathes betulinus</Emphasis>: Chemical Identification and Biological Activity

We identified, synthesized, determined the diel periodicity of release, and tested the bioactivity of components of the male-produced sex pheromone of Hedypathes betulinus (Coleoptera: Cerambycidae: Lamiinae). Gas chromatographic-mass spectrometric analysis of headspace volatiles from adult beetles showed three male-specific compounds, which were identified as (E)-6,10-dimethyl-5,9-undecadien-2-yl acetate (major component), (E)-6,10-dimethyl-5,9-undecadien-2-one (geranylacetone), and (E)-6,10-dimethyl-5,9-undecadien-2-ol. Release of these chemicals was dependent on time of the photoperiod and presence of the host plant. Pheromone release took place primarily during the photophase, with maximum release occurring between 4 and 6 hr after the onset of photophase. The amount of pheromone released by males was much greater when they were in the presence of their host plant than when they were not. In Y-tube olfactometer tests, a ternary mixture of the compounds was attractive to female beetles, although the individual compounds were not attractive by themselves. Addition of volatiles from the host plant greatly increased the attractiveness of the ternary pheromone mixture and of the major pheromone component alone.     

Rosefuran: The Sex Pheromone of an Acarid Mite, Caloglyphus Sp.

Rosefuran was identified as a female sex pheromone from an unnamed species of acarid mite, Caloglyphus sp., whose phoretic hypopi had been collected from the elongated yellowish chafer, Heptophylla picea. Behavior of sexually excited males was demonstrated by exposing them to doses of 1–100 ng of synthetic rosefuran. The pheromone was present in females and also in males and was detected in trace amounts in nymphal stages. Pheromone concentrations were estimated to be 87 ± 14.2 ng per female and 10.4 ± 2.5 ng per male. The quantitative difference between sexes may allow males to discriminate females for purposes of mating.     

Evaluation of Pheromones and a New Trap for Monitoring <Emphasis Type="Italic">Agriotes lineatus</Emphasis> and <Emphasis Type="Italic">Agriotes obscurus</Emphasis> in the Fraser Valley of British Columbia

A prototype ground-based pheromone trap design, baited with various pheromone lures, was field tested for effectiveness in trapping male Agriotes obscurus and Agriotes lineatus click beetles in British Columbia. Pheromone dispensers containing geranyl octanoate and geranyl hexanoate in a 1:1 ratio caught the greatest numbers of A. obscurus, whereas those containing geranyl octanoate and geranyl butanoate in a 9 or 10:1 ratio caught high numbers of A. lineatus. Some differences in A. obscurus attraction to traps were observed between dispensers according to the manufacturer and the number of dispensers deployed in traps. The trap design and optimal pheromone dispensers tested would be suitable for monitoring or surveying A. obscurus and A. lineatus populations in North America.     

Genetic sources of pheromone variation inColias eurytheme butterflies

The courtship pheromone ofColias eurytheme butterflies varies greatly among males in both the quantities and relative proportions of its three chemical components [n-heptacosane (C27), 13-methylheptacosane (13MH),n-nonacosane (C29)]. Narrow-sense heritabilities were high for the blend of 13MH and C27 and for the component quantities in one population (Kansas) but were low for the other population tested (Arizona). Genetic correlations between the three components were high in both populations, indicating a substantial degree of additive genetic influence on the component blends. High variability among populations in phenotypic correlations suggests that much of the male-to-male variation in the courtship pheromone may be attributable to environmental or developmental sources. Pheromone phenotypes do not seem to be associated with alba genotype.Lepidoptera: Pieridae.     

Intrapopulational changes in sex pheromone composition during scotophase in oriental tobacco budworm,Helicoverpa assulta (Guenée) (Lepidoptera: Noctuidae)

Solvent extracts of individual pheromone glands were prepared from femaleHelicoverpa assulta (Guenée) at 2-hr intervals throughout the scotophase. The amounts of female sex pheromone components, (Z)-9-hexadecenal, (Z)-11-hexadecenal, (Z)-9-hexadecenyl acetate, and (Z)-11-hexadecenyl acetate, in the extracts were determined by gas chromatographic analysis. Although females called from early scotophase (2 hr) until late scotophase (6 hr) the quantity of extracted pheromone remained high at 8 hr, the end of the scotophase. More than 70% of the pheromone gland extracts contained sex pheromone components regardless of whether the donor females had been called or resting. Pheromone components were absent from gland extracts prepared at the onset of the scotophase. The quantity of (Z)-9-hexadecenal and (Z)-11-hexadecenal increased rapidly to reach a maximum of approximately 260 and 30 ng/female, respectively, that was maintained for up to 8 hr, the duration of the scotophase. The quantity of (Z)-9-hexadecenyl acetate and (Z)-11-hexadecenyl acetate increased continuously during the scotophase to peak at 600 and 30 ng/female, respectively, 8 hr into the scotophase. At the end of scotophase the quantity of all pheromone components decreased significantly.     

Male bugs modulate pheromone emission in response to vibratory signals from conspecifics

Male Nezara viridula emit a volatile sex pheromone that acts as a long-range attractant to females. Both sexes communicate through vibrations once they are on the same plant. Males respond to the female calling song by emitting a male courtship song, and they orient to the female calling song on a plant. Simultaneity between vibratory and chemical communication during the last steps of mate finding suggests that pheromone emission might be modulated by signals from conspecifics. Male volatile emissions were collected with fibers for solid-phase microextraction, while male bugs were stimulated with natural and artificial signals. Percentages of males releasing pheromone and collected amounts of pheromone increased when males were stimulated with female calling song. Pheromone emission was stable in males stimulated with male rivalry songs, and it decreased in males stimulated with a 100-Hz artificial signal. The ability of male bugs to modulate their pheromone emission may reduce metabolic costs, reduce parasitism, and offer a better synchronization of sexual activity.     

Pheromone emission and blend percentages inEoreuma loftini determined by two methods

Calling behavior and pheromone emission by virgin femaleE. loftini moths were investigated in laboratory experiments. Calling peaked during the last three hours of the night. Three-day-old moths called more than older or younger moths and began calling earlier in the night than younger moths. Female emissions were collected in flasks without airflow and cylinders with airflow. Control tests indicated that the pheromone components (Z)-11-hexadecenyl acetate (HDA) and (Z)-13-octadecenylacetate (ODA) were 69 and 54% adsorbed on moths, respectively, and the component (Z)-13-octadecenal (ODL) was 92–99% adsorbed depending on its concentration, when put into flasks with noncalling females for 4 hr. Pheromone exposed to moths for less than 4 hr was adsorbed less. After correction for adsorption, the pheromone blend from females calling in flasks was 9:42:49% of HDA/ODL/ODA with an overall emission rate of 58 ng/female/4 hr. Three-day-old females emitted more pheromone than 0- to 2- or 4- to 5-day-old moths, in flasks. Little or no pheromone put into cylinders either downwind or upwind from a male moth was adsorbed by the moth. The pheromone blends from females calling in cylinders, corrected using downwind and upwind control test results, respectively, were 15:35:50 and 13:40:48% of HDA/ODL/ODA with overall emission rates of 32 and 35 ng/female/night.Lepidoptera: Pyralidae.     

The Effect of Atmospheric Pheromone Concentrations on Behavior of Lightbrown Apple Moth in an Apple Orchard

A previously validated Lagrangian model was used to estimate the threshold of atmospheric pheromone concentration required to prevent trap catch and wing fanning in mating disruption plots in an apple orchard. Electroantennogram (EAG) traces of 10 min duration were recorded, along with supporting meteorological data needed for the model, to better define the conditions in which successful mating disruption will occur. Pheromone was released from polyethylene tubing dispensers into orchard blocks treated with 10, 100, 1000, and 2000 dispensers/ha. Predicted dusk concentrations of atmospheric pheromone at a height of 1.85 m varied nightly between 4 and 90 ng pheromone/m³ (in plots treated with 1000 dispensers/ha) over 11 weeks. Disruption of traps baited with 1000-g pheromone lures followed an asymptotic curve with predicted concentration, but they did not show a significant effect of trap height (1.5 and 3.0 m). Wing fanning was reduced by increasing the density of dispensers, but was not completely eliminated even at 1000 dispensers/ha. At this density, the concentrations were usually <16 ng pheromone/m³. Electroantennogram recordings of 10 min duration showed a higher frequency of pheromone pulses in plots treated with more point sources per hectare. There was also a positive correlation between the number of pulses recorded by the EAG and predicted concentration for plots treated with 1000 or 2000 dispensers/ha. These results give added support to our model of pheromone release and transport in treated apple orchards.     

Three European corn borer populations in New York based on sex pheromones and voltinism

Pheromone blend analyses of glands from individual female European corn borers,Ostrinia nubilalis (Hübner), from field-collected larvae or pupae associated with bivoltine flights in June and August and a univoltine flight in July have shown that: (1) a site in western New York has a bivoltine biotype utilizing (Z)-11-tetradecenyl acetate as its primary pheromone component (designatedZ), (2) two sites in central New York have mixed populations consisting of a bivoltine biotype utilizing theE pheromone isomer (designatedE) and a univoltine biotype utilizingZ, and (3) one site in central New York was found to have only the univoltineZ biotype. The combinations of voltine biotypes and pheromone strains found in New York support the existence of three European corn borer populations designated bivoltineE, bivoltineZ, and univoltineZ.     

Rhythms of maleAntheraea polyphemus Attraction and female attractiveness,and an improved pheromone sythesis

WildAntheraea polyphemus (Cramer) (Lepidoptera:Saturniidae) males were attracted to synthetic pheromone and to laboratory-reared females from 2300 (EDT) until dawn. Males were attracted to the synthetic pheromone at a mean time of 01:33 and to the females at 0323 (EDT). Synthetic traps accumulated the most males (61 compared to 19 in the female-baited traps), but there was no large difference in catch during the main interval of female attractiveness. Pheromone used in the study was prepared by an improved synthesis that utilizescis-4-nonen-1-yl bromide as a key intermediate.Lepidoptera:Saturniidae.     

Semiochemicals of the honeybee queen mandibular glands

The ontogeny of the five queen mandibular gland semiochemicals that initiate and maintain the retinue behavior of worker honeybees was investigated by quantitative splitless capillary gas chromatography. No detectable pheromone is present at the time of eclosion, but decenoic acid levels build up rapidly during the first week of the queen's life. Two aromatic components attain detectable levels later, with the more plentiful methylp-hydroxybenzoate preceding the 4-hydroxy-3-methoxyphenylethanol. Pheromone levels are maximal in mature, mated, laying queens. The ratio of (R,E)-(–)-9-hydroxy-2-decenoic acid to the (S,E)-(+) enantiomer increases with the age of the queen. Pheromone levels in queen mandibular glands are largely unaffected by queen banking, restraint with workers in mailing cages, and limited storage on dry ice. All major body parts of typical queens, especially the head and legs, have sufficient mandibular exudate to be highly attractive to worker bees.     

Mechanism and Behavioral Context of Male Sex Pheromone Release in <Emphasis Type="Italic">Nasonia vitripennis</Emphasis>

Males of the parasitic wasp Nasonia vitripennis (Hymenoptera: Pteromalidae) attract virgin females by releasing a sex pheromone composed of (4R,5R)- and (4R,5S)-5-hydroxy-4-decanolide (HDL). The pheromone is biosynthesized in the rectal vesicle of males. In the present study, we investigated the mechanism and behavioral context of pheromone release, and determined the range of activity and the longevity of the chemical signal. Our data show that the sex pheromone of N. vitripennis is substrate-borne and is deposited on surfaces by dabbing movements of the abdominal tip, a behavior previously described in N. vitripennis males as ‘abdomen dipping’. Chemical markings deposited by a single male were highly attractive to virgin females. Chemical analyses revealed the presence of HDL in surface washings of marked areas, and HDL amounts correlated with male marking activity. Pheromone deposition occurred spontaneously without any additional cues being present, but marking intensity increased greatly after copulation or after a single contact with a virgin female. In contrast, marking intensity was not influenced by the presence of host puparia. Male pheromone deposits were perceived by females in a still-air olfactometer at distances of up to 4.5 cm and remained attractive for at least 2 h. The function of the substrate-borne sex pheromone is discussed with respect to the mating system of N. vitripennis.     

(Z)-7-Tricosene and Monounsaturated Ketones as Sex Pheromone Components of the Australian Guava Moth Coscinoptycha improbana: Identification, Field Trapping, and Phenology

Pheromone gland extracts of the Australian guava moth Coscinoptycha improbana (Lepidoptera: Carposinidae), contained four compounds that elicited responses from male moth antennae in gas chromatography-electroantennogram detection (GC-EAD) analyses. These were identified by GC-mass spectrometry as (Z)-7-tricosene (Z7-23Hy), (Z)-7-octadecen-11-one (Z7-11-one-18Hy), (Z)-7-nonadecen-11-one (Z7-11-one-19Hy), and (Z)-7-tricosen-11-one (Z7-11-one-23Hy) at a ratio of 65:23.5:1.5:10, respectively. Z7-23Hy, Z7-11-one-18Hy, and Z7-11-one-23Hy have not previously been reported as lepidopteran sex pheromone components. Z7-11-one-18Hy was active as a single component, and was synergized by Z7-11-one-23Hy but not Z7-11-one-19Hy, although the latter compound was weakly attractive as a single component. Addition of Z7-23Hy further increased attraction. The amount of the major pheromone component, Z7-11-one-18Hy in female pheromone gland extracts was estimated to be 16.4 ng/female (N = 8). Phenological data gathered over a 12-mo period in 2002 and 2003 using the binary blend indicated that moths are active throughout the year. The pheromone has already been employed to monitor the spread of C. improbana in New Zealand and detect its presence in Queensland, Australia.     

Sex pheromone communication in the screwworm,Cochliomyia hominivorax: Ontogenetic and strain effects

A laboratory behavioral assay was used to examine ontogenetic and strain effects on sex pheromone production and reception in the screwworm, which employs a female-produced contact pheromone to stimulate male copulatory attempts. Pheromone levels peaked between three and six days after adult emergence in females of two strains that had been colonized fewer than 50 generations. Pheromone was detectable at low levels in newly emerged flies of both sexes but disappeared from males by two days of age, when males first became responsive to females. A similar decline in pheromone with ontogenetic age was previously described for females of a strain colonized over 100 generations. Interstrain tests between the two newer strains, which differed by 35 generations in duration of colonization, demonstrated lower female pheromone activity but higher male responsiveness to pheromone in the older strain, despite the similar shape within these strains of curves relating female age and pheromone activity. The data suggest that conditions of screwworm colonization result in gradual loss of the pheromone peak that develops three to six days after emergence in newly colonized females. Higher male responsiveness associated with longer colonization involved change in both thresholds and dose dependency and may be relevant to control of the screwworm via the sterile insect technique.     

Production of pheromone by hairpencil glands of males obtained from interspecific hybridization betweenHeliothis virescens andH. subflexa (Lepidoptera: Noctuidae)

Pheromone produced by the hairpencil glands of interspecific hybrid- and backcross-generation males from crosses betweenHeliothis virescens (F.) withH. subflexa (Gn.) was studied. Males of reciprocal F₁ hybrids, all of which had hairpencil glands morphologically similar to those ofH. virescens, produced neither the same pheromone blend nor amounts of pheromone that were produced by males ofH. virescens. Instead, these hybrid males produced pheromone that was quantitatively and qualitatively similar to that produced byH. subflexa. Hairpencil gland extracts from males obtained from backcrossing F₁ females of either cross to males ofH. subflexa were the same as those ofH. subflexa. However, extracts from backcross males of crosses between F₁ females andH. virescens were variable. Some extracts from these backcross males were like those ofH. virescens while others were either likeH. subflexa or were intermediate between those of the parent species. These results showed that the production of pheromone by the hairpencil glands of hybrid and backcross males is under the dominant regulation of autosomal genes of theH. subflexa genome.     

Sex Pheromone of <Emphasis Type="Italic">Elater ferrugineus</Emphasis> L. (Coleoptera: Elateridae)

The rare European click beetle, Elater ferrugineus L., develops exclusively in old, hollow deciduous trees. As a result of massive habitat loss caused by modern forestry, it is threatened throughout its entire distribution range and regarded as an indicator species for undamaged natural forests. As E. ferrugineus lives cryptically and its populations are frequently overlooked, we investigated its sex pheromone to develop a reliable detection tool. Pheromone gland extracts of single female E. ferrugineus were examined by using gas chromatography–mass spectrometry (GC–MS). All samples contained 7-methyloctyl 5-methylhexanoate, 7-methyloctyl octanoate, 7-methyloctyl 7-methyloctanoate, and 7-methyloctyl (Z)-4-decenoate in a ratio of approximately 1:1:3:3. Structures of all four esters, which have not been reported as pheromone compounds before, were confirmed by synthesis. A blend of the components was tested in the field and proved to be attractive for E. ferrugineus males, which were found to swarm exclusively during the day. This blend provides a noninvasive and effective monitoring method for this cryptic species, promising future collection records of E. ferrugineus in regions where it exists below the limit of detection by conventional collecting methods.