Field evaluation ofAnomala schonfeldti ohaus (Coleoptera: Scarabaeidae) synthetic sex pheromone

Synthetic 2-(E)-nonenol, previously identified as the sex pheromone ofAnomala schonfeldti (Coleoptera: Scarabaeidae), is demonstrated to be very attractive to males in the field. Nevertheless, no significant differences were found between treatments with 1, 5, 10, and 20 mg dosages. Males ofA. schonfeldti were more significantly attracted to traps at 30 cm high than at 90 cm. Although the observed behavior seemed to indicate a trend of more attraction to buried traps than those placed at 30 cm, there was no statistical difference between the two treatments. Pheromone-baited traps caught significantly more beetles than traps containing three virgin females. Over 70% of released beetles were recaptured in six traps surrounding the point of release and separated from each other by 50 m, suggesting a possible use of the pheromone (in combination with floral compounds) in mass trapping.     

The Absolute Configuration of the Sex Pheromone of the Citrophilous Mealybug, <Emphasis Type="Italic">Pseudococcus calceolariae</Emphasis>

The absolute configuration of the sex pheromone of the citrophilous mealybug, Pseudococcus calceolariae, was determined to be (1R,3R)-[2,2-dimethyl-3-(2-methylprop-1-enyl)cyclopropyl]methyl (R)-2-acetoxy-3-methylbutanoate. NMR, derivatization reactions, chiral gas chromatography-mass spectrometry, and comparison with synthetic chiral reference compounds, were used to determine the absolute configuration of this compound. This activity of this compound was further confirmed by testing synthetic stereoisomers of the compound as lures in traps for adult male mealybugs. Traps baited with 1,000 μg of the pheromone compound caught 36 times more males than traps baited with virgin females. A mixture of stereoisomers of the pheromone compound can be used for field trapping without adverse effects on trap catch. A comparison with the structures of other sex pheromones of mealybugs is presented.     

Enhancement of Attraction to Sex Pheromones of Spodoptera exigua by Volatile Compounds Produced by Host Plants

We measured the effects of exposure to volatile compounds produced by host plants on the rate of capture of male Spodoptera exigua using synthetic sex pheromones. Exposure to volatile compounds stimulated strong electroantennographic responses of male S. exigua. The behavioral responses of male moths to combinations of sex pheromone and volatile compounds were tested in wind tunnel experiments. When lures were baited with synthetic sex pheromone plus benzaldehyde, phenylacetaldehyde, (Z)-3-hexenyl acetate, or linalool, respectively, the landing rate of S. exigua males was increased by 101.4%, 79.6%, 60.6%, and 34.3%, respectively, compared to sex pheromone alone. In field tests, traps baited with either pheromone + (E)-2-hexenal, pheromone + phenylacetaldehyde, pheromone + (Z)-3-hexenyl acetate, or pheromone + (Z)-3-hexenol enhanced moth catches by 38.8%, 34.6%, 24.6%, and 20.8%, respectively compared to traps baited with pheromone alone. In a second field experiment, more S. exigua males were trapped with a combination of a synthetic sex pheromone blend and several individual host plant volatiles compared to synthetic sex pheromone alone. These results suggest that some host plant volatiles enhance the orientation response of S. exigua male moths to sex pheromone sources.     

Laboratory and Field Study of the Attraction of Male Pea Midges, Contarinia pisi, to Synthetic Sex Pheromone Components

Behavioral activity of the recently identified sex pheromone components of the pea midge, Contarinia pisi, (2S,11S)-diacetoxytridecane, (2S,12S)-diacetoxytridecane, and 2-acetoxytridecane, was tested in wind tunnel and field-trapping experiments. In the wind tunnel, the attractancy of the three-component blend in a 7 : 10 : 0.1 ratio (following the above order, mimicking the ratios found in gland extract) did not differ significantly from female gland extract, whereas a mixture of the two major components (7 : 10) only attracted 2% of the males to the source. In the field, traps baited with the three-component blend caught by far the largest number of males. Traps baited with the two major components only caught slightly more than the blank traps, and catches in traps baited with 2-acetoxytridecane alone did not differ from catches in the blank traps. Traps baited with the racemate of all three components did not catch more than the blank traps, indicating that some of the enantiomers are inhibitory.     

Ethyl 4-Methyl Heptanoate: A Male-Produced Pheromone of <Emphasis Type="Italic">Nicrophorus vespilloides</Emphasis>

Sexually mature male beetles of the genus Nicrophorus (Coleoptera: Silphidae) exhibit a conspicuous behavior, recognized as pheromone-releasing activity. Laboratory and field studies demonstrated that females are attracted to males that exhibit this behavior, both on or off reproductive resources. Here, we report the results of a study in which volatile chemicals released by calling Nicrophorus vespilloides were collected by solid-phase microextraction and analyzed by using coupled gas chromatography–mass spectrometry. These analyses revealed that ethyl 4-methyl heptanoate and (E)-geranylacetone are emitted by males that engage in the behavior. In the field, traps baited with racemic ethyl 4-methyl heptanoate caught roughly equal numbers of male and female N. vespilloides. Some male and female Nicrophorus vespillo and male Nicrophorus humator were also caught in traps baited with this compound. Traps baited with (E)-geranylacetone did not catch significant numbers of beetles.     

Attraction of male beetles to grubs: Evidence for evolution of a sex pheromone from larval odor

Females of the scarabaeid beetleCyclocephala lurida produce a volatile sex pheromone which attracts conspecific males. Field experiments demonstrated that larvae of both sexes also emit volatile chemicals that stimulate similar responses in adult males, including attempts by the attracted males to mate with the nonreproductive immature stage. Significantly more adult males were caught in traps baited with conspecific male or female larvae or adult females than in blank control traps. Hexane extracts of both male and female grubs were at least as effective as live larvae in trapping male adults, demonstrating that the behavioral responses are mediated by volatile chemicals. Sensory and behavioral responses of males to sex pheromones emitted by adult females are part of the functional communication system. However, their response to grubs is not functional, because grubs are normally temporally and spatially inaccessible to mate-seeking males. In theory, the evolution of a communication system is problematic because it requires the development of a signal in one sex and the sensory and behavioral attributes to respond to that signal in the other sex. The ontogeny of sex pheromone communication inC. lurida suggests a partial solution to this evolutionary problem. We propose that this sex pheromone communication system is probably derived from noncommunicative volatile chemicals that are lost in adult males and retained by adult females.     

Identification of the Aggregation-sex Pheromone Produced by Male <Emphasis Type="Italic">Monochamus saltuarius</Emphasis>, a Major Insect Vector of the Pine Wood Nematode

In this study, we isolated and identified an aggregation-sex pheromone from Monochamus saltuarius, the major insect vector of the pine wood nematode in Korea. Adult males of M. saltuarius produce 2-undecyloxy-1-ethanol, which is known as an aggregation-sex pheromone in other Monochamus species. We performed field experiments to determine the attractiveness of the pheromone and other synergists. More M. saltuarius adult beetles were attracted to traps baited with the pheromone than to unbaited traps. Ethanol and (?)-α-pinene interacted synergistically with the pheromone. Traps baited with the pheromone + (?)-α-pinene +ethanol were more attractive to M. saltuarius adults than traps baited with the pheromone, (?)-α-pinene, or ethanol alone. Ipsenol, ipsdienol, and limonene were also identified as synergists of the aggregation-sex pheromone for M. saltuarius adults. In field experiments, the proportion of females was much higher in the beetles caught in traps than among the beetles emerging from naturally-infested logs in the laboratory. Our results suggest that a combination of aggregation-sex pheromone and synergists could be very effective for monitoring and managing M. saltuarius.     

Sex Pheromone Components of the Pear Fruit Moth, <Emphasis Type="Italic">Acrobasis pyrivorella</Emphasis> (Matsumura)

We analyzed the sex pheromone of the pear fruit moth, Acrobasis pyrivorella, by means of gas chromatography–electroantennographic detection (GC-EAD) and GC–mass spectrometry. Two EAD-active compounds were detected in the pheromone gland extract of females. They were identified as (Z)-9-pentadecenyl acetate (Z9-15:OAc) and pentadecyl acetate (15:OAc). The amounts per female gland (mean ± standard error) of these compounds were 12.9 ± 2.8 and 0.8 ± 0.1 ng, respectively. Synthetic Z9-15:OAc (300 μg) attracted conspecific males in field trapping experiments. When 15:OAc (21 μg; 7% of Z9-15:OAc quantity) was added, the number of males trapped increased significantly. Catch in traps baited with the mixture of these compounds was greater than that in traps baited with 1–3-day-old virgin females. We, therefore, conclude that Z9-15:OAc and 15:OAc are sex pheromone components of this species.     

Sex Pheromone of Callosobruchus subinnotatus

Sex pheromone produced by Callosobruchus subinnotatus females stimulates conspecific males to walk upwind toward the source. Gas chromatographic and mass spectrometric analyses of sex pheromone components and their hydrogenated derivatives suggested that the sex pheromone consisted of two short-chain fatty acids, (E)-3-methyl-2-heptenoic acid (E32C7) and (Z)-3-methyl-2-heptenoic acid (Z32C7). The composition of the sex pheromone was confirmed by electrophysiological and behavioral bioassays with synthetic compounds. A mixture of 5 ng E32C7 and 5 ng Z32C7 elicited a 2.1-mV male EAG response, whereas the solvent control elicited 0.1 mV. Mixtures of the two compounds at various ratios were attractive to males in Y-tube bioassays. A pitfall-type trap equipped with a lure impregnated with 1 ng E32C7 and 1 ng Z32C7 was effective in trapping males. Traps baited with the lure caught 80% of males in a glass aquarium during nighttime and 50% during daytime, whereas control traps (solvent treated) in a separate aquarium caught 20% and 10%, respectively.     

Semiochemical attractants ofDiabrotica undecimpunctata howardi barber,southern corn rootworm,andDiabrotica virgifera virgifera leconte,the western corn rootworm (Coleoptera: Chrysomelidae)

During the summers of 1984 and 1985, a variety of structurally related benzenoid compounds was evaluated in sweet corn plots as attractants for adult southern corn rootworms (SCR), western com rootworms (WCR), and northern corn rootworms (NCR). Field response to the volatiles was measured by beetle counts on baited cylindrical sticky traps placed inside the corn plots at a height of l m above ground level. SCR adults were attracted late in the season (last week of August through September, 1984 and 1985) to numerous aromatic compounds, including phenylacetaldehyde, benzyl acetone, phenethyl alcohol, phenyl acetate, indole, veratrole, methyl eugenol, methyl isoeugenol, eugenol, and isoeugenol. Although many compounds attracted SCR adults late in the season, only veratrole, phenylacetaldehyde, and chavicol were significantly active in early and middle August 1985. WCR adults were attracted to a different group of compounds, namely estragole,trans-anethole, and indole. Estragole (4-methoxy-1-allylbenzene) was an effective WCR attractant from corn tasseling in early August 1985, until the end of the trapping period in late September and early October 1985. Indole andtrans-anethole (4-methoxy-1-propenylbenzene) were less effective attractants than estragole and were most active at the beginning and/or end of the corn season. Traps baited with 100 mg of estragole caught an average of 20 times more WCR adults than unbaited control traps, and the females outnumbered the males in the baited traps. Estragole dosage tests were conducted in three sweet corn plots on different dates in 1985 and the minimum effective dose ranged between 5 and 30 mg/trap. Field tests with structural analogs revealed the importance of the site of unsaturation in the allylic side chain of estragole and the effect of different ring substituents on WCR response. The phenylpropanoids, eugenol and isoeugenol, significantly attracted NCR adults, even though these beetles were in low abundance in the test corn plots. Field tests indicate there is no cross-species response by WCR and NCR adults to their related phenylpropanoid attractants. However, in late August, SCR adults do respond to some WCR and NCR attractants (indole and several eugenol analogs). Electroantennographic analysis of SCR males revealed they can perceive peripherally a wide range of benzenoid compounds.     

Male-Produced Aggregation Pheromones of the Cerambycid Beetles <Emphasis Type="Italic">Xylotrechus colonus</Emphasis> and <Emphasis Type="Italic">Sarosesthes fulminans</Emphasis>

Adults of both sexes of the cerambycid beetles Xylotrechus colonus (F.) and Sarosesthes fulminans (F.) were attracted to odors produced by male conspecifics in olfactometer bioassays. Analyses of headspace volatiles from adults revealed that male X. colonus produced a blend of (R)- and (S)-3-hydroxyhexan-2-one and (2 S,3 S)- and (2R,3R)-2,3-hexanediol, whereas male S. fulminans produced (R)-3-hydroxyhexan-2-one and (2 S,3R)-2,3-hexanediol. All of these compounds were absent in the headspace of females. Two field bioassays were conducted to confirm the biological activity of the synthesized pheromones: (1) enantiomerically enriched pheromone components were tested singly and in species-specific blends and (2) four-component mixture of racemic 3-hydroxyhexan-2-one plus racemic 2-hydroxyhexan-3-one and the four-component blend of the stereoisomers of 2,3-hexanediols were tested separately and as a combined eight-component blend. In these experiments, adult male and female X. colonus were captured in greatest numbers in traps baited with the reconstructed blend of components produced by males, although significant numbers were also captured in traps baited with (R)-3-hydroxyhexan-2-one alone or in blends with other compounds. Too few adult S. fulminans were captured for a statistical comparison among treatments, but all were caught in traps baited with lures containing (R)-3-hydroxyhexan-2-one. In addition to these two species, adults of two other species of cerambycid beetles, for which pheromones had previously been identified, were caught: Neoclytus a. acuminatus (F.) and its congener Neoclytus m. mucronatus (F.). Cross-attraction of beetles to pheromone blends of other species, and to individual pheromone components that are shared by two or more sympatric species, may facilitate location of larval hosts by species that compete for the same host species.     

Sex attractant of the alfalfa looperAutographa californica and the celery looperAnagrapha falcifera (Lepidoptera: Noctuidae)

In field tests, traps baited with a combination of (Z)-7-dodecen-1-ol acetate (previously proposed to be the sex pheromone ofA. californica) and (Z)-7-dodecen-1-ol formate caught about 100 times as many males as (Z)-7-dodecen-1-ol acetate did alone. Highest catches of males were obtained with traps baited with 0.5 mg of (Z)-7-dodecen-1-ol acetate and 0.1 mg of (Z)-7-dodecen-1-ol formate impregnated on red rubber sleeve stoppers. The celery looper,Anagrapha falcifera, was also caught in traps baited with a combination of these two chemicals.     

Identification of Semiochemicals Associated with Jeffrey Pine Beetle, Dendroctonus jeffreyi

Analysis of frass extracts and aerations from adult beetles confirmed earlier studies identifying 1-heptanol as a principal pheromone constituent produced by female Dendroctonus jeffreyi Hopkins. The aerations also indicated that males produced 33% (+) and 67% (–)-frontalin, previously unreported for this species, and >99% (+)-exo-brevicomin. Both males and females were responsive to these compounds in electrophysiological studies. Laboratory bioassays and field trapping experiments indicated that males and females were attracted to a mixture of 1-heptanol plus the principal host resin component heptane, but females were less attracted than males. Inclusion of racemic exo-brevicomin at 0.1% concentration in the traps increased the response of females. Inclusion of racemic frontalin above a 1% concentration in the normally attractive lures blocked arrival of beetles to the traps. While the female-produced pheromone components and host synergists are very different between the sibling species D. jeffreyi and Dendroctonus ponderosae Hopkins, the principal male-produced compounds are the same, and the response of the female beetles to those compounds appears to be similar.     

Identification and Field Activity of a Male-Produced Aggregation Pheromone in the Pine Sawyer Beetle, <Emphasis Type="Italic">Monochamus galloprovincialis</Emphasis>

The pine sawyer beetle, Monochamus galloprovincialis, is a pest of pine trees in Europe and North Africa. Previously considered a secondary pest of stressed and dying trees, it is now receiving considerable attention as a vector of the pine wood nematode, Bursaphelenchus xylophilus, the causal agent of a lethal wilting disease in susceptible species of pines. Adult beetles are attracted to traps baited with a kairomone blend consisting of a host volatile, α-pinene, and two bark beetle pheromone components, ipsenol and 2-methyl-3-buten-2-ol. More recently it has been shown that mature male M. galloprovincialis produce a pheromone that attracts mature females in a laboratory bioassay. Here, volatiles were collected from mature male and female M. galloprovincialis, and a compound produced specifically by mature males was identified as 2-undecyloxy-1-ethanol from its gas chromatographic retention times, its mass spectrum, and by comparison with synthetic standards. The naturally-derived and synthetic compounds elicited electroantennographic responses from both females and males. Sealed polyethylene vials and polyethylene sachets were shown to be effective dispensers with zero-order release, the latter giving a higher release rate than the former. In two field tests, multiple-funnel traps baited with synthetic 2-undecyloxy-1-ethanol caught both female and male M. galloprovincialis, with higher catches at the higher release rate. This compound also synergized the attractiveness of the kairomone blend, the combined mixture catching 80–140% more beetles than the sum of the catches to each bait separately and luring up to two beetles/trap/d in a moderate-density population. We conclude that 2-undecyloxy-1-ethanol is a male-produced aggregation pheromone of M. galloprovincialis. This is the first example of a sex-specific compound in the cerambycid subfamily Lamiinae with significant behavioral activity in the field at a range sufficient to make it a useful trap bait. The possible roles of this pheromone in the chemical ecology of M. galloprovincialis and its potential use in pine wilt disease management are discussed.     

Trapping Efficiency and Sex Ratio of Maladera matrida Beetles in Yellow and Black Traps

In field experiments, which started several years ago to investigate the means of chemical communication of the Maladera matrida beetle, we found that the ratio of males to females attracted to the bait (live females with food) was 3 : 2–5 : 4 60 : 40–55 : 45). These findings suggested that an aggregation pheromone is involved in the chemical communication, but the constant small preference for attracted males raised the question whether the active compound(s) is indeed an aggregation pheromone or whether it is a sex pheromone released by the female to attract the male. Since the traps used in our field studies were made of yellow plastic, we had to consider the possibility that the yellow color could have influenced the trapping of the flying beetles and biased the findings for the behavior and mode of attraction toward the source of the chemical communication. To clarify this point, we set out, in this study, to conduct field experiments in which we compared the standard yellow traps with black traps. We found that the bright yellow color did indeed affect the results for chemical communication: The total catch in the yellow traps was double that in black traps, and the male–female ratio in the black traps increased to 4 : 1(80 : 20). This result hints that a sex pheromone, and probably not an aggregation pheromone, as previously thought, is involved in the chemical communication of the M. maladera beetle.     

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.     

Identification and Field Evaluation of Attractants for the Cranberry Weevil, <Emphasis Type="Italic">Anthonomus musculus</Emphasis> Say

Studies were conducted to develop an attractant for the cranberry weevil, Anthonomus musculus, a pest of blueberry and cranberry flower buds and flowers in the northeastern United States. In previous studies, we showed that cinnamyl alcohol, the most abundant blueberry floral volatile, and the green leaf volatiles (Z)-3-hexenyl acetate and hexyl acetate, emitted from both flowers and flower buds, elicit strong antennal responses from A. musculus. Here, we found that cinnamyl alcohol did not increase capture of A. musculus adults on yellow sticky traps compared with unbaited controls; however, weevils were highly attracted to traps baited with the Anthonomus eugenii Cano aggregation pheromone, indicating that these congeners share common pheromone components. To identify the A. musculus aggregation pheromone, headspace volatiles were collected from adults feeding on blueberry or cranberry flower buds and analyzed by gas chromatography-mass spectrometry. Three male-specific compounds were identified: (Z)-2-(3,3-dimethyl-cyclohexylidene) ethanol (Z grandlure II); (Z)-(3,3-dimethylcyclohexylidene) acetaldehyde (grandlure III); and (E)-(3,3- dimethylcyclohexylidene) acetaldehyde (grandlure IV). A fourth component, (E)-3,7-dimethyl-2,6-octadien-1-ol (geraniol), was emitted in similar quantities by males and females. The emission rates of these volatiles were about 2.8, 1.8, 1.3, and 0.9 ng/adult/d, respectively. Field experiments in highbush blueberry (New Jersey) and cranberry (Massachusetts) examined the attraction of A. musculus to traps baited with the male-produced compounds and geraniol presented alone and combined with (Z)-3-hexenyl acetate and hexyl acetate, and to traps baited with the pheromones of A. eugenii and A. grandis. In both states and crops, traps baited with the A. musculus male-produced compounds attracted the highest number of adults. Addition of the green leaf volatiles did not affect A. musculus attraction to its pheromone but skewed the sex ratio of the captured adults towards females. Although the role of plant volatiles in host-plant location by A. musculus is still unclear, our studies provide the first identification of the primary A. musculus aggregation pheromone components that can be used to monitor this pest in blueberry and cranberry pest management programs.     

Sex pheromone differences in populations of the brownheaded leafroller,Ctenopseustis obliquana

Ctenopseustis obliquana females collected from Christchurch were found to produce a mixture of (Z)-5-tetradecenyl acetate and tetradecyl acetate in their sex pheromone gland, in contrast toC. obliquana from Auckland which produce an 80∶20 mixture of (Z)-8-tetradecenyl acetate and (Z)-5-tetradecenyl acetate. This identification has been made on the basis of instrumental and chemical analyses. Antennae of maleC. obliquana from Christchurch gave a maximal electroantennogram response to (Z)-5-tetradecenyl acetate. A field trapping program in Christchurch using combinations of synthetic (Z)-5-tetradecenyl acetate and tetradecyl acetate caughtCtenopseustis males equally well if the latter chemical was present or absent. No males were caught in traps baited with the Auckland-type pheromone. In Alexandra,Ctenopseustis males were caught in traps baited with Auckland-type pheromone and not in traps baited with Christchurch-type pheromone. This phenomenon is ascribed to the existence of sibling species within the describedC. obliquana.     

Laboratory and field evidence for maleproduced aggregation pheromone inRhynchophorus cruentatus (F.) (Coleoptera: Curculionidae)

Laboratory and field assays were conducted to determine if palmetto weevil,Rhynchophorus cruentatus (F.), adults produce an aggregation pheromone. Attraction of females in a Y-tube olfactometer to conspecific males was greater than to clean air. Male and female attraction to conspecific male volatiles combined with host-palm,Sabal palmetto (Walter), volatiles was greater than to host-palm volatiles alone. Similarly, more weevils were caught in the field in traps baited with conspecific males plus host-palm tissue than in similar traps baited with only males, or palm tissue, or females, or females plus palm tissue. These results suggest thatR. cruentatus males produce an aggregation pheromone(s) that is highly attractive to conspecific adults of both sexes when combined with host-palm volatiles. This study is an important step towards understanding the chemical ecology ofR. cruentatus.     

Identification of an attractant for the caneborerSesamia grisescens walker (Lepidoptera: Noctuidae)

The composition of the sex pheromone ofSesamia grisescens was investigated using gas chromatography, electroantennograms, and field trapping. (Z)-11-Hexadecenyl acetate and (Z)-11-hexadecenol were identified in field tests as the major attractants. Trapping trials identified a 3:2 blend of these compounds as the most effective bait. Gas chromatography indicated the presence of hexadecyl acetate. (Z)-9-hexadecenyl acetate, (Z)-9-hexadecenol, and (E)-11-hexadecenyl acetate in the pheromone gland, but these compounds had no significant effect on trap catches when added to the major components. Traps baited with the major components in a 1:1 ratio caught more male moths than traps baited with virgin females.