Male-produced aggregation pheromone ofCarpophilus mutilatus (Coleoptera: Nitidulidae)

Males ofCarpophilus mutilatus Erichson produce an aggregation pheromone to which both sexes respond. The pheromone includes two hydrocarbon components, (3E,5E,7E)-5-ethyl-7-methyl-3,5,7-undecatriene (1) and (3E,5E,7E)-6-ethyl-4-methyl-3,5,7-decatriene (2). These were emitted in a 101 ratio and in a total amount of ca. 5 ng per feeding male per day. All tested doses of1 and2, from 0.03 to 30 ng, were more attractive than controls in wind-tunnel tests, but there was no evidence of synergism between these trienes. Dramatic synergism between the pheromone and a food-type coattractant occurred in the field, however. In a date garden in southern California, traps with a combination of synthetic1 and fermenting whole-wheat bread dough attracted 22 times more beetles than dough by itself and 295 times more than1 by itself. Volatile collections from males also contained three oxygenated compounds that were absent from females. One of these was tetradecanal (ca. 5 ng per male per day), but the structures of the other two are presently undetermined (0.8 and 1.1 ng per male per day). No function for these was demonstrated. One compound originating in the artificial diet, 2-phenylethanol, was particularly attractive in the wind-tunnel bioassay, as was the chromatographic solvent, methanol.     

Male-produced aggregation pheromone ofCarpophilus obsoletus (Coleoptera: Nitidulidae)

Males ofCarpophilus obsoletus Erichson produce an aggregation pheromone to which both sexes respond. The pheromone was identified by GC-MS as (2E,4E,6E,8E)-3,5,7-trimethyl-2,4,6,8-undecatetraene (1), which is also a minor constituent of the pheromone blends ofC. hemipterus (L.),C. freemani Dobson, andC. lugubris Murray. The pheromone was synergized in wind-tunnel bioassays by propyl acetate, a host-type coattractant. In a dose-response study, 50 pg of1, plus propyl acetate, was significantly more attractive than just propyl acetate. Pheromone emission from groups of 65 males, feeding on artificial diet, averaged 2.2 ng/male/day. Emissions from individual males were larger, averaging 72 ng/day and ranging as high as 388 ng/day. Synthetic1 was tested in a date garden in southern California (500 µg/rubber septum), using fermenting whole-wheat bread dough as the coattractant. The pheromone plus dough attracted significantly more beetles than dough alone (means were 4.2 and 0.0 beetles per week per trap). Captured beetles were 54% females. Field trap catches were highest during the months of July and August.All programs and services of the U.S. Department of Agriculture are offered on a nondiscriminatory basis without regard to race, color, national origin, religion, sex, age, marital status, or handicap. Mention of firm names or trade products does not imply endorsement by the U.S. Department of Agriculture over similar firms or products not mentioned.     

Attraction ofCarpophilus Spp. (Coleoptera: Nitidulidae) to volatile compounds present in figs

Various volatile compounds present in ripening figs were attractive toCarpophilus hemipterus, C. mutilatus, C.freemani, andC. lugubris. Field tests demonstrated that traps baited with a mixture of acetaldehyde, ethyl alcohol, and ethyl acetate caught more adultC. hemipterus than those baited with (1) other mixtures involving various combinations of 19 compounds, (2) with 16 single compounds, or (3) with fig paste.This investigation was supported in part by a grant from the California Dried Fig Advisory Board.     

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.     

Aggregation pheromone of Australian SAP beetle,Carpophilus davidsoni (Coleoptera: Nitidulidae)

A male-produced aggregation pheromone was identified for the Australian sap beetle,Carpophilus davidsoni Dobson (Coleoptera: Nitidulidae), by bioassay-guided fractionation of volatiles collected from feeding beetles. The most abundant components were: (2E,4E,6E)-5-ethyl-3-methyl-2,4,6-nonatriene, (3E,5E,7E)-6-ethyl-4-methyl-3,5,7-decatriene, (2E,4E,6E,8E)-3,5,7-trimethyl-2,4,6,8-undecatetraene, and (2E,4E,6E,8E)-7-ethyl-3,5-dimethyl-2,4,6,8-undecatetraene. The relative abundance of these components in collections from individual males feeding on artificial diet was 100:7:9:31, respectively. Pheromone production began within several days after males were placed onto diet medium and continued for at least 20 weeks. Peak production was >3 µg total pheromone per male per day. Males in groups of 50–60 emitted less pheromone (the peak level was 0.09 µg per beetle per day), and the emissions from groups contained relatively little tetraene (proportions of the components listed above were 100:7:2:7, respectively). Three additional trienes and one additional tetraene were identified in minor amounts; the entire eight-component male-specific blend is qualitatively identical and quantitatively similar to that of the North American sibling species,C. freemani Dobson. A synthetic blend of the four major components on rubber septa, prepared to emit in the same proportions as from individual males, was highly attractive in the field when synergized with fermenting whole-wheat bread dough. Cross-attraction was observed in the field involving the pheromones ofC. davidsoni, C. hemipterus (L.), andC. mutilatus Erichson. Potential uses of the pheromones in pest management are discussed.Names are necessary to report factually on available data; however, the USDA neither guarantees nor warrants the standards of the products, and the use of the names by USDA implies no approval of the products to the exclusion of others that may also be suitable.     

Aggregation pheromone ofCarpophilus dimidiatus (F.) (Coleoptera: Nitidulidae) and responses toCarpophilus pheromones in South Carolina

The major component of the male-produced aggregation pheromone ofCarpophilus dimidiatus (F.) is (3E, 5E, 7E, 9E)-6,8-diethyl-4-methyl-3,5,7,9-dodecatetraene. It attracts beetles of both sexes in the field and is synergized by odors from fermenting bread dough; mean trap catches for the tetraene alone, tetraene plus dough, dough alone, and control were 24.5, 48.3, 0.02, and 0.00, respectively. In the laboratory, individual males produced 0.58 µg±0.35 µg (SD) of the tetraene per day, but males in groups of 10–50 produced <2% as much per beetle. A second male-specific compound, (3E, 5E, 7E, 9E)-5,7-diethyl-9-methyl-3,5,7,9-tridecatetraene, was also identified fromC. dimidiatus and is about 5% as abundant as the major pheromone component.Carpophilus flight activity was monitored for one year in South Carolina corn fields with the pheromones forC. dimidiatus, C. freemani Dobson,C. mutilatus Erichson,C. hemipterus (L.),C. lugubris Murray, andC. obsoletus Erichson, all in combination with bread dough. The first four of these species accounted for 18, 70, 5.7, and 0.03%, respectively, of the totalCarpophilus trapped, but noC. lugubris orC. obsoletus were captured. Captures ofC. freemani were as high as 11,400/trap/week. Species specificity for the first four pheromones was high, except that a synthetic impurity in theC. dimidiatus pheromone was somewhat attractive toC. freemani andC. mutilatus. Three other species captured.C. antiques Melsheimer,C. marginellus Motschulsky, andC. humeralis (F.), accounted for 0.005, 5.0, and 1.3% of the total catch, respectively.C. antiquus was attracted primarily to the pheromone ofC. dimidiatus, butC. marginellus andC. humeralis responded to most of the test pheromones. There were two major periods ofCarpophilus flight activity: February through June and September through November.Names are necessary to report factually on available data; however, the USDA neither guarantees nor warrants the standard of the product, and the use of the names by USDA implies no approval of the product to the exclusion of others that may also be suitable.     

Mass-trapping ofCarpophilus spp. (Coleoptera: Nitidulidae) in stone fruit orchards using synthetic aggregation pheromones and a coattractant: Development of a strategy for population suppression

Experiments were conducted in southern New South Wales to evaluate the potential of mass-trapping using synthetic aggregation pheromones and a coattractant as a control option forCarpophilus spp. in stone fruit orchards. A cordon of 54 pipe and 54 funnel traps (one trap of each type per perimeter tree) baited with pheromones ofC. mutilatus andC. davidsoni and coattractant (fermenting bread dough) was maintained around an apricot orchard for three weeks prior to harvest. The incidence ofCarpophilus spp. in ripe fruit in the center of the orchard was significantly reduced compared to a nearby orchard or the perimeter trees containing traps. A cordon of 16 water-filled Magnet funnel traps baited with pheromones ofC. mutilatus andC. davidsoni and coattractant was placed around a 9 × 9 block of trees in a peach orchard (single traps on alternate perimeter trees). This trapping regime significantly reduced infestation of fruit baits byCarpophilus spp. in the center tree over a period of six weeks compared to fruit baits in trap trees and distant (100 m) control trees. However, cordons of eight pheromone traps within 1 m of single trees or a single trap adjacent to a tree increasedCarpophilus spp. infestation of fruit baits by up to 7.5 × compared to trees without pheromone traps. Mass-trapping based on perimeter positioning of pheromone traps (at a yet to be determined distance from protected trees) appears to show potential as a control strategy forCarpophilus spp. in stone fruit orchards during fruit ripening and harvest but traps too close to trees must be avoided. Development of a strategy for population suppression is discussed with respect to trap type, efficacy, positioning, and density; pheromone and coattractant delivery systems; and orchard sanitation.     

Chemical characterization of fruit and fungal volatiles attractive to dried-fruit beetle,Carpophilus hemipterus (L.) (Coleoptera: Nitidulidae)

The chemical basis underlying orientation to fruit and fungal odors was investigated for the dried-fruit beetle,Carpophilus hemipterus (L.). In wind-tunnel bioassays of walking and flight response from 1.8 m, beetles were attracted to odors of the yeastSaccharomyces cerevisiae on agar, aseptic banana, or banana inoculated withS. cerevisiae, although both banana substrates elicited greater response than the yeast alone. When presented in a two-choice bioassay, the yeast-inoculated banana attracted approximately twice as many beetles as did the aseptic banana. GC-MS analysis of the headspace volatiles above these odor sources revealed a somewhat more complex and concentrated volatile profile for yeast-inoculated banana than for aseptic banana. The odor from yeast on agar had fewer components, and these were present at lower concentrations than the odors of either banana substrate. By blending mineral-oil or aqueous solutions of the 18 components of inoculated-banana odor in varying concentrations, it was possible to mimic closely the headspace profile of the natural odor. This synthetic odor also elicited beetle attraction in the wind tunnel at levels comparable to the inoculated banana. Through a series of bioassays in which individual components were subtracted from or added to a synthetic odor blend, it was determined that ethyl acetate, acetaldehyde, 2-pentanol, and 3-methylbutanol comprised the simplest blend of compounds evoking full behavioral response. However, 2-methylpropanol or butanol were apparently interchangeable with 3-methylbutanol in this blend, and comparable response could also be elicited by replacing acetaldehyde with a combination of both 2-pentanone and 3-hydroxy-2-butanone. Thus, our results suggest that this generalist insect herbivore locates its hosts by a long-range response to a variety of blends of common fruit volatiles, whose concentrations are enhanced by fungi.     

Identification of food volatiles attractive to dusky sap beetle,Carpophilus lugubris (Coleoptera: Nitidulidae)

The chemical mediation of host-finding was investigated for the dusky sap beetle,Carpophilus lugubris Murray. GC-MS analysis of the headspace volatiles above whole-wheat bread dough inoculated with baker's yeast, a substrate previously determined to be an effective attractant, revealed seven major components in the following order of decreasing concentration: ethanol, acetaldehyde, 2-methylpropanol, 3-methylbutanol, propanol, 2-methylbutanol, and ethyl acetate. Solutions of these seven compounds blended so as to mimic the odor of whole-wheat bread dough elicited upwind orientation from 1.8 m in a wind tunnel byC. lugubris at a level comparable to that elicited by the bread dough. A series of bioassays investigating the role of individual components from the synthetic blend determined that all seven compounds contributed to behavioral activity; however, the simplest blend evoking attraction comparable to bread dough included acetaldehyde, ethyl acetate, 2-methylpropanol, and 3-methylbutanol. Of these compounds, acetaldehyde was essential, ethyl acetate was interchangeable with ethanol or partially replaceable with propanol, and 2-methylpropanol and 3-methylbutanol were partially replaceable with a combination of the other alcohols. Headspace volatiles above aseptic or fungus-inoculated tomato, banana, sweet corn, and strawberry were also qualitatively and quantitatively analyzed. This study suggests thatC. lugubris locates its food sources by response to variable blends of common volatile constituents of plants and fungi.     

Structure-activity studies on aggregation pheromone components ofPityogenes chalcographus (Coleoptera: Scolytidae)

Syntheses of all four Stereoisomers (2S,5S; 2S,5R;2R,5R; and2R,5S) of chalcogran, a major component of the aggregation pheromone ofPityogenes chalcographus, and of all four isomers (2Z,4Z; 2Z,4E; 2E,4E; and 2E,4Z) of methyl 2,4-decadienoate (MD), the second major pheromone component, are briefly described. Attraction responses of walking beetles of both sexes were tested to mixtures of the synergistic pheromone components or analogs. These bioassays showed that theE,Z isomer of MD is the most active when tested with chalcogran. When tested with (E,Z)-MD, (2S,5R)-chalcogran was the most active stereoisomer, while 2R,5R and 2R,5S isomers had intermediate activities, and the 2S,5S isomer was inactive. There was no evidence that the relatively less active Stereoisomers of chalcogran inhibited or promoted attraction to (2S,5R)-chalcogran with (E,Z)-MD. Male beetles only produce the activeE,Z isomer of MD (inactive alone) and their hindguts contain the most active (2S,5R)- and least active (2S,5S)-chalcogran. A mixture of all MD isomers with racemic chalcogran was not significantly different in attractivity compared to (E,Z)-MD with racemic chalcogran, indicating no synergistic or inhibitory effects of the inactive isomers of MD.     

Chemical ecology of the palm weevilRhynchophorus palmarum (L.) (Coleoptera: Curculionidae): Attraction to host plants and to a male-produced aggregation pheromone

Attraction to host plants by adultRhynchophorus palmarum (L.) palm weevils was studied in the field and in the laboratory. Chemical analysis revealed the presence of ethanol and ethyl-acetate in stems of coco palms and in pineapple fruits and of pentane, hexanal, and isopentanol in coco stems. In the olfactometer, the first two compounds and isoamyl-acetate were attractive to the insects and the last three compounds, although not attractive by themselves, increased attractiveness when mixed with the first two compounds. Mixtures of these compounds, in proportions similar to the one occurring in attractive plant tissue, were as attractive as natural coconut tissue. In the field, the chemical compounds, either presented alone or as a mixture, did not attract the weevil. Males produce an aggregation pheromone when smelling ethyl-acetate. Rhynchophorol, 2(E)-6-methyl-2-hepten-4-ol, the known active component of the aggregation pheromone, attracts weevils in the olfactometer and in the field only if plant tissue, ethyl-acetate, or the above-mentioned odor mix are present. We propose that a complex mix of ethanol, ethyl-acetate, pentane, hexanal, isolamyl-acetate, and/or isopentanol serve as a short-range orientation cue to fresh wounds on the plant and that additional host odors, attracting weevils from a distance, have still to be discovered. Rhynchophorol can be considered to be a Synergist, having an anemotactic action at a distance. We recommend the use of retention traps baited with rhynchophorol, ethyl-acetate, and sugar cane as an alternative control method for the pest.     

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.     

Determination of distribution of harmful click beetle species (Coleoptera,Elateridae) by synthetic sex pheromones

By means of pheromone traps containing synthetic sex pheromones, areas of the most harmful click beetle species,Agriotes obscurus,A. lineatus, A. sputator, A. gurgistanus, A. ustulatus, A. tauricus Heyd, andA. lineatus, occurring in southern regions and differing biologically from the so-called northern species, have been specified and charted in the European and central Siberian areas of the former USSR.     

Attraction of bark beetles (Coleoptera: Scolytidae) to a pheromone trap

The movement of bark beetles near an attractive pheromone source is described in terms of mathematical models of the diffusion type. To test the models, two release experiments involving 47,000 marked spruce bark beetles [Ips typographus (L.)] were performed. The attractive source was a pheromone trap, surrounded by eight concentric rings with eight passive trap stations on each ring. Captures were recorded every 2–10 minutes for the pheromone trap and once for the passive traps. The models were fitted to the distribution in time of the central pheromone trap catch and to the spatial distribution of catch among the passive traps. The first model that gives a reasonable fit consists of two phases: Phase one—After release the beetles move according to a diffusion process with drift towards the pheromone trap. The strength of the drift is inversely proportional to the distance from the traps. Phase two—those beetles attracted to, but not caught by, the pheromone trap are no longer influenced by the pheromone, and their movement is described by a diffusion process without drift. In phase two we work with a loss of beetles, whereas the experiment seems to indicate that the loss of beetles in phase one is negligible. As a second model, the following modification of phase one is considered: After release the beetles move according to a diffusion process without drift, until they start responding to the pheromone (with constant probability per unit time), whereafter they start moving according to a diffusion process with drift. This study, like other release experiments, shows that the efficiency of the pheromone trap is rather low. What is specific for the present investigation is that we try to explain this low efficiency in terms of dynamic models for insect movement. Two factors seem to contribute: Some beetles do not respond to pheromone at all, and some beetles disappear again after having been close to the pheromone trap. It also seems that the motility of the beetles decreased after they ceased responding to the pheromone. Furthermore, the data lend some support to the hypothesis that flight exercise increases the response of the beetles to pheromone.     

Male olive fruit fly attraction to synthetic sex pheromone components in laboratory and field tests

Male olive fruit fly attraction to the four synthetic components of the female sex attractant pheromone was studied under laboratory and field conditions. In laboratory tests males responded to all four components tested separately. Component I, (1,7-dioxaspiro[5.5]undecane) was more attractive than any of the remaining three components alone, but a combination of all four was more attractive than component I alone. In field tests with polyethylene vials as pheromone dispensers, the complete mixture, although not statistically significant, was constantly more attractive to males than component I alone. A tendency of enhancement of attraction of component I by combining it with component II (-pinene) or III (n-nonanal) was also observed. In field tests with rubber septa as pheromone dispensers only component I was attractive. Mixtures containing component I were also attractive but not more attractive than component I alone. Evaporation rate and ratio of components as they come out of the dispenser appear to be critical for male response.     

Attraction of pinyon pine bark beetle,Ips hoppingi,to conspecific andI. confusus pheromones (Coleoptera: Scolytidae)

Females of a pinyon pine bark beetle,Ips hoppingi Lanier, were less attracted by the aggregation pheromone produced by conspecific males than by the pheromone produced by the neighboring sibling species,I. confusus (LeConte). Cross-attraction was elicited by males infesting the regional pinyon pine hosts (P. discolor andP. edulis) of eitherIps species in south-eastern Arizona. Pheromonal specificity has not accompanied speciation in this species pair.     

Components of male aggregation pheromone of strawberry blossom weevil, Anthonomus rubi herbst. (Coleoptera:Curculionidae)

The strawberry blossom weevil, Anthonomus rubi, is a major pest of strawberries in the United Kingdom and continental Europe. As part of a project to develop noninsecticidal control methods, the pheromone system of this species was investigated. Comparison of volatiles produced by field-collected, overwintering individuals of each sex led to identification of three male-specific compounds—(Z)-2-(3,3-dimethylcyclohexylidene)ethanol, (cis)-1-methyl-2-(1-methylethenyl)cyclobutaneethanol, and 2-(1-methylethenyl)5-methyl-4-hexen-1-ol (lavandulol)—in amounts of 6.1, 1.2, and 0.82 g/day/male. The first two compounds are components of the aggregation pheromone of the boll weevil, Anthonomus grandis, grandlure II and grandlure I, respectively. Grandlure I was the (1R,2S)-(+) enantiomer and lavandulol was a single enantiomer, although the absolute configuration was not determined. Trace amounts of the other two grandlure components (Z)-(3,3-dimethylcyclohexylidene)acetaldehyde (grandlure III) and (E)-(3,3-dimethylcyclohexylidene)acetaldehyde (grandlure IV) were also detected. (E,E)-1-(1-Methylethyl)-4-methylene8-methyl-2,7-cyclo-decadiene (germacrene-D), a known volatile from strawberry plants, Fragaria ananassa, was collected in increased amounts in the presence of pheromone-producing weevils. Male weevils only produced pheromone on F. ananassaand not on scented mayweed, Matracaria recutita, or cowparsley, Anthriscus sylvestris, although these are known food sources. In field trials using various combinations of synthetic grandlures I, II, III, and IV and lavandulol, significantly more weevils were caught in traps baited with blends containing grandlure I and II and lavandulol than in those baited with blends without lavandulol or unbaited controls. Addition of grandlure III and IV had no significant effect on attractiveness. Horizontal sticky traps were found to be more effective than vertical sticky traps or standard boll weevil traps. In mid-season females predominated in the catches, but later more males than females were trapped.     

Aggregation pheromones inDryocoetes affaber (Mann.) (Coleoptera: Scolytidae): stereoisomerism and species specificity

Chemical analysis of whole body extracts and volatiles produced by feeding malesDryocoetes affaber (Mann.) disclosed (+)-exo-brevicomin and (+)-endo-brevicomin [(+)EXOB and (+)ENDOB], as the major insect-produced potential pheromones. Laboratory bioassays and field-trapping experiments demonstrated that (+)ENDOB is the main pheromone component, and (-)ENDOB has an inhibiting effect. EXOB either as (+) or (±) appears to be a multifunctional pheromone. It has a synergistic effect in blends of EXOB and ENDOB in ratios up to 1:1, and it is inhibitory at higher ratios. (-)EXOB was inactive. The most attractive blend forD. affaber was a 1:2 blend of (+)EXOB and (+)ENDOB. When this blend was compared with a 9:1 blend, the best known blend forDryocoetes confusus Swaine, the responses by beetles of each of the two species were highly specific, providing evidence for pheromonal exclusion between the two congenerics. We conclude that the combined effect of chirality and the ratio of geometrical isomers of brevicomin determines both the level of response and the species-specificity of the chemical signal inD. affaber.On educational leave from the Escuela Nacional de Ciencias Biológicas. I.P.N. Depto. de Zoología, Prol. Carpio y Plan de Ayala, México 11340 D.F. México.     

Effect of juvenile hormone analog,fenoxycarb, on pheromone production byIps paraconfusus (Coleoptera: Scolytidae)

Topical application of the juvenile hormone analog, fenoxycarb, in acetone induced newly emerged male California five-spined ips,Ips paraconfusus Lanier, to become attractive to females, as measured by positive responses to male abdominal extracts in a laboratory bioassay. Two pheromones, ipsdienol and ipsenol, were detected by gas chromatography in the abdominal extracts of fenoxycarb-treated males. Pheromone production was minimal at a dose of 0.1 g/insect of fenoxycarb, maximal at 10 g, and was reduced to unmeasurable amounts at a dose of 100 g. In comparison, peak production of pheromones was induced at a dose of 0.1 g/insect of natural juvenile hormone (JH III). Treatment with 10 g of fenoxycarb resulted in the occurrence of pheromones 12 hr after exposure, maximal pheromone content between 16 and 20 hr, and undetectable amounts after 36 hr. The demonstration that fenoxycarb is an active juvenile hormone analog for a bark beetle suggests that it may have practical utility in managing these insects.     

Sensitivity of antennae of male and femaleIps paraconfusus (Coleoptera: Scolytidae) to their natural aggregation pheromone and its enantiomeric components

Antennae of male and femaleIps paraconfusus were equally and highly sensitive to their male-produced, multicomponent aggregation pheromone. Female and male antennae were highly sensitive to the pheromonal component, (S)-(–)-ipsenol, but essentially insensitive to its antipode, (R)-(+)-ipsenol. Further, female and male antennae were more sensitive to the pheromonal component, (S)-cis-verbenol, than to its antipode, (R)-cis-verbenol. Dramatic sexual dimorphism in chiral sensitivity to the ipsdienol enantiortiers was found, with female antennae being more sensitive to the conspecific pheromonal enantiomer, (S)-(+)-ipsdienol, and male antennae being more sensitive to the antipode, (R)-(–)-ipsdienol. Since (R)-(–)-ipsdienol is the principal pheromone of CaliforniaIps pini and interruptsI. paraconfusus aggregation, male antennae appear to be more sensitive to an interspecific allomone than a conspecific pheromone. Of the conspecific pheromonal enantiomers, both male and female antennae were most sensitive to (S)-(+)-ipsdienol, intermediately sensitive to (S)-(–)-ipsenol, and least sensitive to (S)-cis-verbenol. However, when enantiomeric sensitivities were compared to the estimated concentrations of these components in the natural pheromone, (S)-(~)-ipsenol tended to equal or approach the potency of (S)-(+)-ipsdienol as an antennal stimulant, while antennal responsiveness to (S)-cis-verbenol was dramatically less than for the other two pheromonal components. The behavioral implications of such physiological sensitivities are discussed in regard to perception of multicomponent synergistic pheromones and the relative efficacy of each component as an orientation cue.This paper is based in part upon a dissertation submitted to the University of California, Davis, in partial fulfillment of the requirements for the PhD in entomology.