Structure-activity relationship observations oftrans-trimedlure enantiomers.

tert-Butyl 4- (and 5-) chloro-trans-2-methylcyclohexane-1-carboxylate (TML), a mixture of four majortrans and four minorcis isomers, is used as an attractant for detecting and monitoring the male Mediterranean fruit fly (medfly),Ceratitis capitata (Wiedemann). The eight isomers (racemic mixtures) were isolated by HPLC, and their relative attractiveness in the field was determined. A quantitative structure-activity relationship (QSAR) was proposed that related a molecular measurement (Å(3)) of the TML structure to male medfly captures. More recently, thetrans-TML enantiomers were synthesized in sufficient quantities for field testing. This paper reports the computer-aided molecular modeling, via Chem-X, of thetrans-TML enantiomers and the staggered and superimposed fitting with the most attractive isomer, (1S,2S,4R)-TML-C, to determine common volumes and surface areas from Van der Waals (VdW) maps. Observations of structure-activity relationships (SAR) are reported for the staggered fittings.

Quadrupole storage mass spectrometry of mono- and dimethylalkanes.

Monomethyl and dimethylalkanes with one, two, three, four, five, and seven methylene groups separating the methyl branches were synthesized and analyzed by magnetic sector and quadrupole storage (ion trap) mass spectrometry. The spectra produced by the magnetic sector instrument were in good agreement with previously reported data, whereas the ion trap spectrometer produced ions resulting from cleavages adjacent to the branching points, markedly different than those from the magnetic sector instrument. Fragmentation patterns show that the ion trap mass spectrometer can be used to characterize branched alkanes in nanogram and subnanogram quantities.

Synergism of an insect sex pheromone specialist neuron: Implications for component identification and receptor interactions.

Extracellular recordings show that the response to the sex pheromone component, (Z)-7-dodecenyl acetate (Z7-12:Ac) by the HS(a) antennal olfactory specialist neuron of the cabbage looper,Trichoplusia ni (Hübner), is synergized by two synthetic sex pheromone analogs and two components of the female sex pheromone. Complementary behavioral measures of upwind flight and copulatory responses to mixtures ofZ7-12:Ac with the analogs and sex pheromone components in a wind tunnel produced behavioral evidence consistent with the neuron's electrophysiological responses. The phenomenon of receptor neuron synergism impacts several areas and provides a note of caution for common practices of identifying secondary sex pheromone components only from field traps and/or wind tunnel tests.

Field tests of syntheticManduca sexta sex pheromone.

In field experiments traps were baited with live females or with a two-, four-, or eight-component blend of the 16-carbon aldehydes previously identified as components of the sex pheromone emitted by femaleManduca sexta moths. The blends were formulated on rubber septa. Traps baited with a blend of all eight aldehydes captured moreM. sexta males than any other treatment. Septa loaded with 600 µg of the eight-component blend were attractive to males for about seven days in the field. Septa loaded with the eight-component blend and stored in a refrigerator at 4°C for a year released the conjugated diene and triene aldehydes at the same rate as freshly prepared septa and were equally attractive in the field.

Sex attractants for the white-barred groundling moth (Recurvaria leucatella clerck) and the lesser bud moth (R. nanella Hübner) (Lepidoptera: Gelechiidae).

In field tests synthetic (3E,5Z)-3,5-tetradecadienyl acetate was found to attract large numbers of males ofRecurvaria leucatella Clerck into sticky traps. The other geometrical isomers did not influence catches. Of the corresponding monoenic compounds, (3E)-3-tetradecenyl acetate was highly attractive to a close relative,Recurvaria nanella Hübner. The catches of the latter species were suppressed by higher amounts of (5Z)-5-tetradecenyl acetate added to the bait, and the addition of (3E)-3-tetradecenol or (3Z)-3-tetradecenyl acetate was without effect. The attractive compounds can be used in traps for monitoring the two pests.

Analysis, synthesis, formulation, and field testing of three major components of male mediterranean fruit fly pheromone.

Three major components, ethyi-(E)-3-octenoate, geranyl acetate, and (E,E)-α-farnesene, emitted as volatiles by laboratory-reared and wild male medflies were collected and analyzed qualitatively and quantitatively. Peak emission of these compounds occurred during the third to fifth hours of the photophase and differences were observed in the ratios of the three components emitted by male laboratory-reared and wild flies. These three compounds were synthesized, and a method was developed to formulate a synthetic blend that released the compounds in a ratio similar to that emitted by wild male medflies. Attractiveness of the blend to female medflies was demonstrated under field conditions by comparing trap catches. Black spherical traps, baited with the synthetic blend to release 1.6 male equivalents, caught significantly more females than blank traps and traps from which the blend released was 0.3, 3.2 or 6.4 male equivalents.

Isolation and identification of allelochemicals that attract the larval parasitoid,Cotesia marginiventris (Cresson), to the microhabitat of one of its hosts.

Volatiles released from corn seedlings on which beet armyworm larvae were feeding were attractive to females of the parasitoid,Cotesia marginiventris (Cresson), in flight tunnel bioassays. Analyses of the collected volatiles revealed the consistent presence of 11 compounds in significant amounts. They were: (Z)-3-hexenal, (E)-2-hexenal, (Z)-3-hexen-1-ol, (Z)- 3-hexen-1-yl acetate, linalool, (3E)-4,8-dimethyl-1,3,7-nonatriene, indole, α-trans-bergamotene, (E)-ß-farnesene, (E)-nerolidol, and (3E,7E)-4,8,12-trimethyl-1, 3,7,ll-tridecatetraene. A synthetic blend of all 11 compounds was slightly less attractive to parasitoid females than an equivalent natural blend. However, preflight experience with the synthetic blend instead of experience with a regular plant-host complex significantly improved the response to the synthetic blend. Our results suggest thatC. marginiventris females, in their search for hosts, use a blend of airborne semiochemicals emitted by plants on which their hosts feed. The response to a particular odor blend dramatically increases after a parasitoid experiences it in association with contacting host by-products.

Trimedlure enantiomers: Differences in attraction for mediterranean fruit fly,Ceratitis capitata (Wied.) (Diptera: Tephritidae).

The most biologically active enantiomer of trimedlure, a synthetic lure attractive to male Mediterranean fruit flies, is the 1S,2S,4R enantiomer of isomer C, the fert-butyl ester of ris-4-chloro-trans-2-methylcyclohexanecarboxylic acid. We also determined that the 1R,2R,5S enantiomer of isomer A is significantly more attractive than its optical antipode. Essential differences in the current synthetic work that are critical to possible commercialization of this preparation are detailed herein.

Sex pheromone ofManduca Sexta (L) Stereoselective synthesis of (10E,12E,14Z)-10,12,14-Hexadecatrienal and Isomers.

Three isomeric conjugated triene aldehydes,(10E,12E,14Z)-10, 12-14-hexadecatrienal (IX), (10E,12Z,14E)-10,12,14-hexadecatrienal (XX), and (10E,12E,14E)-10,12,14-hexadecatrienal (X), two of which are components of theManduca sexta (L.) sex pheromone, have been stereoselectively synthesized and spectroscopically characterized.

Identification of female-produced sex pheromone from banded cucumber beetle,Diabrotica balteata leconte (Coleoptera: Chrysomelidae).

A sex pheromone produced by female banded cucumber beetle adults,Diabrotica balteata LeConte, was isolated from volatiles trapped on Porapak Q and identified as 6,12-dimethylpentadecan-2-one. The structure was elucidated by spectroscopic analyses and confirmed by synthesis. The synthesized racemic compound was equal to the purified natural pheromone in eliciting responses by banded cucumber beetle males to field traps. A doseresponse characteristic was demonstrated for the racemic material formulated on filter paper or rubber septa and placed in field traps. The absolute configuration at the C-6 and C-12 positions was not established.

Stereoselective synthesis of (Z,E)-3,5-tetradecadienyl acetate: Sex attractant for carpenterworm moth,Prionoxystus robiniae (Peck) (Lepidoptera: Cossidae) and effect of isomers and monounsaturated acetates on its attractiveness.

A new efficient stereoselective synthesis for (Z,E)-3,5-tetradecadienyl acetate (Z3,E5-14∶Ac) a potent male sex attractant for the carpenterworm,Prionoxystus robiniae (Peck), was developed. The effects of the other three isomers (Z,Z; E,Z; E,E) on the field attractiveness of the Z,E isomer toward male P. robiniae were determined. The Z, Z isomer inhibited attraction, the E, E isomer synergized attraction, and theE,Z isomer had no effect on attraction. Seven monounsaturated 14-carbon acetates were evaluated for their effect on the attractiveness of Z3,E5-14∶Ac. (E)-3-Tetradecenyl acetate enhanced attraction and (Z)-9- and (E)-5-tetradecenyl acetate reduced trap captures. (Z,E)-3,5-Tetradecadien-1-ol also reduced the attractiveness of Z3,E5-14∶Ac.

Japanese beetle (Coleoptera: Scarabaeidae) : Response to synthetic sex attractant plus phenethyl propionate: Eugenol.

A combination of the synthetic sex attractant (R,Z)-5-(1-decenyl) dihydro-2(3H)-furanone with a 3∶7 mixture of phenethyl propionate (PEP) and eugenol (4-allyl-2-methoxphenol) caught significantly morePopillia japonica Newman than either the sex attractant or the mixture did alone. Also, the synthetic sex attractant captured significantly more males than the PEP-eugenol did during the period of heavy adult emergence of the beetles. The two lures were not significantly different in their attractancy to males about a week later and thereafter. A combination of PEP-eugenol and virgin females in the same trap late in the season also significantly increased beetle captures.

Identification of the female Japanese beetle sex pheromone: inhibition of male response by an enantiomer.

(Z)-5-(1-Decenyl)dihydro-2(3H)-furanone, isolated from virgin female Japanese beetles (Popillia japonica) attracted males of the species infield bioassays. However, the synthesized racemic mixture of this compound did not attract male Japanese beetles. The Z and E isomers and the saturated analog of both enantiomers of this compound were synthesized stereospecifically. Pure synthetic (R,Z)-5-(1-decenyl)dihydro-2(3H)-furanone was competitive with live females and with the pheromone isolated from live females in attracting males. Male response was strongly inhibited by small amounts of the S,Z isomer. Although the E isomer and the saturated analog of the pheromone are present in the material obtained from females, the role of these compounds in mediating the insect's behavior is unclear.

Sex pheromones and reproductive isolation of the lesser peachtree borer and the peachtree borer.

(E,Z)-3,13-octadecadien-1-ol acetate, and (Z,Z)-3,13-octadecadien-1-ol acetate, isolated from the female lesser peachtree borer, Synanthedon pictipes (Grote and Robinson), and the female peachtree borer, Sanninoidea exitiosa (Say), respectively, strongly attract the respective males of these species in field bioassays. These compounds are the largest pheromones isolated thus far from a lepidopterous species. Sanninoidea exitiosa males did not respond to the synthesized (E,Z)-isomer, and low concentrations of it in the synthesized (Z,Z)-isomer did not interfere with their response to the (Z,Z)-isomer. In contrast, even very low concentrations of the (Z,Z)-isomer (1 percent) in the (E,Z)-isomer significantly inhibited the response of Synanthedon pictipes males.