Journal of Chemical Ecology

The copulatory behavior of the male whitemarked tussock moth,Orgyia leucostigma, was released by extracts of female body scales applied to rubber septum models baited with a female sex pheromone gland. The major compounds in the scale extracts were identified by GC-MS as a series ofn-alkanes from C-21 to C-29. Of these,n-tricosane,n-tetracosane,n-pentacosane, andn-heptacosane, applied at 10 ng/septum, caused significantly more males to attempt copulation than hexane-treated controls. Mixtures of then-alkanes, resembling the composition in the scale extracts, were no better than the two most active alkanes,n-tetracosane andn-pentacosane, alone. The releaser effect of then-alkanes was dose dependent. EAG responses to the identifiedn-alkanes were small suggesting, along with the behavioral observations, that their perception occurred at very close range. Other factors releasing male copulatory behavior are discussed.

Gustatory responsiveness of six adult squirrel monkeys, four spider monkeys, and five pigtail macaques to six bitter tastants was assessed in two-bottle preference tests of brief duration (2 min). Animals were given the choice between a 30-mM sucrose solution and defined concentrations of a bitter tastant dissolved in a 30-mM sucrose solution. With this procedure, Saimiri sciureus, Ateles geoffroyi, and Macaca nemestrina were found to significantly discriminate concentrations as low as 0.2, 0.05, and 0.1 mM quinine hydrochloride; 1, 1, and 0.05 mM caffeine; 20, 5, and 1 mM naringin; 5, 2, and 1 mM salicin; 0.01, 0.001, and 0.02 mM sucrose octaacetate; and 0.05, 0.01, and 0.5 mM denatonium benzoate, from the alternative stimulus. With the exception of naringin in the pigtail macaques, all three species rejected all suprathreshold concentrations of all bitter tastants tested. The spider monkeys and the pigtail macaques displayed the lowest taste avoidance thresholds with three of the six tastants each; in contrast, the squirrel monkeys displayed the highest taste avoidance thresholds with four of the six tastants. The across-tastant patterns of taste avoidance thresholds were identical in spider monkeys and squirrel monkeys; both species displayed the following order of sensitivity: sucrose octaacetate > denatonium benzoate > quinine hydrochloride > caffeine > salicin > naringin. All three primate species were more sensitive to the two artificial tastants (sucrose octaacetate and denatonium benzoate) compared to the four naturally occurring tastants. However, the concentrations detected by all three primate species with the four naturally occurring tastants are well below those reported in plants or arthropods consumed by these species suggesting that they may use bitterness as a criterion for food selection.

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.

The true auklets (Genus Aethia) are small planktivorous seabirds of the Bering Sea and North Pacific. Two species, the crested and whiskered auklets produce volatile citrus-like odorants. We here show that the whiskered auklet odorant is composed predominantly of two odd-numbered aldehydes (heptanal and nonanal) with no detectable unsaturated aldehydes. By comparison the crested auklet odorant is dominated by even-numbered aldehydes, both saturated and monounsaturated, ranging in size from 6 to 12 carbons. This is evidence of species-specific acquisition or biosynthetic pathways. We clarify the chemistry of the crested auklet odorant. We cite evidence that the C-12:1 aldehyde in crested auklets is actually two isomers, (Z)-4-dodecenal and (Z)-6-dodecenal. We also report on experimental evidence that aldehyde constituents kill and repel ectoparasites. Efficacy of the aldehydes may increase when they are combined in a mixture. The repellency of the mixture increases with chemical concentration. This suggests that individuals with higher chemical production are likely to repel ectoparasites more effectively.

Twelve compounds identified from honeybee,Apis mellifera L., sting extracts were evaluated in a standardized laboratory test for their effectiveness in eliciting an alarm response from caged worker honeybees. Two-1-decanol and phenol-were judged ineffective as alarm pheromones. The other ten-1-butanol, isopentyl acetate, isopentyl alcohol, 1-hexanol, 2-heptyl acetate, 2-heptanol, 1-octanol, 1-acetoxy-2-octene, 2-nonyl acetate, and 1-acetoxy-2-nonene-produced alarm responses of similar speed and intensity. Three non-sting-derived compounds-β-ionone, methyl benzoate, andtrans-cinnamaldehyde—caused weak or no responses, indicating that the responses were not simply a reaction to concentrated odoriferous substances.

Factors determining the acceptance of Eucalyptus ovata foliage by common ringtail possums (Pseudocheirus peregrinus) were studied. Bioassay-guided fractionation was used with foliage from both browser-susceptible and browser-resistant trees to identify the chemical components underlying the resistance. In foliage from browser-resistant trees, the deterrent principles were contained in the base-soluble fraction of the chloroform extract. Further fractionation of this material yielded polar and nonpolar fractions that contained acylphloroglucinol derivatives, and from the polar fraction we isolated macrocarpal G. Addition of this compound to an artificial diet at a concentration of 2.1% of dry matter resulted in a 90% reduction of voluntary food intake compared with solvent-treated controls. This is the first time that a specific compound in Eucalyptus has been shown to inhibit feeding of any marsupial folivore.