Laboratory and field tests with the synthetic sex pheromone of threeMatsucoccus (1) pine bast scales.

Matsunone, (2E,4E)-4.6,10,12-tetramethyl-2,4-tridecadien-7-one, is the primary sex pheromone ofMatsucoccus resinosae, M. thunbergianae, andM. matsumurae. The synthetic compound was tested in the laboratory and in field tests with all three species, and significantly more males responded to synthetic matsuone than to controls. The attraction of synthetic matsuone to males in field tests was not significantly different from that of virgin females at the same matsuone release rate. An analog of matsuone previously shown to be biologically active was also tested in the laboratory withM. resinosae andM. thunbergianae, and field tested withM. resinosae. The active analog required a dose approximately 100 times greater than matsuone to yield maximum laboratory bioassay response, and in field tests, attraction was not significantly different from controls at doses at which matsuone was significantly attractive.

Chirality in insect communication.

In dealing with chiral molecules, the natural-products chemist must be knowledgeable in several areas of stereochemistry. This brief survey will serve for simple situations and as a source of references for more complex molecules.

Identification of trail pheromone of larva of eastern tent caterpillarMalacosoma americanum (Lepidoptera: Lasiocampidae).

Previous studies have shown that larvae of the eastern tent caterpillar (Malacosoma americanum F.) mark trails, leading from their tent to feeding sites on host trees, with a pheromone secreted from the posterior tip of the abdominal sternum. 5ß-Cholestane-3,24-dione (1) has been identified as an active component of the trail. The larvae have a threshold sensitivity to the pheromone of 10(-11) g/mm of trail. Several related compounds elicit the trail-following response. Two other species of tent caterpillars also responded positively to the pheromone in preliminary laboratory tests.

Extreme sensitivity of grandisal to acids.

Attempted purification of synthetic racemic grandisal1 by silica gel chromatography resulted in severe decomposition. The nature of this reaction was studied on silica gel and in an ether solution ofp-toluenesulfonic acid. The same products resulted from both reaction systems, although in different ratios. Five racemic, rearrangement products were isolated by preparative GC and identified as follows: (1RS, 3SR, 6RS)-1-methyl-5-methylenebicyclo[4.2.0]octan-3-ol (4); (1RS, 3RS, 6RS)-1-methyl-5-methylenebicyclo[4.2.0]octan-3-ol (5); (1RS,3RS,6RS)-1,5-dimethylbicyclo[4.2.0]oct-4-en-3-ol (6); (1RS,3SR,6RS)-1,5-dimethylbicyclo[4.2.0]oct-4-en-3-ol(7); and 3-methyl-7-methylenecyclooct-3-en-l-ol (8). The stereochemical assignments are based on our proposed mechanism, which also accounts for all products observed. The racemic bicyclic enone (3) was a by-product of grandisol (2) oxidation.

Components of moribund American elm trees as attractants to elm bark beetles,Hylurgopinus rufipes and Scolytus multistriatus.

Hylurgopinus rufipes male and female beetles were attracted to American elms infected with Dutch elm disease, and to American elms killed by injection of cacodylic acid.H. rufipes was also attracted to solvent extracts of elm, or to Porapak Q-trapped volatiles from elm. The major components of attractive fractions of Porapak Q-trapped volatiles were isolated, identified, and tested in field bioassays. Several artificially compounded mixtures of sesquiterpenes were attractive toH. rufipes, although no bait tested was as attractive as diseased tree controls. Laboratory bioassays with H. rufipes were marginally successful. In laboratory bioassays, nine of 14 sequiterpenes identified from active fractions of Porapak extracts elicited significant response from Scolytus multistriatus male and female beetles: δ- and γ-cadinene, α-cubebene, γ-muurolene, and ß-elemene were most active. However, in field tests, none of the sesquiterpenes alone or in combination significantly attracted S. multistriatus, nor did they significantly enhance the attraction of S. multistriatus to female-produced pheromone components (4-methyl-3-heptanol [H] and α-multistriatin [M]). In other field tests, α-cubebene (C) significantly enhanced response of S. multistriatus to H plus M, but foliage, logs, or chips of healthy elm did not enhance trap catch to HMC.

Cross-attraction between two species of Matsucoccus : Extraction, bioassay, and isolation of the sex pheromone.

In laboratory bioassays, males of Matsucoccus resinosae from Pinus resinosa in New York and Matsucoccus n. sp. from Pinus thunbergiana in Korea were strongly attracted to crude hexane extracts of M. resinosae females, and M. resinosae males responded strongly to extracts of Matsucoccus n. sp. females. Males of the two species responded similarly to gas chromatographic fractions and subfractions of a pentane extract of M. resinosae females. Sex pheromones of these two species appear to be the same or very similar.

Studies on possible role of catecholamines in regulation of sex pheromone gland activity in American dog tick,Dermacentor veriabilis (Say).

Administered monoamines affected sex pheromone activity in the foveal glands of the tick,Dermacentor variabilis (Say). Flooding the tissues of the female tick with reserpine, α-methyl-m-tyrosine methyl ester hydrochloride, and pilocarpine prior to feeding led to reductions in female sex attractant activity during engorgement. Similar treatments with cyclic AMP, dopamine, serotonin, 6-hydroxydopamine, and acetylcholine had no apparent effects on the attractiveness of feeding females. Assays (by gas chromatography) demonstrated substantial reductions in 2,6-dichlorophenol content following treatment with α-methyl-m-tyrosine methyl ester, pilocarpine, and, in most cases, with reserpine. Reserpine was effective only when administered in near-lethal concentrations to unfed females. In contrast, treatment with dopamine led to elevated 2,6-dichlorophenol content in most trials. X-ray microanalysis corroborated the evidence with reserpine and dopamine. These and other findings reported elsewhere implicate monoamines, presumably catecholamines, in the regulation of sex pheromone secretion in this species. The significance of these findings for understanding the physiological mechanisms involved in the regulation of sex pheromone secretion and biosynthesis is discussed.

Genital sex pheromones of ixodid ticks: 1. Evidence of occurrence in anterior reproductive tract of American dog tick,Dermacentor variabilis (Say) (Acari: Ixodidae).

The occurrence of a genital sex pheromone in the anterior reproductive tract of partially fed femaleDermacentor variabilis was demonstrated by extraction and bioassay. A new type of bioassay, the "neutered" female assay, was developed to test the potency of extracts or chemically defined fractions to stimulate males to copulate. Electrophysiological tests confirmed the ability of males to detect the pheromone with sensilla on their cheliceral digits. Males of bothD. variabilis andD. andersoni exhibited neuronal excitation when stimulated with extracts of theD. variabilis reproductive tissues. The pheromone, which is soluble in methanol, was fractionated and found to contain at least two fractions that stimulated copulation by sexually excited males. Evidently, the pheromone is a mixture of two or more compounds. Histologic, ultrastructural, and histochemical studies suggest the vestibular vagina as the site of genital sex pheromone occurrence, presumably from secretions of the surrounding lobular accessory gland. The identity of the compounds that comprise the pheromone remains unknown.

Occurrence of sex attractant pheromone, 2,6-dichlorophenol, in relation to age and feeding in American dog tick,Dermacentor variabilis (say) (Acari:Ixodidae).

No detectable sex pheromone, 2,6-dichlorophenol (2,6-DCP), was found inDermacentor variabilis engorged nymphs, teneral females, replete females, or unfed males. The amount of 2,6-DCP present in unfed females of different ages was extremely variable; no relationship between age and 2,6-DCP content in these unfed females was observed. Partially fed virgin females had less 2,6-DCP than unfed females, but there was no change in pheromone content during the course of feeding. Sex pheromone was also found in partially fed males.

Aggregation pheromone of the deodar weevll,Pissodes nemorensis (Coleoptera: Curculionidae): Isolation and activity of grandisol and grandisal.

The bark weevilPissodes nemorensis, a pest of pines and exotic cedars in the southeastern United States, utilizes a male-produced aggregation pheromone. The presumed pheromone components, grandisol (cis-2-isopropenyl-1-methylcyclobutaneethanol) and its corresponding aldehyde, grandisal, were isolated from extracts of male volatiles and male hindguts. A field test in northern Florida showed that the combination of grandisol, grandisal, and slash pine (Pinus elliottii) bolts acted synergistically to attract large numbers of male and femaleP. nemorensis. These components deployed in various paired combinations were not as attractive as the tripartite mixture. There was no evidence that flying weevils were attracted to unbaited pine bolts. The aggregation pheromone forP. nemorensis appears to be similar to that of a parapatric sibling species,P. approximatus.

Urine fractions that release flehmen in black-tailed deer,Odocoileus hemionus columbianus.

Flehmen (or "lipcurl") is a response of male mammals primarily to female urine, performed primarily during the reproductive season. To elucidate the components of female urine that release the Flehmen, urine of black-tailed deer (Odocoileus hemionus columbianus) was fractionated, and the fractions were presented to captive male conspecifics during three rutting seasons. The active principle (one or more compounds) is watersoluble, of low volatility, not readily extractable with organic solvents, and between 200 and 12,000 daltons in molecular weight. Several urine components were identified, but none of these showed activity.

Aggregation pheromone components of two species ofPissodes weevils (Coleoptera: Curculionidae) Isolation, identification, and field activity.

Two related volatile compounds were identified from each of two species ofPissodes bark weevils and implicated as components of their aggregation pheromones. Grandisol (cis-2-isopropenyl-1-methylcyclobutaneethanol), and its corresponding aldehyde, grandisal, were isolated from males of bothP. strobi andP. approximatus and were found in the abdomens and hindguts of the respective species. In field tests synthetic grandisol and grandisal together with odors from cut pine acted synergistically in attracting both sexes ofP. approximatus. This response was similar to that elicited by maleP. approximatus feeding on cut pine. Males and females of natural populations ofP. strobi were more responsive to caged males feeding on leaders of white pine than they were to leaders alone. The combination of grandisol, grandisal, and leaders was less attractive than males on leaders, but more attractive than leaders alone. From isolation of pheromone components at different times of the year, it was determined that males of both species produced grandisol and grandisal only at times when cohort females were reproductively mature.

Occurrence of 2,6-dichlorophenol in hard ticks,Hyalomma dromedarii andHyalomma anatolicum excavatum, and its role in mating.

2,6-Dichlorophenol (2,6-DCP) is the major volatile sex pheromone component in the extracts ofHyalomma dromedarii (35 ng/female) andHyalomma anatolicum excavalum (20 ng/female). The GC fraction containing essentially pure 2,6-DCP, as well as an equal amount of synthetic 2,6-DCP, elicits from the male of each species a hierarchy of responses culminating in attempted copulation.