Chemical Ecology

Background: Vertebrate predators use a broad arsenal of behaviors and weaponry for overcoming fractious and potentially dangerous prey. A unique array of predatory strategies occur among snakes, ranging from mechanical modes of constriction and jaw-holding in non-venomous snakes, to a chemical means, venom, for quickly dispatching prey. However, even among venomous snakes, different prey handling strategies are utilized, varying from the strike-and-hold behaviors exhibited by highly toxic elapid snakes to the rapid strike-and-release envenomation seen in viperid snakes. For vipers, this mode of envenomation represents a minimal risk predatory strategy by permitting little contact with or retaliation from prey, but it adds the additional task of relocating envenomated prey which has wandered from the attack site. This task is further confounded by trails of other unstruck conspecific or heterospecific prey. Despite decades of behavioral study, researchers still do not know the molecular mechanism which allows for prey relocation. Results: During behavioral discrimination trials (vomeronasal responsiveness) to euthanized mice injected with sizefractionated venom, Crotalus atrox responded significantly to only one protein peak. Assays for enzymes common in rattlesnake venoms, such as exonuclease, L-amino acid oxidase, metalloproteinase, thrombin-like and kallikreinlike serine proteases and phospholipase A 2 , showed that vomeronasal responsiveness was not dependent on enzymatic activity. Using mass spectrometry and N-terminal sequencing, we identified the proteins responsible for envenomated prey discrimination as the non-enzymatic disintegrins crotatroxin 1 and 2. Our results demonstrate a novel and critical biological role for venom disintegrins far beyond their well-established role in disruption of cellcell and cell-extracellular matrix interactions. Conclusions: These findings reveal the evolutionary significance of free disintegrins in venoms as the molecular mechanism in vipers allowing for effective relocation of envenomated prey. The presence of free disintegrins in turn has led to evolution of a major behavioral adaptation (strike-and-release), characteristic of only rattlesnakes and other vipers, which exploits and refines the efficiency of a pre-existing chemical means of predation and a highly sensitive olfaction system. This system of a predator chemically tagging prey represents a novel trend in the coevolution of predator-prey relationships.

Despite their perceived inaccessibility, the marine intertidal and benthic environments of Antarctica, southern Africa and South America have continued to provide marine natural products for chemists with unique opportunities to study the secondary metabolite constituents and chemical ecology of a diverse array of marine gastropod molluscs. This review covers the literature up to 31 January 2005 and describes the structures and, where applicable, biological activities of 100 secondary metabolites isolated from 21 species of marine gastropod molluscs. Not unexpectedly, the chemistry of chemically defended shell-less opisthobranchs dominates the natural product studies of molluscs collected from these regions of the southern hemisphere.

Natural leachates of Eucalyptus globulus (throughfall, stemflow, and soil percolates) were collected daily during rainy spells in the vegetative period (February-July), and their effects on the germination and radicle growth ofLactuca sativa were measured. Concurrently, the effects ofL. sativa of topsoil and leachates from decaying litter were determined. The results suggest that toxic allelochemicals released by Eucalyptus globulus may influence the composition and structure of the understory of the plantation and that this effect is attributable mainly to the decomposition products of decaying litter rather than to aerial leachates. The soil may neutralize or dilute allelopathic agents, at least below the top few cms.

The sex pheromone of females of the carob moth, Ectomyelois ceratoniae, was identified to be a mixture of (Z,E)-9,11,13_tetradecatrienal, (Z,E)-9,11-tetradecadienal and (Z)-9-tetradecenal in the ratio of 1O:l:l. A synthetic blend proved to be attractive.

6,10,14-Trimethylpentadecan-2-one (Hexahydrofarnesyl acetone; HHA) previously has been found to be a major component in tibial fragrances of male orchid bees, Euglossa spp. HHA is a chiral molecule with four possible stereoisomers, (6R, 10R)-, (6R, 10S)-, (6S, 10R)-, and (6S, 10S)-6,10,14-trimethylpentadecan-2-one. In the present study, we characterized HHA extracted from Euglossa as the pure enantiomer (6R, 10R)-6,10,14-trimethylpentadecan-2-one. During bioassays in Mexico and Panama, the synthetic RR-isomer attracted males of six species of orchid bees, including three that were known to contain HHA in their tibial fragrances. Possible sources of HHA for wild bees are flowers of euglossophilous orchids and aroids. With a molecular weight of 268, HHA is the largest natural molecule known to attract male orchid bees in pure form. Its attractiveness to males suggests that low-volatility compounds have a function in male signals, e.g., serve as a "base note" in complex odor bouquets.

Eleven allelochemicals (ferulic acid, cinnamic acid, 4-hydroxybenzoic acid, hydroxycinnamic acid, methyl propionate, oxalic acid, methylmalonic acid, p-anisic acid, butyric acid, 3-hydroxybutyric acid, and azulene) were identified in the exudate of Cistus ladanifer L. We studied the effect of each on germination, cotyledon emergence, root length, and cotyledon length of Rumex crispus. Three groups were distinguished with respect to phytotoxic activity: compounds with low activity (ferulic acid, 4-hydroxybenzoic acid, oxalic acid, methylmalonic acid, p-anisic acid, hydroxybutyric acid, and azulene), with intermediate activity (cinnamic acid and hydroxycinnamic acid), and with high activity (methyl propionate and butyric acid). The effect of the interaction of the compounds was studied. When acting conjointly, all combinations tested produced a more negative effect on both germination and seedling growth than when acting alone. The interaction affected cotyledon emergence and root length more negatively than germination and cotyledon length. When hydroxycinnamic acid and cinnamic acid were added to these mixtures there was an enhancement in the phytotoxic activity, accentuating the effect of the other allelochemicals.

Accessions of cultivated barley (Hordeum vulgare ssp. vulgare) and its wild progenitor Hordeum vulgare ssp. spontaneum (H. ssp. spont.) were screened for gramine content at the seedling stage. H. ssp. spont. generally had higher gramine concentration compared with cultivated spring barley. Thus gramine concentrations might be raised in modern barley through crossings with selected H. ssp. spont. accessions and repeated back-crossings (BC) of selected offspring to cultivated barley. In the present study, the barley cultivar Lina was used as the recurrent parent. Lina was exceptional among the two-rowed barleys in that it contained moderate levels of gramine, whereas most of the others were very low in gramine. Chromosome-doubled haploid lines (DHs) from the first generation (F1) had a skewed distribution towards higher gramine concentrations and so had the first back-cross generation (BC1F1-DHs). A hairy plant surface, another character proposed to confer resistance to aphids, was al...

and 1986 to investigate the possible allelopathic potential of alfalfa (Medicago sativa L.) and its decomposed residues on bladygrass (Imperata cylindrica L. Beauv.), a noxious weed in Iraq, and to isolate, characterize, and quantify possible allelopathic agents in alfalfa residues and root exudates. Results indicated that decomposed alfalfa roots and their associated soil produced a 51-56% reduction in bladygrass seed germination. Root and shoot length of bladygrass seedlings were reduced by an average of 88 %. Decayed and undecayed mixtures of alfalfa roots and soil at 0.015 : 1 (w/w) inhibited bladygrass seedlings reproduced from rhizomes by 30 and 42%. It was found that root exudates of alfalfa seedlings caused significant reduction in shoot and root dry weights of bladygrass seedlings when alfalfa and bladygrass were grown together in nutrient culture. Caffeic, chlorogenic, isochlorogenic, p-coumaric, p-OH-benzoic, and ferulic acids were detected in alfalfa root exudates and residues. The highest amount (126 /~g phenolic acids/g soil) of these compounds was found in alfalfa root residues after six months of decomposition in soil.

The event chain leading to germination blockage in durum wheat (Triticum turgidum ssp. durum Desf.) seeds exposed to the allelochemical coumarin (2H-chromen-2-one) was studied. The physiological and biochemical aspects thought to be critical for a successful seed germination were measured. At concentrations above 200 2M, coumarin inhibited seed germination in a concentration-dependent manner. Inhibition occurred early during seed imbibition (phase I), was rapid, and irreversible. During phase I, coumarin inhibited water uptake, electrolyte retention capacity, and O 2 consumption. Later on, coumarin delayed the reactivation of peroxidases, enhanced the activity of superoxide dismutase, decreased the activities of selected marker enzymes for metabolic resumption, and repressed the transcription of molecular chaperons involved in secretory pathways. Insufficient and/or late seed rehydration caused by coumarin could have delayed membrane stabilization or decreased respiratory O 2 consumption, both of which are conducive to an overproduction of reactive O 2 species. Being unbalanced by an adequate upsurge of antioxidant defense systems, the resulting oxidative stress might have ultimately interfered with the germination program.

A comparative chemical analysis of the larval nectar secretions and hemolymph from three unspecifically and facultatively ant-attended lycaenid species (Polyommatus coridon, P. icarus, and Zizeeria knysna) was performed by using high-performance liquid chromatography techniques. Sucrose was the main sugar component in all three species. In half of the samples of P. coridon, it was accompanied by glucose, whereas other sugars occurred only rarely. In P. icarus and Z. knysna, melezitose was the secondmost important component, followed by fructose and glucose. Total sugar contents were 43.6 T 14.8 g/l (mean T SD) for P. coridon, 74.2 g/l for P. icarus, and 68.3 T 22.6 g/l for Z. knysna. Up to 14 different identified amino acids were found in P. coridon nectar, with a total content of 9.7 T 3.4 g/l. Leucine was always the major component (contributing 50% of overall amino acid content). Other important amino acids were tyrosine, proline, arginine, and phenylalanine. P. icarus nectar contained up to six amino acids with a total content of 1.2 g/l, dominated by tyrosine and phenylalanine. Z. knysna nectar contained alanine and proline, with only 0.3 T 0.17 g/l total content. In the hemolymph of all species, up to 16 different amino acids occurred relatively regularly, with histidine dominating, followed by serine and proline. The amino acid pattern in hemolymph was considerably different from that of the nectar secretions. Larval diet weakly influenced P. coridon nectar sugars, and with a semisynthetic diet, a more homogeneous amino acid pattern was detected. Comparison with reports from other lycaenid species shows that secretions rich in amino acids are related to intimate, often obligate ant associations, whereas facultative, unspecific myrmecophiles rely on carbohydrates.

By depositing scent marks on flowers, bees reduce both the search time and the time spent with the handling of nonrewarding flowers. They thereby improve the efficiency of foraging. Whereas in honey bees the source of these scent marks is unknown, it is assumed to be the tarsal glands in bumble bees. According to histological studies, however, the tarsal glands lack any openings to the outside. Foragers of the stingless bee Melipona seminigra have previously been shown to deposit an attractant pheromone at sugar solution feeders, which is secreted at the tips of their tarsi. Here we show that the claw retractor tendons have specialized glandular epithelia within the femur and tibia of all legs that produce this pheromone. The secretion accumulates within the hollow tendon, which also serves as the duct to the outside, and is released from an opening at the base of the unguitractor plate. In choice experiments, M. seminigra was attracted by feeders baited with pentane extracts of the claw retractor tendons in the same way as it was attracted by feeders previously scent marked by foragers. Our results resolve the seeming contradiction between the importance of foot print secretions and the lack of openings of the tarsal glands.

Two types of Barbarea vulgaris var. arcuata, the G-type and the P-type, differed in resistance to larvae of the diamondback moth (DBM) Plutella xylostella. Rosette plants of the G-type were fully resistant to the DBM when grown in a greenhouse or collected in the summer season, but leaves collected during the late fall were less resistant, as previously found for flea beetle resistance. The P-type was always susceptible. Extracts of resistant leaflets inhibited larval growth in a bioassay, and a growth-inhibiting fraction was isolated by activity-guided fractionation. A triterpenoid saponin (1) was isolated from this fraction and identified as 3-O-β-cellobiosyloleanolic acid from spectroscopic data and analysis of hydrolysis products. The decrease in resistance of the Gtype in the fall was correlated with a decrease in the level of 1, from 0.6-0.9 to <0.2 µmol/g dry wt. Compound 1 was not detected in the susceptible P-type. We conclude that 1 is correlated with the variable resistance of B. vulgaris foliage to the DBM.

This study aimed to quantify and evaluate the level of Azadirachtin in neem seed kernel from ten ecotypes in Sudan over two seasons and establish relationship to the agro-ecological attributes. Extraction was done in two replicates using 12 g. After extraction, separation and concentration to 10 ml the samples quantified using HPLC. Neem trees growing in different habitats in Sudan showed variations in Azadirachtin (Az)-content depending on the climate, rainfall, soil type, latitude and altitude. The Az-content ranged from 1.08 -2.3 mg/g of the seed kernel in the first season and from 0.48 -3.09 mg/g in the second season. The average content of neem oil was 44.6% in the neem seed kernel (NSK); no variation was found between these regions in oil-content. Trees growing in regions with moderate climate, average rainfall of 400 mm, and altitude of > 470 m above sea level, proved to be rich in Az-content. However, trees growing in lower altitudes, alluvial or sandy soil, with hot climate reflected very low Az-content. Rainfall was found to be the major factor affecting the level of Az in NSK, and the optimal rainfall was 717 mm. Temperature and relative humidity had no direct effect on the Az-content. However, the combination of temperature and the rainfall showed a positive correlation with the Az level in NSKs. Latitude and altitude have direct effect on Az level. Seasonal variations were clear over the two seasons, and no relationship was found between the two seasons.

Allelopathy in rice (Oryza sativa, L.) effective against weeds has been found in about 3.5% of tested rice germplasm in both laboratory and field experimentation. However, the allelochemicals responsible for growth inhibition of rice-associated weeds have not yet been identified. In the literature, phenolic acids are often mentioned as putative allelochemicals. If phenolic acids commonly reach growth inhibitory concentrations in rice ecosystems, it must be expected that the degree of tolerance to phenolic acids will vary among traditional rice cultivars or plant species adapted to rice environments having inherently different phenolic acid concentrations. Phenolic acids concentrations are normally greater in submerged than in aerobic soils. A dose-response study, however, showed that seedlings of rice cultivars adapted to submerged anaerobic soils did not have higher level of tolerance against p-hydroxybenzoic acid than did seedlings of varieties adapted to aerobic upland soils. Mor...

In this study, the novel data mining technique Market Basket Analysis (MBA) was applied for the first time in biogeochemical and ecological investigations. The method was tested on the fern Athyrium distentifolium, in which we measured concentrations of the elements Ca, Cd, Cr, Cu, Fe, K, Mg, Mn, Na, Ni, Pb, and Zn. Plants were sampled from sites with different types of bedrock in the Tatra National Park in Poland. MBA was used to investigate whether specimens of Athyrium distentifolium that contain elevated levels of certain elements occur more frequently on a specific type of bedrock and to identify relationships between the type of bedrock and the concentrations of the elements in this fern. The results were compared with those of the commonly used principal component and classification analysis (PCCA) technique. MBA and PCCA ordination both yielded distinct groups of ferns growing on different types of bedrock. Although the results of MBA and PCCA were similar, MBA has the advantage of being independent of the size of the data set. In addition, MBA revealed not only dominant elements but, in the case of limestone bedrock, also showed very low concentrations of Cd, Fe, Mn, and Pb in ferns growing on this type of parent material. MBA, thus, appeared to be a promising data mining method to reveal chemical relations in the environment as well as the accumulation of chemical elements in bioindicators. This technique can be used to reveal associations and correlations among items in large data sets collected on a national or even larger scale.

The behavior ofReticulitermes hesperus Banks pseudergates (workers) was assessed on artificial trails containing different concentrations of sternal gland extract. On nongiadient trails, more pseudergates were recruited to trails of greater pheromone concentration, they traveled a greater distance without pausing, and their rate of locomotion increased over that observed on trails of lesser concentration (positive orthokinesis). Of the individuals pausing before completing trails of high concentration, fewer left the trails or reversed direction (negative klinokinesis) than on trails of lower concentration. Termites walking down concentration gradients failed to complete these trails to the low-concentration termini. At a point representing an average decrease of slightly more than 10-fold in the original concentration of pheromone, individuals reversed their direction of travel and returned to the high-concentration terminus. Termites walking up pheromone gradients proceeded to the high-concentration termini without reversing direction.R. hesperus pseudergates are thus able to orient along a gradient of trail pheromone by longitudinal klinotaxis.

In order to decrease the risk of pathogen transmission, ants remove corpses from the vicinity of nests, but little is known about the underlying mechanisms. In particular, it is unclear how the odor profile of corpses changes with time since death and how any changes might relate to behavior. We have addressed these questions in the red ant Myrmica rubra, where we asked how the time since death determines the ability of workers to discriminate a dead individual from a live one, and whether dead workers are removed in a similar way when they originate from the same or an alien colony. We found that ants could discriminate alien from nestmate corpses up to 2 days after death, since the former continued to elicit aggressive behavior over that period. For dead nestmates, only 15 % of corpses were removed when freshly killed but this rises to 80 % for corpses between 1 to 6 days post mortem. Using gas chromatography, we found that oleic and linoleic acids, which are absent on freshly killed corpses, appeared post mortem and were in higher quantities on those corpses that were ejected from the nest vicinity. When added to fresh corpses, linoleic and oleic acids, alone or blended, enhanced removal to levels observed for corpses of 2-6 days postmortem. Thus, oleic and linoleic acids appear to be important cues involved in corpse recognition and necrophoresis over a long timeframe, and we advance the hypothesis that these fatty acids in combination with other cues may also trigger other behaviors such as prey retrieval.

Field evaluations demonstrate that the addition of the minor pheromone component (3E,8Z)-tetradecadien-1-yl acetate to the major component (3E,8Z,11Z)-tetradecatrien-1-yl acetate does not significantly increase the trap catches of Tuta absoluta males in the field. The triene acetate itself is highly attractive, catching about 869 ± 255 males per trap in three consecutive nights. The addition of two isomers of the minor component (3E,8Z)-tetradecadien-1-yl acetate, (3E,11Z)-tetradecadienyl-yl acetate and (8Z,11Z)-tetradecadien-1-yl acetate, to the major component (3E,8Z,11Z)-tetradecatrien-1-yl acetate also did not significantly alter the number of the males caught in the traps.

A simple, inexpensive, and highly efficient NMR sample preparation technique for volatile chemicals has been devised using a micropreparative GC system. The recovery efficiency of a volatile chemical using this technique was >80% with sample sizes of 0.05 to 0.5 µg. The purity of the acquired NMR samples was sufficient for high sensitive NMR analyses including two dimensional experiments.

A wheat seedling bioassay was used to indicate the relationship between the chemical structure of alfalfa saponins and their alMopathic activity. None of the tested saponins significantly influenced wheat germination. Seedling growth bioassays indicated significant differences among the activities of individual glycosides. The most active were medicagenic acid, its glycosides substituted at the C-3 position with glucose, and hederagenin monoglycoside. Medicageuic acid glycosides, substituted at the C-3 position with glucuronic acid, and zahnic acid tridesmoside were less active. No significant correlation was found among the aHelopathic, hemolytic, and antifungal activities of the individual glycosides.

Defensive secretions of the callipodidan species Apfelbeckia insculpta contain a p-cresol as the main component and phenol in traces. This is the first identification of these compounds in a European callipodidan species. The repugnatory glands of A. insculpta are of the spirobolid type and consist of a spherical reservoir, a simple duct, and a valvular cuticular infolding that opens onto the lateral surface of the millipede via a pore.

Twelve products related to the sex pheromone main components (Z)-9-and (Z)-I l-tetradecenyl acetate (Z9-14 : Ac and Z11-14 : Ac, respectively), were identified in female pheromone gland extracts of the laboratoryreared summerfruit tortrix moth, Adoxophyes orana F.v R. These are the geometric isomers and the alcohols of the main components, (Z)-9-dodecenyl acetate, (Z)-11-hexadeeenyl acetate, and saturated acetates of 12-22 carbons. The ratio of Z9-14 : Ac to Z11-14 : Ac in individuals varied from 3.5 : 1 to 11 : 1 with an average of 6.2; their total added up to 462 ng/female with an average of 182 ng for 2-to 7-day-old individuals. No qualitative or quantitative differences were observed between laboratory and field insects. Z9-14:Ac, Z11-14:Ac and the corresponding alcohols were also found in female effluvia. Addition of either of the two alcohols to a blend of the two acetates augmented trap catch in the field. The same was true for (Z)-9,(E)-12-tetradecadienyl acetate which was not detected in gland extracts.

Two new quinones, (an isoprenoid quinone, and a dimeric anthraquinone) named naphthotectone and anthratectone, respectively, were isolated from bioactive leaf extracts from Tectona grandis. Their structures were determined by a combination of 1D and 2D NMR techniques. The bioactivity profile of naphthotectone was assessed using the etiolated wheat coleoptiles bioassay in aqueous solutions at concentrations ranging from 10 −3 to 10 −5 M, as well as the standard target species lettuce, cress, tomato, and onion. Naphthotectone showed high level of activities in both bioassays. This fact, along with the presence of this compound as the major component in Tectona grandis, suggests that it may be involved in the allelopathic activity previously described for this species, and probably in other defense mechanisms.

Robinia pseudo-acacia L. (black locust) is a nonindigenous species currently invading the central part of Japanese grasslands. Several allelochemicals were identified and characterized from the leaf tissue. The growth of both radicle and hypocotyl in the tested species (barnyard grass, white clover, lettuce, and Chinese cabbage) was reduced when grown in soil mixed with the leaves of R. pseudo-acacia at various concentrations. Aqueous leaf extracts, when bioassayed, exhibited a significant suppression of radicle growth. Chromatographic separation of an ethanolic extract of R. pseudo-acacia leaves resulted in isolation of three compounds, identified as robinetin (1), myricetin (2), and quercetin (3) by nuclear magnetic resonance and mass spectroscopy. All inhibited root and shoot growth of lettuce. Robinetin, found in a large amount, caused 50% suppression of the root and shoot growth of lettuce at 100 ppm. The presence of these bioactive substances in leaf tissue suggests a potential role for flavonoids in R. pseudo-acacia invasion in introduced habitats.

Insecticidal and growth-reducing properties of extracts of 14 species of American neotropical Piperaceae were investigated by inclusion in diets of a polyphagous lepidopteran, the European corn borer,Ostrinia nubilalis. Nutritional indices suggested most extracts acted by postdigestive toxicity.Piper aduncum, P. tuberculatum, andP. decurrens were among the most active species and were subjected to bioassay-guided isolation of the active components. Dillapiol was isolated from the active fraction ofP. aduncum, piperlonguminine was isolated fromP. tuberculatum, and a novel neolignan fromP. decurrens. The results support other studies on Asian and AfricanPiper species, which suggest that lignans and isobutyl amides are the active defence compounds in this family.

... MIGUEL MICHEREFF FILHO,1 EVALDO F. VILELA,1 ATHULA B. ATTYGALLE,2,* JERROLD ... LCL, ROA, FG, SILVA, CN, SOUZA J ´UNIOR, MM, and SILVA, MIV 1995. Manejo Integrado de Scrobipalpuloides absoluta (Povolny) (Lepidoptera: Gelechiidae) no Subm´edio S˜ao ...

The urinary volatiles from dominant and subordinate male mice were chromatographically compared, both immediately and seven days after dominant-subordinate relationships between pairs were formed. Statistical comparison of the peak areas of volatile constituents present in male urine revealed that 16 urinary compounds exhibited substantial concentration differences depending upon social status of the animals. Urinary dihydrofurans, ketones, and acetates exhibited a significant, long-term (seven-day) decrease in the urine of subordinates when compared to control and dominant males. Two sesquiterpenic compounds, c~-and/~-farnesene, were elevated only in the dominant urine one week after dominance was established. 2-(see-Butyl)-4,5-dihydrothiazole was found in higher concentration in bladder or excreted urine of dominant males when compared to subordinates. Of the 16 compounds subjected to statistical analysis, four exhibited hormonal dependency: c~-and ~-farnesene, dehydro-exo-brevicomin, and 2-(sec-butyl)-4,5-dihydrothiazole. Neither dehydro-exo-brevicomin nor 2-(see-butyl)-4,5-dihydrothiazole was present in the urine of immature and castrated males. Testosterone treatment restores their presence in male urine. Also, c~-and r were absent in the urine of immature males and significantly reduced in the urine of castrated males. The absence of c~-and/3-farnesene in bladder urine suggests that one of the sex-accessory glands may be the site of their origin.

AIHh'ad-The sulfur-rich anal sac secretion of the mink, Mustela vison, consisted of immiscible lipid (1.7% sulfur) and aqueous (0.7% sulfur) phases. Light and electron microscopy revealed secretory tissue of two types, sebaceous (holocrine) and apocrine. A major input of sulfur into the sac appeared to be associated with glycoprotein granules present in the apical portions of the apoerine cells as X-ray energy probe microanalysis showed these to contain relatively high levels of sulfur. The lipid of the secretion, presumed to be largely of sebaceous origin, consisted mainly of wax monoesters, while the aqueous phase contained volatile fatty acids, ammonia, and amines, including putreseine (l,4-diaminobutane). The identity of'the major headspace volatiles was confirmed by NMR, MS, and Raney nickel desulfuration as being 2,2-dimethylthiacyclobutane and 3,3dimethyl-l,2-dithiaeyclopentane. These compounds were not detected by GC-MS in the headspace volatiles of the anal sac secretions of eight other mustelid species examined. Other sulfur compounds detected included isomeric dimethylthiaeyelobutanes, a number of disulfides and 3-methylbut-3-enyl methyl sulfide (isopentenyl methyl sulfide). The significance of these findings is discussed.

In a previous study, lavender (Lavandula spp.) was found to be highly phytotoxic towards annual ryegrass (Lolium rigidum, ARG), a major weed of winter wheat crops in Australia. This research aimed to further explore this relationship and determine the chemical(s) responsible for the observed effect. In bioassay, it was determined that the stem and leaf extract of L. x intermedia cv. Grosso ranked highest and had the potential to reduce significantly the root growth of several plant species. An extract concentration of 10% almost completely inhibited ARG root growth. When the extract was tested for stability, there was no loss in phytotoxicity after the 256 day trial. Via bioassay-guided fractionation and chromatographic techniques, it was determined that the sub-fraction consisting of coumarin and 7-methoxycoumarin was most phytotoxic towards ARG. Chemoassays of 18 structural analogues of coumarin showed that coumarin itself was the most phytotoxic and largely responsible for the observed phytotoxicity of the extract. Soil trials were conducted using pure coumarin and the lavender extract, and in both instances, shoot length and weight were significantly reduced by post-emergence application at all concentrations evaluated.

The cardenotide extracts from latex and aerial parts of Asctepias fruticosa and of Danaus plexippus reared on A. fruticosa or A. curassavica were purified by adsorption chromatography on silica gel. HPLC analysis on a C~8 reverse-phase column with an acetonitrile-water gradient as mobile phase, separated 28 compounds with a UV spectrum typical for cardenolides. Afroside and gomphoside (major components), as well as calotropagenin, calotoxin, calotropin, calactin, uscharidin, uscharin, and voruscharin, occurred as single peaks in the profiles of latex and aerial plant parts of A. fruticosa. Catactin and calotropin were the major cardenolides in Danaus plexippus reared on A. fruticosa or A. curassavica. Quantitative data obtained with digitoxin as internal standard showed that 1.3-1.5 % of the leaf cardenolides were sequestered by Danaas plexippus in which levels of 70-80 /zg cardenolide per butterfly were measured. The calotropin from the leaves was almost completely sequestered, and 10-13% of the calactin was stored by the butterfly, assuming that no conversion occurred in larval tissues.

The antennae of Sitophilus granarius (L.) (Coleoptera: Curculionidae) adults detect a wide variety of compounds in the odor blend of various cereal grains (Germinara et al., Tec. Molit., 53:27-34, 2002). In the present study, we looked at the behavioral responses of the granary weevil to 20 of these individual volatiles (aliphatic alcohols, aldehydes, ketones, and aromatics) in a two-choice pitfall olfactometer, using the aggregation pheromone and propionic acid as the attractant and repellent controls, respectively. Five doses, ranging from 1 μg to 1 mg, of each compound were tested. At least one concentration of eight compounds attracted beetles but required doses 1,000-to 5,000-fold higher than the concentration of aggregation pheromone to elicit a response. Three compounds, while attractive at lower concentrations, acted as repellents at higher doses. Twelve compounds were repellent at concentrations similar to the quantity of propionic acid that significantly repelled beetles. The data show that granary weevil adults have the ability to respond behaviorally to a wide range of cereal volatiles and that responses may change as a function of concentration. The results suggest that host finding behavior of weevils will depend on the balance of positive and negative volatile stimuli from grain as the relative concentrations of volatiles may change during storage. An understanding of how the weevils respond to such changes could be useful for the development of effective integrated pest management strategies.

Laboratory and field investigations were carried out to investigate the nature and role of the male pheromone emitted by the Dynast beetle Scapanes australis and to develop a mass trapping technique against this major coconut pest in Papua New Guinea. We report the biological data obtained from natural and synthetic pheromone, previously described as an 84:12:4 (w/w) mixture of 2-butanol (1), 3-hydoxy-2-butanone (2), and 2,3-butanediol (3). EAG recordings from natural and synthetic pheromone and a pitfall olfactometer were poorly informative. In contrast, extensive field trapping trials with various synthetic pheromone mixtures and doses showed that 1 and 2 (formulated in polyethylene sachets in 90:5 v/v ratio) were necessary and sufficient for optimum long-range attraction. Beetles were captured in traps baited with racemic 1 plus 2, with or without a stereoisomer mixture of 3 (2.5- to 2500-mg/day doses). Plant pieces, either sugarcane or coconut, enhanced captures by the synthetic...

When ovulated, female fish of many species are known to release a F-prostaglandin-derived sex pheromone that attracts conspecific males. Recently, this pheromone was identified in the common carp as a mixture of prostaglandin F 2α (PGF 2α ) and unidentified body metabolites, which we termed a 'pheromone complex.' The present study sought to test the activity of this pheromone complex in the field by developing a system using carps implanted with PGF 2α as pheromone donors. An initial experiment determined that osmotic pumps that delivered up to 0.4 mg of PGF 2α per hour could be implanted into carp without any apparent effects on their health. A second experiment found that PGF 2α -implanted male and female carp released biologically relevant (and equivalent) quantities of PGF 2α , along with two of its seemingly inactive metabolites, for up to 2 weeks. Laboratory experiments demonstrated that the odor of PGF 2α -implanted carp was highly attractive to male conspecifics, and included necessary body metabolites; it attracted males as strongly as ovulated carp odor, and much better than PGF 2α alone. Finally, a field test demonstrated that PGF 2α -implanted female carp attracted mature male, but not female carp, from a distance of 20 m. This is the first demonstration of the activity of a PGF 2αbased pheromone in a natural environment and confirms the use of a PGF-pheromone complex in the carp. We suggest that the implant technique may be useful in future studies of how PGF pheromones function and could be further developed to attract invasive fish for use in control.

Laboratory experiments were carded out to investigate the efficacy of seed extracts of pithraj, Aphanamixis polystachya (Wall & Parker), a locally grown plant in Bangladesh, against the red flour beetle, Tribolium castaneum (Herbst.). Results of three different bioassays showed that crude extracts of pithraj seeds have strong repellent effects and moderate feeding deterrent and insecticidal (direct-contact) effects on adult Tribolium castaneum.

Age of host eggs can be a limiting factor for egg parasitoids. It is expected that old eggs are less preferred by egg parasi- toids, which can discriminate between eggs of different ages by using chemical cues. The objective of this study was to determine the preference, development and arrestment of Telenomus remus Nixon (Hymenoptera: Scelionidae) parasitizing Spodoptera frugi- perda (J.E. Smith) (Lepidoptera: Noctuidae) eggs of different ages. This egg parasitoid preferred to parasitize 1- and 2-day-old eggs rather than 3-day-old eggs in choice and no-choice assays. However, although the percentage emergence of parasitoids is signifi- cantly lower from 2- and 3-day-old eggs the sex ratio and developmental time are unaffected. Parasitoids spent longer searching sub- strates impregnated with extracts of 1- and 2-day old eggs than 3-day-old eggs. Our results reveal that T. remus is able to distinguish the most suitable (1-day-old) from the least suitable (3-day-old) host eggs, but unable to recognize the unsuitability of intermediate aged eggs. Egg arrestants may be responsible for the preference of T. remus for ovipositing in 1- and 2-day old eggs.

The aerial parts of Melilotus messanensis (sweet clover) afforded, from moderately and polar bioactive fractions, 11 triterpenes and five steroids. A series of aqueous solutions at 10−4–10−9 M of five steroids and nine triterpenes was monitored to test their effects on germination and growth of the monocots Hordeum vulgare and Allium cepa, and the dicots Lactuca sativa (var. nigra and var. romana) and Lycopersicon esculentum. An important stimulatory effect on H. vulgare germination (between 40% and 80% for almost all tested compounds) was observed. Some considerations about the ecological role of triterpenes on M. messanensis are made. In addition to known lupane triterpenes (platanic acid and 3β,28,30-lup-20(29)-enetriol), oleanane triterpenes (soyasapogenol B, soyasapogenol G, and messagenolide), a gammacerane triterpene (gammacer-16-en-3-one), five new lupane triterpenes (messagenic acids A–E: (27-cis-4-hydroxycinnamoyloxy)-betulinic acid; 27-(trans-4-hydroxycinnamoyloxy)betulinic acid; 20(S)-3β-hydroxy-29-oxolupan-28-oic acid; 3β,30-dihydroxylup-20(29)-en-28-oic acid; and 3β,20-dihydroxylup-18(19)-en-28-oic acid, respectively), and sterols (β-sitosterol, ergosterol peroxide, 7α-hydroxysitosterol, 7β-hydroxysitosterol, and 7-oxositosterol) were isolated and chemically characterized. Their structures and stereochemistry were elucidated by spectroscopic methods (one- and two-dimensional 1H and 13C NMR, IR, MS).

Serious side effects from the conventional use of traditional chemical pesticides for routine arthropod pest management have prompted the investigation and development of alternate strategies for the minimization of pest damage. Insect sex pheromones have been proposed as a potential group of alternative control agents for over twenty years. The possible uses of these substances for insect control are discussed and factors influencing their development for pest management are presented. The scientific research and commercial development of oriental fruit moth mating disruption is presented as a case study for the commercialization of this approach. Advantages and limitations of pheromone-based control tactics are presented. Mating disruption technology is starting to find its place in a number of diverse cropping situations. The use of pheromones for pest control promises to be an important component of the ongoing challenge to develop alternatives that may help to solve major environmental and human health problems associated with chemical pesticide use in agriculture.

Invasive plants have a multitude of impacts on plant communities through their direct and indirect effects on soil chemistry and ecosystem function. For example, plants modify the soil environment through root exudates that affect soil structure, and mobilize and/or chelate nutrients. The long-term impact of litter and root exudates can modify soil nutrient pools, and there is evidence that invasive plant species may alter nutrient cycles differently from native species. The effects of plants on ecosystem biogeochemistry may be caused by differences in leaf tissue nutrient stoichiometry or secondary metabolites, although evidence for the importance of allelochemicals in driving these processes is lacking. Some invasive species may gain a competitive advantage through the release of compounds or combinations of compounds that are unique to the invaded community-the "novel weapons hypothesis." Invasive plants also can exert profound impact on plant communities indirectly through the herbicides used to control them. Glyphosate, the most widely used herbicide in the world, often is used to help control invasive weeds, and generally is considered to have minimal environmental impacts. Most studies show little to no effect of glyphosate and other herbicides on soil microbial communities. However, herbicide applications can reduce or promote rhizobium nodulation and mycorrhiza formation. Herbicide drift can affect the growth of non-target plants, and glyphosate and other herbicides can impact significantly the secondary chemistry of plants at sublethal doses. In summary, the literature indicates that invasive species can alter the biogeochemistry of ecosystems, that secondary metabolites released by invasive species may play important roles in soil chemistry as well as plant-plant and plantmicrobe interactions, and that the herbicides used to control invasive species can impact plant chemistry and ecosystems in ways that have yet to be fully explored.