Sex-identifying urine and molt signals in lobster (Homarus americanus)

During courtship, premolt female lobsters,Homarus americanus, choose a male and initiate a pair bond by repeated approaches to his shelter. The male allows such a female to share his shelter for about one week. This knowledge formed the basis to search for quantitative evidence for lobster sex pheromone(s) used in courtship: male cues to allow premolt females to identify a preferred male, and female cues to allow males to identify a premolt mature female. In each of four 1500-liter naturalistic aquaria, the behavioral responses of one female and two male lobsters to male and female lobster urine (0.5 ml) and body odor (20 ml) stimuli were observed. These stimuli were injected once or twice per day into a continuously flowing delivery tube attached to lobster shelters. Habituation to stimulus introduction—a serious problem in earlier experiments—was apparently avoided in the more natural social and physical environment we employed in these experiments. We demonstrated that male and female molt body odors contain different chemical substances: females responded to male molt body odor and males responded to female molt body odor but not vice versa. In general, male and female intermolt urine caused strong responses; however, females responded only weakly to male urine. This suggests that male and female urine are chemically different. Female urine and molt body odor caused a typically male high-on-legs response. These results show that molt body odors and intermolt urine contain sex-specific substances, which may be used in lobster courtship as well as other social interactions.     

Selective improvement in responses to prey odors by the lobster,Homarus americanus,following feeding experience

Lobsters can detect odors from two natural prey species, the horse musselModiolus modiolus and the blue musselMytilusedulis. When lobsters fed exclusively on one of these two prey species for one month, their behavioral response threshold for the prey odor from this species was lowered relative to the threshold for odor from the nonexperienced prey.     

Development of chemically mediated prey-search response in postlarval lobsters (Homarus americanus) through feeding experience

Postlarval lobsters were fed live amphipods (Gammarus oceanicus), soft clam spat (Mya arenaria), or frozen brine shrimp (Artemia salina) for five weeks in order to determine by behavioral bioassay if chemically mediated prey-search behavior is established by feeding experience. Chemosensory responses of predatorily naive lobsters to live clam and amphipod metabolites were low and erratic. After five weeks, amphipod-fed lobsters had developed strong responses towards amphipod metabolites but not clam metabolites. In contrast, clam-fed lobsters did not develop responses to either prey. Chemical fractionation of amphipod metabolites indicated that attractants were confined to the same fraction as for prey extracts, i.e., polar, low-molecular-weight compounds. Survival (80–90%) was similar for each diet group; growth was greatest for amphipod-fed lobsters (100%), followed by clam-fed lobsters (72%) and brine shrimp-fed lobsters (18%); and feeding rates increased for amphipod-fed lobsters and decreased for clam-fed lobsters. Coloration of lobsters indicated that only amphipod diet provided desirable pigments. Differences in ingestive conditioning results between clamfed and amphipod-fed lobsters may have been related to (1) clam metabolites being qualitatively or quantitatively less attractive than amphipod metabolites or (2) differences in the predisposition of lobsters to show ingestive conditioning to different prey and their associated metabolites as a function of quality of prey as a diet.     

Chemosensitivity of lobster,Homarus americanus,to secondary plant compounds: Unused receptor capabilities

Chemosensitivity to secondary plant substances was examined electrophysiologically and behaviorally for the lobsterHomarus americanus. Neurophysiological experiments show that some chemoreceptor cells in the antennules (representing the sense of smell) and walking legs (representing the sense of taste) were excited by secondary compounds from plants of marine and terrestrial origin. These compounds include amygdalin, atropine sulfate, bromoform, caffeine,p-coumaric acid, diiodomethane, ferulic acid, heliotropin, phloroglucinol, quinine sulfate, salicin, sinigrin, tannic acid, and tomatine. The possible behavioral function of three of these compounds was tested. Phloroglucinol and ferulic acid had no observable effect on any aspect of feeding behavior at any concentration tested. Tannic acid, which is related to polyphenols found in marine algae, had no observable effect at any concentration tested on orientation to and grasping of food (activities controlled primarily by antennular and leg chemoreceptors, respectively) but did have an inhibitory effect on food ingestion (an activity controlled primarily by mouthpart chemoreceptors). These electrophysiological and behavioral results suggest that potential chemoreceptive information derived from many secondary plant compounds may not be used in feeding behavior. The receptors sensitive to these compounds may represent a common chemical sense as suggested by Dethier (1980). However, at least one compound, tannic acid, that is smelled and tasted by lobsters can function as a feeding inhibitor at the level of the mouthparts.     

Mate Location Mechanism and Phase-Related Mate Preferences in Solitarius Desert Locust, Schistocerca gregaria

Mate location responses of male and female solitary-reared locusts that had either experienced no crowding or that had been crowded for varying periods were studied in a flatbed wind tunnel. Two hypotheses were explored: that both sexes of this phase of the locust participate in locating the other by using a combination of chemical and visual signals, and that individuals that experience some crowding (i.e., undergo varying levels of phase shift) can compete effectively with their solitary counterparts in mate location and mating. Our results confirm that both male and female solitarious locusts actively participate in mate location, although the former is the more aggressive partner. The responses of the insects are stronger when a visual cue is provided with the olfactory signal. Crowding of solitary-reared adults enhances their responsiveness to the other sex in the absence and presence of the visual cue. This phenomenon may constitute one of several mechanisms that are involved in recruiting solitary individuals into gregarizing groups and facilitating the spread of gregarious characters across a reproductively active solitarious population.     

Attraction of predatorily naive postlarval lobsters to extracts of metabolites of common prey:Mytilus edulis,Mya arenaria,Cancer irroratus,andAsterias vulgaris

Postlarval lobsters (4th–7th stage) exclusively fed frozen brine shrimp (Artemia saline) were assayed for food-search response to extracts and metabolites from four common prey: soft clams (Mya arenaria), blue mussels (Mytilus edulis), rock crabs (Cancer irroratus), and sea stars (Asterias vulgaris). Concentrations of soluble primary amines, protein, and ammonia in prey tissues and metabolites were determined. No significant responses were observed for any prey metabolites diluted to 1 and 10%, while onlyA. vulgaris evoked a significant response at full strength, suggesting that predatorily naive lobsters have yet to develop more pronounced chemosensory responses shown by field-collected lobsters. Removal of protein with retention of small-molecular-weight polar molecules did not appear to affect response to prey extracts. EC₅₀s, as micromoles per liter amines, computed from prey extract dose-response curves indicate differences per unit amine between prey extracts, withA. vulgaris extract more potent as an attractant than either bivalve extract.C. irroratus extract was equally attractive as the other three extracts. Ammonia levels excreted into seawater over 3 hr were similar for all prey species, while soluble primary amines and proteins were undetectable. Ammonia and protein per gram whole prey varied significantly between extracts of prey species, while primary amines were similar. Lobsters may be attracted preferentially to carrion species with higher concentrations of amines and/or higher potency of attractants per unit amine.     

Mate choice and toxicity in two species of leaf beetles with different types of chemical defense

Evidence for the use of defensive compounds for sexual purposes is scarce, even though sexual selection might have some importance for the evolution of defensive traits. This study investigates the effect of defense-related traits and body size on mating success in two sister species of leaf beetle differing in their type of chemical defense. Oreina gloriosa produces autogenous cardenolides, whereas O. cacaliae sequesters pyrrolizidine alkaloids from its food plant. Larger O. gloriosa males with more toxin or higher toxin concentration had a mating advantage, likely due to direct or indirect female choice. In the laboratory, particular pairings recurred repeatedly in this species, indicating mate fidelity. O. gloriosa females were also subject to sexual selection, possibly by male choice, because larger females and those with higher toxin concentration mated more readily and more often. In O. cacaliae, in contrast, sexual selection for toxicity and body size was not detected, or at best was much weaker. Because toxicity is heritable in O. gloriosa but environment-dependent in O. cacaliae, individuals of the former species could be choosing well-defended partners with good genes. Our study suggests that sexual selection may contribute to the maintenance of heritable defensive traits.     

Chemical Signal Mediated Premating Reproductive Isolation in a Marine Polychaete, <Emphasis Type="Italic">Neanthes acuminata</Emphasis> (<Emphasis Type="Italic">Arenaceodentata</Emphasis>)

Neanthes acuminata Ehlers (1868) is a monogamous coastal polychaete with male parental care and a high level of sexual selection. We measured the level of prezygotic isolation among allopatric populations of N. acuminata; from the East and West Coast of the USA, a population from Hawaii, and a laboratory culture originating from Los Angeles, CA. All populations were found to preferably mate with members of their own population. Individuals from populations from Atlantic vs. Pacific Ocean failed to pair and to mate, either during the 10 min or 48 hr experiments. Instead, individuals showed high levels of aggressive behavior. Experiments measuring the levels of interpopulation aggression, established that individuals can recognize and discriminate among different populations of N. acuminata on the basis of olfactory cues. Aggressive behavior was induced by exposure of animals to seawater “conditioned” by individuals from the other populations, thus demonstrating the role of olfaction in the detection of “home” populations. The aggressive display was stronger upon exposure to seawater conditioned with “unrelated” populations and especially between Pacific and Atlantic populations.     

Pheromone attraction in the soybean cyst nematodeHeterodera glycines race 3

MaleHeterodera glycines responded to female nematodes during in vitro bioassay. The male's response was dosage-dependent and significant with a pheromone source of more than five females. Male responsiveness was influenced by the pheromone diffusion and response times. Males were most responsive at three days after emergence from the host plant, while females were also most attractive at the same age. Light intensities that ranged from dark to bright had no effect on female location by the male, although bioassay in a nitrogen atmosphere eliminated sexual communication. Mate location was not significant below 25 °C and declined slightly at 30 or 33 °C. Bioassay at pHs from 5 to 8.5 showed a bimodal effect, with maximal attraction around pH 6.     

Chemical mate recognition and release of male sexual behavior in polybiine wasp,Belonogaster petiolata (Degeer) (Hymenoptera: Vespidae)

The results of bioassays using freshly killed gynes ofBelonogaster petiolata (Degeer) and hexane extracts of their tagmata and abdominal glands provide evidence for the existence of chemical signals in the venom, thorax, and head of gynes that serve as mate recognition cues and releasers of copulatory behavior in conspecific males. Attraction of males to the source of the chemicals occurs over short distances (a few centimeters).     

Odors in traps: Does most recent occupant influence capture rates for house mice?

Responses of house mice (Mus domesticus) to odors in live traps were studied in a series of eight 0.1-ha outdoor field enclosures. It was assumed that the most recent mouse capture would provide the predominant odor in a trap for at least one week. Three different populations were tested, one in 1989 and two in 1992, involving over 800 different mice. Similar response patterns were recorded from all three groups. Two types of questions were tested: (1) Were there any biases contingent upon what had been previously caught? (2) Were there consistent responses of mice of particular age, sex, or reproductive classes to trap odors? Traps soiled by juvenile females caught adult females significantly less often than expected, but there were no consistent relationships in terms of the effects of specific residual odors on the subsequent capture at a particular trap. For various age, sex, and reproductive classes, (1) adult males preferred odors from juvenile and estrous females and avoided odors of other males significantly more than expected, (2) juvenile females selected traps with odors of other juvenile females and avoided all other types of female odors significantly more than expected, (3) nonestrous females exhibited a significant preference for adult male odor, and (4) estrous females selected traps containing odors from adult males but avoided those that had previously contained either nonestrous or pregnant/lactating females significantly more than expected. These findings have potential implications with regard to both the methods used for trapping small rodents and the social biology of house mice.     

Sex Pheromone of the Peach Aphid, Tuberocephalus momonis, and Optimal Blends for Trapping Males and Females in the Field

Chemical analysis of the volatiles released by sexual females (oviparae) of the peach aphid, Tuberocephalus momonis, identified two ubiquitous aphid sex pheromone components, (4aS,7S,7aR)-nepetalactone and (4aS,7S,7aR)-nepetalactol, in a ratio of 4 : 1. In field trials in Korea, employing traps releasing the two compounds in differing ratios, the most effective sex pheromone blend for trapping male T. momonis was found to be 85 : 15 nepetalactone–nepetalactol. Surprisingly, large numbers of presexual females (gynoparae) of this species were also collected when the catching rates were highest. In addition to T. momonis, over 20 other species of aphids were caught, particularly Myzus lythri, M. dycei, Lachnus tropicalis and M. persicae, in descending order of abundance.     

Alarm responses in the crayfishOrconectes virilis andOrconectes propinquus

Individuals of two species of crayfish (Orconectes virilis andO. propinquus) were tested in the laboratory for responses to chemicals released from physically damaged conspecifics. Individuals ofO. propinquus did not show an alarm response to crushed conspecifics. Individuals ofO. virilis responded to a water-borne substance released from crushed conspecifics by assuming an intermediate posture and ceasing movement. Similar alarm responses were shown by individuals ofO. virilis to crushed congeneric individuals (O. propinquus), and these responses were not eliminated by either freeze-thawing the crayfish used to prepare the signal or by treating freshly crushed crayfish with the enzyme trypsin. Individuals ofO. virilis showed strong feeding responses to solutions prepared from frozen fish flesh but showed a mixture of alarm and feeding responses to freshly killed fish. These results indicate that the alarm substance used byO. virilis is widespread.     

Pheromone production by the bark beetle,Ips paraconfusus,in the nonhost,white fir

MaleI. paraconfusus confined to artificial entrance tunnels in white fir logs produced the pheromone compounds ipsenol and ipsdienol in their hindguts. The hindguts were attractive to females in a laboratory olfactometer and the male infested logs were attractive in field bioassay. The amount of pheromones produced and the amount of feeding and boring activity is much less in white fir than in ponderosa pine. There were no pheromones detected in the hindguts of recently emerged, unfed males.Coleoptera; Scolytidae.Research supported by the Rockefeller Foundation, an NIH training grant, USDA/SEA Regional Research Project W-110, and the USDA Forest Service.From a thesis submitted by J.S. Elkinton in partial satisfaction of the requirements for the PhD degree, University of California, Berkeley, California, 1979.     

Role of secondary metabolites in feeding associations between a predatory nudibranch,two grazing nudibranchs,and a bryozoan

The carnivorous nudibranchRoboastra tigris preys preferentially upon two nudibranchs,Tambja abdere andT. eliora, that in turn feed upon the bryozoanSessibugula translucens. All four organisms contain tambjamines A–D (I–IV) that were shown to be fish feeding inhibitors. When attacked byRoboastra, T. abdere secretes a distasteful mucus containing a total of 3 mg of the tambjamines that sometimes causes theRoboastra to break off the attack. Under similar circumstancesT. eliora attempts to swim away; it presumably contains insufficient of the tambjamines to deterRoboastra. Roboastra follows the slime trail of nudibranchs using contact chemoreception and reverses direction when the trail is broken. The slime trail ofT. abdere contains low concentrations of the tambjamines. In Y-maze experiments,T. eliora was attracted towards seawater containingS. translucens and seawater containing 10^–10 M tambjamines A and B (11) but was repelled by seawater containing > 10^–8 M tambjamines A and B. At higher concentrations the mixture of tambjamines may be recognized as an alarm pheromone.     

Identification, Synthesis, and Field Evaluation of the Sex Pheromone from the Citrus Leafminer, Phyllocnistis citrella

Using male antenna as the sensing element, three electroantennographic detection (EAD)-active peaks were detected from pheromone gland extracts of the citrus leafminer, Phyllocnistis citrella. Based on gas chromatography (GC)-mass spectrometry and GC-infrared data, the semiochemicals were tentatively identified as a novel pheromone, (Z,Z,E)-7,11,13-hexadecatrienal, a previously identified attractant, (Z,Z)-7,11-hexadecadienal, and (Z)-7-hexadecenal in a ratio of 30:10:1, respectively. Identification was confirmed with synthetic compounds, which gave retention times identical to those of the natural products on three capillary columns with polar and nonpolar phases. While traps baited only with the previously identified attractant alone did not catch any males in Brazil, binary and tertiary mixtures with the major constituents caught significantly more male moths than traps baited with five virgin females. This paper and the following paper (Moreira et al.) were submitted within a few days of each other. The editors and the authors agreed that they should be published in tandem.     

Chemical and behavioral ecology of foraging in prairie rattlesnakes (Crotalus viridis viridis)

Free-ranging prairie rattlesnakes (Crotalus viridis viridis) exhibit lengthy vernal migrations upon emergence from winter hibernation. A series of laboratory experiments was designed to test hypotheses regarding the function and causation of vernal movements. Rattlesnakes obtained from Wyoming and Colorado populations were used. First, we hypothesized that the function of vernal movements is to locate small mammal prey. Second, we predicted that activeC. v. viridis use prey chemicals, as well as other cues, to decide whether or not rodents are present in an area. Third, we hypothesized that vernally active males would be more responsive to rodent prey and their odors than females, given observed differences in behavior in the field. Fourth, we predicted that rattlesnakes captured in Colorado would be more sensitive to prey odors than those obtained in Wyoming, because of disparate community structure and, hence, small mammal spatial distributions. As expected, snakes exhibited reduced activity, as well as certain other dependent measures reflecting predatory investigation, in arena zones containing either live rodents or their chemicals. However, responses to the latter were reduced in Wyoming rattlesnakes tested with chemicals from deer mice (Peromyscus maniculatus), relative to Colorado animals tested with chemicals obtained from house mice (Mus musculus). In contrast to patterns observed in nature, males and females exhibited almost no differences in overall responsiveness. Results are discussed in the context of simulation modeling and ongoing studies of prairie rattlesnake behavior.     

Mammalian Exocrine Secretions. XIII: Constituents of Preorbital Secretions of Bontebok, Damaliscus dorcas dorcas, and Blesbok, D. d. phillipsi

The 42 compounds identified in the pale yellow preorbital secretions of the bontebok, Damaliscus dorcas dorcas, and the blesbok, D. d. phillipsi, include acetic acid, 2-methylbutanoic acid, (E)-2-methyl-2-butenoic acid, benzoic acid, 4-hydroxybenzoic acid, saturated and unsaturated long-chain carboxylic acids, 4-hydroxybenzaldehyde, saturated and unsaturated, unbranched, long-chain alcohols and aldehydes, 2-heptanone, pentane, heptane, pepiritone, dimethylsulfone, isopropyl tetradecanoate, isopropyl hexadecanoate, hexadecyl acetate, -lactones, cholesterol, -tocopherol, and squalene. Some qualitative and quantitative differences were found between the secretions of males and females of both subspecies.     

Sex pheromone-induced chemolocation in the male American cockroach,Periplaneta americana

Males of the American cockroach,Periplaneta americana, have evolved an efficient search strategy enabling them to locate a source of sex pheromone in the absence of directional information derived from wind. Since these animals are able to utilize chemotaxis to orient almost directly to the source from 45–50 cm away, it is only necessary that they maximize their chances of getting within that range once they perceive the pheromone. They accomplish this by: (1) increasing their overall levels of activity and (2) initiating local search. In this way, they are able to cover a rather large area in a short period of time, i.e., before the source female changes location. If their paths take them to within 45 cm of the source, they are able to locate it soon thereafter. It is probable that very similar strategies are utilized by many other nonflying insects to locate sources of airborne odors.     

Field evidence of synergism and inhibition in the sesiidae sex pheromone system

The E,Z, Z,Z, and Z,E geometric isomers of 3,13 octadecadien-1-ol acetate were used singly and in binary combinations to trap sesiids in Wisconsin cherry orchards. The Z,E isomer alone did not capture any sesiids. A synergistic effect, however, of Z,E onSynanthedon pictipes response to its pheromone E,Z was demonstrated for the first time. Strong inhibitory effects of the Z,Z isomer onS. pictipes response to E,Z, and of the E,Z isomer onS. scitula response to Z,Z, were found. As little as 0.5% of Z,Z in E,Z completely inhibited theS. pictipes response. This species' response was also reduced by 85% when Z,Z was evaporated at 4 points, each ca. 6 m from the pheromone trap. Consistencies and discrepancies of the data with relevant experimental results from other geographical areas are briefly discussed.Lepidoptera: Sesiidae (=Aegeriidae), the clearwing moths.Research supported by the College of Agriculture and Life Sciences, University of Wisconsin, Madison, and by the Wisconsin Red Tart Cherry Ind. Market. Order.