Description of an automatic copulation induction system used to establish a free-mating laboratory colony of Nyssorhynchus deaneorum from Brazil

BACKGROUND Nyssorhynchus deaneorum is a potential malaria vector because it has been shown to be competent to transmit Plasmodium vivax and Plasmodium falciparum, and because it exhibits antropophilic and endophilic behaviors in some regions of the Amazon. This profile makes Ny. deaneorum a useful mosquito for experiments that model Plasmodium-vector interactions in the Amazon. OBJECTIVE Herein we describe how a free-mating colony of Ny. deaneorum has been established using an automated light stimulation system. METHODS Mosquitoes were captured in São Francisco do Guaporé, Rondônia. The F1 generation was reared until adult emergence at which point copulation was induced using an automatic copulation induction system (ACIS). FINDINGS After four generations, natural mating and oviposition began to occur without light stimulation. The number of pupae and adult mosquitoes increased from the F5 to F10 generations. The new Ny. deaneorum colony exhibited susceptibility to P. vivax. MAIN CONCLUSIONS Automated light stimulation is an effective method for establishing an Ny. deaneorum colony under laboratory conditions as it produces enough adults to create a stenogamic colony. The establishment of a stable, P. vivax-susceptible colony of Ny. deaneorum makes it possible to model parasite-vector interactions and to test novel drug therapies that target parasite development in mosquitoes.

Caracterización del comportamiento y las señales vibratorias en Euthyrhynchus floridanus (Hemiptera: Pentatomidae) durante el cortejo y la cópula / Characterization of the behavioral and vibrational signals in Euthyrhynchus floridanus (Hemiptera: Pentatomidae) during courtship and copulation

Euthyrhynchus floridanus (Linnaeus) (Hemiptera: Pentatomidae) is a neotropical species belonging to the family Pentatomidae with over 4 000 species described, and is distributed from Florida to Brazil. This study describes the sexual behavior and reported for the first time the production of substrate vibrations by males and females during copulatory behavior and mating. Courtship and copulatory behavior, as well as the diverse signals, were recorded with a phonographic cartridge connected to a video camera. Female vibrations were reproduced in the absence of females and the responses by males were recorded. At least three types of substrate vibrations were distinguished in males and one in females, and these signals were characterized by their low frequency, varying from 127 to 180Hz. The sounds of E. floridianus males were significantly different in frequency, duration and number of pulses, both in courtship and in copulation, for the purring and drumming sounds. The production of sounds in this species is associated principally with mechanical, stimulatory behavior during courtship and copulation. Patterns of behavior and their relation to substrate vibrations suggest that these signals are important for the males in the context of mate location and sexual selection.

Euthyrhynchus floridanus (Linnaeus) (Hemiptera: Pentatomidae) es una especie neotropical perteneciente a la familia Pentatomidae con más de 4 000 especies descritas, y se distribuye desde la Florida hasta Brasil. Este estudio describe el comportamiento sexual y reporta por primera vez la producción de vibraciones de sustrato por machos y hembras durante el comportamiento precopulatorio y la cópula. Se grabó tanto el comportamiento de cortejo y de cópula como las diversas señales producidas utilizando un cartucho fonográfico, conectado a una cámara de video. Posteriormente se reprodujo las vibraciones de las hembras en ausencia de estas y se registró las respuestas de los machos. Se distinguieron al menos tres vibraciones de sustrato distintas para los machos y una para las hembras, y se caracterizaron por ser señales de baja frecuencia que van desde los 127 hasta 180Hz. Las sonidos de los machos en E. floridianus fueron significativamente diferentes en la frecuencia, duración y número de pulsos tanto en el cortejo como en la cópula para los sonidos de ronroneo y tamborileo. La producción de sonidos en esta especie se asoció principalmente con comportamientos estimulatorios- mecánicos durante el cortejo y copula. Patrones de comportamiento y su relación con las vibraciones del sustrato sugiere que estas señales pueden ser importantes para los machos en el contexto de la localización de su compañera y la selección sexual.

Mating latency, duration of copulation and fertility in four species of the Drosophila bipectinata complex.

Significant interspecific variations in mean duration of copulation and fertility were observed in four species of the Drosophila bipectinata species complex. However, D. bipectinata showed positive correlation between duration of copulation and fertility. Similarly, D. malerkotliana showed negative correlation between mating latency and duration of copulation. Likewise, D. pseudoananassae showed positive correlation between mating latency and fertility. These results suggest that D. pseudoananassae has distant relatedness from the other three species with respect to mating latency, duration of copulation and fertility which supports the previous findings.

Avaliação de dois métodos para condicionamento e coleta de sêmen em quatro espécies do gênero Mazama / Assessment of two methods for conditioning and semen collection in four species of Mazama genus

O desenvolvimento de técnicas não invasivas para a obtenção de sêmen de cervídeos facilita a criação de bancos genômicos, que são importantes instrumentos para a conservação ex situ e in situ. Este trabalho teve como objetivo criar uma metodologia não-invasiva de coleta de sêmen e comparar duas técnicas de coleta em quatro espécies do gênero Mazama: M. americana, M. gouazoubira, M. nana e M. nemorivaga. Para tanto, foram utilizados seis machos (M) e duas fêmeas (F) da espécie M. americana, 3M e 2F de M. gouazoubira, 1M e 1F de M. nana e 2M e 1F de M. nemorivaga. Para cada técnica testada, foi realizado um período de habituação dos animais ao manejo. Em seguida, duas técnicas de condicionamento e coleta foram avaliadas. Na primeira delas foi utilizada uma fêmea em estro com desvio lateral do pênis para vagina artificial (FEDL), obtendo-se a coleta de 50% dos indivíduos (100% dos machos de M. gouazoubira e 50% dos machos de M. americana), não obtendo ejaculados das demais espécies. Na segunda técnica, utilizando um manequim taxidermizado com urina de fêmea em estro (MUFE) não foi possível a coleta de nenhum ejaculado. Em todas as fases foi observado o comportamento do macho quanto ao tempo de interesse e aproximação, reflexo de "Flehmen", ato de cheirar ou lamber, exposição do pênis, ereção, número de falsas montas, tentativas de cópula e ocorrência de agressividade entre os animais.

The development of noninvasive techniques for obtaining semen from deer facilitates the creation of genome banks, which are important tools for ex situ and in situ conservation. This study aimed to establish a noninvasive method of semen collection and compare two techniques of collection in four species of the genus Mazama: M. americana, M. gouazoubira, M. nana and M. nemorivaga. To achieve this, 6 males (M) and 2 females (F) of the species M. Americana, 3M and 2F of M. gouazoubira, 1M and 1F of M. nana and 2M and 1F of M. nemorivaga were used. For each technique tested, a period of habituation to animal handling was conducted; then, the two conditioning techniques and collection were evaluated. In the first, a female in estrus was used with lateral deviation of the penis to an artificial vagina (FEDL), yielding collection from 50% of the males (100% from M. gouazoubira and 50% from M. americana), with no ejaculate from the remaining species. In the second technique, using a taxidermized dummy with urine from females in estrus (MUFE), no semen collection was possible. During all stages, male behavior was observed regarding the time of interest and approximation, the "Flehmen" response, the act of sniffing or licking, exposure of the penis, erection, number of false mounts, attempts at copulation and the occurrence of aggression between the deer.

Copulatory behaviour and the process of intromission in Anastrepha ludens (Diptera: Tephritidae)

Complex genitalia occur in many arthropods and in some species extreme female morphologies lead to serious mechanical difficulties for males. Tephritid flies offer examples of such complex genitalia. Because of their economic importance and the extensive use of sterile male releases for tephritid control in Texas and Mexico, studies have been done on various aspects of their basic reproductive biology, but the process of intromission has received little attention. The distiphallus of the male of Anastrepha ludens is complex. One membranous sac on the distiphallus is capable of rhythmic cycles of inflation and deflation. Inflations of the sac near the base of the distiphallus probably help propel the aedeagus deeper into the female along with stiffening of the basiphallus and may drive the genital rod (which does not transfer sperm) into the ventral receptacle. We were unable to establish an association between some of the behaviours displayed by males during mating and intromission process. Rev. Biol. Trop. 59 (1): 291-297. Epub 2011 March 01.

En muchos artrópodos, se observan genitales complejos; la morfología extrema en las hembras podría conducir a serios problemas mecánicos para los machos (Kamimura & Matsuo 2001). Las moscas tefrítidas tienen ejemplos de tales órganos genitales complejos. Debido a su importancia económica y la amplia utilización de machos estériles para el control biológico en Texas y México, se han realizado estudios sobre diversos aspectos de su biología reproductiva, pero el proceso de penetración ha recibido muy poca atención. El distiphallus de los machos de Anastrepha ludens es complejo. Un saco membranoso en el distiphallus es capaz de realizar ciclos rítmicos de inflación y deflación. El inflado de la bolsa cerca de la base del distiphallus, junto con la rigidez del basiphallus probablemente ayuda a impulsar el edeagus más profundamente en la hembra y orientar la vara genital (que no transfiere esperma) en la región del receptáculo ventral. No pudimos establecer una asociación entre algunas de las conductas mostradas por los machos durante el apareamiento y el proceso de intromisión.

Rat dorsal prostate is necessary for vaginal adhesion of the seminal plug and sperm motility in the uterine horns

The rat prostate comprises dorsal, ventral and lateral lobes that are morphologically and biochemically distinct. Lesions to these structures are expected to affect the quality of the ejaculate and male fertility. In experiment 1, we analyzed ejaculate parameters of males that had chemical lesions of the dorsal or ventral lobes. At pre-lesion and at 5 and 20 days post-lesion males were mated, and after ejaculation, seminal fluid and seminal plug were obtained from the mated females. In experiment 2, the ventral lobes were ablated, and the ejaculate was analyzed. In experiment 3, the fertility of males with chemically-lesioned dorsal lobes or ablation of the ventral lobes was evaluated. Chemical lesion of the dorsal lobe prevented the adhesion of the seminal plug to vaginal walls. When these males were tested at 5-days postlesion, no sperm were found in uterus, and at 20-days post-lesion, the few sperm encountered showed slow progressive motility. None of the females that mated with dorsal lobe-lesioned males became pregnant. However, chemical lesion or ablation of the ventral lobes did not affect ejaculate or fertility. Our results indicate that the dorsal prostatic lobes are indispensable for reproductive success in males, and define parameters of ejaculate with which fertility can be estimated.

Copulatory courtship song in Lutzomyia migonei (Diptera: Psychodidae)

Lutzomyia migonei is a vector of leishmaniasis with a wide distribution in South America, which could favour population differentiation and speciation. Cryptic species of the Lutzomyia longipalpis complex, the widely distributed sand fly vector of visceral leishmaniasis in Latin America, have previously been shown to display distinct copulation songs. We found that Lu. migonei males also produce a song during copulation. This "lovesong" presents short trains (6-8 pulses) with an inter-pulse interval around 26 ms and is potentially involved in cryptic female choice and insemination success.

Efectos de la cópula y el tamaño del macho sobre el comportamiento de ovipostura en la mosca estercolera Archisepsis diversiformis (Diptera: Sepsidae) / Effects of copulation and male size on the oviposition behavior of the manure fly Archisepsis diversiformis (Diptera: Sepsidae)

Effects of copulation and male size on the oviposition behavior of the manure fly Archisepsis diversiformis (Diptera: Sepsidae). I evaluated the effect of copulation as a stimulation factor for oviposition of Archisepsis diversiformis by using two different age groups of females. In addition, I tested the effect of copulation on female longevity and progeny sex ratio, taking into account female and male size, and oocyte development in relation to female age. A delay in copulation leads to a delay in oviposition. Females of both age groups started to oviposit between four and five days after copulation. The number of eggs that were laid during the first ten days after copulation, the average number of ovipositions (number of eggs laid per day) during the female’s life, and the average time between ovipositions were all similar. I found further evidence for the effect of copulation on oviposition: when females copulate, they oviposited faster than virgin females. In addition, these females laid a lower number of eggs after the age of 13 days, while females of the same age (that have copulated before, when they were two or six days old) laid a higher number of eggs (an average of 75 eggs). Oocytes in virgin females became larger with age; 57 % of the variation in the number of eggs laid by females depends on female’s longevity. As in other studies, female size had an effect on the total number of eggs laid. However, male size significantly affected the oviposition rate (total number of eggs/female longevity). Females tended to have a higher oviposition rate after copulating with larger males. These data suggest that for this fly species, sexual selection through female choice might be occurring. Rev. Biol. Trop. 57 (Suppl. 1): 239-250. Epub 2009 November 30.

Se evaluó el efecto de la cópula como factor esti­mulante de la oviposición en Archisepsis diversiformis utilizando hembras de dos edades, y en la longevidad de la hembra y en la proporción sexual de la progenie, tomando en cuenta el tamaño de hembra y macho, y el desarrollo de los ovocitos en relación a la edad de la hembra. Se demostró que una demora en copular indujo una demora en oviponer. También hubo similitud en el número de huevos puestos en los diez primeros días después de la cópula, en el número promedio de posturas (grupo de huevos puestos por día) durante toda la vida de una hembra, y en el tiempo promedio transcurrido entre posturas. Otra evidencia del efecto de la cópula en la ovipostura, fue que las hembras que copularon ovipositaron más rápido que las vírgenes. Además, éstas colocaron un número muy bajo (en prome­dio 14) de huevos a partir de los 13 días de edad, mientras que hembras de esta misma edad (que previamente habían copulado a los dos o seis días de edad) colocaron un mayor número (en promedio 75) de huevos. Como en otros estu­dios, el tamaño de la hembra tuvo un efecto significativo sobre el número total de huevos puestos. Sin embargo, el tamaño del macho afectó significativamente la tasa (Nº total de huevos/duración de la vida de la hembra) de ovipostura. Estos datos sugieren la posibilidad de que la selección sexual por elección femenina actúe en hembras de esta especie de mosca.

Aislamiento reproductivo asimétrico entre Lutzomyia pseudolongipalpis y Lutzomyia longipalpis (especie C2), vectores neotropicales de leishmaniasis visceral (Diptera: Pshychodidae)

Asymmetric reproductive isolation between Lutzomyia pseudolongipalpis and Lutzomyia longipalpis (species C2), Neotropical vectors of visceral leishmaniasis (Diptera: Pshychodidae). Lutzomyia pseudolongipalpis and Lutzomyia longipalpis (species C2, L. sp n.) are two endemic species of Phlebotominae sand fly vectors from Venezuela. The two insects are sympatric and monophyletic but have deeply diverging, morphological differences. They belong to the L. longipalpis complex. A study of their reproductive isolation is necessary to understand the process of speciation and maintenance of the two sister species as two discrete taxonomic and biological entities. Cross-mating tests were conducted (homo and hetero-specific) and monitored under two criteria: biological (presence of copulation and offspring) and genetic (using two isozymic markers diagnostic for the L. longipalpis complex; enzyme diagnosis AK and HK). Results indicate reproductive isolation, with an asymmetrical genetic exchange in a direction of hybridization between the two species under experimental conditions, and production of a low number of heterozygotes. These findings support the existence of negative selection on hybrids, and explain the absence of hybrids under natural conditions, in the sympatric locality. Rev. Biol. Trop. 57 (1-2): 23-31. Epub 2009 June 30.

Lutzomyia pseudolongipalpis y Lutzomyia longipalpis (especie C2, L. n. sp) son dos especies de flebotominos vectores endémicos de Venezuela, simpátricas, monofiléticas, con profundas divergencias, morfológicamente diferentes y pertenecientes al complejo de especies L. longipalpis. El estudio de su aislamiento reproductivo es clave para entender el proceso de especiación y el mantenimiento de estas dos especies hermanas como entidades taxonómicas y biológicas discretas. Por tal motivo, se realizaron ensayos de entrecruzamiento homo y heteroespecíficos, los cuales fueron monitoreados por dos criterios: biológico (presencia de cópula y progenie) y genético (utilizando dos marcadores isoenzimáticos diagnósticos para el complejo L. longipalpis, las enzimas AK y HK). Los resultados indican aislamiento reproductivo, con un intercambio genético asimétrico hacia la hibridización en condiciones experimentales, y producción de un bajo número de heterocigotos, lo que apoya la existencia de selección negativa sobre los híbridos y explica su ausencia en condiciones naturales en la localidad simpátrica.

Reproductive isolation between sympatric and allopatric Brazilian populations of Lutzomyia longipalpis s.l. (Diptera: Psychodidae)

Lutzomyia longipalpis s.l., the main vector of Leishmania chagasi in Latin America, is a species complex although the exact number of siblings is yet unknown. In Brazil, the siblings differ in male copulatory courtship songs and pheromones that most certainly act as pre-zygotic reproductive barriers. Here we analysed the reproductive isolation between three allopatric and two sympatric populations of Lu. longipalpis s.l. from Brazil. The results indicate a strong copulatory and pre-mating isolation between the three allopatric populations. In addition, the results also indicate a stronger pre-mating isolation between the two sympatric siblings than between the three allopatric ones, suggesting a role for reinforcement in the speciation of the Lu. longipalpis s.l. complex.

Fitting together: copulatory linking in some Neotropical Chrysomeloidea

Copulatory linking of male and female genitalic structures in 11 Neotropical species of Chrysomelidae and one species of Megalopodidae was studied by freezing and then dissecting pairs of beetles in copula. In Megalopus armatus (Megalopodidae) the male has a long endophallus with complex membranous protuberances and a terminal flagellum that probably reaches the spermatheca. In the subfamily Eumolpinae the females have telescoping ovipositors through which the male endophalli pass, reaching to or near the mouth of the spermathecal duct. A long thin flagellum is probably inserted into the spermathecal duct. The male endophalli are braced inside the female using various structures, including two pairs of lateral appendages and apical appendages (both lateral pairs sclerotized in Colaspis sanjoseana and only the basal pair in Brachypnoea irazuensis), a pair of membranous swellings (in Metaxyonycha amasia), and apical microspicules on the endophallus (in Xanthonia). In the subfamily Galerucinae, males of Metrioidea and Diabrotica (tribe Galerucini) have relatively short endophalli ornamented with sclerotized hooks, spines and needles. In Metrioidea elongata the long needle-like endophallic spines of the male were erected inside the female and penetrated the wall of her bursa. In the tribe Alticini, the male endophallus is very short and does not enter the female in two species, Alagoasa gemmata and Walterianella sp. Instead, the apical parts of the female bursae were everted, and were clamped by sclerites of the male median lobe. The male genitalia of Plectrotetra hirsuta reached deep into the female, to the median oviduct, far beyond the mouth of the spermathecal duct. Both rigid and membranous structures meshed in complex ways. When these observations are combined with published descriptions of mating in other Chrysomelidae, the great diversity of copulatory morphology in these families comes into sharper focus.

Se describen los coajustes mecánicos entre las estructuras genitales de machos y hembras de 11 especies neotropicales de Chrysomelidae y una especie de Megalopodidae. Las parejas fueron congeladas durante la cópula y después disectadas. En Megalopus armatus (Megalopodidae) el macho tiene un endofalo largo, con protuberancias membranosas complejas, y un flagelo terminal que probablemente penetra el largo del ducto de la espermateca hasta el lumen de la espermateca. En la subfamilia Eumolpinae, las hembras tienen ovipositores telescópicos, a través de los cuales los endofali de los machos pasan para llegar hasta o cerca a la boca del ducto de la espermateca. Es probable que el largo y delgado flagelo se inserta en el ducto de la espermateca. El endofalo del macho se apoya dentro de la hembra por varias estructuras, las cuales incluyen dos pares de apéndices laterales y apéndices apicales (ambos pares laterales son esclerotizados en Colaspis sanjoseana, únicamente el par basal en Brachypnoea irazuensis), un par de hinchamientos membranosos (en Metaxyonycha amasia), y espículas apicales sobre el endofalo (en Xanthonia). En la subfamilia Galerucinae, los machos de Metrioidea y Diabrotica (tribu Galerucini) tienen endofalos relativamente cortos, pero adornados con varios ganchos, espinas y agujas. En Metrioidea elongata las largas espinas endofálicas se abrieron dentro de la hembra, y penetraron las paredes de su bursa. En la tribu Alticini, el endofalo del macho de dos especies, Alagoasa gemmata y Walterianella sp., es muy corto y no entró al cuerpo de la hembra. En su lugar, la parte apical de la bursa de la hembra fue evertida, y fue agarrada por escleritos del lóbulo mediano del macho. Los genitales de Plectrotetra hirsuta penetraron profundamente en la hembra, llegando probablemente hasta el oviducto mediano, más profundo que la boca del ducto de la espermateca. Estructuras de...

Field observations of mating behavior in the neck-banded snake Scaphiodontophis annulatus (Serpentes: Colubridae)

We observed the mating behavior of the neck-banded snake Scaphiodontophis annulatus (a common species of colubrid in the South Pacific of Costa Rica) in the pre-montane wet forest of Las Cruces Biological Station (San Vito de Java, Costa Rica). Three S. annulatus were observed during courtship between 10-12 AM in a patch of primary forest. The two males were observed to interact with the female, but not signs of male-male agonistic interactions were observed. Their behavior includes grabbing and holding the female, copula, and biting during the copula.

El comportamiento de apareamiento es descrito para la serpiente Scaphiodontophis annulatus, una especie de colúbrido común en el Pacífico sur de Costa Rica. El comportamiento incluye capturar y sujetar a la hembra, mordiscos durante la cópula y coito. Dos machos fueron observados al interactuar con una sola hembra, pero no se detectó señales de interacciones antagónicas macho-macho.

The function of female resistance behavior: intromission by male coercion vs. female cooperation in sepsis flies (Diptera: Sepsidae)

Female resistance behavior that occurs prior to intromission does not by itself imply forced copulation. Such behavior may function instead as a test of the male in order to favor some males over others, or to induce the male to desist. Thus, male persistence and forcefullness may sometimes be better described as persuasion rather than coercion. Under the persuasion hypothesis, the male only gains intromission due to an active response of the female. Under the coercion hypothesis, male and female are opposed in a physical battle which the female loses if copulation occurs. In species in which males are morphologically incapable of forcing intromission without active female cooperation (I argue here that this is probably a very common situation), data on the behavioral and ecological context in which resistance occurs can distinguish between the two possibilities. Partially congruent functions of resistance, seen from the female point of view, are female resistance to screen (male persuasion), and female resistance to avoid males non-selectively (male coercion). Sepsis flies illustrate these ideas. Females often struggle energetically in apparent attempts to dislodge mounted males and to prevent intromission, and males grasp females with powerful species-specific structures on their front legs and genitalia. This suggests the possibility of coerced intromission. But behavioral and morphological evidence demonstrate that active female cooperation occurs at the moment of intromission, and that males are probably dependent on this cooperation because they are not morphologically equipped to force their genitalia into those of an uncooperative female. Despite the impression from previous publications, male insects in general may seldom be able to achieve intromission by genitalic force. The species-specific forms of the grasping genitalia of male sepsis are probably not the result of an evolutionary arms race between coercive males and unselectively resistant females.

The influence of self-fertilization performance and copulation behaviour in reproduction by cross-fertilization in groups of Biomphalaria tenagophila (Mollusca, Planorbidae)

The following hypothesis were tested for groups of simultaneous hermaphrodites Biompharia tenagophila: (a) snails that have reproductive success during the process of self-fertilization do not increase their reproductive success after the end of grouping; (b) the copulation behaviour and the presence of one snail whose eggs have a low viability rate influence the partner's reproductive success by cross-fertilization. Groups were constituted by a homozygous pigmented snail and two albinos: one with a viability rate higher than 70 per cent ("good reproducers") and the other less than 10 per cent ("bad reproducers"). All pigmented snails had viability rates higher than 70 per cent. The "good" and "bad" reproducer albine snails had similar copulation behaviour. However, after the end of grouping, the "bad reproducers" continued to have viability rates less than 10 per cent over 30 days. In 100 per cent of the cases that pigmented snails copulated (performing either a male role or simultaneously male and female roles) exclusively with "good" reproducer albinos, they presented high reproductive success (producing, on average of 8.4 pigmented embryos/eggs-mass). However, in 100 per cent of cases that pigmented snails copulated with both partners, the "good" reproducer albine snails produced none or very few embryos (the highest average was 2.2 pigmented embryos/eggs-mass). Therefore, the production of viable embryos by cross-fertilization was more influenced by self-fertilization performance than by copulation behaviour. The presence of a snail whose eggs have a low viability rate could decrease their partner reproductive success.

Effects of intrathecal administration of adrenergic agonists on the frequency of copulatory pelvic thrusting of the male rat

The effects of the intrathecal perispinal administration of adregergic agonists on the characteristic of frequency, duration, and vigor of pelvic thrusting displayed by male rats during copulation was assessed by an accelerometric technique. A different dose of one drug (noradrenaline, clonidine or isoproterenol) and saline as control was administered at the lumbosacral level of the spinal cord to sexually active male rats in tests of sexual behavior performed at weekly intervals. The intrathecal administration of noradrenaline (alpha-adrenoceptor agonist) increased the frequency of pelvic thrusting in mount and intromission responses, whereas both the alpha2-adrenoceptor agonist clinidine (25 µg) and the ß-adrenoceptor agonist isoproterenol ( 40 µg) reduced the frequency of pelvic thrusting in these responses as compared to values obtained under the intrathecal administration of saline. On the other hand, the duration of the thrusting trains and the potency or vigor of pelvic thrusting in mounts and intromissions did not differ from values obtained under saline treatment. These findings indicate a possible participation of noradrenaline in the modulation of the spinal mechanisms involved in the generation of rhytmic pelvic thrustint performed by the male rat during copulation

Failure of familiar males to prevent alien male-induced implantation block (the Bruce effect) in laboratory mice.

Implantation failure in newly inseminated females induced by exposure to alien males (the Bruce effect) was significantly reduced when the females were housed with the stud male. By contrast, newly inseminated females housed with a familiar male during exposure to alien males exhibited a high rate of implantation failure. The results suggest that the protective effect of the stud male on implantation is not because of the familiarity of the female with his odour cues. The results are consistent with the view that the newly inseminated female mouse identifies her coital partner as an individual because she becomes 'imprinted' with his odour during the pericopulatory period.