Mount Attempts Research Articles

Effects of group density on call rate, phonokinesis, and mating success in Palmacorixa nana (Heteroptera: Corixidae)

Little information exists on the effects of density on the calling of acoustic insects. In the field, density of Palmacorixa nana males varies markedly. In the laboratory, such variation appears to be a result of males forming groups around each other. When males aggregate, the number of spontaneous calls per male per minute increases exponentially. Females show a phonokinetic preference for the mean call rate of the densest male aggregation. Males show a phonokinetic preference for the less dense aggregations. Females always preferred the greatest acoustic power. Phonokinetic responses of male and female P. nana to groups of conspecific males were consistent with an assessment of the reproductive costs and benefits of associating with a group. As density increased, both the costs and benefits to males of associating with a group increased. In denser aggregations, males had more copulations per mounting attempt but had more agonistic interactions and mating interference from other males.

Physiological correlates of social behaviour in Bighorn sheep: a field study using electrocardiogram telemetry

Telemetered heart rates (HR) were correlated with social interactions of adult free‐ranging Bighorn sheep (0vi.s canadensis canadensis). Minimal cardiac responses suggest that economy of expression is a pervasive feature of social behaviour in this species. Commonly performed courtship, dominance and agonistic displays elicited few HR responses in either sender or receiver; those that did occur, were transitory and usually accompanied motor reactions by the subject. Intense behavioural acts that occurred infrequently, such as mount attempts, rush‐charges and clashes, evoked maximal HR increases in both performer and receiver. These findings are consistent with the complex social behaviour of Bighorn sheep and a life‐strategy demanding frugal investment of resources in maintenance, in order to maximize growth and reproduction.

Neonatal hormonal influences on the development of proceptive and receptive feminine sexual behavior in rats

The objective of this study was to examine the influence of androgen and of the inhibiting of aromatization of androgen to estrogen during the early neonatal period on the development of receptive (lordosis and acceptance of stimulus male mounting attempts) and proceptive (affiliation with and solicitation of stimulus males) feminine sexual behavior. Within 8 hr of birth, male rats were castrated or received subcutaneous implants of the aromatase inhibitor androst-1,4,6-triene-3, 17-dione (ATD) while females received injections of testosterone propionate (TP). At 90 days of age all treated animals and controls were tested for receptive and proceptive feminine sexual behavior. It was found that androgen present neonatally blocked proceptive as well as receptive behavior patterns in adult rats. The proceptive and receptive feminine sexual behavior patterns displayed by adult males deprived of the effects of androgen neonatally either by castration or by treatment with ATD were comparable to those of normal females.

The Relationship between Body Weight and Homosexual Mounting in Palmacorixa nana Walley (Heteroptera: Corixidae)

Homosexual mounting is common in insects. Half the mounting attempts of Palmacorixa nana Walley males are homosexual and weights of mounting and mounted animals show that mounters are seeking animals larger than themselves. Since females are larger than males, this behaviour results in some proportion of correct choice of mates.

Comparison of the behaviour of two strains of rats (S 3 and wezob) in male-female encounters during a normal oestrus cycle

Two trials were conducted to evaluate the effect of diverse socio-sexual cues upon male sexual behavior and the reproductive performance of anestrous does (AD). Trials were conducted in northern Mexico (26°N) during the natural anestrous season (Feb-Mar) with crossbred dairy bucks. In Experiment 1, sexually inactive bucks (SIB, n = 12) were randomly allotted to three groups, four males/group: a) DEE 9novelty stimulation) – daily exchange of estrogenized females (EF) 12&12 h, b) NEE (no novelty stimulation) – no-exchange of EF, 24 h, or c) CON (saline-treated_ -daily exchange of AF 12&12 h. Sexually active bucks (SAB) from the DEE, NEE and CON groups were subsequently exposed to AD (n = 72; n = 24/group) and the reproductive outcomes were recorded. In Experiment 2, SAB (n = 12; n = 6/group) were randomly divided in: 1) B + EF – males + four-EF exposed to AF (n = 36), and 2) B + NEF; males + four-saline-treated AD and exposed to AD (n = 36). Prior to the onset of the experimental breeding in both experiments, the investigative (ISB), consummatory (CSB) and resting (RSB) sexual behavior of males were quantified (2 h × d × 2 d). Sexual behaviors considered were: ISB – flehmen, ano-genital sniffing, approaches, vocalizations, kicking, penis extrusion, CSB; mount attempts and mounts, and RSB – isolation, attempted escape, aggression and distractions. While EF were an effective stimulus (P < 0.05) for evoking mounting in SIB males, daily exchange of estrous does used to stimulate males promoted an enhanced response (P < 0.05) in terms of both ISB and CSB. After being exposed to AD, the B + EF bucks induced an earlier estrous response (P < 0.05) as compared with the B + NEF bucks. The untreated females did not induce any sexual activity in males and stimulation of ovarian function did not occur when saline treated (CON) AD were exposed to AD. Also, the B + EF group induced an enhanced increase (P < 0.05) of the male ISB and CSB, inducing in turn an increase percentage onset of estrus in does that had previously been anestrus (P < 0.05).

Behavioral effects of a synthetic mixture of aliphatic acids in rhesus monkeys ( Macaca mulatta)

The stimulation of sexual behavior by a synthetic mixture of volatile aliphatic acids (acetic, propanoic, methylpropanoic, butanoic, methylbutanoic, methylpentanoic) was studied in male rhesus monkeys. Twelve intact adult males and 12 long-ovariectomized adult females were used in 24 paired combinations (541 tests each of 1 hr). A mixture of authentic acids similar to that found in the vaginal secretions of estrogenized females was applied to the sexual skin area of ovariectomized females immediately before tests with males. There was marked between-pair variability during the application of both control and test substances. However, using rigorous behavioral criteria, there was a well-marked stimulation either of male mounting attempts or of ejaculations in 12 of 24 pairs involving 9 of 12 males. Three males responded with both female partners, three responded with neither female partner, and six responded with one partner only. In the responding pairs, there were highly significant increases in mounting attempts and ejaculations, an effect that could be attributed only to treatment. We conclude, therefore, that these aliphatic acids (copulins), which act via olfactory pathways, have communicatory significance in rhesus monkeys.

Hormonal basis of proceptivity and receptivity in female primates

The role played by steroid hormones in regulating the sexual behavior of female primates is reviewed, with emphasis placed on experiments using nonhuman species. A distinction is made between the effects of hormones on female proceptivity (i.e., behaviors which incite mounting activity in the male) and receptivity (i.e., willingness to accept male mounting attempts). The rationale for distinguishing between proceptivity and receptivity is discussed, and the methods used for measuring each are described. Evidence shows that estrogen of ovarian origin facilitates sexual interaction primarily by stimulating the emission of non-behavioral cues which increase the female's sexual attractivity (i.e., the value of a female as a sexual stimulant for a male). Evidence is presented suggesting that ostrogen may enhance proceptivity by acting on the female's central nervous system; however, there is no clear demonstration that estrogen affects neural mechanisms controlling receptivity. Experiments show that proceptivity and to a lesser extent receptivity are modulated by adrenal androgens, and the possibility is raised that adrenal androgens may act synergistically with estrogen to facilitate sexual behavior. A disruptive effect of progesterone on sexual interaction is described, and evidence is presented suggesting that this effect of progesterone results primarily from a reduction in sexual attractivity caused by the action of the hormone in the female's vagina. Other literature indicates that proceptivity is often maximal at the periovulatory period of the female primate's menstrual cycle whereas cyclic variations in receptivity occur infrequently. Most hormone-dependent changes in sexual interaction associated with the menstrual cycle seem to result from fluctuations in nonbehavioral attributes of female sexual attractivity. The problem of distinguishing between the effects of steroid hormones on proceptivity and receptivity in human females is discussed.

The Development of Sociosexual Behaviour in Free-Living Baboons, Papio Anubis

The development of mounting behaviour and the communicatory functions of mounting were studied in a free-living troop of olive baboons in the Gombe Stream National Park, Tanzania, over a period of 16 months. 1. Early mounting attempts by baboon males were disoriented and incomplete. Components of mounting such as penile erection and pelvic thrusting at first occurred in isolation and in inappropriate contexts, but at 10-15 months of age, males became able, rather suddenly, regularly to orient themselves correctly to the female when mounting. 2. From about 10 months of age, thrusts became more rhythmical and increased in number per mount, and at about 12 months, intromission and the ejaculatory pause first occurred. At this age also, the frequency of male mounting reached a peak. Between 20 and 50 months of age, the characteristics of male-female mounting changed rather little, but after puberty, the proportion of mounts in which an ejaculatory pause occurred was twice as great as in younger age groups, and the number of thrusts required to reach ejaculation decreased. 3. Tumescent adult females were available for mounting by young males throughout the year, though young males could not gain access to females whilst they were maximally swollen and in consort with adult males. From about one year of age, males increasingly selected adult females as mounting partners. Male-male mounts, however, continued into adulthood. 4. The presence of cycling females in the troop with which young males could achieve intromission was thought to be particularly important for the development of the orientation and integration of male mounting patterns in baboons. This is supported by studies of captive peer-raised macaques, in which the course of development of male mounting behaviour tends to be delayed compared with that in naturalistic or wild groups of primates. 5. The nature and time scales of development of male mounting patterns in the genera Papio and Macaca appear to be very similar, though in olive baboons, unlike macaques, the ejaculatory pause occurred before puberty. In primates and in other mammals, important changes in mounting development seem to occur both during the early months of life and around puberty. 6. Mounts were observed in the contexts of 'dominance', play, appeasement/greeting, and enlisting as well as in a 'sexual context. Mounts between males were not always in the direction that agonistic status or play relationships would predict, and for any male-male pair, mounts could occur in either direction. The direction of mounting was dependent on the nature of the communication involved, and in one type of mounting (appeasement/greeting), it was generally the subordinate male that mounted. The general function of non-sexual mounting seemed to be to reduce the likelihood of aggression.

Suppression of lordosis in the hormone-primed female hamster by electrical stimulation of the septal area

The behavior of the female hamster toward the male is altered radically by estrogen and progesterone. Her aggression gives way to sexual receptivity, and the lordosis posture will commonly be maintained in the presence of a sexually active male for greater than 10 min at a time. The septal area is one of the limbic and hypothalamic areas which preferentially accumulate radioactive estradiol in the female hamster. In order to determine whether this region is involved in lordosis control, we examined the effects of electrical stimulation (ES) there on the copulatory behavior of ovariectomized, hormone-primed, sexually receptive females in the presence of sexually active males. Sixty second trains of 100 Hz, 0.2 msec, biphasic, square-wave pulses at either 80 or 90 μA were effective in suppressing the lordosis response in 8 of 13 animals with electrodes in the septal area. In the most effective cases ES would prevent lordosis even during persistent contacts and mount attempts by the male. Some neurons in the septal area may be part of a network acting to inhibit the display of lordosis. One of the ways ovarian hormones could facilitate lordosis is through reduction of the suppressive activity in such a network.

Sexual receptivity of bilaterally adrenalectomised female rhesus monkeys

Bilateral adrenalectomy (with cortisol replacement) of ovariectomised, oestrogentreated rhesus monkeys greatly decreased their sexual receptivity: they presented less to and refused the mounting attempts of males with whom they were paired. As a consequence the levels of the latter's sexual activity was low. Two hundred or 400 μg androstenedione/day increased the receptivity of these females, but dehydroepiandrosterone (up to 5,000 μg/day) was ineffective. Vaginal cornification, sexual skin colour and the size of the clitoris were measured and showed no significant change during the experiment. It is concluded that adrenal androgens are necessary to maintain sexual receptivity in the female rhesus monkey: the site of action of these androgens is discussed.

Aggression and gonadal hormones in captive rhesus monkeys ( Macaca mulatta)

1. 1. Aggressive interactions between pairs of adult rhesus monkeys of opposite sexes were studied quantitatively during 1019 hours observation extending over 2·5 years. 2. 2. The levels of aggression by both males and females changed with pregnancy, ovariectomy, and the administration of gonadal hormones (oestradiol, progesterone, testosterone propionate). 3. 3. Ovariectomy increased the overall level of aggression, particularly, that of the male. In contrast, pregnancy and the administration of hormones to females diminished aggression by males and increased their tolerance of aggression by females. 4. 4. There is evidence that oestradiol administration directly increases female aggressivity while progesterone does so indirectly by diminishing female receptivity and her tolerance of male mounting attempts.

The suppression of mounting behaviour and ejaculation in male rhesus monkeys (Macaca mulatta) by administration of progesterone to their female partners.

SUMMARY Sexual behaviour was studied quantitatively by observing six pairs of oppositely sexed, adult rhesus monkeys during 209 hourly test sessions conducted over a period of 7 months; at all other times, animals were housed singly. The effect on male—female sexual interaction was studied when ovariectomized, oestrogen-treated females were given s.c. injections of progesterone. Administration of 25 mg. progesterone resulted in a highly significant decrease in male mounting activity, in ejaculation, and in the number of sexual invitations made by females. At the same time there was a highly significant increase in the number of female refusal reactions. In three pairs, mounting attempts by males remained constant and the decline in the number of mounts resulted primarily from a large increase in refusal reactions. In three other pairs, the decline in the number of mounts resulted, primarily, from a marked decrease in male mounting attempts. The two principal mechanisms, loss of female receptivity and loss of female attractiveness, previously observed during the luteal phase of the female's menstrual cycle, were thus reproduced by giving progesterone to the ovariectomized, oestrogen-treated female partners.

Ovarian hormones and the sexual behaviour of the female rhesus monkey (Macaca mulatta) under laboratory conditions.

SUMMARY Male and female sexual behaviour was studied quantitatively by observing pairs of oppositely sexed, adult rhesus monkeys during regular hourly test sessions over 2 yr.; at all other times the animals were housed singly. Rhythmic fluctuations in the sexual invitations of both males and females, and in the refusal reactions of females, occurred in relation to the menstrual cycle. A decline in male mounting activity occurred during the luteal phase of the cycle, and resulted from two principal types of change in male—female interaction: in one, males stopped making mounting attempts, although females continued inviting (loss of female attractiveness), and in the other, males continued to attempt to mount, but females stopped inviting and began refusing (loss of female receptivity). Bilateral ovariectomy of females abolished all rhythmic variations, and the behavioural interactions were reduced to low levels; these were restored by subcutaneous injections of oestradiol into the females. These findings indicate that sexual invitations in a female primate are mediated by ovarian hormones, and that the changes in male—female interaction during the menstrual cycle can be understood in terms of endocrine-dependent changes in sexual invitations and their outcome.