Characterization of age and cuticular hydrocarbon variation in mating pairs of house fly,Musca domestica,collected in the field

House flies, Musca domestica L., were collected in copula over two summers from six dairies located in three climatically distinct regions in the U.S.A. southern California, Minnesota and Georgia. Ages of males and females from a total of 511 mating pairs were estimated using pterin analysis. Cuticular hydrocarbon profiles and gonotrophic ages of females also were evaluated. Mean age of mating males ranged from 54 to 102 degree‐days (DD) (4–10 days based on field air temperatures), depending on the farm. Very young males (< 10–20 DD) and old males (> 200 DD) were rare in mating pairs. Mean female age at mating ranged from 20 to 46 DD (2.5–4 days). All mating females had eggs in the early stages of vitellogenesis and 99.2% were nulliparous. However, some older and parous females were collected, demonstrating that re‐mating can occur in the field. Head width measurements of mating pairs suggested that assortative mating by size did not occur. The cuticular hydrocarbon profiles of females were determined, with emphasis on (Z)‐9‐tricosene (muscalure). Overall, only 55% of mating females had detectable amounts (> 4 ηg per fly) of (Z)‐9‐tricosene. Of the females that had detectable (Z)‐9‐tricosene, variation in amount per female was high in all fly populations, and thus was not statistically related to the size or age of the mating female. The proportion of mating females with detectable levels of (Z)‐9‐tricosene varied by geographic region. Seventy‐one, 63, and 27% of females from southern California, Minnesota and Georgia had detectable amounts of (Z)‐9‐tricosene. Principal components analysis of the eight most abundant hydrocarbons from mating females, by state, revealed state‐level distinctiveness of hydrocarbons in house fly populations, which may reflect genetic variation associated with environmental stresses in those geographical zones.     

A Juvenile Hormone analogue enhances homosexual behaviour in female‐deprived males of the migratory locust

In laboratory colonies of crowded migratory locusts Locusta migratoria (L.), homosexual behaviour (i.e. males mounting other males) is commonly observed. Female‐deprived males of Locusta migratoria migratorioides R. & F. mount each other in a characteristic mating position, often forming a group of several insects. When allatectomized males are placed together with intact, female‐deprived males, the former are usually mounted by the latter, demonstrating some degree of control involving the corpora allata over homosexual behaviour. This may be related to the positive effects of Juvenile Hormone (JH) or Juvenile Hormone analogues (JHAs) in enhancing male sexual behaviour, as is shown in some other insects. In the present study, a potent JHA (i.e. pyriproxyfen) is injected into a group of young, crowded L. m. migratorioides males, and an equivalent group of control males is maintained in a separate cage. Both groups are deprived of females. Three times a week, during 2‐h observation periods, JHA‐injected and control males are placed together in the absence of females, and homosexual mountings, per group and per individual, are recorded every 10 min. Observations are performed for 10 weeks. Analysis of these data, including the time spent in mounting behaviour, the percentage of individuals within a group involved in the behaviour during the observation periods and the identity of both partners, reveals that the JHA‐treated males show a more intense homosexual mating behaviour than control males in all quantified parameters. This is the first report of the enhancement of homosexual behaviour by an endocrine factor in insects.     

The control of mating behaviour in Helix pomatia L. (Gastropoda: Pulmonata)

I examined how extirpations of various parts of the reproductive system affected the mating behaviour of Helix pomatia. The integration of the sequence of activities in the mating behaviour was not affected by any of the extirpations performed. It is concluded that the sequence is mainly controlled centrally. The simultaneousness of the performance of dart shooting behaviour and the initiation of a new bout of mating activity was found to be independent of the presence of the dart. The mating activity was decreased by mechanical stimulation of the duct of the bursa copulatrix and increased by extirpation of the digitiform glands. It is concluded that the mating behaviour cycle is caused partly by mechanical effects of dart shooting and copulation.     

Paternal effort and its relation to mating success in the European ground squirrel

The necessity for parental care is a driving force for determining mating systems and social organization. The European ground squirrel, Spermophilus citellus, is a polygynous, gregarious species in which male parental behaviour would not be expected. We had observed males digging in litter burrows that were later occupied by females and their offspring. Males never stayed overnight within these burrows. To determine whether this was some kind of paternal effort we tested the following hypotheses: (1) that male burrowing behaviour was directed towards the male's own offspring or towards the pregnant or lactating mother of the male's offspring; (2) that this behaviour had costs in terms of condition, decreased survival or fecundity; and (3) that it benefited offspring condition or survival. All three assumptions were met. Males worked on the litter burrow of their copulatory partners. Thus, this behaviour was directed towards the male's potential offspring. Male burrowing costs were seen in decreased foraging time and increased body mass loss. Offspring benefits were evident in increased mass at natal emergence. We conclude that male digging at litter burrows can be considered as paternal effort. Lastly, we considered the effects of polygyny on this male parental effort by comparing mating effort, mating success and paternal effort. High mating success was associated with high mating effort and low paternal effort. Moderate to low mating success was associated with lower mating effort and higher paternal effort, indicating a trade-off between the two.     

Endocrine manipulations,juvenile hormone and ontogenesis of male sexual behaviour in locusts

By injection of azadirachtin (AZA) to 5th instar hoppers of Locusta migratoria migratorioides, “over-aged” nymphs were produced, some of which survived for long periods without moulting to adults. Such over-aged male nymphs exhibited mating behaviour belatedly, though at a lower intensity than normal adults. Juvenile hormone (JH) markedly intensifies male sexual behaviour in crowded adult (6th instar) Locusta; thus, the lower intensity of sexual behaviour of the over-aged nymphs might have been caused by a low endogenous JH titre, or by a weaker response to the hormone. To clarify this point, chemically allatectomized over-aged 5th instar nymphs were produced by combined treatment with precocene and AZA. These exhibited a very low intensity of mating behaviour. Injections of exogenous JH III intensified the mating behaviour of the chemically allatectomized over-aged 5th instar male nymphs in a dose-dependent way, but the effect was weaker than in chemically allatectomized adult males. AZA-induced over-aged 4th instar male Locusta hoppers also exhibited mating behaviour. By injection of AZA, 5th instar over-aged hoppers of Schistocerca gregaria were also produced. Males showed mating behaviour belatedly, despite the fact that JH completely controls male sexual behaviour in this species. The intensity of this behaviour was again lower than in adults. Interrelations between integumental morphogenesis, “ethogenesis” of male sexual behaviour, and endocrine factors in locusts are discussed.     

Effects of the juvenile hormone analogue methoprene and dietary protein on male melon fly Bactrocera cucurbitae (Diptera: Tephritidae) mating success

The effect of access to dietary protein (P) and the topical application of a juvenile hormone analogue (methoprene (M)) on mating behaviour of male melon fly Bactrocera cucurbitae was assessed in the laboratory and in field cages. Age, dietary protein and methoprene application increased the mating success and influenced the mating behaviour. Treatment with methoprene (M+) to protein-deprived (P−) males had only a modest effect on the acceleration of sexual maturity, but application of methoprene (M+) to protein-fed (P+) males greatly accelerated sexual maturity. Protein diet (P+) increased mating success of males in comparison to protein-deprived (P−) males. Protein and methoprene have a synergistic effect on mating behaviour, since M + P+ treated males exhibit reduced mating latency and achieved higher mating in younger ages than methoprene and/or protein-deprived males. Copulation duration was correlated with nutritional status and M + P+ males copulated longer at the age of advanced sexual maturity than M − P+ males. Our results suggest that in this species with a lek mating system, females discriminate between the males based on their sexual signals, which were influenced by protein in the adult diet, methoprene application and age. The results are discussed in the light of mating competitiveness of precocious treated young males and their relevance to Sterile Insect Technique application against this pest species.     

Reduced female mating receptivity and activation of oviposition in two Callosobruchus species due to injection of biogenic amines

Analyses of proximate mechanisms that control mating and oviposition behaviours in insects are important because they link behavioural ecology and physiology. Recently, seed beetles have been used as models to study evolution of female multiple mating and cost of reproduction including mating. In the present study, we investigated the effects of biogenic amines into the abdomens of females of two Callosobruchus species, Callosobruchus chinensis and Callosobruchus maculatus, on mating receptivity and oviposition behaviour. In C. chinensis, injection of octopamine and tyramine reduced receptivity to mating and tyramine and serotonin increased the number of eggs laid. Similarly, injection of tyramine reduced the receptivity of females and increased the number of eggs laid by females of C. maculatus. These results show the possibility that biogenic amines control mating receptivity and oviposition behaviour in females of two Callosobruchus species.     

Re-evaluation of the role of corpora cardiaca in calling and oviposition behaviour of giant silk moths

Re-investigation of the role of the corpora cardiaca in the reproductive behaviour of the giant silkmoths, Hyalophora cecropia and Antheraea polyphemus, showed that this pair of glands plays no essential role, either in “calling” behaviour by virgin females or in increased oviposition due to mating. Removal of corpora cardiaca-corpora allata complexes, either from diapausing pupae or from freshly eclosed adult females, had no effect on the calling behaviour or on its timing in either species. Moreover after mating, these operated females laid eggs in the typical mated oviposition pattern. Furthermore, females in which there was only a nervous connection between the brain and the abdomen but no haemolymph circulation called normally and oviposited after mating.Although the corpora cardiaca were not essential for calling behaviour, hormogenates of corpora cardiaca-corpora allata complexes and blood from calling or ovipositing females induced a typical “calling” response in 30–60% of the isolated virgin H. cecropia abdomens tested. This activity was not species-specific as it was also found in Manduca sexta, but the restriction of major activity to corpora cardiaca extracts and haemolymph suggested that a neurosecretory factor may modulate the normal neural control of calling behaviour.     

Mating behaviour and chemical communication in the invasive Chinese mitten crab Eriocheir sinensis

Mating in the Chinese mitten crab (Eriocheir sinensis) was examined; in particular the nature of mating and the role of sex pheromones. A semi-lunar periodicity (16.8 days and 14.5 days, respectively) was observed in the mating frequencies in two consecutive breeding seasons (2001-2002 and 2002-2003). This semi-lunar rhythm coincided with spring tides (full and new moon), and activity peaked in November. Observation of the progression of specific behaviour types in mating and non-mating pairs revealed that pairs which would go on to complete mating progressed from fighting to mating behaviour significantly faster than non-mating pairs. These findings indicate that mate recognition occurs only after physical contact. Reproductively active pairs (ascertained from mating experiments) were then used for several bioassays aiming to assess under which conditions pheromones may be released by females. Firstly, male E. sinensis were exposed to female smell in an actograph experiment and secondly, male antennule flick rate was recorded before and after exposure to the urine of a sexually active female. In both cases no change in male E. sinensis behaviour was observed. Both experiments used females which had not had immediately prior exposure to males. However, in further experiments using water where mating had occurred, a significant response in antennule flick rate was triggered. Finally, a sponge assay was used in order to test the male attraction to a sponge injected with a water sample of varying concentrations (0.5×, 1×, 3×, 4.5×, 9×) of female smell. These samples were conditioned using a female immediately following a mating attempt. Males tried to grasp the sponge at 3× increased concentrations or higher. In conclusion, this study found no indication that E. sinensis females release a distance pheromone, but instead that mate recognition occurs after physical contact between male and female, most likely via a contact pheromone.     

Lack of parasite-mediated sexual selection in a ladybird/sexually transmitted disease system

Despite the clear potential of sexually transmitted diseases (STDs) to affect host mating behaviour via both host and parasite evolution, there have been few explicit tests of the relationships between STDs and sexual behaviour in animals. We investigated the effect of infection on host sexual behaviour within an invertebrate system. Coccipolipus hippodamiae is a sexually transmitted ectoparasite of Adalia bipunctata, the two-spot ladybird. The parasite feeds on host haemolymph, develops rapidly, and is deleterious to A. bipunctata hosts of both sexes. We examined whether infection affected mating success, and whether males or females showed any preferences with respect to infection status. We observed field mating rates of infected and uninfected ladybirds and carried out controlled laboratory experiments. We did not detect any negative effects of parasite infection on host mating vigour, nor any evidence for the existence of a host mating preference based on infection status. In addition, there was no evidence of parasite-induced changes in behaviour, such as increased promiscuity, which would increase transmission opportunities for the parasite. In summary, contrary to a body of speculation, there was no evidence of any connection between infection and mating rate, in either sex. We discuss possible explanations for these findings.     

Dominance hierarchies and factors influencing dominance in the guppy Poecilia reticulata (peters)

Dominance behaviour and factors influencing dominance were investigated in small heterosexual and homosexual groups of guppies (Poecilia reticulata) in the laboratory. Straight line nip-right hierarchies were the most frequent type of dominance relationship. In heterosexual groups separate homosexual hierarchies were formed, and females were the more dominant sex. Dominant males performed significantly more reproductive behaviour than lower rank individuals. Agonistic behaviour appears early in young P. reticulata. Factors involved in determining dominance were size, sex and aggressiveness. Individual or role recognition or both may occur in this species. Advantages of dominance are discussed.     

Sexual Attraction and Mating Patterns in Cylindrocorpus longistoma and C. curzii (Nematoda: Cylindrocorporidae)

Females of Cylindrocorpus longistoma and C. curzii excrete attractants which probably function to bring the sexes together before mating. Intraspecific and interspecific heterosexual and homosexual pairing experiments showed the attractants to be species specific as well as sex specific. Observations on mating behavior support the hypothesis that sexual attraction and copulation require independent stimuli.     

Family, sex and testosterone effects on garter snake behaviour

To better understand how genes and hormones interact to affect behaviour in nature, I used a factorial design to test for effects of family membership, sex and testosterone level on activity and defensive behaviour of the common garter snake, Thamnophis sirtalis. Behaviours (latency to move, defensive strikes, response distance) were scored prior to hormone manipulation (when snakes were 39 days of age), while sham or testosterone-containing implants were in place (190 days), following implant removal and simulated hibernation (284 days), and when snakes were 428 days of age. Family membership had pervasive effects on all three behaviours and on their ontogenetic trajectories, suggesting strong genetic or maternal components to behavioural variation. Sex had a significant effect on the number of defensive strikes; females struck more frequently than males, but ontogenetic trajectories were similar between the sexes. Testosterone manipulation also had an effect on strikes: snakes in the elevated-testosterone treatment group struck less frequently than shams while implants were in place. Sex and treatment effects on latency to move and response distance were lacking. Family*treatment interaction effects were lacking for latency to move and number of defensive strikes but were present for response distance. Possibly, genetic or maternally induced variation in strikes is mediated through variation in circulating hormone levels, whereas variation in response distance is mediated through receptor-level phenomena. Copyright 2002 The Association for the Study of Animal Behaviour. Published by Elsevier Science Ltd. All rights reserved.     

Learning enhances female control over reproductive investment in the Japanese quail

The adaptive significance of learning is supported by studies showing its positive effects on mating behaviour, but they rarely go beyond fertilization success. Here we studied how learning contributes to qualitative reproductive investment, by testing the hypothesis that mating in the context that predicts male appearance has positive effects on female reproductive investment compared with unsignalled mating. Using Japanese quail (Coturnix japonica), we found that effects of mating in the context predicting mating opportunity depend on female body condition and receptivity, while the outcome of unexpected mating depends on male behaviour. In particular, among females mated with the familiar male in the context predicting that he will appear, female condition positively affected the number of fertilized eggs and egg mass and more receptive females tended to produce more sons. Additionally, conditioned females laid heavier eggs for daughters than for sons. In contrast, in females that were mated unexpectedly and with a novel male, the number of fertilized eggs was highly dependent on male behaviour and was negatively related to maternal body condition. Egg mass was not related to body condition, and there were no indications of sex allocation. This is, to our knowledge, the first study demonstrating how female body condition and behaviour interact with the context of mating in shaping maternal reproductive investment.     

Reproductive success in Zygogramma bicolorata: A role of post-insemination association of male and female

Reproductive success is attained by various mechanisms in insects. Prolonged post insemination association is one such mechanism to increase the reproductive success. The present study was conducted to assess the role of post insemination association of mating partners on reproductive performance in Chrysomelidae beetle, Zygogramma bicolorata Pallister. The matings were disrupted at different time intervals and fecundity and percent egg viability of the females were recorded. In addition, the mounting attempts, mating attempts, time to commencement of mating and latent period were also recorded. It was hypothesized that: (1) the mounting and mating attempts would not exist, (2) copulation duration, would not affect the reproductive performance, and (3) the beetle would not exhibit the mate guarding behaviour. Interestingly, results revealed that 6.00 ± 1.3 and 6.59 ± 0.93 mounting and mating attempts are needed to establish successful mating. The results revealed that males improved their percent egg viability with a mating duration ranging from nearly 30–50 min. While fecundity increased with a mating duration of above 30 min and up to a duration of 60 min. This result concluded that males of this beetle display post copulatory mate guarding behaviour after 60 min in which male rides on female’s back with his aedeagus inserted in the female genital tract.     

The roles of vision and olfaction in mate location by males of the tsetse fly Glossina morsitans morsitans

The roles of visual and/or olfactory stimuli in eliciting mating responses from male Glossina morsitans morsitans Westwood were examined, using a system for automatically recording the number and duration of mating strikes made towards decoys, under controlled conditions. The results confirm that there is no olfactory component of the female sex recognition pheromone sensed by the male antennae, and the attraction of males to females appears to be visual. The absence of male-male mating strikes was the result of the absence of female sex-pheromone, rather than the presence of a repellent mating deterrent in the male cuticle. Experiments with coloured, artificial, sex-pheromone-dosed, cotton decoys showed that colour had only weak effects on attractiveness and number of encounters with decoys, and that no colour caused significant enhancement of mating responses over those shown to decoy females.     

Effects of hexane extract of Lantana camara leaves on reproductive bioactivities of Dysdercus koenigii Fabricius (Heteroptera: Pyrrhocoreidae)

Effects of hexane extract of Lantana camara leaves were investigated on reproductive bioactivities of Dysdercus koenigii by assessing mating behavior, oviposition behavior and fertility of the adults emerged from treated fifth instar nymphs. Leaves of L. camara were extracted in hexane by ‘cold extraction method’. The fifth instar nymphs were treated with the extract by ‘dry film residual method’ for 24 h and the adults emerged from these nymphs were used for the experiments. The results indicated that treated males showed altered courtship behaviour, lesser number of mounting attempts and took relatively more time to mate than the normal males. The treated females, very often, exhibited mating refusal and non-receptive behaviour towards the courting males. This led to decrease in percent successful mating. Also, the mating in the treated insects frequently got disrupted and terminated prior to insemination. The treatment of the females with the extract resulted in alteration of their oviposition behaviour. Consequently, the treated females laid lesser number of egg batches and total number of eggs in their life span. Although the eggs laid by the treated females were fertile, the percent hatchability was lesser than normal. The results signify that hexane leaf extract of L. camara possesses phytochemicals, which adversely impaired the reproductive bioactivities of D. koenigii. Therefore, some of these compounds individually or synergistically can be employed in integrated pest management of D. koenigii by hampering its reproductive potential.     

Influence of male competition on male mating behaviour in the cave molly, Poecilia mexicana

In many species, male mating behaviour is correlated with male body size, with large males often being preferred by females. Small surface-dwelling Poecilia mexicana males compensate for this disadvantage by being more sexually active and using sneaky copulations. In a cave-dwelling population, however, small males do not show this behaviour. Do small males alter their behaviour in the presence of a large rival? Here, we investigated the influence of male competition on male mating behaviour in the cave form. Two males of different sizes were mated with a female either alone or together with the other male. No aggressive interactions were observed between either fish. There was no statistically significant difference in the frequency of sexual behaviours between the two treatments. In both treatments, large males were more sexually active than small males. Thus, small cave molly males do not switch to an alternative mating behaviour in the presence of a larger rival. Possibly, the extreme environmental conditions in the cave (e.g. low oxygen content and high levels of hydrogen sulphide) favour saving energetic costs, resulting in the absence of alternative mating behaviour in small males.     

Social context-dependent modification of courtship behaviour in Drosophila prolongata

Induction of alternative mating tactics by surrounding conditions, such as the presence of conspecific males, is observed in many animal species. Satellite behaviour is a remarkable example in which parasitic males exploit the reproductive investment by other males. Despite the abundance of parasitic mating tactics, however, few examples are known in which males alter courtship behaviour as a counter tactic against parasitic rivals. The fruit fly Drosophila prolongata shows prominent sexual dimorphism in the forelegs. When courting females, males of D. prolongata perform ‘leg vibration’, in which a male vibrates the female''s body with his enlarged forelegs. In this study, we found that leg vibration increased female receptivity, but it also raised a risk of interception of the female by rival males. Consequently, in the presence of rivals, males of D. prolongata shifted their courtship behaviour from leg vibration to ‘rubbing’, which was less vulnerable to interference by rival males. These results demonstrated that the males of D. prolongata adjust their courtship behaviour to circumvent the social context-dependent risk of leg vibration.     

The effect of hunger on mating behaviour and sexual selection for male body size in Gerris buenoi

The set of mating behaviours expressed by an individual may depend upon the state of that individual and local environmental conditions. Understanding how these factors affect mating behaviours may elucidate how a mating system operates, and its consequences for the form and strength of sexual selection. We conducted two experiments on the water striderGerris buenoi to (1) determine the effect of hunger on the mating behaviour of both sexes and (2) examine female choice for large males. In our first experiment, we manipulated hunger (20 h starvation) in both sexes and recorded mating, male harassment, copulation duration and guarding duration. We predicted that hunger would increase female reluctance to mate because mating conflicts with foraging. Female hunger (20 h starvation) decreased mating rate by two-thirds but had no significant effect on male mating behaviour. In a second experiment, we examined the effect of female hunger, and resulting reluctance, on sexual selection for large male size. Hungry females (5 h starvation) were placed with two fed males (one large, one small) and we recorded male premating and mating behaviours. We observed significant large-male mating advantage when females were hungry, but not when satiated. Mating efforts (harassment, premating struggles) were similar for both male phenotypes in both female hunger treatments, suggesting that the mating advantage of large males resulted from increased reluctance of hungry females to mate. Neither male body size nor female hunger explained a significant amount of variation in copulation duration or guarding duration. We discuss our results in light of two competing hypotheses for female choice (active and passive) on male body size and suggest that passive choice for large males acts in this system. Copyright 2002 Published by Elsevier Science Ltd on behalf of The Association for the Study of Animal Behaviour