The effect of feeding status on sexual attractiveness of Ixodes ricinus (Acari: Ixodidae) females

Sexual attractiveness of unengorged, semiengorged and fully engorged females of both field and laboratory populations of Ixodes ricinus was studied under laboratory conditions by means of a computerised video tracking system. A male and a female were allowed to walk freely in a glass arena during 1 h and their behavioural interactions were observed. Obtained results revealed that the feeding status of I. ricinus females affects their sexual attractiveness. The highest attractiveness was observed in engorged females, the lowest in unengorged females of the field population. Copulation occurred in all experimental groups with the highest frequency observed in the unengorged virgin laboratory females. Despite engorged females being highly attractive for males on distance, the frequency of copulation was low. Differences between field and laboratory populations were found in both behavioural parameters and frequency of copulation. This revised version was published online in July 2006 with corrections to the Cover Date.     

Effect of male and female multiple mating on the fecundity, fertility, and longevity of diamondback moth, Plutella xylostella (L.)

Abstract:  The effect of diamondback moth (DBM), Plutella xylostella (Lep., Plutellidae) male and female multiple mating on fecundity, fertility, and longevity was studied. Males could mate for five times with virgin females during scotophase. The successful copulation rates, fecundity of female, and longevity of both females and males decreased when male mating times increased, whereas copulation duration increased. Correlation coefficient between copulation duration and male mating times was significant ( r  = 0.7358, P = 0.0001, spearman rank-order correlation). There were linear relationships between mating history of males and longevities of males and females, and regression relationships between them were significant. Mated females had similar daily reproductive pattern, which laid the most eggs on the first day after mating in spite of their mates' mating history. Virgin females laid some infertile eggs before they died. Most of the females mated once during their lifespan but 19.9% of females mated twice when one female kept with one male during scotophase. There were no significant differences in the fecundity, fertility and longevity between the single- and twice-mated females. Correlation coefficient between copulation duration and female mating times was not significant ( r  = 0.0860, P = 0.8575). Results suggested that DBM females may be monandrous. Multiple mating did not increase male or female mating fitness.     

Hyperparasitism in Amblyomma rotundatum (Acari: Ixodidae)

In the present study, we report a case of hyperparasitism in Amblyomma rotundatum. During examination of live ticks immediately after collecting them from Boa constrictor snakes held in a reptile facility in Mossoró, RN, northeastern Brazil, 1 unengorged tick female was seen attached to the venter of a partially engorged female. The hypostome and chelicerae of the unengorged female had penetrated the integument of the partially engorged female to the level of the basis capitulli and the palps were splayed outward. To our knowledge, we present the second report of hyperparasitism for the genus Amblyomma.     

Mated Redback Spider Females Re-Advertise Receptivity Months after Mating

In many species, selection acts on males to recognize female reproductive status at a distance using pheromones. Unmated females may actively seek to attract males; however, mated females may become cryptic to avoid attracting additional males if multiple matings are costly. Although females of many species cease pheromone production after mating, it is often unclear whether this is a strategic part of a female reproductive strategy, or whether this is because of chemical manipulation by males. If variation in pheromone production is part of the female’s strategy, then we predicted mated females should eventually re‐advertise receptivity if the benefits of multiple mating increase with time since copulation (e.g. because of sperm depletion). Here, we tested this prediction in Australian redback spiders (Latrodectus hasselti). First, we replicated earlier results by showing that virgin males discriminate female maturity and mating status based exclusively on web‐borne chemicals. Our results show this difference must arise from a change in chemical deposition in the web as we controlled for web volume differences between mated and virgin females. Male activity on extracts from webs of virgin females exceeded activity on a solvent control and on extracts of webs of just‐mated females—confirming that female redbacks cease pheromone production immediately after mating. Second, we tested a new prediction that mated females might re‐advertise receptivity near the end of their normal breeding season to replenish diminished sperm stores prior to overwintering. Consistent with the prediction of strategic advertisement, we show that male activity on extracts from females’ webs increased significantly 3 mo after the female first mated (typical length of the breeding season). Thus, these females had begun to add pheromone to their web again. At this time, 26% of these females re‐mated with a second male. If females re‐advertise receptivity to ensure adequate sperm stores, then we predicted a positive relationship between female reproductive output during the 3‐mo interval after copulation and the subsequent intensity of male response to web extracts. However, differences in male activity time were not related to the total number of spiderlings or the number of egg sacs a female had produced during the 3‐mo interval after the first copulation. This result could arise if male chemical manipulation of female receptivity decreases with time after copulation, or if the testing interval used in our study was too long to reveal variation in sperm depletion in females. Thus, although our results are consistent with the idea that females strategically alter pheromonal advertisement, we cannot distinguish this from the hypothesis that female receptivity arises from chemical manipulation by males.     

Sexual selection in a tropical fruit fly: role of a plant derived chemical in mate choice

The specific mechanisms by which selective pressures affect individuals are often difficult to resolve. In tephritid fruit flies, males respond strongly and positively to certain plant derived chemicals. Sexual selection by female choice has been hypothesized as the mechanism driving this behaviour in certain species, as females preferentially mate with males that have fed on these chemicals. This hypothesis is, to date, based on studies of only very few species and its generality is largely untested. We tested the hypothesis on different spatial scales (small cage and seminatural field‐cage) using the monophagous fruit fly, Bactrocera cacuminata. This species is known to respond to methyl eugenol (ME), a chemical found in many plant species and one upon which previous studies have focused. Contrary to expectation, no obvious female choice was apparent in selecting ME‐fed males over unfed males as measured by the number of matings achieved over time, copulation duration, or time of copulation initiation. However, the number of matings achieved by ME‐fed males was significantly greater than unfed males 16 and 32 days after exposure to ME in small cages (but not in a field‐cage). This delayed advantage suggests that ME may not influence the pheromone system of B. cacuminata but may have other consequences, acting on some other fitness consequence (e.g., enhancement of physiology or survival) of male exposure to these chemicals. We discuss the ecological and evolutionary implications of our findings to explore alternate hypotheses to explain the patterns of response of dacine fruit flies to specific plant‐derived chemicals.     

Sexual receptivity and age in Glossina pallidipes Austen (Dipt., Glossinidae)

The recent success of the sterile insect technique (SIT) in eradicating Glossina austeni from Zanzibar has stimulated interest in applying this technology to control Glossina pallidipes. However, little is known about the mating behaviour of this species in relation to the development and implementation of an effective SIT programme. The effect of age on male and female receptivity to mating was evaluated together with copulation duration, sperm transfer and the growth of the accessory gland and follicle A in males and females, respectively. Females and males reached their optimal sexual receptivity 9–13 days after emergence. Mean copulation duration was 20–30 min for mature males and females. The growth of follicle A and the accessory gland (apical body) was a function of age of females and males, respectively. Ovulation was not observed in virgin females up to 15 days of age whereas mated females ovulated by day 9. Males aged 7–15 days were equally effective in inseminating. Cages of males and females of different ages were set up to monitor puparial production in relation to optimization of mass rearing. The results are discussed in relation to the development of an efficient mass rearing protocol for this species and an optimal release strategy for sterile males.     

Behavioural correlates with hemipenis morphology in New World natricine snakes

Copulatory organs (hemipenes) of male snakes vary markedly among species in shape and ornamentation. We suggest that sexual conflict over copulation duration may have shaped the evolution of hemipenis morphology, favouring more elaborate organs in species in which a long duration of copulation is especially beneficial to males, despite the associated costs to females. To test this proposition, we compare mating behaviour between two species of gartersnakes differing in hemipenis morphology. In addition, we review data on copulation duration and hemipenis morphology and relate hemipenis morphology to phylogeny among of New World natricines. As predicted, copulation duration was significantly shorter in the common gartersnake ( Thamnophis sirtalis ), a species with simple subcylindrical hemipenes, than in the plains gartersnake ( Thamnophis radix ), a species with more complex, bilobed organs. Furthermore, female T. radix frequently exhibited vigorous body rolls during copulation, a behaviour associated with copulation termination, whereas female T. sirtalis never exhibited this behaviour. Copulations were of shorter duration when female T. radix (but not T. sirtalis ) more greatly exceeded males in body size, suggesting that females can more easily disengage from small males. Our review of New World natricines provides only weak evidence for an association between copulation duration and hemipenis morphology. Our mapping of hemipenis morphology onto the New World natricine phylogeny suggests that hemipenis morphology is evolutionarily plastic; both simple and bilobed hemipenes occur in all three major natricine clades, as well as in two of three gartersnake subclades and several sister-species pairs.  © 2009 The Linnean Society of London, Biological Journal of the Linnean Society , 2009, 98 , 110–120.     

Effects of myoinhibitory peptides on food intake in the German cockroach

Abstract.  Insect myoinhibitory peptides were discovered through their inhibitory activity on visceral muscle contraction. The present study tests the antimyotropic gut properties of three galanin-related myoinhibitory peptides (Mas-MIP II: GWQDLNSAW-NH2; Grb-AST-B1: GWQDLNGGW-NH₂; and Grb-AST-B3: AWRDLSGGW-NH2) in adult females of the cockroach Blattella germanica (L.) (Dictyoptera, Blattellidae). The three peptides elicit a strong inhibitory effect on both foregut and hindgut contractions, with ID₅₀ values in all the cases within the nanomolar range. In addition, the modulatory effects of these three peptides on food intake are studied on previously starved female cockroaches. The results show that Grb-AST-B3 is the most active peptide, inhibiting food intake by 60–80% at doses between 15 and 50 µg, followed by Grb-AST-B1 (45% inhibition of food intake at the 50 µg dose), whereas Mas-MIP II is inactive even at the 50 µg dose. The differences between the three peptides may be due to a differential effect of their structure on activity or to a differential degradation. These results show that myomodulatory gut activity in vitro and antifeeding effects do not always correlate.     

The effect of differences in body size on the male territorial system of the fly Dryomyza anilis

Drymyza anilis nales defend carcasses, the oviposition sites for females. On carcasses less than 100 g in weight, a single male establishes a teriitory. Ther sex ratio at carcasses is male-biased. Territorial males are larger than other males on average, and move and attack other males more frequently than non-territorial males do. Large carcasses attract more males than smaller ones, but the female, but the advantage of territorial behaviour decreases with increasing density of males. Copulating males are significantly larger than average males, but smaller than territorial males, suggesting than some non-territorial males have access to females. Males seem to be albe to assess a female's egg load, and to adjust the duration of copulation accordingly.     

Female Pygmy Squid Cryptically Favour Small Males and Fast Copulation as Observed by Removal of Spermatangia

Females can express mate (or fertilisation) preferences after copulation. In the Japanese pygmy squid, Idiosepius paradoxus, in which males do not show any conspicuous pre-copulatory displays, the females remove the spermatangia attached to their bodies after copulation. In this study, we observed pre- and post-copulatory behaviours and analysed which variables associated with copulation were correlated with spermatangia removal. When females mated with larger males or copulation lasted longer female squid elongated their buccal mass after copulation and removed more spermatangia. We also investigated the effects of spermatangia removal on the retained spermatangia to predict whether cryptic female choice (CFC) influenced fertilisation success. Spermatangia removal by females had a stronger effect on the number of spermatangia retained than did the number of spermatangia ejaculated by males. These results suggest that spermatangia removal after copulation by buccal mass elongation works as a CFC in Japanese pygmy squid, and females cryptically favoured small males and fast copulation.     

Ultrasonic courtship songs of male Asian corn borer moths assist copulation attempts by making the females motionless

Males of the Asian corn borer moth Ostrinia furnacalis (Guenée) produce an ultrasonic courtship song of extremely low‐intensity during copulation attempts. The song has been shown to significantly increase the mating success of the male; however, the mode of action of the sound in courtship remains to be resolved. Behavioural experiments using pairs with deafened females or muted males show that, without the aid of the sound, 63% of males eventually succeed in mating after several copulation attempts, whereas the remainder (37%) make repeated attempts in vain until interrupted by the escape of the female. Because few (2%) males fail to copulate when females hear the courtship song, it is evident that the song has an effect on females, promoting the success of copulation attempts. In support of this view, males produce louder songs if the first copulation attempt fails, suggesting that the males increase their sound levels to achieve successful copulation. It is suggested that the ultrasonic songs of the male render the females motionless, which is the same response as that to ultrasonic bat calls. Because even slight movements by the female can interfere with the attempt of the male to copulate, it is likely that, by making her motionless, the success rate of a single copulation attempt is increased greatly.     

Sperm transfer during mating in the pharaoh's ant, Monomorium pharaonis

Abstract.  Sperm transfer in the pharaoh's ant Monomorium pharaonis (L.) is studied by making longitudinal sections through the gasters of mating pairs fixed in copula. Sperm is transferred inside a spermatophore similar to those found in two other ants, Diacamma sp. from Japan and Carebara vidua . Sharp teeth-ridges are present on the penis valves and, during copulation, these teeth make contact with a thick and soft cuticular layer covering the bursa copulatrix. This ensures an attachment long enough for the successful transfer of the spermatophore to the right position inside the female oviduct. The thick cuticle also protects the queen from serious damage by the male's sharp claspers. After a first successful copulation, sperm is still present inside the male's seminal vesicles, suggesting that males can mate multiply. Additional experiments, where single, initially virgin males are presented to several virgin females, confirm this.     

Function and genetics of long versus short copulations in the cactophilic fruit fly,drosophila mojavensis (diptera: drosophilidae)

Variation in copulation duration of Drosophila mojavensisstrains was influenced by both sexes. Males maintained predominant control, as copulation duration of pairs from different strains was more similar to that of the strain from which the male was derived, but female origin also contributed significantly to the duration of copulation. Variation among strains was controlled by genes acting additively in both sexes. The size of both males and females also affected copulation duration. Small males copulated longer on average than large males, while males paired with large females copulated longer than those paired with small females. The importance of copulation duration to fitness was tested by correlation analyses with male size, female size, female remating latency, and number of eggs laid prior to female remating. Longer copulations stimulated earlier oviposition, possibly by increasing accessory gland secretions that are passed by males during copulation.     

Role of the petasma and appendices masculinae during copulation and insemination in the penaeoid shrimp,Sicyonia dorsalis (Crustacea: Decapoda: Dendrobranchiata)

Summary

The role of presumed male gonopods in the insemination of females was investigated in the penaeoid shrimp Sicyonia dorsalis. Males with partially ablated petasmata or with ablated appendices masculinae did not copulate with females, while control males with exopods removed from the third pleopods copulated frequently and successfully inseminated females. However, males with petasmata altered by blockages at the tip or at the base did copulate with females but were unable to inseminate them. The hypothesis that the petasma of Sicyonia is a sperm injection device is rejected. Evidence against this hypothesis includes the structure of the gonopods, the position of the male at right angles below the female during copulation, the brevity of copulation, the frequency of copulation during normal matings, and the ability of males to inseminate only the spermatheca on one side per successful copulation. It is hypothesized that the male uses the petasma, supported by the endopods of the second pleopods, to hook onto the female thelycum, adjusting position so that one erect genital papilla directly injects sperm mass into the aperture of one of the paired spermathecae. It is suggested that female selection on male petasma structure and use has resulted in the complex form of the petasma, rather than a purely mechanical selection for an efficient sperm injection device.     

Chastity belts in gartersnakes: the functional significance of mating plugs

Male red-sided gartersnakes (Tfiamnophis sirtalis parietalis) deposit a thick gelatinous plug that occludes the female cloaca after copulation. Previous workers have interpreted the plug as a sexually-selected adaptation to (1) physically prevent re-mating by the female, and/or (2) provide pheromonal cues to discourage courtship by rival males or to decrease receptivity by females. Our data support the former hypothesis, but not the latter. Plugs serve as effective physical barriers to additional copulation for <72 h, but this is long enough for most females to become unreceptive, and/or disperse from the mating aggregation. Experimental removal of plugs immediately after copulation results in some re-mating by females, but plug removal several hours later does not rekindle sexual receptivity. Contrary to previous work, our experiments show that fluids associated with copulation (rather than the plug per se) are responsible for the rapid decline of male interest in mated females. Thus, the plug's primary function is to physically prevent matings rather than as a source of pheromonal cues to manipulate the behaviour of females or rival males. Plug mass is determined not only by a male's body size, but by his prior mating history (plug mass decreases with repeated mating) and by the size of his partner (males allocate larger plugs to larger females). Gartersnakes are unusual not only in their production of mating plugs, but also in their brief duration of copulation compared to other snakes. Mating plugs may have evolved in gartersnakes to reduce mating times, because of the extremely high 'opportunity cost' of prolonged mating to a male gartersnake in a mating aggregation.     

Males of the two-spotted spider mite attempt to copulate with mated females: effects of double mating on fitness of either sex

In Tetranychus urticae (Acari: Tetranychidae), when the intervals between first and second copulation are more than 24 h, only the first copulation is effective for females. Therefore, adult males should copulate only with virgin females, but not with females that copulated more than 1 day ago. Indeed, T. urticae males preferred virgin females to mated females under dual choice conditions. In the absence of virgin females, however, 60% of males copulated with mated females (n = 30). Therefore, the effects of male copulation behaviour on male and mated-female fitness were examined, respectively. Since T. urticae is arrhenotokous (i.e., only daughters have genes derived from their father), the proportion of females among the offspring was used as an index of male fitness. After males had lived with/without a mated female, the males were allowed to copulate with a virgin female. The proportion of females among the offspring did not differ between males with and without a female. On the other hand, when mated females lived with an adult male, their egg production was lower than mated females without a male. These results suggest that males do not seem to obtain fitness benefit from the copulation behaviour and that mated females incur a fitness cost due to the male behaviour.     

Securing paternity: mating plugs in the dwarf spider Oedothorax retusus (Araneae: Erigoninae)

One of the various male strategies to prevent or impede female remating is the production of a mating plug that covers the female genital opening or remains inside of the female genital tract after mating. Such structures have been described for many species in many animal taxa; however, in most cases, we know little or nothing about their specific adaptive value. Our investigations demonstrate that females of the dwarf spider species Oedothorax retusus (Westring, 1851) (Linyphiidae, Erigoninae) exhibit a substance on one or both of her paired genital openings only after copulation. We performed double-mating trials and forced the second male to mate into the previously used or unused spermathecal duct of the female by amputating one of his paired male gonopods (pedipalps). Furthermore, to investigate whether the duration of the first mating has an effect on the size and efficiency of the mating plug, we interrupted first matings after either 1 or 3 min, categorized plug size and recorded mating behaviour of subsequent males. The amount of secretion transferred was larger in long compared to short copulations. A long first copulation successfully prevented subsequent males from mating into the used ducts, whereas mating success after short first matings was similar to matings into unused copulatory ducts of the females. The present study demonstrates that a male O. retusus can prevent a rival from transferring sperm into the same spermatheca by applying a mating plug, but only if he mates for long enough.  © 2009 The Linnean Society of London, Biological Journal of the Linnean Society , 2009, 96 , 574–583.     

The role of mating history and male size in determining mating behaviours and sexual conflict in a water strider

We conducted three experiments to test the effects of mating history of both sexes and of male body size on mating behaviours in the water strider, Gerris buenoi. Our manipulations influenced the interests of both sexes and, thus, the degree of conflict over mating behaviours. Mating history was a dichotomous variable (deprived/mated), depending on holding conditions in the laboratory. Experiment 1 considered and found independent effects of male and female mating history on latency to copulation and copulation duration. In experiment 2, we manipulated only female mating history, using unsuccessful struggle rates as evidence for female reluctance and conflict over mating. Finally, we investigated the relation between male body size and mating history on copulation duration. We predicted that intersexual conflict over mating would be lowest when females were deprived, because female interests under these conditions should more closely match those of males. Deprived females began mating in half the time of mated females and were twice as likely to mate because of reduced reluctance. Furthermore, copulation duration for deprived males was about one and a half times longer than that for mated males. Although previous studies examining nonrandom mating patterns by size predicted longer copulations for small males, we found that small males prolonged copulation when deprived more than large males. We conclude that females primarily influence copulation frequency, but males primarily influence copulation duration. Our results favour the hypothesis that reduced mating opportunity for small males accounts for their extended copulation duration. Finally, our findings provide evidence for strong effects of male body size on selection mechanisms in water striders, and support the hypothesis of conflicting pre- and postcopulatory selection mechanisms in this group. Copyright 2003 Published by Elsevier Science Ltd on behalf of The Association for the Study of Animal Behaviour.     

Remating inhibition in the melon fly,Bactrocera (=Dacus) cucurbitae (Diptera: Tephritidae): Copulation with spermless males inhibits female remating

Eight hour copulation of the melon fly,Bactrocera cucurbitae, which usually mates at dusk and finishes copulation at dawn, inhibited female remating, while 3 h copulation did not. Copulation of females with either normal or virgin sterile males inhibited female remating. Sperm-depleted sterile males inhibited female remating at the same rate as normal males when the copulation duration was 8 h, indicating that existence or amount of sperm in females' spermathecae is not important in remating inhibition. Females of a wild strain remated later than females of a mass-reared strain, irrespective of strains of 1st and 2nd males. This suggests that the females may control their own remating, or that there is a difference between wild and mass-reared strains in their sensitivity to a male substance that inhibits females' receptivity.     

The secondary copulatory organ in female ground weta (Hemiandrus pallitarsis,Orthoptera: Anostostomatidae): a sexually selected device in females?

Secondary sexual devices in female insects, primarily abdominal modifications, appear to function as a means of thwarting coercive mating attempts by males or are, in rare cases, sexually selected adaptations. Female ground weta, Hemiandrus pallitarsis (Orthoptera: Anostostomatidae), have an elaborate elbowed device on the underside of the mid-abdomen. Experimental removal of this accessory organ shows that it does not increase the probability of mating as predicted by the thwart-copulation hypothesis. Instead, removal prevents copulation, thus demonstrating that it is a secondary copulatory device. The male attaches to the organ both at the beginning of copulation and at the end, when he positions himself to adhere a spermatophylax food gift onto the mid-ventral region of his mate. The female accessory organ does not function to manipulate eggs or larvae (females provide care to their single clutch of offspring) and is unlikely to be a copulatory structure that prevents hybridization. The great extent of the modification of the ventral abdominal segments of H. pallitarsis females compared to other Hemiandrus species is consistent with a history of sexual selection on the accessory organ. Taken together, these results and the finding that the length of the accessory organ of H. pallitarsis correlates with female fecundity, suggest that this structure evolved under sexual selection to acquire nuptial gifts from males.  © 2005 The Linnean Society of London, Biological Journal of the Linnean Society , 2005, 85 , 463–469.