Male Accessory Gland Substances Research Articles

Hidden female physiological resistance to male accessory gland substances in a simultaneous hermaphrodite.

ABSTRACTTo increase fertilization chances compared with rivals, males are favoured to transfer accessory gland proteins to females during mating. These substances, by influencing female physiology, cause alteration of her sperm usage and remating rate. Simultaneously hermaphroditic land snails with love-darts are a case in point. During courtship, a love-dart is pierced through the partner's body wall, thereby introducing accessory mucous gland products. This mucus physiologically increases paternity by inhibiting the digestion of donated sperm. The sperm, which are packaged in a spermatophore, are exchanged and received in an organ called the diverticulum. Because of its length, this organ was previously proposed to be a female anatomical adaptation that may limit the dart interference with the recipient's sperm usage. For reproductive success of the donor, an anatomically long spermatophore, relative to the partner's diverticulum, is beneficial as sperm can avoid digestion by exiting through the spermatophore's tail safely. However, the snail Eobania vermiculata possesses a diverticulum that is three times longer than the spermatophore it receives. Here, we report that the love-dart mucus of this species contains a contraction-inducing substance that shortens the diverticulum, an effect that is only properly revealed when the mucus is applied to another helicid species, Cornu aspersum. This finding suggests that E. vermiculata may have evolved a physiological resistance to the manipulative substance received via the love-dart by becoming insensitive to it. This provides useful insight into the evolution of female resistance to male manipulations, indicating that it can remain hidden if tested on a single species.

Satyrization without evidence of successful insemination from interspecific mating between invasive mosquitoes.

Previous research has documented low frequencies of interspecific mating in nature between the invasive vectors Aedes aegypti and Aedes albopictus. It is also known that heterospecific male accessory gland substances transferred during mating sterilize A. aegypti but not A. albopictus females, leading to satyrization, a form of reproductive interference. This paper demonstrates that satyrization of A. aegypti by A. albopictus may occur without evidence of successful insemination. Our results show that A. aegypti females, previously exposed to A. albopictus males, are rendered refractory to subsequent conspecific mating even though their spermathecae contain no heterospecific sperm. Additional experiments demonstrating transfer of labelled semen from A. albopictus males to A. aegypti females and low production of viable eggs of females housed with conspecific males, following exposure to A. albopictus males, confirm higher incidences of satyrization than expected, based on heterospecific insemination rates. We conclude that frequencies of satyrization based on detection of interspecific sperm in spermathecae may underestimate the impact of this form of reproductive interference.

Male Aedes aegypti mosquitoes use JH III transferred during copulation to influence previtellogenic ovary physiology and affect the reproductive output of female mosquitoes

The effect of male accessory gland substances on female reproductive physiology has been previously described as “activating” egg development. However, no mechanism has been described that can explain how male mosquitoes are able to influence egg development in female mosquitoes. To investigate how male mosquitoes are able to influence ovarian physiology and reproductive output we explored three main questions: (1) Do mating and male accessory gland substances affect ovarian physiology and alter markers of oocyte quality during the previtellogenic resting stage? (2) Does the male accessory gland contain JH III and is JH III transferred to the female during copulation? (3) Finally, does the nutritional history of the male affect the amount of JH III transferred to the female and alter reproductive output? By answering these questions it is clear that male mosquitoes are able to alter the female’s resource allocation priorities towards reproduction by transferring JH III during copulation; reducing the rate of previtellogenic resorption and increasing the amount of stored ovarian lipids. These changes improve an individual follicle’s likelihood of development after a blood meal. In addition, males maintained under better nutritional conditions make and transfer more JH III, prevent more follicular resorption and realize higher fecundities than other males. Together these results illustrate one mechanism behind the “activating” effect of mating described as well as the role sugar feeding plays in male mosquitoes.

Inhibition of female mating by male accessory gland substances in the ground beetle Leptocarabus procerulus

AbstractThe ground beetle Leptocarabus procerulus (Chaudoir) possesses seminal substances that have a physical function to form mating plugs and a physiological function to induce female refractory behaviour, which act together to hinder female remating. Little is known about the physiological properties of the substances inducing female refractory behaviour, especially with respect to their secretory organ, dose‐dependency, molecular characteristics and the effect of female maturity. By injecting male‐derived substances into females, substances that induce female refractory behaviour are shown to be produced in the male accessory gland but not in the testis. Injection of extracts from the accessory gland increases the female refractory period at moderate doses but not at lower or higher doses. By contrast, injection of extracts from the testis reduces the female refractory period at high doses. The lack of an effect of accessory gland substances at higher doses could be the result of an anomalous effect of unnaturally large doses of seminal products by direct injection, the toxicity of seminal substances that deter female responses, or counteraction by injected substances that promote female receptivity. The accessory gland substances lose their activity when heated, although the testis substances do not. Females without mature eggs tend to reject mating entirely, although variation in the number of mature eggs (one or more) is not associated with the female refractory period, indicating the limited effect of female reproductive maturity. These findings may help to clarify the physiological basis of the evolution of the elaborated male mating behaviour in L. procerulus.

Male accessory gland substances from Aedes albopictus affect the locomotor activity of Aedes aegypti females

Dengue is one of the world’s most important mosquito-borne diseases and is usually transmitted by one of two vector species: Aedes aegypti or Aedes albopictus . These two diurnal mosquitoes are frequently found coexisting in similar habitats, enabling interactions between adults, such as cross-mating. The objective of this study was to assess cross-mating between Ae. aegypti females and Ae. albopictus males under artificial conditions and evaluate the locomotor activity of Ae. aegypti virgin females injected with male accessory gland (MAG) homogenates to infer the physiological and behavioural responses to interspecific mating. After seven days of exposure, 3.3-16% of Ae. aegypti females mated with Ae. albopictus males. Virgin Ae. aegypti females injected with conspecific and heterospecific MAGs showed a general decrease in locomotor activity compared to controls and were refractory to mating with conspecific males. The reduction in diurnal locomotor activity induced by injections of conspecific or heterospecific MAGs is consistent with regulation of female reproductive activities by male substances, which are capable of sterilising female Ae. aegypti through satyrisation by Ae. albopictus .

Identity and transfer of male reproductive gland proteins of the dengue vector mosquito, Aedes aegypti: Potential tools for control of female feeding and reproduction

Male reproductive gland proteins (mRGPs) impact the physiology and/or behavior of mated females in a broad range of organisms. We sought to identify mRGPs of the yellow fever mosquito, Aedes aegypti, the primary vector of dengue and yellow fever viruses. Earlier studies with Ae. aegypti demonstrated that “matrone” (a partially purified male reproductive accessory gland substance) or male accessory gland fluid injected into virgin female Ae. aegypti affect female sexual refractoriness, blood feeding and digestion, flight, ovarian development, and oviposition. Using bioinformatic comparisons to Drosophila melanogaster accessory gland proteins and mass spectrometry of proteins from Ae. aegypti male accessory glands and ejaculatory ducts (AG/ED) and female reproductive tracts, we identified 63 new putative Ae. aegypti mRGPs. Twenty-one of these proteins were found in the reproductive tract of mated females but not of virgin females suggesting that they are transferred from males to females during mating. Most of the putative mRGPs fall into the same protein classes as mRGPs in other organisms, although some appear to be evolving rapidly and lack identifiable homologs in Culex pipiens, Anopheles gambiae, and D. melanogaster. Our results identify candidate male-derived molecules that may have an important influence on behavior, survival, and reproduction of female mosquitoes.

Switchover to the mated state by spermathecal activation in female Anopheles gambiae mosquitoes

Both Aedes aegypti and Anopheles gambiae mosquitoes undergo physiological and behavioral changes after the females mate, but unlike Ae. aegypti, the mated state in An. gambiae is not attained through the action of male accessory gland substances. Experiments in which the spermathecae of mated females were manipulated suggest that a spermatheca filled with sperm is responsible for triggering oviposition behavior. An estimated 48% of the previously mated An. gambiae females mated again when the interval between encounters with males was less than 24 h. Unlike male Ae. aegypti that can inseminate up to seven females after their testes are removed, An. gambiae do not store sperm in the vas deferens and without testes would be unable to inseminate any females.

The Male Accessory Gland Substances of Lucilia illustris (I): Its Effect on Mating Receptivity

ABSTRACT In order to verify the physiological functions of male accessory gland (MAG) substances of the blowfly, Lucilia illustris Meigen, the growth and changes in metabolites of male accessory gland with aging, and the effect of male accessory gland extract on mating receptivity of L. illustris were examined. There was not a significant difference in length of MAG with aging, but the width of MAG was grown widely from 0 to 5‐days old apparently. Changes in glycogen, total protein and lipid of male accessory gland substances showed same patterns but total protein content was higher than the others. Therefore, male nutrition affected the production of male accessory proteins. During the mating fed unmated male transferred larger amount of protein than that of starved male. When male accessory gland homogenates injected, mating receptivity of gravid female was greatly inhibited comparing to control, suggesting that the accessory gland substances of L. illustris alters female mating receptivity after mating.

Sexual receptivity in Anopheles gambiae mosquitoes: absence of control by male accessory gland substances

Although male accessory gland substances modulate female receptivity in most mosquito genera that have been studied, they are not active in the development of sexual refractoriness in the malaria vectors, Anopheles gambiae or Anopheles albimanus. Neither the implantation of male accessory glands nor the injection of gland homogenates affected the insemination rate of unmated females. Similarly, portions of the male genital tract and spermathecae from mated females were also inactive when introduced into these females. Interruption of nervous transmission from the brain reduced the tendency of females to become inseminated and removal of the terminal abdominal ganglion completely abolished insemination. Oviposition behavior did not occur unless the spermatheca containing sperm was present, suggesting that this may be the mechanism that mediates the switchover to mated behavior.

Exogenous juvenile hormone and methoprene, but not male accessory gland substances or ovariectomy, affect the blood/nectar choice of female Culex nigripalpus mosquitoes.

When newly emerged females of the mosquito Culex nigripalpus Theobald (Diptera: Culicidae) take a sugar meal, they develop both a propensity to seek a host and resting-stage ovarian follicles. As follicle growth is indicative of Juvenile Hormone (JH) activity, we searched for possible roles of JH in the behavioural shift from nectar to blood-host odour preference by Cx. nigripalpus after emergence, using an olfactometer-choice assay. Topically applied or injected methoprene (a JH analogue) resulted in a behavioural shift and follicular growth in unfed females that increased with increasing dosages. Topical methoprene 500 ng and 4 microg resulted in a switch to bird-odour preference. JH III injection resulted in a lesser shift from honey responses to bird responses. Methoprene application caused no detectable changes in glycogen, total sugars or total lipid when assayed 24h after treatment. Additionally, as male accessory glands (MAG) have been shown to synthesize JH, we implanted intact paired MAGs from either conspecific or Aedes aegypti (L.) donors, or injected 1/3 gland pair equivalents of conspecific MAG homogenate into unfed newly emerged females. All MAG treatments failed to induce behavioural or ovarian modifications. Ovariectomy had no effect on the sugar-induced shift from nectar to host preference in the olfactometer. Thus JH, but not MAG, mimicked the effects of a sugar meal by causing both follicular growth and the shift to preference for a host.

Male accessory gland substances modify the host-seeking behavior of gravid Aedes aegypti mosquitoes

Male accessory gland (MAG) substances of the mosquito, Aedes aegypti (L.), when transferred during mating or injected directly into females, significantly reduced the host-seeking behavior of the females when they were gravid. The effect on female behavior was modulated by the nutritional state of the male; compared to well-fed males, starved males contained less total protein in their MAGs, transferred less protein to females during mating, and had less of an effect on the inhibition of host-seeking behavior by the gravid females to which they mated. Juvenile hormone (JH) administered to starved males increased the levels of total MAG proteins in their accessory glands, but the host-seeking behavior of gravid females mated to JH-treated males was not significantly affected, suggesting that the production of specific substances did not increase. Injection of MAG homogenates from other mosquito species into Ae. aegypti indicated that there was some degree of specificity in the inhibition of the host-seeking behavior.

Multiple mating in female mosquitoes—evidence from a field population of Anopheles freeborni (Diptera: Culicidae)

AbstractWe determined how frequently multiple mating occurs in a field population of Anopheles freeborni Aitken. We used enzyme electrophoresis to analyse field collected females and their offspring, and determined the parity rates of females mating in swarms. The genotypes of progeny in one of the 36 families examined showed conclusive evidence of two sires. 4·3% (n═93) of females mating in swarms were parous, as opposed to 33·9% of host seeking females (n═103). We conclude that multiple mating in A. freeborni occurs at low frequency in the field, and may be ascribed to incomplete transfer of sperm or male accessory gland substance, rather than to routine renewal of receptivity by females.

Male accessory gland substances activate egg development in nutritionally stressed Aedes aegypti mosquitoes

The effect of mating on egg development in starved Aedes aegypti mosquitoes was examined. Mated females that were maintained on water for 4 days before ingesting blood were more likely to develop eggs than were unmated females. The implantation of a single male accessory gland from either A. aegypti or A. albopictus males increased the proportion of unmated females that developed eggs, but glands from A. bahamensis or A. taeniorhynchus did not. Male accessory gland homogenates from A. aegypti were also active when injected at concentrations of 0.02 gland equivalents or greater, but heating them destroyed their activity. When a small blood meal was supplemented with saline to increase abdominal distention, only mated females responded to the distention with increased egg development. Juvenile hormone topically applied to sugar-deprived, blood-fed unmated females also enhanced egg development. If males were starved for 3 days before they mated, they were less likely to stimulate oögenesis in sugar-deprived blood-fed females than if the males were maintained on sucrose before mating.

Effects of male accessory gland substances on the pre-oviposition behaviour of Aedes aegypti mosquitoes

Secretions of the male accessory glands of Aedes aegypti (L.) induce gravid virgin females to engage in pre-oviposition behaviour. Normal mating, the implantation of whole glands, or the injection of male accessory gland homogenates, all induced pre-oviposition behaviour in gravid virgin females, but implants of testes did not. Injection of male accessory gland extracts from other mosquito species, including A. albopictus, A. sierrensis, A. taeniorhynchus and Anopheles nr. salbaii into gravid virgin A. aegypti females did not induce pre-oviposition, suggesting that the male components were species-specific. Male accessory gland substances retained their biological activity when stored at 4°C for 24 h or when maintained at −10°C for 2 weeks, but lost their activity after longer periods and were inactivated by heating.

Male accessory gland substances and the control of sexual receptivity in female Culex tarsalis

ABSTRACT. Homogenates of accessory glands from male Culex tarsalis Coquillet (Diptera; Culicidae) were fractionated using gel filtration column chromatography. A component of low molecular weight capable of suppressing female sexual receptivity was obtained and partially characterized. Proteins present in homogenates of isolated accessory glands formed aggregates with other proteins in extracts of whole mosquitoes. Consequently, previous reports of the molecular weight of biologically active components in homogenates from accessory glands from other mosquito species may be inaccurate.When female Cx. tarsalis were mated with 3H‐leucine labelled males. radioactivity could be found throughout the body of the female 24 h after mating. Autoradiography showed that the radioactivity was incorporated into the cells of various organs, and was not specifically localized in a particular target tissue. Approximately 30% of the total radioactivity transferred to the female was found in the head and thoracic regions, and proteins from the head had a specific activity twice that of the thoracic proteins. Bioassay of isolated body parts from mated and virgin females showed that injections of head tissues from mated females into virgin females suppressed sexual receptivity. These results suggest that the head is involved in the physiological mechanisms resulting in refractory mating behaviour.

Anopheles stephensi (Diptera: Culicidae): changes in male mating competence and reproductive system morphology associated with aging and mating.

Laboratory observations on the mating behavior of the Khano-Harni ( KH ) strain of Anopheles stephensi indicated that females and males become sexually mature by their 2nd night of life. Some females (10%, n = 67) mated on their night of emergence when crossed with 3-day-old males. At 28–30 °C maximum male mating activity occurred between 3 and 7 days of age. Comparisons between the percentage of laboratoryadapted KH females inseminated by KH males and wild-caught ( WC ) males indicated that little change in group mating occurs during colonization, while the ability of males to mate singly improves with laboratory selection. Dissections of KH males of known age and mating history indicated that the number of spermatocysts decrease and the proportion of the testes occupied by the sperm reservoir increases with age, while the quantity of spermatozoa present in the sperm reservoir and postgonadal system and the degree of repleteness of the male accessory glands with secretory material decreases with successive matings. The male reproductive system was found to rejuvenate after mating, with the replenishment of male accessory gland substance in the accessory glands and spermatozoa in the sperm reservoir and postgonadal system. Males that multiplymated during an abbreviated interval took longer to rejuvenate their reproductive systems than did males mating once. Morphological changes associated with age and mating were used to develop a method to determine age and the reproductive history of male An. stephensi

Autogeny in saltmarsh mosquitoes induced by a substance from the male accessory gland

OVARIAN maturation by mosquitoes and other haematophagous Diptera without a prior blood meal is called autogeny, while the term anautogeny applies to those cases where blood is necessary. Many populations of the saltmarsh mosquito, Aedes taeniorhynchus, contain both autogenous and anautogenous females1–2. Moreover, within this species there are two types of autogenous females : (1) those that need a stimulus from mating to produce eggs autogenously and (2) those that lack this requirement3. We report that autogenous egg production associated with mating is triggered by a substance from the male accessory gland. The stimulation of normal oviposition behaviour and the termination of sexual receptivity in the female mosquito are also caused by a male accessory gland substance which is introduced into the female during mating4,5. Both of these responses are uniformly exhibited by all females of several species6.

Rôle of male accessory gland substance in the regulation of blood intake by mosquitoes

The presence of male accessory gland substance during mating is shown to increase the blood intake in the adult female Aedes aegypti and Culex pipiens fatigans. Females mated with males whose accessory glands were surgically removed took significantly less blood than females mated with normal males. However, females mated with males whose seminal vesicles were surgically removed took as much blood as the controls.

Involvement of male accessory gland substance in the fertility of mosquitoes

The male accessory gland substance is shown to be involved in the fertility of eggs for the first time in Aedes aegypti and Culex pipiens fatigans. Surgical removal of the paired accessory glands of males did not impair their mating ability. However, the eggs laid by the females after mating with operated males were found to be sterile. This condition could be reversed if the accessory gland substance was later received by the females. Evidence suggests that the accessory gland substance is essential for fertilization.

The effect of matrone on oviposition in the mosquito, Aedes aegypti

Male Aedes aegypti produce a substance made or stored in their accessory glands, which when passed on to females via mating, will prevent subsequent insemination. In addition to becoming refractory with regard to further insemination, mated females also oviposit far more eggs than virgins. The male accessory gland substance, called matrone, has been highly purified and when injected into virgin females, prevents any initial insemination, and will also stimulate oviposition. Matrone can be fractionated into two protein fractions both of which are needed to prevent insemination. However, only one of the fractions will stimulate oviposition; the other has no discernible biological effect when administered by itself.