Drosophila male sex peptide inhibits siesta sleep and promotes locomotor activity in the post-mated female

Quiescence, or a sleep-like state, is a common and important feature of the daily lives of animals from both invertebrate and vertebrate taxa, suggesting that sleep appeared early in animal evolution. Recently, Drosophila melanogaster has been shown to be a relevant and powerful model for the genetic analysis of sleep behaviour. The sleep architecture of D. melanogaster is sexually dimorphic, with females sleeping much less than males during day-time, presumably because reproductive success requires greater foraging activity by the female as well as the search for egg-laying sites. However, this loss of sleep and increase in locomotor activity will heighten the risk for the female from environmental and predator hazards. In this study, we show that virgin females can minimize this risk by behaving like males, with an extended afternoon ‘siesta’. Copulation results in the female losing 70 per cent of day-time sleep and becoming more active. This behaviour lasts for at least 8 days after copulation and is abolished if the mating males lack sex peptide (SP), normally present in the seminal fluid. Our results suggest that SP is the molecular switch that promotes wakefulness in the post-mated female, a change of behaviour compatible with increased foraging and egg-laying activity. The stress resulting from SP-dependent sleep deprivation might be an important contribution to the toxic side-effects of male accessory gland products that are known to reduce lifespan in post-mated females.     

Description of Thecavermiculatus andinus n.sp. (Meloidoderidae), a Round Cystoid Nematode from the Andes Mountains of Peru

Thecavermiculatus andinus n.sp. is described and illustrated from Oxalis tuberosa originally collected in the vicinity of Lake Titicaca high in the Andes mountains of southern Peru. This new species differs markedly front the other two species in the genus, especially in having a much greater female vulval-anal distance and annules with lined punctation on most of the female body with a lacelike pattern restricted to the posterior portion, particularly at the vulva and anus which do not protrude. Females are essentially spherical with protruding neck, white to yellowish in color, and can easily be mistaken for potato cyst nematodes. Among the dozen or more known weed and crop host plants are potato and eggplant. In order to accommodate this new species, the genus Thecavermieulatus is emended. A key to the species of this genus is presented.     

Males of the orb-web spider Argiope bruennichi sacrifice themselves to unrelated females

Costs of inbreeding can lead to total reproductive failure and inbreeding avoidance is, therefore, common. In classical sex roles with no paternal care, the selective pressure to avoid inbreeding is mostly on the female, which carries the higher costs. In some orb-web spiders, this situation is very different because females are polyandrous and males are monogynous or at most bigynous. Additionally, females of many entelegyne orb weavers are thought to bias paternity post-copulatorily towards a desired mate. This increases the selective pressure on males to adjust their investment in a mating with regard to the compatibility to a female.Here, we examine whether genetic relatedness influences mating behaviour in the orb-web spider Argiope bruennichi. We mated either a sibling or a non-sibling male to a female in single copulation trials and compared copulation duration, cannibalism rate and female fecundity.Our experiment revealed that males prolonged their copulation duration and were cannibalized more frequently when mating with a non-sibling female. Males mating with a sibling female were more likely to escape cannibalism by copulating briefly, thus presumably increasing their chances of re-mating with a more compatible female. This suggests that males can adaptively adjust their investment relating to the compatibility of a female.     

I'm sexy and I glow it: female ornamentation in a nocturnal capital breeder

In many species, males rely on sexual ornaments to attract females. Females, by contrast, rarely produce ornaments. The glow-worm (Lampyris noctiluca) is an exception where wingless females glow to attract males that fly in search of females. However, little is known about the factors that promote the evolution of female ornaments in a sexual selection context. Here, we investigated if the female ornament of the glow-worm is a signal of fecundity used in male mate choice. In support of this, we found brightness to correlate with female fecundity, and males to prefer brighter dummy females. Thus, the glow emitted by females is a reliable sexual signal of female fecundity. It is likely that male preference for the fecundity-indicating ornament has evolved because of large variation among females in fecundity, and because nocturnal males cannot directly assess female size and fecundity. These results indicate that female ornamentation may evolve in capital breeders (i.e. those in which stored resources are invested in reproduction) when females vary significantly in fecundity and this variation cannot be assessed directly by males.     

Laboratory Culture and Life History of Heleidomermis magnapapula in Its Host, Culicoides variipennis (Diptera: Ceratopogonidae)

The mermithid parasite Heleidomermis magnapapula was maintained in larvae of the midge Culicoides variipennis for 20 months in enamel pans containing nutrient-rich water and polyester pads as a substrate. Inseminated female mermithids were introduced to the pad surface when the host was in the late second or early third-instar. Host larvae were harvested from the pans 9 days after exposure and held in tap water for nematode emergence. Preparasite yield was positively correlated with female nematode size and averaged 1,267 preparasites/female. Male and female nematodes emerged an average of 12.2 and 13.4 days after host exposure, respectively. Supplemental host food (Panagrellus) during the final days of parasitism did not alter time of emergence. Parasites emerging singly were 64% females, whereas superparasitized hosts yielded males (up to nine/host). Nematode carryover into the adult midge normally occurred at a level of 0.5-2.5%. Parasite load (nematodes/ parasitized individual) in midge adults was lower than that of larvae from the same cohort, and adult midges were more likely to harbor female parasites. Exposure of fourth-instar host larvae resulted in higher levels of adult parasitism (up to 17%).     

Hormonal regulatory role of eyestalk factors on growth of heart in mud crab,Scylla serrata

The present study was attempted to know the growth regulation of eyestalk factors on the growth of heart in Scylla serrata using eyestalk extractions and bilateral eyestalk ablations. The bilateral eyestalk ablation led to the maximum growth indices of the heart ((H) indices) to 0.162 and 0.158 in ablated male and female, respectively, in comparison to 0.153 and 0.167 in the control male and female and 0.147 and 0.157 in injected male and female, respectively. The data have shown that the heart of male crabs grows faster than female crabs. The study has also shown that bilateral eyestalk ablation resulted in a significant increase in the heart indices in males and has least effect on the growth of the female heart. The results presented strongly support a potential role of the eyestalk factors and molting hormone regulating the growth of the heart in S. serrata.     

The enigmatic Otway odd-clawed spider (Progradungula otwayensis Milledge, 1997, Gradungulidae,Araneae): Natural history,first description of the female and micro-computed tomography of the male palpal organ

The recently described cribellate gradungulid Progradungula otwayensis Milledge, 1997 is endemic to the Great Otway National Park (Victoria, Australia) and known from only one male and a few juvenile specimens. In a recent survey we recorded 47 specimens at several localities across the western part of the Great Otway National park. Our field data suggest that this species is dependant on the microclimate in the hollows of old myrtle beech trees since other hollow trees were very much less inhabited. Furthermore, we describe the female for the first time and study the male palpal organ by using X-ray microtomography. The female genitalia are characterized by eight spermathecae which are grouped in two quartets. The spermophor resembles the general organization of gradungulids, but is similar to Kaiya Gray, 1987 by a convoluted appearance within the embolus. The muscle 30 is located in the cymbium and resembles the organization of other non-entelegyne Araneomorphae.     

A Case of Ocular Angiostrongyliasis with Molecular Identification of the Species in Vietnam

A 23-year-old female residing in a village of Cao Bang Province, North Vietnam, visited the Hospital of Hanoi Medical University in July 2013. She felt dim eyes and a bulge-sticking pain in her left eye for some days before visiting the hospital. In the hospital, a clinical examination, an eye endoscopy, and an operation were carried out. A nematode specimen was collected from the eye of this patient. The body of this worm was thin and long and measured 22.0×0.3 mm. It was morphologically suggested as an immature female worm of Angiostrongylus cantonensis. By a molecular method using 18S rRNA gene, this nematode was confirmed as A. cantonensis. This is the first molecular study for identification of A. cantonensis in Vietnam.     

Gamete membrane dynamics during double fertilization in Arabidopsis

In the double fertilization of angiosperms, one sperm cell fertilizes an egg cell to produce a zygote, whereas the other sperm cell fertilizes a central cell to give rise to an endosperm. There is little information on gamete membrane dynamics during double fertilization even though the cell surface structure is critical for male and female gamete interactions. In a recent study, we analyzed gamete membrane behavior during double fertilization by live-cell imaging with Arabidopsis gamete membrane marker lines. We observed that the sperm membrane signals occasionally remained at the boundary of the female gametes after gamete fusion. In addition, sperm membrane signals entering the fertilized female gametes were detected. These findings suggested that plasma membrane fusion between male and female gametes occurred with the sperm internal membrane components entering the female gametes, and this was followed by plasmogamy.     

Function and evolution of sterile sex organs in cryptically dioecious Petasites tricholobus (Asteraceae)

Background and Aims

Why are sterile anthers and carpels retained in some flowering plants, given their likely costs? To address this question, a cryptically dioecious species, Petasites tricholobus, in which male and female plants each have two floret types that appear pistillate and hermaphroditic, was studied. The aim was to understand the function of sterile hermaphroditic florets in females. In addition, the first examination of functions of sterile female structures in male plants was conducted in the hermaphroditic florets on males of this species. These female structures are exceptionally large in this species despite being sterile.

Methods

Differences in floret morphology between the sex morphs were documented and the possible functions of sterile sex organs investigated using manipulative experiments. Tests were carried out to find out if sterile female structures in male florets attract pollinators and if they aid in pollen dispersal, also to find out if the presence and quantity of sterile hermaphroditic florets in females increase pollinator attraction and reproductive success. To investigate what floret types provide nectar, all types of florets were examined under a scanning electron microscope to search for nectaries.

Key Results

The sterile female structures in male florets did not increase pollinator visits but were essential to secondary pollen presentation, which significantly enhanced pollen dispersal. Sterile pistillate florets on male plants did not contribute to floral display and disappeared in nearly half of the male plants. The sterile hermaphroditic florets on female plants attracted pollinators by producing nectar and enhanced seed production.

Conclusions

The presence of female structures in male florets and hermaphroditic florets on female plants is adaptive despite being sterile, and may be evolutionarily stable. However, the pistillate florets on male plants appear non-adaptive and are presumably in decline. Differential fates of the sterile sex organs in the species are determined by both the historical constraints and the ecological functions.     

Female and male genetic contributions to post-mating immune defence in female Drosophila melanogaster

Post-mating reduction in immune defence is common in female insects, and a trade-off between mating and immunity could affect the evolution of immunity. In this work, we tested the capacity of virgin and mated female Drosophila melanogaster to defend against infection by four bacterial pathogens. We found that female D. melanogaster suffer post-mating immunosuppression in a pathogen-dependent manner. The effect of mating was seen after infection with two bacterial pathogens (Providencia rettgeri and Providencia alcalifaciens), though not after infection with two other bacteria (Enterococcus faecalis and Pseudomonas aeruginosa). We then asked whether the evolution of post-mating immunosuppression is primarily a ‘female’ or ‘male’ trait by assaying for genetic variation among females for the degree of post-mating immune suppression they experience and among males for the level of post-mating immunosuppression they elicit in their mates. We also assayed for an interaction between male and female genotypes to test the specific hypothesis that the evolution of a trade-off between mating and immune defence in females might be being driven by sexual conflict. We found that females, but not males, harbour significant genetic variation for post-mating immunosuppression, and we did not detect an interaction between female and male genotypes. We thus conclude that post-mating immune depression is predominantly a ‘female’ trait, and find no evidence that it is evolving under sexual conflict.     

The need to re-investigate the nature of homoplastic characters: an ontogenetic case study of the 'bracteoles' in Atripliceae (Chenopodiaceae)

Background and Aims

Within Chenopodioideae, Atripliceae have been distinguished by two bracteoles enveloping the female flowers/fruits, whereas in other tribes flowers are described as ebracteolate with persistent perianth. Molecular phylogenetic hypotheses suggest ‘bracteoles’ to be homoplastic. The origin of the bracteoles was explained by successive inflorescence reductions. Flower reduction was used to explain sex determination. Therefore, floral ontogeny was studied to evaluate the nature of the bracteoles and sex determination in Atripliceae.

Methods

Inflorescences of species of Atriplex, Chenopodium, Dysphania and Spinacia oleracea were investigated using light microscopy and scanning electron microscopy.

Key Results

The main axis of the inflorescence is indeterminate with elementary dichasia as lateral units. Flowers develop centripetally, with first the formation of a perianth primordium either from a ring primordium or from five individual tepal primordia fusing post-genitally. Subsequently, five stamen primordia originate, followed by the formation of an annular ovary primordium surrounding a central single ovule. Flowers are either initially hermaphroditic remaining bisexual and/or becoming functionally unisexual at later stages, or initially unisexual. In the studied species of Atriplex, female flowers are strictly female, except in A. hortensis. In Spinacia, female and male flowers are unisexual at all developmental stages. Female flowers of Atriplex and Spinacia are protected by two accrescent fused tepal lobes, whereas the other perianth members are absent.

Conclusions

In Atriplex and Spinacia modified structures around female flowers are not bracteoles, but two opposite accrescent tepal lobes, parts of a perianth persistent on the fruit. Flowers can achieve sexuality through many different combinations; they are initially hermaphroditic, subsequently developing into bisexual or functionally unisexual flowers, with the exception of Spinacia and strictly female flowers in Atriplex, which are unisexual from the earliest developmental stages. There may be a relationship between the formation of an annular perianth primordium and flexibility in floral sex determination.     

Temperature Effects on Race Determination in Heterodera glycines

Currently there are 16 possible races for Heterodera glycines, and these are differentiated based on ability of a nematode population to develop on a set of four differential soybean genotypes. Because results are based on numbers of nematode females that develop to a specific stage rather than on the reproductive capability of these females, race determinations based on female indices may not represent results obtained after several reproductive cycles of H. glycines. Counting numbers of eggs and juveniles, and then developing corresponding indices, would allow reproduction to be considered in making race determinations. Our objectives were to compare the present race identification scheme for H. glycines based on female indices with those using egg and juvenile indices and to examine the effect of temperature on race designations using female, egg, and juvenile indices. Race designations for H. glycines populations from two locations in Illinois were determined at 20, 27, and 30 °C in a water bath. The numbers of females, eggs, and juveniles (at 19 days) were recorded, and an index based on each life stage was calculated. Race determinations based on female, egg, or juvenile indices were inconsistent when conducted at 20 °C, which demonstrates that this temperature is not suitable for identifying races of H. glycines. However race designations at 27 and 30 °C were consistent for all three indices. This indicates that counting females, eggs, or juveniles should be equally reliable when race determinations are conducted at these two temperatures, and choice of method would depend on investigator preference or research objective.     

Spermidine promotes stress resistance in Drosophila melanogaster through autophagy-dependent and -independent pathways

The naturally occurring polyamine spermidine (Spd) has recently been shown to promote longevity across species in an autophagy-dependent manner. Here, we demonstrate that Spd improves both survival and locomotor activity of the fruit fly Drosophila melanogaster upon exposure to the superoxide generator and neurotoxic agent paraquat. Although survival to a high paraquat concentration (20 mM) was specifically increased in female flies only, locomotor activity and survival could be rescued in both male and female animals when exposed to lower paraquat levels (5 mM). These effects are dependent on the autophagic machinery, as Spd failed to confer resistance to paraquat-induced toxicity and locomotor impairment in flies deleted for the essential autophagic regulator ATG7 (autophagy-related gene 7). Spd treatment did also protect against mild doses of another oxidative stressor, hydrogen peroxide, but in this case in an autophagy-independent manner. Altogether, this study establishes that the protective effects of Spd can be exerted through different pathways that depending on the oxidative stress scenario do or do not involve autophagy.     

Social preferences based on sexual attractiveness: a female strategy to reduce male sexual attention

Male sexual harassment of females is common across sexually reproducing species and can result in fitness costs to females. We hypothesized that females can reduce unwanted male attention by constructing a social niche where their female associates are more sexually attractive than themselves, thus influencing the decision-making of males to their advantage. We tested this hypothesis in the Trinidadian guppy (Poecilia reticulata), a species with high levels of male sexual harassment. First, we confirmed that non-receptive females were harassed less when they were paired with a more sexually attractive (receptive) female than with another non-receptive female. We then found that, indeed, females exploit this as a strategy to reduce sexual harassment; non-receptive females actively preferred to associate with receptive over non-receptive females. Importantly, when given access only to chemosensory cues, non-receptive females still showed this preference, suggesting that they use information from chemical cues to assess the sexual attractiveness of potential female partners. Receptive females in contrast showed no such preferences. Our results demonstrate that females can decrease male harassment by associating with females that are more sexually attractive than themselves and that they perform active partner choices based on this relative attractiveness. We propose that this strategy is likely to represent an important pathway by which females can construct social niches that influence the decision-making of others to their advantage; in this case, to reduce the sexual harassment they experience.     

Eavesdropping in crabs: an agency for lady detection

Although conspicuous courtship displays are an effective way of attracting the attention of receptive females, they could provide valuable information to rival males on the location of these females. In fiddler crabs, males that see a receptive female wave their single, greatly enlarged claw in a highly conspicuous courtship display. We test whether other males use this courtship display to alert them to the presence of receptive females that they cannot directly see. We show that male fiddler crabs (Uca mjoebergi) eavesdrop on the courtship displays of nearby males to detect mate-searching females. This allows males to begin waving before a female becomes visible. Furthermore, males appear to adjust their waving according to the information available: eavesdropping males wave 12 times faster than non-courting males but only 1.7 times slower than males in full visual contact with the female.     

Two New Species of Actinolaimidae Thorne, 1939 (Nemata: Dorylaimida) from China

Two new species of Actinolaimidae are described from China. Trachactinolaimus brevicaudatus n. sp. is 3.4-4.4 mm long; a = 40-60, b = 3.5-5.2, c = 20-21 in female and 34-39 in male; odontostyle length is 29-33 µm; spicules are 67-77 µm long; and the stoma has four onchia with numerous mural denticles. The female has a longitudinal vulva, and the male has 20 to 23 contiguous ventromedian supplements. Egtitus sinensis n. sp. is 1.7-2.2 mm long; a = 24-33, b = 3.1-3.9, c = 16-19 in female and 0.7-0.9 in male; odontostyle length is 25-29 µm; spicules are 55-56 µm long; and the prerectum 53-77 µm long. The cardia is short and blunt conoid, 13-19 µm long. The male has 12 to 13 ventromedian supplements at intervals of 2-3 µm.     

Histological Observations of Rotylenchulus reniformis on Gossypium longicalyx and Interspecific Cotton Hybrids

Observations on the development of reniform nematode (Rotylenchulus reniformis) on roots of Gossypium longicalyx, G. hirsutum, and two interspecific hybrids derived from them were made by light microscopy. Gossypium longicalyx is reported to be immune to reniform nematode, but the mechanism(s) for resistance are unknown. Penetration of G. longicalyx roots by female nematodes was confirmed, and incipient swelling of the females, indicating initiation of maturation of the reproductive system, was observed. Female maturation occurred up to the formation of a single embryo inside the female body but not beyond this point. In both hybrids, development was inhibited but progressed further than in the immune parent. Reactions ranged from highly compatible, with the formation of active syncytia and full development of females, to incompatible with little or no development of the female. Compatible plants showed characteristic hypertrophied cells, enlarged nuclei, dense cytoplasm, and partial dissolution of cell walls, whereas incompatible plant reactions included lignification of the cells adjacent to the nematode head, or the complete collapse and necrosis of the cells involved. The need to characterize reactions and to carefully select among the plants descended from the hybrids during the introgression process, as well as the importance of combining the results of reproduction tests with histological observation of the plant-nematode interactions, is discussed.