Effect of female group size on harem male roosting behavior of the Indian short-nosed fruit bat <Emphasis Type="Italic">Cynopterus sphinx</Emphasis>

Mate guarding has been known to incur costs and cause constraints for harem males in many polygynous species. However, the effect of female group size on the harem male’s time budget in bats has received very limited attention. The Indian short-nosed fruit bat, Cynopterus sphinx, exhibits resource defense polygyny, in which tent roosting males construct tents and defend multiple female bats. We studied the effect of female group size on three aspects of harem male behavior: social grooming by reciprocal licking, tent maintenance, and tent guarding in the mast tree Polyalthia longifolia. In the process of reciprocal licking, all the bats in the harem were drenched in saliva before emergence, and this activity was positively and significantly correlated with female group size. Once females departed for foraging, harem males remained in their respective tents at night-time between intermittent foraging bouts and engaged in tent maintenance and tent guarding. Time invested by harem male bats in tent maintenance and tent guarding were positively and significantly correlated with female group size. Harem males extended their presence in tent by utilizing tents as feeding roosts. Female group size also influenced the emergence time of harem male bats, where males with largest group emerged later than did the smallest group. Likewise, harem male with the smallest group had more time available for foraging than the male with the largest group. Findings of this study suggest that having a larger harem may indeed be costly for the males by reducing their foraging time.     

Monogamous mating system and sexuality in the gobiid fish, <Emphasis Type="Italic">Trimma marinae</Emphasis> (Actinopterygii: Gobiidae)

The mating system and sexuality of the gobiid fish Trimma marinae were investigated in aquaria and by gonadal histological examination. The male to female sex ratio in the study aggregation was female biased (14:27), and females were larger than males. T. marinae were monogamous because they established continuous pairs and spawned repeatedly with the same individuals. Observations of aggressive behavior suggested that the monogamous mating system resulted from female mate guarding. We also performed a rearing experiment to test whether sex change occurs in this species. None of the males or females reared separately in aquaria for 63 days changed sex. Additionally, gonadal histology revealed that mature fish had unisexual gonads (testis or ovary). These results strongly suggest that T. marinae is gonochoristic. However, immature fish had a bisexual gonadal structure, indicating juvenile hermaphroditism.     

Mate guarding and male mate choice in the chameleon grasshopper <Emphasis Type="Italic">Kosciuscola tristis</Emphasis> (Orthoptera: Acrididae)

In the wild, male chameleon grasshoppers (Kosciuscola tristis) are frequently observed mounted on the back of females even when not in copula, and will fight off other usurping males. If this behaviour is mate guarding and reflects investment in male mate choice, then we expect males to preferably guard females based on reliable cues of quality. Cues for female quality likely include female size and egg development that together may indicate fecundity. We investigated male mate choice in the field expressed as mate-guarding preference, by comparing size and egg development in guarded and unguarded females. We found no difference between guarded and unguarded females in measures of fecundity or body size. The majority of females sampled did not contain any viable eggs. This finding suggests that male K. tristis indiscriminately guard females in a scramble mating system.     

Susceptibility and Interactions of <Emphasis Type="Italic">Drosophila suzukii</Emphasis> and <Emphasis Type="Italic">Zaprionus indianus</Emphasis> (Diptera: Drosophilidae) in Damaging Strawberry

Drosophila suzukii (Matsumura) has been recently detected causing damage to strawberries in Brazil. Infestation in strawberry culture has often been observed jointly with the presence of Zaprionus indianus Gupta. This study investigated the susceptibility of strawberries at three ripening stages to infestation of D. suzukii and Z. indianus and their interaction. In the laboratory, strawberries cv. Albion at different ripening stages (green, semi-ripe and ripe) were exposed to D. suzukii and Z. indianus for 24 h in choice and no-choice bioassays. Additionally, we evaluated the effects of mechanical damage incurred artificially or by D. suzukii oviposition on Z. indianus infestation. In no-choice bioassay, there were no significant differences in fruit susceptibility to D. suzukii infestation at different ripening stages. However, in choice bioassay, D. suzukii adults preferred to oviposit on R fruit. The presence of mechanical damage did not increase susceptibility of fruit to D. suzukii oviposition. For Z. indianus, there was greater susceptibility of R fruit in relation to SR and G fruit in both the choice and no-choice bioassays. There was a significant and positive interaction of mechanical damage and damage caused by D. suzukii to R fruit and infestation by Z. indianus, which was not observed in SR and G fruit. Although infestation of Z. indianus is related to attack damaged or decaying fruit, this work shows that this species has the ability to oviposit and develop in healthy strawberry fruit with and increased infestation level when the fruit has damage to its epidermis.     

Effects of male apparent length on female preference for absolute body size in <Emphasis Type="Italic">Xiphophorus helleri</Emphasis>

Female green swordtails (Xiphophorus helleri) prefer males of longer body and sword lengths, which may reflect perceptual constraints. Larger males project a larger image onto the female’s retina at a given viewing distance, which may elicit greater stimulation of the visual system and a stronger behavioral response. This study investigates the effects of male apparent size, as affected by proximity and sword length, on female preference for absolute body size in X. helleri. Females were presented pairs of dummy males in ten treatments organized into six categories: (1) the Actual Length Control where identically sized males were held at different viewing distances from the female; (2) the Sword Compensation Treatment in which viewing distance and apparent length (body + sword) were held constant, pairing sworded with swordless dummies of equal total length; (3) the Body Length Preference Treatment where male distance from the female was held constant, while varying body size; (4) the Apparent (Sword) Length Preference Treatments where male distance from the female was held constant, while varying sword length; (5) the Apparent Length Controls where body length, sword length, and viewing distances varied while holding apparent length constant; and (6) the Experimental Treatment in which the smaller-sworded male of the pair appeared larger. In each of the Actual Length Control, Body, and Sword Length Treatments, females preferred the closer, larger-bodied, and longer-sworded males, respectively. However, females exhibited preferences in neither any of the Apparent Size Control treatments nor any of the Sword Compensation Treatment. Additionally, females in the Experimental Treatment preferred the apparently longer-sworded dummy to the male whose sword was actually longer. These results suggest that female preference for male body and sword length is based on the male’s apparent rather than actual size.     

Social Relationships between Males and Females in Rock Lizard (<Emphasis Type="Italic">Darevskia brauneri</Emphasis>, Lacertidae). 2. Searching for an Area of Stable Residence,Criteria for Choice of Social Partner,and Factors of Friendly Integration of Dyads

Long-termed intersexual friendly relationships between males and females of the Brauner’s lizard are characterized by high levels of spatial association and high frequency of affiliative behavior between partners (see report 1). In present article we consider changes in the frequency of affiliative behavior in males (Am) and females (Af) after the first appearance of female on the male’s territory and conditions for the transition of lizard to stable residency (SR). Generally, Am becomes stable during the first days of initial period and does not change later. This fact suggests that in most instances male’s choice criteria are some peculiarities of the female’s exterior. In the initial period, Af is always low, however, gradually rises to the level of Am if Am is high. The main condition of female’s SR is high Am of the owner of the territory where female establishes her comfort areas. Hence, social partner choice in female is based on male’s behavior, and high Am triggers the formation of friendly interrelations. Significant correlation between social and sexual interrelations is absent. As can be judged by female’s reactions to male’s sexual behavior, his sexual activity is rather a factor of social disintegration. Structure of costs for social partner search is different in males and females, and these differences well harmonize with differences in gender strategies of partner choice. The social strategies are well interpreted in terms of the optimal foraging theory.     

Grouping Patterns and Competition Among Female <Emphasis Type="Italic">Pan troglodytes schweinfurthii</Emphasis> at Ngogo,Kibale National Park,Uganda

In mammals, access to mates is probably the most important influence on male reproductive success, whereas foraging efficiency is probably the most important influence on female reproductive success Emlen and Oring (Science 197:215–223, 1977). Male chimpanzees (Pan troglodytes) are highly gregarious and form cooperative relationships with other males. In contrast, female social relationships vary within and between populations. Females in most East African populations, e.g., Gombe, Mahale, Kibale-Kanyawara, are less gregarious than males and spend most of their time alone or with only their dependent offspring. Researchers have attributed low female gregariousness to the high potential for feeding competition. I provide the first data on association patterns and agonistic interactions of female chimpanzees (Pan troglodytes schweinfurthii) from the unusually large Ngogo community, Kibale National Park, Uganda. Ngogo females were less gregarious than males, but spent a mean of 64% of their time in association with ≥1 other females and as much time in all-female parties as they did alone. Further, female dyads associated nonrandomly and they formed associative cliques. Association levels within cliques were similar to those among the relatively gregarious West African chimpanzee females at Taï (Pan troglodytes verus) and among bonobo (P. paniscus) females. Agonistic interfemale interactions were extremely rare, and monthly mean party size and the numbers of anestrous females per party do not correlate significantly with fruit availability. Thus, Ngogo females maintained relatively high levels of gregariousness, but avoided detrimental feeding competition by preferentially associating with a small subset of other community females.     

Life History and Mating Behavior of <Emphasis Type="Italic">Rhagoletis solanophaga</Emphasis> (Diptera: Tephritidae), a Non-Diapausing Species with Highly Variable Mating Duration

As an initial contribution to understanding the adaptive value of behavioral and life-history strategies, the life cycle and mating behavior of an unstudied species of tephritid fruit fly in the genus Rhagoletis are characterized for the first time. Over a 9-month fruiting period, a small proportion of Solanum appendiculatum Dunal (< 10 %) was found to be infested with a single larva of Rhagoletis solanophaga (Hernández & Frías). The average duration of R. solanophaga lifecycle (c.a. 140 days from egg laying to death of adults) exceeded the three month fruitless period. Additionally, R. solanophaga is capable of exploiting Solanaceous plants in at least two genera. These features could have selected for a non-diapausing species of Rhagoletis, a genus where most species are univoltine. Nevertheless, some individuals in the population became dormant. As other members of the genus, R. solanophaga exhibited a resource defense mating system with forced copulations and multiple mating. Both males and females could be highly promiscuous and individual mating success exhibited a wide range of outcomes. Regardless of mating success, mated females stored similar amounts of sperm in two spherical spermathecae. Long copulations were observed, perhaps functioning as a form of mate guarding with probable disadvantages for females. We outline hypotheses and opportunities for future comparative studies examining sperm competition and mate guarding.     

Effect of gut bacteria on fitness of the Chinese citrus fly, <Emphasis Type="Italic">Bactrocera minax</Emphasis> (Diptera: Tephritidae)

A likely symbiotic association between tephritid fruit flies and gut bacteria has been recognized since the beginning of the last century. However, direct evidence for a link between gut bacteria and fruit fly fitness is still limited or absent for many species. Similar to other tephritids, the gut of Bactrocera minax (Enderlein) (Diptera: Tephritidae) is known to contain bacteria throughout the life stage, but what, if any, impact these bacteria have on B. minax fitness is entirely unknown. In order to elucidate the effects of bacteria on the fitness of B. minax, resident bacteria were isolated from the adult gut using culture-dependent techniques. Adult fly diets were subsequently supplemented with three bacterial isolates (Klebsiella pneumonia, Citrobacter braakii and Pantoea dispersa), or bacteria were removed from flies by antibiotics treatment: untreated adults provided a control. Adult fitness parameters (male and female longevity, female fecundity, male copulation number) were measured for the two treatments and one control group. Results were complex depending on the fitness parameter measured and the bacterial species. Compared to the controls, antibiotic treated B. minax had significantly decreased fecundity, but male and female longevity was increased. When flies were fed diets supplemented with any of the three bacterial isolates, female fecundity was significantly enhanced. However, only Citrobacter braakii significantly increased male mating frequency than control males. The results show that gut bacteria directly influence fitness of B. minax, but impacts are dependent on the bacterial species and the fitness parameters measured.     

Sources contribution for benthic invertebrates: an inter-lake comparison in a flood plain system

Dwarfism in males is a common phenomenon in planktonic monogonont rotifers. Considering the small body size of males, some studies suggested that the development time of male rotifers is faster than that of females. However, empirical studies associated with such a speculation are scarce. In this study, we used two common rotifer species, Brachionus calyciflorus and Brachionus plicatilis (each with two geographical populations), to test the hypothesis that the development time of dwarf males is significantly shorter than that of females. Results showed that male eggs (embryos) were deposited much faster than female eggs (embryos) in both Brachionus species. However, the embryonic development time of these small male eggs (embryos) was longer than that of large female eggs (embryos). As a result, males needed significantly longer total development time than females. The total development time of males was 2–3 h longer than that of females in both Brachionus species. Male-producing and female-producing females in the two Brachionus species did not show any difference in development time. Because sexual reproduction begins at high population densities in both species, postponement of development in males will be advantageous by decreasing mating costs in male rotifers.     

A preliminary study on distributions and oviposition sites of <Emphasis Type="Italic">Drosophila suzukii</Emphasis> (Diptera: Drosophilidae) and its parasitoids on wild cherry tree in Tokyo,central Japan

Distributions and oviposition sites of Drosophila suzukii (Matsumura) and its parasitoids on wild cherry tree were studied in early summer in a suburb of Tokyo, central Japan. Adults of D. suzukii occurred in the foliage layer as well as in the undergrowth layer. The number of D. suzukii that emerged did not significantly differ between wild cherry fruit collected from the foliage layer and those from the undergrowth layer. In addition, the number of D. suzukii that emerged per fruit decreased when fruit were left on the ground longer. It is therefore assumed that D. suzukii females rarely oviposit eggs in fallen wild cherry fruit. The suzukii-associated type of Ganaspis brasiliensis (Ihering) was the major parasitoid that emerged from D. suzukii in the study area. The rate of parasitism by this parasitoid did not significantly differ between larvae in fresh fruit from the foliage layer and those in fallen fruit from the undergrowth layer. This may also suggest that this wasp rarely attacks D. suzukii larvae in fallen fruit. Adults of the suzukii-associated type of G. brasiliensis, Asobara sp. TK1, and Leptopilina japonica that attack D. suzukii were mainly collected from the foliage layer. On the basis of the present results, some proposals for the control of D. suzukii were discussed.     

Lekking Behaviour and Male-Male Rivalry in the Melon Fly <Emphasis Type="Italic">Bactrocera cucurbitae</Emphasis> (Coquillett) (Diptera: Tephritidae)

Most studies on the sexual behaviour of tephritid fruit flies are conducted in laboratory or field cage settings. Here, we present field data on the mating behaviour of the melon fly, Bactrocera cucurbitae (Coquillett). A number of Tephritidae are lekking species, forming aggregations in which males fight to defend a small territory where they court females and mate. Our results confirm that males of the melon flies congregated and engaged in wing vibration in the late afternoon on non-host plants, such as Ficus carica, Cydonia oblonga and Prunus persica which bordered cucurbit fields. The nature and outcome of male-male aggressive encounters are described, and a high degree of female mate selectivity is documented.     

Stridulation and Courtship Behaviour of Four Endemic Pill-Millipedes, <Emphasis Type="Italic">Arthrosphaera</Emphasis> spp. (Sphaerotheriida: Arthrosphaeridae) of the Western Ghats of India

Mating behaviour of four species of pill-millipedes under genus Arthrosphaera Pocock (Arthrosphaera dalyi Pocock and Arthrosphaera disticta Pocock, Arthrosphaera fumosa Pocock and Arthrosphaera magna Attems) endemic to the Western Ghats of Southern India was analyzed in mesocosms. Stridulation is a classical communication signal in males as well as females for mate selection. Conglobation (or volvation) is a mechanism of defence to protect from disturbance or avoid predation. If male touches female or vice versa they conglobate. To avoid disparity among individuals of the same species, volvating pill-millipedes evolved stridulation behaviour for communication. The male broadcasts appropriate signal to female through stridulation to advertise its interest in mating. The females test the male’s fitness by conglobation and suitable male uncoils the partner through stridulation signals. Male with its pygidium successfully uncoils the female and attains suitable orientation for courtship. Male pairs with female ventro–ventro contact in opposite direction to deposit sperm into the vulva of female. The duration of mating varies from species to species and usually a lapse from 3 to 30 min. Vibration generated by stridulation is species-specific and its perception mechanism in pill-millipedes is yet to be clearly understood. Present study emphasized the structure of stridulatory organs, mechanism of stridulation and pattern of mating behaviour in four species of pill-millipedes.     

Influence of Nematode Parasitism,Body Size,Temperature, and Diel Period on the Flight Capacity of <Emphasis Type="Italic">Sirex noctilio</Emphasis> F. (Hymenoptera: Siricidae)

Sirex noctilio F. (Hymenoptera: Siricidae) is a woodwasp of pine trees that has recently invaded and established in North American forests. Although S. noctilio has had a limited impact in North America to date, there is some concern that it could have a significant impact on pine plantations, especially in the southeastern U.S.A. Moreover, there are few data on the flight capacity of male S. noctilio. We found no association between parasitism by D. siricidicola and whether or not S. noctilio initiated flight on the flight mill. Male wasps that were parasitized by nematodes were heavier than non-parasitized males, but there was no significant difference in mass between parasitized and non-parasitized females. We also examined the flight capacity of male and female S. noctilio in relation to nematode parasitism, body mass, temperature (for only males), and diel period. Body mass, temperature, and diel period affected flight in S. noctilio such that wasps were generally observed to fly faster, farther, and more frequently if they were heavier, flying at warmer temperatures, and flying during the photoperiod. The fact that nematode-parasitized male wasps were found to fly farther than the non-parasitized males is consistent with the hypothesis that nematode parasitism does not negatively affect the flight capacity of S. noctilio.     

Reproductive interference between two serious pests,oriental fruit flies <Emphasis Type="Italic">Bactrocera carambolae</Emphasis> and <Emphasis Type="Italic">B. dorsalis</Emphasis> (Diptera: Tephritidae), with very wide but partially overlapping host ranges

Bactrocera carambolae and B. dorsalis (Diptera: Tephritidae) are extremely destructive pests of fruits and vegetables in the Asia-Pacific region. Earlier reports have described that B. carambolae and B. dorsalis, respectively, use mainly star fruit and mango, suggesting a certain level of host partitioning which can be ascribed neither to differences in larval food qualities nor host-specific parasitoid mortality. This study specifically examined reproductive interference (antagonistic sexual interaction) between B. carambolae and B. dorsalis as a potential factor strongly affecting their host partitioning. We observed mating behaviors, especially interspecific courtships and mating, by cohabiting the conspecific and heterospecific pairs together. Consequently, we quantified their effects on the reproductive success of females. Males of both species frequently courted their own females, but they also courted females of other species. Courtship refusal by females was not selective in males of either species. This incomplete discrimination of both sexes led to frequent occurrences of interspecific sexual interactions in both species, but only B. carambolae females showed reduced reproductive success. These results suggest that B. dorsalis, superior in reproductive interference, can occupy high-quality mango, whereas B. carambolae, inferior in reproductive interference, must use low-quality star fruit.     

Female preference for both behavior and morphology traits of the male Japanese newt <Emphasis Type="Italic">Cynops pyrrhogaster</Emphasis>

Males of the Japanese newt (Cynops pyrrhogaster) display complex courtship behaviors and are sexually dimorphic in terms of tail morphology. Pair encounter experiments were conducted to investigate which males are preferred by female newts. Male courtship behavior consisted of four stages, namely, Approach, Fan, Creep and Spermatophore deposition. The Fan behavior was classified into four sub-patterns. Males which showed a specific sub-pattern were accepted at a significantly higher probability by females than males which showed the other sub-patterns. The accepted males had a smaller snout–vent length, higher tail, and larger body mass than the rejected males, and their body weight was relatively heavier. Our results suggest that females of C. pyrrhogaster select their mates based on both behavioral patterns and morphological characters.     

Comparative study on intestinal bacterial communities of <Emphasis Type="Italic">Boleophthalmus pectinirostris</Emphasis> and <Emphasis Type="Italic">Periophthalmus magnuspinnatus</Emphasis> with different sexes and feeding strategies

Intertidal mudflats are unique, highly productive ecosystems. Boleophthalmus pectinirostris and Periophthalmus magnuspinnatus are common fish species that are distributed in the intertidal mudflats of the Yangtze Estuary in China. They perform important ecological functions and have different feeding strategies. Herein, we studied the intestinal microbial diversity and structure of wild B. pectinirostris and P. magnuspinnatus with different sexes and feeding strategies during their breeding season. Gut samples of B. pectinirostris and P. magnuspinnatus individuals (female:male ratio?=?1:1) were collected and subjected to high-throughput DNA sequencing. The results showed Proteobacteria was the most dominant phylum in all the four sample groups: 73.5% in the males and 52.6% in the females of B. pectinirostris and 40.2% in the males and 40.9% in the females of P. magnuspinnatus. Aeromonas, Shewanella, Halomonas, and Acinetobacter of the phylum Proteobacteria were dominant genera in all the sample groups and accounted for 62.13% of the ten dominant genera. The diversity of the intestinal microflora in the omnivorous P. magnuspinnatus was significantly higher (P?<?0.05) than that in the herbivorous B. pectinirostris. Beta diversity, including PCoA and UPGMA of unweighted UniFrac distances, showed that B. pectinirostris samples were clustered together, and P. magnuspinnatus samples were clustered together, implying the effect of the feeding habits on the microbial community structure is more considerable than that of sex.     

An omnivorous arthropod, <Emphasis Type="Italic">Nesidiocoris tenuis</Emphasis>, induces gender-specific plant volatiles to which conspecific males and females respond differently

Nesidiocoris tenuis Reuter (Heteroptera: Miridae) is an omnivorous mirid bug that preys on diverse generalist herbivorous arthropods. N. tenuis adults are attracted to volatiles from plants induced by their prey, such as tobacco cutworms (CCW) (Spodoptera litura larvae) and two-spotted spider mites (Tetranychus urticae). N. tenuis adults also induce volatiles when they infest plants. In this study, we focused on olfactory responses of N. tenuis males and females to volatiles from eggplants and sesame plants induced by conspecifics of the same or different gender by using a Y-tube olfactometer. Males were attracted to volatiles from plants of both species induced by either males or females. The male preference was biased to volatiles from plants of both species induced by females, probably because the biased response would facilitate their mate-finding. Females were attracted only to volatiles from plants of both species induced by females. Mating occurs multiple times in this species. Thus, the responses would indirectly affect mating of males and females. Slight but significant qualitative and quantitative differences were detected between the volatiles of plants of both species induced by N. tenuis females and those of the plants induced by conspecific males. N. tenuis might use such differences in their gender-specific responses.     

Female Responses to Synthetic Pheromone and Plant Compounds in <Emphasis Type="Italic">Agriotes brevis</Emphasis> Candeze (Coleoptera: Elateridae)

Traps baited with synthetic pheromone components of Agriotes brevis [geranyl butanoate + (E,E)-farnesyl butanoate] captured significantly higher numbers of not only male, but also female beetles, compared to unbaited controls. Catches of both sexes showed a clear positive relationship with increasing doses. In electroantennogram tests, antennal responses of females and males to a number of known Agriotes pheromone components, identified from pheromone glands, showed a similar trend, with geranyl butanoate eliciting the strongest responses. This suggests that the female and male A. brevis antennae are similar with respect to the perception of pheromone compounds, and female beetles have the sensory capabilities to perceive the pheromone components which they produce. Addition of the plant-derived compounds (Z)-3-hexenyl acetate, methyl benzoate, (Z)-3-hexenol and methyl salicylate (identified earlier from foliage as attractive for A. brevis) to the synthetic pheromone significantly increased catches. All the above results suggest that geranyl butanoate and (E,E)-farnesyl butanoate are constituents of an aggregation pheromone of A. brevis, in contrast to the general view of click beetle pheromones being “classical” sex pheromones. These findings could be useful for more precise monitoring and forecasting of damage, based on female catches.