Presence Of Conspecific Females Research Articles

Males of Aedes aegypti show different clock gene expression profiles in the presence of conspecific females

BackgroundThe study of behavioral and physiological traits in mosquitoes has been mainly focused on females since males are not hematophagous and thus do not transfer the parasites that cause diseases in human populations. However, the performance of male mosquitoes is key for the expansion of populations and the perpetuation of mosquito species. Pre-copulatory communication between males and females is the initial and essential step for the success of copulation and studying the male facet of this interaction provides fertile ground for the improvement of vector control strategies. Like in most animals, reproduction, feeding, and oviposition are closely associated with locomotor activity in mosquitoes. Rhythmic cycles of locomotor activity have been previously described in Aedes aegypti, and in females, they are known to be altered by blood-feeding and arbovirus infection. In previous work, we found that males in the presence of females significantly change their locomotor activity profiles, with a shift in the phase of the activity peak. Here, we investigated whether this shift is associated with changes in the expression level of three central circadian clock genes.MethodsReal-time PCR reactions were performed for the gene period, cycle, and cryptochrome 2 in samples of heads, antennae, and abdominal tips of solitary males and males in the presence of females. Assays with antennae-ablated males were also performed, asking whether this is an essential organ mediating the communication and the variation in activity profiles.ResultsThe gene period showed a conserved expression pattern in all tissues and conditions, while the other two genes varied according to the male condition. A remarking pattern was observed in cry2, where the difference between the amplitude of expression at the beginning of photophase and the expression peak in the scotophase was greater when males were in the presence of females. Antennae ablation in males did not have a significant effect on the expression profiles, suggesting that female recognition may involve other senses besides hearing and olfaction.ConclusionOur results suggest that the expression of gene cryptochrome 2 varies in association with the interaction between males and females.Graphical abstract

Effect of interference and exploitative competition on associative learning by a parasitoid wasp: a mechanism for ideal free distribution?

Competition among foraging individuals of the same species occurs for several resources including, but not limited to, food, mates, nesting sites and, in parasitoid wasps, hosts. Individuals should therefore adapt their resource exploitation decisions accordingly and learning ability has been shown to be used in intraspecific competition situations to optimize fitness. We investigated the effect of interference and exploitative competition on aversive learning of a parasitoid wasp Venturia canescens (Hymenoptera: Ichneumonidae) as a model. We studied the effect of the presence of one to five competitors and of prior competitors, that is, the presence of parasitized hosts, on olfactory learning of wasps based on a Pavlovian conditioning system. We found that the odour of peppermint, which was previously positively associated with the reward of an oviposition, was rejected by females that experienced this odour while exploiting a patch of unparasitized hosts in the presence of conspecific females. Unexpectedly, the number of competitors in cases of interference did not increase the level of aversion to the peppermint odour. Thus conditioned stimuli previously encountered during the exploitation of a patch of parasitized hosts were rejected when females oviposited in the presence of unparasitized hosts. Our results suggest that intraspecific competition, by interference and by exploitation, acts as motivation for females to avoid stimuli related to competition; this may explain how an ideal free distribution can be reached by learning processes.

The effects of conspecific and heterospecific interactions on foraging and oviposition behaviours of two parasitoids of Diaphorina citri

ABSTRACTDirect observation was used to construct activity budgets for Diaphorencyrtus aligarhensis (Shafee, Alam & Agarwal) (Hymenoptera: Encyrtidae) and Tamarixia radiata (Waterston) (Hymenoptera: Eulophidae), foraging for nymphs of Asian citrus psyllid, Diaphorina citri Kuwayama (Hemiptera: Liviidae). Two populations of D. aligarhensis were used in experiments: a biparental population from Pakistan and a uniparental population from Taiwan. Parasitoids were provisioned with 20 D. citri nymphs, second through fifth instar; female parasitoids from all three populations foraged alone, in conspecific pairs, or in heterospecific pairs. Walking occupied approximately 40% of the activity budget of D. aligarhensis and ovipositor probing occupied 10–20%. In contrast, probing and walking each accounted for approximately 30% of the activity budget of T. radiata. The presence of conspecific females affected the activity budget of D. aligarhensis females, such that the focal female was observed walking less often and probing more frequently. Heterospecific females did not affect D. aligarhensis activity. These results suggest mutual interference may occur between D. aligarhensis females foraging on the same host patch. The behaviour of T. radiata was not significantly affected by the presence of conspecific or heterospecific competitors. These results are discussed with respect to the release of multiple species of natural enemies in the classical biological control programme targeting D. citri in California.

Conspecific females promote calling behavior in the noctuid moth, Pseudaletia adultera

AbstractChanges in female calling behavior in response to the presence of conspecific pheromones (pheromone autodetection) have been demonstrated in a number of moth species. However, the observed changes vary between species, and several ecological and adaptive explanations for autodetection have been proposed. We studied the effect of conspecific females on the calling behavior of the noctuid moth Pseudaletia adultera (Schaus) (Lepidoptera: Noctuidae, Hadenini), by comparing the age of first calling, as well as the onset and pattern of calling, when females were held individually or in the presence of conspecifics. Grouped females started calling at a lower age, a higher percentage of females called during the scotophase, and they called longer compared to females held in isolation. We also demonstrated that female antennae respond to each of the three main components of the sex pheromone – (Z)‐11‐hexadecen‐1‐ol, (Z)‐11‐hexadecen‐1‐yl acetate, and (Z)‐11‐hexadecenal – and that the response patterns differed from those of male antennae. By calling more and extending her calling window in presence of conspecific females, a female may increase her chances of accessing males. However, the potential benefits need to be considered within an ecological context, considering factors such as migration, oviposition, and foraging.

Does insect mother know under what conditions it will make their offspring live?

According to the optimal oviposition theory, the larval success of insects depends on the oviposition site selection by females. Females are expected to choose a site with many resources and few competitors or predators to allow the best performance for their progeny, assuming that "mother knows best." However, this is not systematically observed. The Aphidoletes aphidimyza larvae are generalist aphid predators and females consequently lay their eggs near or inside aphid colonies. The goal of this study was to investigate the impact of intraspecific competition on oviposition behavior of A. aphidimyza females. First, we counted the number of eggs laid by a female on a leaf with 20 aphids, in the presence of 0, 2, 4, or 6 conspecific eggs or in the absence of eggs but in presence of 3 virgin females. The same experiment was also performed under choice condition with 2 oviposition sites. Our results show that the presence of low densities of conspecific eggs, or the presence of conspecific females, have no significant impact on the number of eggs laid by A. aphidimyza females. One of the hypotheses advanced to explain these results is the advantages of conspecifics presence. At low densities, the presence of eggs on an oviposition site can indicate the suitability of the site for the females. The conspecific presence can also insure a dilution effect against predator and increase the presence of potential mating partners for this monogenic species.

Factors Affecting the Spatial Distribution of Oviposition Sites for Tandem Black Saddlebags Dragonflies (Odonata: Libellulidae)

Oviposition site location may be affected by (1) factors influencing the costs and benefits to the offspring (e.g., resource availability, competition, predation risk) and (2) factors influencing the costs and benefits to the female (e.g., predation risk or mate harassment). In cases in which both the male and female are involved in locating a site, costs and benefits may differ for each parent and the resulting oviposition site location may represent the outcome of selection pressures on one or both of them. We studied oviposition behavior in the black saddlebags dragonfly (Tramea lacerata Hagen), a species in which the male and female typically remain together (i.e., in tandem) while traveling among potential oviposition locations. Oviposition sites tended to be away from pond shoreline at the outer edge of the vegetation on the water’s surface. We found that tandems distributed their oviposition locations widely around the pond, and interactions with other dragonflies (typically other T. lacerata, either territorial males or tandems) led to a larger distance between consecutive oviposition locations. Interestingly, for 10% of the tandems, the female became separated from the male and oviposited solitarily multiple times. These solitary females spent significantly less time and traveled significantly smaller distances between successive oviposition sites than when in tandem. Our results indicate that while some aspects of oviposition behavior and site selection may be consistent between the male and female (e.g., the characteristics that make a site suitable), other aspects, such as the distribution of sites, may be a result of a differing benefits and costs for the two sexes, perhaps as a consequence of potential sperm competition.

Role of Egg-Laying Experience in Avoidance of Superparasitism by Fruit Fly Parasitoid <I>Fopius arisanus</I> (Hymenoptera: Braconidae)

The effect of prior oviposition experience on the avoidance of superparasitism was investigated in the solitary endoparasitoid Fopius arisanus (Sonan) (Hymenoptera: Braconidae), a highly successful biological control agent of tephritid fruit fly pests. Individual female wasps, either naive or having prior egg-laying experience in unparasitized hosts, were allowed to sequentially visit two coffee berries, each infested with a clutch of host eggs of the Mediterranean fruit fly, Ceratitis capitata (Wiedemann) (Diptera: Tephritidae). One of the two berries had been previously exploited by a conspecific female or the test-female herself. The wasp was allowed to visit the previously exploited or unexploited berry first while either in the presence or absence of a conspecific female. Naive wasps readily accepted previously parasitized hosts only when they visited the previously exploited fruit first. In contrast, wasps that had experienced prior oviposition, and wasps that visited the unexploited berry first, never accepted previously parasitized hosts, even when the test wasps contained relatively high egg-load or had been exposed to hosts in the presence of conspecific females. These results demonstrate a dramatic effect of egg-laying experience on the avoidance of superparasitism by this parasitoid. We discuss the adaptive value of avoiding superparasitism in relation to the mechanism of intraspecific competition in this species.

Influence of optical cues from conspecific females on escalation decisions during male–male interactions of jumping spiders

An important prediction from game theory is that the value of a resource influences the level to which male-male conflict escalates. An earlier experimental study showed that males of Hypoblemum albovittatum, a common salticid in New Zealand, can discern by sight alone whether a female is in the vicinity and that, having detected a female's presence, males escalate (i.e., adopt behaviour that is likely to put them at greater risk of injury). Seeing a bare moving cork, a conspecific male or a prey item also elicits escalation, but not to the level elicited by seeing a conspecific female. Here the earlier study is extended by using non-conspecific females in control tests and by undertaking experiments with an additional six salticid species. Findings from these experiments suggest that the ability of interacting males to detect by sight alone that a conspecific, instead of a non-conspecific, female is present is widespread in the family Salticidae and that it may be routine for salticid males to use information about the presence of conspecific females when making strategic decisions related to escalation during encounters with other males.

Phenotypic plasticity of Rhyzopertha dominica pheromone signaling: the effects of different hosts and presence of conspecific females on male produced aggregation pheromone.

Male Rhyzopertha dominica (F.) (Coleoptera: Bostrichidae) release an aggregation pheromone consisting of a blend of two components, dominicalure 1 (D1) and Dominicalure 2 (D2). Pheromone from single insects, in different contexts, was collected and measured to determine if this signal is phenotypically plastic. Release rates were lowered when males were moved from maize grains to groundnut kernels or when moved from solitary occupation of maize grain to grain occupied by seven females. The pheromone release was increased again once these moves were reversed. The release of D1 was more affected than D2: thus, on groundnuts or in the presence of females, less pheromone was released and the proportion of D1 in the blend was lowered. Possible reasons for the modifications of the signal are discussed.

The scent of food and defence: green leaf volatiles and toluquinone as sex attractant mediate mate finding in the European cockchafer Melolontha melolontha

Mate finding in the European cockchafer, Melolontha melolontha, has been investigated in the field. Our data suggest that mainly males show flight activity at dusk. In a landing cage bioassay, male cockchafers preferred cages baited with females over cages baited with males. Gas chromatographic analysis of beetle extracts with electronantennographic detection revealed the presence of electrophysiologically active compounds, among them toluquinone. In funnel trap bioassays none of these compounds was attractive towards males per se. A mixture of green leaf volatiles (GLV) mimicking the bouquet of mechanically damaged leaves was highly attractive to M. melolontha males. The attractiveness of the same GLV mixture was synergistically enhanced when toluquinone was added to the lure. GLV attract males to damaged leaves. Toluquinone as a sex pheromone indicates the presence of conspecific females and synergistically enhances the attractiveness of GLV.

Sound Production and Reproductive Ecology of Strongly Acoustic Fish in Africa: Pollimyrus Isidori, Mormyridae

[We have studied the reproductive ecology and bioacoustic signals of weakly electric mormyrid fish in Africa in order to discover the natural conditions under which acoustic signals are used and to gain insight into the evolution of their acoustic behaviour and hearing. Pollimyrus isidori migrated from a tributary of the Niger River (Mali) into a shallow (2-3 m) flood plain during the onset of the flooding seasons (August, 1991 and 1994). The fish were fully primed for reproduction upon entering the plain, females were significantly larger than males, and the sex ratio was skewed toward males (about 2 males per female). Males established territories (d ~ 1 m) within the roots of floating rafts of grasses, about 0.5 m below the water surface. Males produced conspicuous acoustic displays consisting of Grunts and Moans during the night (130 dB peak re 1 μLPa at approximately 10 cm). These sounds had a fundamental of 340 Hz, but the band-width of the grunt extended to over 3 kHz. Experiments at the field site with captive animals showed that male sound production was stimulated by the presence of conspecific females. The P. isidori repertoire included 3 additional sounds. Analysis of environmental noise showed that these communication sounds fall within a distinct spectral window, thereby minimizing potential interference from other aquatic animals and abiotic noise sources. Waveform analyses showed that the sounds remained coherent over short distances (0.5 m) but lost amplitude more rapidly than would be predicted in a deep water free-field., We have studied the reproductive ecology and bioacoustic signals of weakly electric mormyrid fish in Africa in order to discover the natural conditions under which acoustic signals are used and to gain insight into the evolution of their acoustic behaviour and hearing. Pollimyrus isidori migrated from a tributary of the Niger River (Mali) into a shallow (2-3 m) flood plain during the onset of the flooding seasons (August, 1991 and 1994). The fish were fully primed for reproduction upon entering the plain, females were significantly larger than males, and the sex ratio was skewed toward males (about 2 males per female). Males established territories (d ~ 1 m) within the roots of floating rafts of grasses, about 0.5 m below the water surface. Males produced conspicuous acoustic displays consisting of Grunts and Moans during the night (130 dB peak re 1 μLPa at approximately 10 cm). These sounds had a fundamental of 340 Hz, but the band-width of the grunt extended to over 3 kHz. Experiments at the field site with captive animals showed that male sound production was stimulated by the presence of conspecific females. The P. isidori repertoire included 3 additional sounds. Analysis of environmental noise showed that these communication sounds fall within a distinct spectral window, thereby minimizing potential interference from other aquatic animals and abiotic noise sources. Waveform analyses showed that the sounds remained coherent over short distances (0.5 m) but lost amplitude more rapidly than would be predicted in a deep water free-field.]

Neural androgen receptors and scent marking of male gerbils: Modulation by females

The involvement of brain cytosolic androgen receptors in the female-induced increase in scent-marking behavior of male Mongolian gerbils was studied. Scent-marking activities and serum testosterone concentrations were measured in low-marking control males and in males with increased scent-marking activities, stimulated by the presence of conspecific females in the same room. For every individual male the concentrations and affinities of androgen receptors were determined in four parts of the brain, which contained the hippocampus, septum, corpus striatum, amygdala, stria terminalis, and the hypothalamus. Compared to the basal unstimulated period, the marking activities of male gerbils significantly increased 58% during the presence of female conspecifics in their housing room. The serum testosterone concentrations did not change significantly during female presence. The association constants of the cytosolic androgen receptors were higher in female-stimulated males compared to isolated control males. In contrast, the cytosolic receptor concentration was reduced. The difference reached significance in one of the brain parts. Individual levels in scent-marking activities could not be explained by correlation with individual androgen receptor parameters. The present results suggest that increased androgen binding in the brain may be involved in the elevation of scent-marking activities in male gerbils, caused by urinary chemical signals of female conspecifics.

Experimental Assessment of Factors Affecting the Distribution of Adult Female Tree Lizards

In the Sonoran desert of southeastern Arizona, we conducted transplant experiments with adult female tree lizards (Urosaurus ornatus) to test the hypothesis that the presence of conspecific females plays a role in their settlement and home range use. We have observed aggregations of female tree lizards, most frequently in dry washes of mesquite (Prosopis juliflora) woodland, but also in flatland desert habitat where the experiments were conducted. We did two types of transplants. In the first, we added a transplant female to the home range and territory of a resident pair (male-female), thereby creating a two-female site. In the second, we removed the resident female and replaced her with a transplant female, thus producing a one-female site

Sex ratios of Spalangia endius (Hymenoptera: Pteromalidae), in relation to current theory

Abstract. 1. Spulungiu endius Walker is a solitary parasitoid of house fly puparia.2. The sex and size of S.endius was not related to host size.3. In the laboratory the mean sex ratio of all offspring of nine groups, each comprising twenty females, was consistently female‐biased (x = 83.5%, range 79–87%). The sex ratio in the field was less female‐biased and showed greater fluctuation (61–75%). This may be a consequence of females laying male eggs before mating, some females remaining unmated, possible shorter adult life expectancy in the field than in the laboratory, and, perhaps, the presence of conspecific females.4. The sex ratio of offspring of individual females varied from 66% to 100% females, and males were deposited early in the oviposition sequence.5. Although a large number of fly puparia died before adult flies or parasitoids emerged (64.5%; n= 5874), there was no differential mortality of either sex.6. Our results fit no general sex ratio hypothesis and we conclude that (i) the genetic nature of sex ratios in these insects needs careful examination, and (ii) the prevalence of female‐biased sex ratios in solitary parasitoids needs investigation.

Chemically Mediated Reproductive Isolation between Cabbage Looper and Soybean Looper Moths (Lepidoptera: Noctuidae)

In release-recapture studies, male cabbage looper (CL), Trichoplusia ni (Hubner), and soybean looper (SBL), Pseudoplusia includens (Walker), moths readily distinguished between and responded selectively to their respective conspecific females. Consequently, most males were recaptured in traps baited with conspecific females, fewer with both females in combination, and the least with heterospecific females. Actographic analysis indicated that males tend to fly more frequently in the presence of conspecific females and that males arrest female activity. CL males also arrest the movement of SBL males and females. Although CL and SBL males flew to calling females of both species in an observation chamber, only the CL females aggressively rejected courting SBL males. Thus, before courtship, CL and SBL females stimulate and attract discriminating males that subsequently arrest the movement of females and probably that of competing males.

Territorial and courtship songs of birds.

THE usual interpretation of passerine song is that it simultaneously attracts potential mates and repulses neighbouring territory holders1. The male black-throated green warbler (Dendroica virens, family Parulidae), however, sings two similar but distinct songs2: song A (Fig. 1a) chiefly in the presence of conspecific males and song B (Fig. 1b) chiefly in the presence of conspecific females. There seem thus to be separate songs for territorial defence (song A) and courtship and pair-bond maintenance (song B).

Pheromonal stimulation of the sexual activity of males of the sheep blowfly Lucilia cuprina (Calliphoridae) by the female

Males of the Australian sheep blowfly, Lucilia cuprina (Wied.): Calliphoridae, are sexually stimulated by the presence of conspecific females. A stimulatory effect of the odour of females is demonstrated but a greater effect is seen when the males are able to contact the females. Male flies do not attain their maximal level of responsiveness to the odour of mature females until their 4th day after emergence. Neither is maximal male response to odour from females achieved until the females have reached their 2nd or 3rd day after emergence. The relatively poor stimulation by females of less than 3 days after emergence is reflected in their pattern of acceptance of males for mating. Protein feeding of the male flies causes a heightening of their potential sexuality. Protein fed assay males are more stimulated by the odour of protein fed females than by that of non-protein fed females, and they show no response to odour of protein fed and non-protein fed males. Non-protein fed assay males are equally stimulated by protein fed females, non-protein fed females and protein fed males but not by non-protein fed males. Selective orientation by males toward a protein fed female but not a non-protein fed female in close proximity to them may be largely due to differences in the behavioural traits of those females.