Effects of large-scale cattle grazing on populations of Coenonympha glycerion and Lasiommata megera (Lepidoptera:Satyridae)

The effects of large-scale cattle grazing by herdsmen (Allmende) on the populations of two butterfly species, Coenonympha glycerion and Lasiommata megera, were analysed on a study plot in the foothills of the Eastern Carpathians, Republic of Ukraine, in the summer and autumn of 1995. In all, 280 individuals of C. glycerion (115 females) and 230 individuals of L. megera (61 females) were individually marked. At recapture rates of 35 to 39%, maximum population size was calculated at 410 and 434 individuals. C. glycerion reacted to high densities by shifting to smaller neighbouring habitats. An increased emigration rate was recorded for L. megera when the population maximum was reached.Both species essentially require habitats formed by the activity of cattle. C. glycerion significantly preferred south facing woodland margins, close to moderately and infrequently grazed grassland. Heavily grazed areas were avoided. L. megera mainly occupied well-trod cattle paths or landslips with rather sparse vegetation, induced by cattle. Preferred habitats are characterized by linear structures for patrolling, steep slope areas and a wide range of nectar resources. Smaller, sporadically used cattle paths did not show these features and were occupied mainly by males at times of high population densities. Both species depend on patchy habitat mosaics which will be lost by intensification as well as by a complete cessation of grazing. The low-intensity, large-scale system utilized in the Eastern Carpathians is therefore favourable to both species.     

Sexual inhibition of female Queensland fruit flies mated by males treated with raspberry ketone supplements as immature adults

Raspberry ketone (RK) dietary supplements accelerate the emergence of sexual behaviour in developing Queensland fruit fly (Q‐fly) males and show promise as a pre‐release supplement for use in sterile insect technique (SIT) programs. However, the value of RK supplements in SIT programs would be greatly reduced if RK‐treated males are ineffective at inducing sexual inhibition in mated females. To test the effectiveness of matings by RK‐treated males, we here investigate the remating propensity of females mated by RK‐treated (1.25% or 5% RK in food) and RK‐untreated (control) males. Tested males received RK supplements mixed in sugar and yeast hydrolysate for 2 days after emerging and then received only sugar. To test for male age‐dependent effects, virgin females were mated to treated and untreated males that were 6, 8, 10, 20 or 30 days old. To test for persistence of sexual inhibition, mated females were tested for remating propensity at 1, 7 or 15 days after their first mating. RK‐treated males did not differ from control males in copula duration, and females mated by RK‐treated males did not differ from those mated by control males in remating propensity, second copula latency or second copula duration. RK‐treated Q‐fly males not only mate at younger ages but also their matings are as effective as those of untreated controls at inducing sexual inhibition in mates.     

Laboratory breeding studies of freshwater crayfish, Austropotamobius pallipes (Lereboullet)

SUMMARY. 1. Mature crayfish, collected from an Irish lake before breeding had started, were held in breeding combinations and their mating and brooding activities observed.
2. All mating attempts were initiated by the male. A single mating led to spawning within 6 days but a subsequent mating cancelled the effects of the first. Males mated more often when there were more females present. Males lacking a major cheliped mated less often than did normal males.
3. Larger males mated more often than did smaller males, and although males showed no female size preference, matings were less frequent and generally unsuccessful when males were much larger than females; the female was usually killed. Large females mated successfully with smaller males.
4. Females held at high densities with a larger male mated earlier than at low densities. However, aggression also increased with density; at high densities males fought and killed females.
5. Males held in pairs without females fought; in occasional mating attempts spermatophores were not positioned correctly. Paired females rarely fought; all spawned normally although unmated. Although their eggs soon died and were removed during grooming, brooding behaviour continued for at least 2 months.
6. Brooding females held in pairs shed pleopodal eggs during aggressive encounters. Females held singly showed a lower initial rate of egg loss.     

The effect of male mating history on paternal investment, fecundity and female remating in the seed beetle Callosobruchus maculatus

1. In many organisms, males provide nutrients to females via ejaculates that can influence female fecundity, longevity and mating behaviour. The effect of male mating history on male ejaculate size, female fecundity, female longevity and female remating behaviour in the seed beetle Callosobruchus maculatus was determined.
2. The quantity of ejaculate passed to females declined dramatically with successive matings. Despite the decline, a male's ability to fertilize a female fully did not appear to decline substantially until his fourth mating.
3. When females multiply mated with males of a particular mated status, the pattern of egg production was cyclic, with egg production increasing after mating. Females multiply mated to virgins had higher fecundity than females mated to non-virgins, and females mated to twice-mated males had disproportionately increased egg production late in their life.
4. Females that mated to multiple virgins, and consequently laid more eggs, experienced greater mortality than females mated only once or mated to non-virgins, suggesting that egg production is costly, and rather than ameliorating these costs, male ejaculates may increase them by allowing or stimulating females to lay more eggs.
5. Females mating with non-virgin males remated more readily than did females mated to virgins. Females given food supplements were less likely to remate than females that were nutritionally stressed, suggesting that females remate in part to obtain additional nutrients.     

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

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

Comparative phenology of four satyrine butterflies inhabiting dry grasslands in Sweden

The phenology of the satyrine butterflies Coenonympha pamphilus L., Lasiommata megera L., Hipparchia semele L. and Maniola jurtina L. was compared under seminatural conditions with Festuca ovina as the food-plant. Coenonympha pamphilus shows striking phenotypic plasticity as revealed by initiating cohorts at successive dates during the whole flight period. Growth rate is finely tuned depending on season, and larvae can hibernate in any of the three first instars, but also aestivate when 'surplus'time is available. Hipparchia semele and M. jurtina have reduced growth rates as last instar larvae at the beginning of summer. Lasiommata megera , which has an obligate bivoltine life cycle, shows the highest overall growth rate of all four species. Results suggest that egg size variation has consequences for the life cycles of these species.     

Effects of gender and mating status on self-directed dispersal by the whitefly parasitoid Eretmocerus eremicus

1. The impacts of gender and mating on short‐range (< 10 km) dispersal by the whitefly parasitoid Eretmocerus eremicus Rose and Zolnerowich (Hymenoptera: Aphelinidae) were examined. A fluorescent dust‐marking technique was also tested. 2. In a vertical flight chamber, female flight duration was significantly longer than that of males, and unmated parasitoids flew for longer than mated parasitoids. The mean flight durations were: unmated females 34 min, mated females 10 min, unmated males 7 min, mated males < 1 min. 3. The dispersal behaviour of E. eremicus was investigated in the field using fluorescent dust. Before doing so, it was determined in the laboratory that this dust did not affect flight behaviour, was retained over the length of the experiments, and allowed large samples to be processed quickly and inexpensively. 4. In the field, traps were placed along annuli at 3, 5, 7, and 10 m from release points. Eighty‐seven per cent of the 4153 parasitoids captured were males. Sex ratios were near parity on release. 5. The difference in dispersal characteristics between males and females may be resource based, suggesting that certain requirements were met within the field plots for males that were not met for females. 6. Locally, males dispersed in a manner consistent with a simple diffusion model while females engaged in wind‐directed flight soon after leaving release sites. The fact that the genders exhibited dissimilar dispersal characteristics, supports the claim that insect flight, even by small species, can be self‐directed.     

Effects of mating on the oviposition behaviour of the parasitic wasp,Apanteles glomeratus L. (Hymenoptera: Braconidae)

The oviposition behaviour of mated or virgin females of the parasitic wasp,Apanteles glomeratus L., was investigated. Virgin females laid fewer eggs in a shorter time than did mated females (P<0.01), though the attack ratio and attack time of these 2 female types were the same. Progeny sex ratios of mated females suggested the occurrence of sperm shortage, because old mated females produced clutches of a high male proportion, sometimes consisting of males only. Recopulation of females was also observed, but actual insemination did not occur, and therefore,A. glomeratus females are considered to be fundamentally monogamous.     

Spermatophore and Sperm Allocation in Males of the Monandrous Butterfly Pararge aegeria: the Female’s Perspective

In insects, spermatophore production represents a non‐trivial cost to a male. Non‐virgin males have been shown to produce small spermatophores at subsequent matings. Particularly in monandrous species, it may be an issue to receive a sufficiently large spermatophore at the first and typically only mating. Females of the monandrous Speckled wood butterfly Pararge aegeria (L.) produce fewer offspring after mating with a non‐virgin male. After mating, females spend all their active time selecting oviposition sites and typically ignore other males. Here, we show that females did not discriminate between a virgin male and a recently mated male in our laboratory experiments. We demonstrate that the number of eupyrene sperm bundles relative to spermatophore mass differed with subsequent male matings. Males transferred a significantly smaller spermatophore after the first copulation, but the spermatophore mass did not decrease further with subsequent matings. However, the number of eupyrene sperm bundles decreased linearly. Therefore, there was proportionally more eupyrene sperm in the male’s second spermatophore compared with the first and the later spermatophores. Such a pattern has been shown in polyandrous species. Hence, it suggests that differences in sperm allocation strategy between polyandrous and monandrous butterflies may be quantitative rather than qualitative. There was also a tendency for females that had mated with a recently mated male to have higher propensity to remate than did females that had mated with a virgin male. We discuss the results relative to the mating system in P. aegeria, including female remating opportunities in the field and male mate‐locating behaviour.     

Pea plant volatiles guide host location behaviour in the pea moth

Identification of plant volatiles that attract mated insect females for oviposition can provide important information about plant–insect relationships that can be used to develop pest control strategies involving manipulation of the female host search. Our study represents a first step towards identifying volatiles that affect the host location behaviour of the pea moth Cydia nigricana. The behaviours of virgin and mated males and females were analysed in cage experiments testing a two-choice situation at close range and in wind tunnel experiments evaluating upwind orientation over a distance. In both experimental setups, flowering pea plants constituted the most attractive phenological stage for mated females, with 58 % landing on such plants in the wind tunnel. Testing headspace extracts of different phenological stages of pea and of detached pea buds and flowers in the wind tunnel, mated females showed the highest landing responses to volatiles during flower development (budding 42 % and flowering 56 %) and from detached buds (46 %) and flowers (66 %). Volatile compounds collected from the various phenological stages of pea were analysed by gas chromatography–mass spectrometry, and the antennal responses to these headspace collections were evaluated by gas chromatography–electroantennography. Ten antennally active compounds were identified, nine of which were present in the headspace extracts of the whole pea plants at all tested phenological stages and in detached buds and flowers. Overall, our results demonstrate a clear link between host plant phenology, the corresponding plant odour, and the behaviour of mated C. nigricana females.     

Female sexual receptivity and male copula guarding during prolonged copulations in the damselflyIschnura senegalensis (Odonata:Coenagrionidae)

Laboratory experiments were conducted to clarify the relationship between female sexual receptivity and male copula guarding inI. senegalensis, a species that copulates for several hours. In insectaries, most copulations were initiated early in the morning, and terminated relatively synchronously between 11 00 and 13 00. Females refused males with wing-flutter display and oviposited alone in the afternoon regardless of copulation events of that morning. Females could sexually receive males only in the morning. Males copulated for several hours until 12 00 after which females could oviposit. To determine whether copulations that last for hours function as male copula guarding or only of sperm displacement, emerged males were kept at various densities and permitted to copulate with virgin and mated females in insectaries. Both with virgin and mated females, “social” (not solitary; 2–4 males / insectary) males initiated copulations early in the morning and always terminated at around 12 00. However, both with virgin and mated females, solitary (one male / insectary) males terminated copulations in the morning. In both cases, duration of copulations did not significantly differ for virgin females and mated females. Therefore, long (several hour) copulation is more likely to function as male copula guarding than as sperm displacement, and duration of copulations is predicted to be shortened when male density is very low.     

Spermatophore formation and regulation of egg maturation and oviposition in female Heliothis virescens by the male

This study was undertaken, using various surgical manipulations, to examine the role and functions of accessory sex glands and testes in Heliothis virescens in spermatophore formation and stimulation of egg maturation in mated females. Normal females mated to accessory sex glandectomized (-ASG) males produced fewer eggs and retained most of their eggs in ovarioles compared with females mated to sham-operated (+ASG) or normal males. The ASG are the source of the components for spermatophore formation in H. virescens. Females mated to castrated (-Testes) males showed similar pattern of egg production as did females mated to -ASG males. Females mated to -Testes males and those mated to sham-operated (+Testes) or normal males were found to have spermatophore in the bursa after uncoupling. Normal females mated to allatectomized (-CA) males developed similar numbers of total eggs as did females mated to sham-operated (+CA) males and normal males.     

Cuticular lipid diversification in Lasiommata megera and Lasiommata paramegaera: the influence of species, sex, and population (Lepidoptera: Nymphalidae)

Numerous studies have investigated the presence and the effectiveness of volatile pheromones in Lepidoptera. Conversely, very few studies have focused on the composition and the perception of the relatively low volatile components of cuticular mixtures. Yet, cuticular lipids are implied in the recognition processes of several solitary and social insects. In the present study, the cuticular signatures of the satyrid butterflies Lasiommata megera and Lasiommata paramegaera were examined by gas chromatography. General linear model and discriminant analyses on chemical data clearly revealed large differences between sexes, which showed the same diversification pattern in both species. Moreover, a strong diversification between the two species was found, as were differences among populations. These results represent a first step in demonstrating the communicative function of cuticular compounds in the L. megera / paramegaera complex. Moreover, the discrimination among different species and populations on the basis of cuticular mixtures could represent a platform for studying chemotaxonomy and chemical biogeography in butterflies, as already found in several other insect groups.  © 2007 The Linnean Society of London, Biological Journal of the Linnean Society , 2007, 91 , 703–710.     

Copulatory behaviour of the bank voleMyodes glareolus: matings with one and two males do not make a difference

In promiscuous species in which females mate with more than one male during oestrus, males may increase their sperm expenditure or change their copulatory behaviour in response to the risk of sperm competition. I used an experimental approach to investigate the pattern of copulatory behaviour of the bank voleMyodes glareolus Schreber, 1780 depending on whether the female mated with one or two males. The work showed that the copulatory period of the bank vole lasted about 80 minutes and consisted of 4–5 ejaculatory series, with multiple intromissions preceding ejaculation. There were no significant changes in number of intromissions across the first four ejaculatory series, but I did find a relationship between number of intromissions and first ejaculation latency; also, ejaculation latencies grew shorter as the ejaculatory series proceeded. Litter size did not differ significantly between females that mated with one male and those mating with two, nor did the reproductive success of males that mated with the same female. Mating with an oestrus female appears to be advantageous for bank vole males even if they mate as the second one, and the risk of sperm competition did not trigger changes in male copulatory behaviour. The similar durations of the copulatory period and patterns of change of ejaculation latencies during copulations with one and two males point to the role of the female in temporal copulatory behaviour of the bank vole.     

Vibratory courtship in a web-building spider: signalling quality or stimulating the female?

Courtship behaviour in spiders in the form of premating vibrations by males may function (1) as a male identity signal used for species recognition, (2) in suppression of female aggressiveness, (3) to stimulate female mating behaviour, or (4) as a quality signal used in female choice. We investigated the function of web vibration by male Stegodyphus lineatus in a series of experiments. Regardless of vibratory performance, all males mated successfully with virgin females but only 56.4% of males mated with nonvirgin females. Vibratory performance did not influence male mating success, but heavier males had a higher probability of mating with mated females. Males vibrated less often and produced fewer vibrations when introduced on the web of a mated female. Males that vibrated webs of virgin females mated faster than nonvibrating males, but there was no effect of vibration rate or body mass. There was no effect of male vibratory effort or vibration rate on female reproductive success measured as time to egg laying, clutch size, number of hatched young, number of dispersed young and offspring body mass after a single mating. Males vibrated on abandoned virgin female webs but the response decreased with increasing duration of female absence, suggesting that females produce a web-borne pheromone, which elicits male vibrating behaviour. Mated females were less receptive and not stimulated by male vibrating behaviour. We conclude that male premating vibrations in S. lineatus do not function as a male quality signal selected via female choice. Rather, the primary function of this behaviour may be to stimulate a receptive female to mate. Copyright 2003 Published by Elsevier Ltd on behalf of The Association for the Study of Animal Behaviour.      

Variation in energy reserves and role of body size in the mating system of Anopheles gambiae

Anopheles gambiae mates in flight. Males gather at stationary places at sunset and compete for incoming females. Factors that account for male mating success are not known but are critical for the future of any genetic control strategy. The current study explored variations in nutritional reserves (sugars, glycogen, lipids, and proteins) in wild‐caught swarming and resting males and evaluated the effect of body size and wing symmetry on male mating success. Our results showed that glycogen and sugar reserves are mobilized for flight. Males consume proportionally 5.9‐fold as much energy derived from sugars in swarming activities than when they are at rest. Mated males were on average bigger than unmated ones (P<0.0001). A strong correlation between the left and right wings in both mated and unmated males was found and additional analysis on fluctuating asymmetry did not show any indication of mated males being more symmetrical than unmated ones. The distribution of wing size of mated males was focused around a central value, suggesting that intermediate size of males is advantageous in the An. gambiae mating system. The results are discussed in the context of sexual selection.     

Reproductive behaviour of the South American fruit fly Anastrepha fraterculus (Diptera: Tephritidae): laboratory and field studies

Abstract. The mate choice, courtship and oviposition behaviour of laboratory-reared and field-collected Anastrepha fraterculus (Wied.) were compared. In laboratory cultures in Southampton the duration of male calling activity in small leks increased gradually from 1-2h at 5 days old to up to 7 h at 10 days. This finding correlates with previous reports on the time at which male salivary glands, which are believed to produce sex pheromone, are fully developed. Wild flies which emerged from infested fruits in Brazil began to oviposit on the day they mated, whereas in laboratory flies oviposition began 1 day following the first mating. Both types of fly usually defended their position on a particular fruit throughout the day, and re-mated with either virgin or mated males. There was no significant difference in mating duration. Females did not copulate before the mean age (±SE) of 16.8±0.9 days. For both types of flies mating initiation occurred in the first 2h of photophase, with virgin females choosing mainly mated males. The average number of matings in the laboratory was three for females and four for males, and the interval between matings in females was significantly increased after the second mating. It is suggested that the tendency of virgin females to mate with mated males will lead to increased fitness, as males are on average 48 days old at their second mating. The potential life span of around 200 days for both sexes would allow adults to bridge the gap between seasonally available fruits in warm-temperate and sub-tropical South America.     

Male house mice produce fewer offspring with lower viability and poorer performance when mated with females they do not prefer

We report experimental results consistent with the hypothesis that constraints on the expression of male mating preferences affect breeder fitness, offspring viability and performance. If constraints on the expression of mating preferences are common, tests of fitness variation associated with mate preferences must eliminate as many constraints on mate preferences as possible. We tested whether male mate preferences influenced breeder fitness, offspring performance and viability in typically polygynous house mice, Mus domesticus, from a feral source population. Our ‘free mate choice’ trials not only eliminated female preferences, male-male and female-female competition, but also our best guesses of the traits mediating choosers' preferences. Males mated with their preferred (P) females sired more litters than males mated with their nonpreferred (NP) females. Offspring viability was significantly lower when males' reproduced with females they did not prefer compared with females they did prefer. Adult sons of males that mated with their P females were socially dominant to sons of males that mated with their NP females. Adult offspring from P pairings built better nests than offspring from NP pairings. The slope of the survivorship curve for P offspring was significantly higher than for NP offspring. These results showed (1) males' mate preferences affected their fitness, (2) males that mated with females they preferred produced more litters than males that mated with females they did not prefer, and (3) their offspring were significantly more viable and performed significantly better on standardized performance tests. This is the first demonstration of fitness benefits of male choice behaviour in a mammal species with typical paternal investment. Copyright 2003 The Association for the Study of Animal Behaviour. Published by Elsevier Science Ltd. All rights reserved.      

Geometric morphometrics reveal male genitalia differences in the Lasiommata megera/paramegaera complex (Lepidoptera, Nymphalidae) and the lack of a predicted hybridization area in the Tuscan Archipelago

The recognition of specific demarcation between allopatric populations, as for island endemics, is particularly difficult according to the Biological Concept of Species. However, the recognition of the specific status of island taxa is decisive in evaluating important areas of endemism for conservation purposes. The recent taxonomic inflation of European butterfly species calls into question the validity and objectivity of taxonomic practices, and of databases dependent on them, which are used in biogeography and conservation. In this paper I applied rigorous morphometric analyses instead of visual evaluation to solve the long debated question of whether Lasiommata paramegaera butterfly from Sardinia and Corsica should be considered as a separated entity from the widespread Lasiommata megera . First, I carried out analyses of male genitalia shape comparing the populations from Corsica and Tuscany. Thereafter, I also searched for possible hybridization evidence in the sole area where it is strongly predicted: the Tuscan Archipelago. These islands are located between Tuscany and Corsica and there is large evidence of a continuous immigration of butterflies from these two main sources. I found that Corsican L. paramegaera and Tuscan L. megera can be clearly distinguished on the basis of genitalia shape. Furthermore, the Lasiommata population of each islet clearly maintains the characteristics of one of the two species without evidence of intermediate individuals. In conclusion, I suggest that the two entities should be considered as separate species maintaining their homogeneity by a reduced gene flow across sea, mating avoidance and/or by some depletion of F1 hybrids in developmental or mating success.     

Do female great tits (Parus major) assess males by eavesdropping? A field study using interactive song playback

Male singing behaviour correlates with extra-pair success in several passerine birds. Singing interactions during territorial contests provide relative information on the males involved. Such information may be important in female extra-pair behaviour and eavesdropping on singing interactions among males may allow females to make such relative assessments. We used interactive playback to instigate singing contests with male great tits during the peak fertile period of their mate in an attempt to alter females'' assessment of mates'' quality relative to neighbours (potential extra-pair partners). We escalated a contest to one male (by overlapping his songs) and then subsequently de-escalated a contest (by alternating) to a neighbour. Intrusions onto neighbouring territories by females mated to either treatment male were then monitored. Females mated to escalation treatment males were more likely to intrude following playbacks than females mated to de-escalation treatment males. Although the absolute song output of males did not differ between treatments, males produced more song relative to playback in de-escalation treatments and relative song output was positively correlated with female intrusions. Therefore, female great tits eavesdrop on singing interactions and change their visitation rates to neighbouring territories according to their mate''s singing performance relative to neighbours.