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1.
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.  相似文献   

2.
Capital breeding species, those that do not acquire resources over their reproductive period, are hypothesized to have more flexible reproductive strategies than income breeding species, enabling the former to better cope with environmental changes. Yet, empirical study of this life history attribute in a changing environment is rare. Hemileuca eglanterina (Saturniidae), a strict capital breeding, day-flying moth, should employ a different reproductive strategy to exploit temporary increases in host plant nutrient quality following fire. In wetlands, where one half was burned and the other left unburned, the number of eggs/clutch was positively correlated with host plant abundance in the absence of fire, suggesting that H. eglanterina uses a resource abundance matching reproductive strategy by default. However, following fire, H. eglanterina laid greater numbers of eggs/clutch and did not adjust clutch size to host plant abundance, appearing to shift to a host plant quality based reproductive strategy. Coinciding with the fire-induced shift in reproductive strategy, host plants from burned habitat contained a greater proportion of N-containing compounds in their foliage than plants from unburned habitat, and larvae fed only leaves from the burned habitat had significantly greater survival than siblings fed unburned foliage. These results suggest the shift in reproductive strategy by H. eglanterina following fire was adaptive and that capital breeding species can cope with sudden environmental changes via alternative reproductive strategies.  相似文献   

3.
Demographic parameters such as survival, sex ratio and abundance can profoundly affect the viability of populations and thus are of primary importance in species of conservation concern. Although numerous studies have been published on certain aspects of the ecology and evolution of the endangered Large Blue butterfly Maculinea arion, there is still a lack of detailed knowledge on its populations’ demography. Moreover, M. arion populates a variety of xerothermic habitats throughout its European range using various food plants and host ants, which leads to complications in its conservation. Our aim was to estimate demographic parameters of M. arion populations in different parts of its European range. Detailed mark-recapture sampling was conducted on populations in four different countries. We often found that daily apparent survival probability declined with increasing age of individuals, but there was no difference between male and female survival. In smaller populations, the sex ratio was rather female-biased. Our most interesting result was the lack of protandry in some populations that might be a consequence of selection against reproductive asynchrony in small populations or a polyandrous mating system. The perfect coincidence of male and female phenology can positively affect the effective population size, because the lack of reproductive asynchrony increases the chance of male–female encounters. Abundance of the studied populations ranged between 100 and 1,600 individuals, smaller populations were on the verge of extinction. Habitat of the threatened small populations was either overgrazed or abandoned, while habitat of larger, stable populations was lightly grazed.  相似文献   

4.
Understanding ecological requirements of endangered species is a primary precondition of successful conservation practice. Regrettably, we know surprisingly little about the life history of numerous threatened insects, and about their use of larval host plants in particular. The brown butterflies (Nymphalidae: Satyrinae) have traditionally been considered polyphagous on grasses and indiscriminatory in their oviposition behavior. However, detailed studies on several species have revealed local specialization in host plant use as well as the decisive role of microlimatic conditions as determinants of habitat quality. The present study addresses host plant relationships in the endangered brown butterfly Coenonympha hero (L.) at the northern limit of its European distribution. We combine laboratory-based host preference and performance tests with an analysis of microhabitat use by adult butterflies in the field. Both lines of evidence suggest that C. hero is polyphagous enough not to be associated with one particular host species. Oviposition choices of C. hero are not driven by host plant species but rather by structural characteristics of the substrate. The preferred rigid needle-like structures may serve as cues of ‘transparent’ vegetation which allows the larvae to benefit from sunlight reaching the lower strata of the tuft. Our results suggest that conservation efforts should prioritize microclimatic parameters, rather than the presence of any particular host plant species, as decisive determinants of habitat quality in C. hero.  相似文献   

5.
Mistletoe infection between conspecific and interspecific hosts can be restricted by seed dispersal, host-mistletoe compatibility and abiotic factors, yet no studies have linked mistletoe infection patterns and pollination together for understanding mistletoe distribution at a local scale. Psittacanthus calyculatus (Loranthaceae) is a hemiparasitic plant with a broad host range across its geographic distribution. The potential for local host adaptation has been shown using cross-inoculation experiments, in which plants of mistletoe seeds collected from a given host are more likely to survive when they are inoculated on conspecific host trees compared with those inoculated on other host provenances. Here we evaluate host adaptation by describing the local patterns of infection (prevalence and intensity) of P. calyculatus mistletoes on three native host tree species (Alnus acuminata, Quercus crassipes, Salix bonplandiana) and one introduced species (Populus alba) and carried out cross-pollination experiments to examine how pollination affects infection patterns of different host species. Mistletoe infection prevalence (proportion of infection) and infection intensity (mean number of mistletoes per tree) were in general disproportional with respect to the availability of native host tree species but higher to that of non-native host tree species. Cross-pollination experiments showed higher mating success on the native host tree species, suggesting higher local adaptation to specially Q. crassipes. The observed spatial distribution of host tree species and mistletoe infection along with the non-random mating could contribute to local genetic structuring of mistletoe populations.  相似文献   

6.
Tranosema rostrale (Brischke) (Hymenoptera: Ichneumonidae) is an important parasitoid of low-density spruce budworm Choristoneura fumiferana (Clemens) (Lepidoptera: Tortricidae) populations. To investigate the effectiveness of this parasitoid in attacking low-density spruce budworm populations, we conducted a detailed laboratory study on its reproductive biology and behavior including mating behavior, potential fecundity, longevity, host searching, and oviposition behavior. We found that the occurrence of mating increases with the number of males present in the cage but that it drastically decreases when females mated previously. Females may mate multiple times with different males in one breeding session and mating duration is significantly longer when a male mates the second time with the same female. Dissections of T. rostrale’s oviducts showed that it is a synovigenic species emerging with about 17 % of its lifetime egg load and develops most of its eggs in the first three days after emergence at 20 °C. Sugar, but not pollen, significantly increased the insect’s longevity compared to water. Spruce budworm larvae, silk from larvae and damaged balsam fir foliage triggered probing in T. rostrale females significantly more often than larval feces. The sequence of the parasitoid’s behaviors leading to successful attack is described as antennation, probing, insertion of the ovipositor, oviposition, and subsequent disinterest or resuming of the sequence. Defense mechanisms of the host larva such as vigorous movements, biting, and/or regurgitation and behavioral countermeasures by T. rostrale are described in detail.  相似文献   

7.
Understanding the factors that determine habitat quality is of vital importance in ensuring appropriate habitat management. Here we used the Niobe fritillary (Argynnis niobe) as a study system to analyse the larval habitat preferences in a small network of heavy-metal grasslands in western Germany. The data were compared with the results of a previous study in coastal dune grasslands of the German North Sea. Based on this knowledge, we give management recommendations for the conservation of this threatened species. The key factors for the survival of A. niobe in heavy-metal grasslands were (i) open vegetation with a warm microclimate and (ii) sufficient host plants for the larvae. This reflects similar results from the previous study in coastal grey dune grasslands. However, in the heavy-metal grasslands, physiological stress generally slows down succession and favours the fritillary’s host plant, the metallophyte Viola calaminaria. As a result, the cover of the host plant was nearly twice as high in heavy-metal grasslands compared to the dune grasslands. Heavy-metal grasslands are of great significance for the conservation of A. niobe and overall butterfly diversity. Usually, the speed of succession in heavy-metal grasslands is slow and, hence, sites with high heavy-metal concentrations are characterised by relatively stable plant composition and vegetation structure. However, on soils with low heavy-metal content a loss of habitats of A. niobe and associated species of conservation concern may occur without management. On those sites sheep grazing seems to be an appropriate way to keep the habitats open and rich in violets.  相似文献   

8.
Effective population size (N e) quantifies the effects of micro-evolutionary processes and the rate of loss of genetic diversity in a population. Several demographic and mating parameters reduce N e. Theoretical studies elucidate the impacts of various demographic and mating system parameters on N e, while empirical studies illustrate realized N e for species with differing life histories and mating systems. However, effect of intra-specific variation in mating system on effective size remains largely unexplored. In this paper we investigated the effect of promiscuous and polygynous mating on N e in two wild populations of the short-nosed fruit bat, Cynopterus sphinx. N e/N (ratio of effective population size to census size) was lower than unity in both populations, and much lower for the polygynous population compared to promiscuous population. Elasticity analyses reveal that N e/N was sensitive to deviations in the sex ratio. Variance in female reproductive success had a higher impact on N e compared to variance in male reproductive success in the promiscuous population. However, for the polygynous population, impact of variance in male reproductive success on N e was higher than that of variance in female reproductive success. Our results suggest that depending on mating system, different populations of the same species could have alternate evolutionary trajectories. The rate of loss of genetic diversity would be lower for the promiscuous population compared to the polygynous population. Our study is the first to highlight which parameters would most significantly impact population specific N e under different mating systems.  相似文献   

9.
In order to maximize the lifetime reproductive success of parasitoids, they should be induced to dynamically accept individual hosts that have different suitability for oviposition. Parasitoids tend to exhibit higher host-selective behavior when their egg load is limited, and are less selective if they are facing time constraints. Here, we evaluated the effects of parasitoid age on egg load, fecundity and host instar preference of a honey-fed aphid parasitoid, Aphelinus asychis Walker (Hymenoptera: Aphelinidae). Host selective experiment was conducted to measure host-preference of honey-fed A. asychis females at different ages, using the second and fourth instars of the green peach aphid Myzus persicae as their hosts. The results showed that the choice of host-instar for oviposition was significantly influenced by the parasitoid age. Honey-fed parasitoids in the age groups of 1, 5, 10 and 20 days tended to parasitize predominantly second-instar aphids, whereas 15-days old parasitoids showed no significant preference of host instars. On the other hand, host-feeding preference was not affected by parasitoid age. Parasitoid females of all ages preferred younger aphids to older aphids. This result could help evaluate the effectiveness of A. asychis for biological control of M. persicae when they encountered mixed-instar aphids in the field. In addition, the results might be helpful in assessing the host killing effects of other host-feeding parasitoids.  相似文献   

10.
Natural floodplains belong to the most species-rich ecosystems worldwide. However, over the last decades there has been a strong decrease in the extent of natural floodplains. As a consequence, the biodiversity of these ecosystems has experienced a dramatic decline. In this study, we investigated the habitat and food preferences of the grasshopper species Chorthippus binotatus on gravel banks of a nearly natural river system in the Spanish Pyrenees. The studied plots on the alluvial gravel banks in the Spanish Pyrenees were characterised by strong differences in habitat structure. However, C. binotatus only occurred in sparsely-vegetated sub-Mediterranean dry grasslands. The abundance of the grasshopper species was also strongly related to habitat structure and cover of the main food source and dominant plant species of these open grasslands, the dwarf shrub Genista scorpius. Concerning habitat structure, the grasshopper species preferred habitats with sparse and low-growing vegetation with a high cover of bare ground and gravel/stones. C. binotatus occupies a very narrow ecological niche within the studied floodplain. It requires sparsely-vegetated gravel banks that ensure sufficient oviposition sites and a favourable ambient temperature for optimal development. G. scorpius dwarf shrubs have to be considered as multi-functional key elements in the habitats of C. binotatus. They offer high-quality food, shelter against predators and allow thermoregulation in a hot and dry Mediterranean environment. For the conservation of C. binotatus, we recommend maintaining and restoring both natural floodplain dynamics as well as traditional grazing systems.  相似文献   

11.
In order to improve our understanding of habitat preferences and optimal management of open woodland insects, we analyse patch occupancy and oviposition electivity of the endangered Duke of Burgundy butterfly, Hamearis lucina, in three regions across German habitat types. Some newly available forest clearings created by a severe winter storm in the Schönbuch region were colonised within 2 years, whereas some suitable patches remained unoccupied for several years. We discuss how small population sizes, limited patch connectivity, and habitat quality may contribute to such an intermediate colonisation power. Across study regions, we document differences in oviposition site electivity. On calcareous grassland in the Diemeltal, shaded Primula plants on western slopes were preferentially used, probably to avoid desiccation of the natal food plant. To the contrary, sun-exposed Primula stands were preferred in forest clearings in the Schönbuch and calcareous fens in the Allgäu. In these regions, the risk of desiccation is low, but the overall cool and moist microclimate conditions may hamper larval development in shaded conditions, favouring oviposition at sites with maximum exposition to solar radiation. Optimal management strategies depend on the abiotic and biotic conditions and conservation priorities for the given region and habitat type, and we suggest management regimes that promise to sustain suitable H. lucina habitat at a landscape-level.  相似文献   

12.
Shrubby field margins and hedgerows play an important role for many species of flora and fauna in agro-ecosystems, including those which are rare or endangered. A characteristic species of these semi-natural habitats in agricultural landscape is the Eastern eggar, Eriogaster catax (Linnaeus, 1758): a moth species threatened in many European countries. In this study we investigated the oviposition preferences of E. catax at host plant level in agricultural landscape in south-western Poland, near of the northern limit of the species distribution in Europe. In total we surveyed 796 host plants. Altogether we found 439 eggs batches or caterpillar webs of E. catax on 373 occupied plants. Most of them (92.3%) were on blackthorn Prunus spinosa, which was preferred host plant next to pear Pyrus spp. However, the most important predictor of the presence of egg batches were microclimatic conditions. We recorded that females preferred host plants exposed to direct sunlight and with south and west-facing slopes for oviposition and avoided those inside of the dense shrub canopy. Eggs were laid more often on the trunk and on the upper half of the host plant, however there was a significant difference in vertical and horizontal position of egg batches in relation to the position of the plant. Inside of the shrub canopy, eggs were laid in higher parts of host plant and closer to the trunk, than at the edge and on solitary plants. Based on our observations the management strategies for the habitats of the species are proposed and discussed.  相似文献   

13.

Key message

Genetic diversity in quantitative loci associated with plant traits used by insects as cues for host selection can influence oviposition behavior and maternal choice.

Abstract

Host plant selection for oviposition is an important determinant of progeny performance and survival for phytophagous insects. Specific cues from the plant influence insect oviposition behavior; but, to date, no set of host plant quantitative trait loci (QTLs) have been shown to have an effect on behavioral sequences leading to oviposition. Three QTLs in wheat (Triticum aestivum L.) have been identified as influencing resistance to the wheat stem sawfly (WSS) (Cephus cinctus Norton). Wheat near-isogenic lines (NILs) for each of the three QTLs were used to test whether foraging WSS were able to discriminate variation in plant cues resulting from allelic changes. A QTL on chromosome 3B (Qss-msub-3BL) previously associated with stem solidness and larval antibiosis was shown to affect WSS oviposition behavior, host preference, and field infestation. Decreased preference for oviposition was also related to a QTL allele on chromosome 2D (Qwss.msub-2D). A QTL on chromosome 4A (Qwss.msub-4A.1) affected host plant attractiveness to foraging females, but did not change oviposition preference after females landed on the stem. These findings show that oviposition decisions regarding potential plant hosts require WSS females to discriminate signals from the plant associated with allelic variation at host plant quantitative loci. Allele types in a host plant QTL associated with differential survival of immature progeny can affect maternal choices for oviposition. The multidisciplinary approach used here may lead to the identification of plant genes with important community consequences, and may complement the use of antibiosis due to solid stems to control the wheat stem sawfly in agroecosystems.
  相似文献   

14.
The specific features of mating females and males of different morphs collected from a population of the wasp P. dominulus in Southern Ukraine were studied. Data analysis of mating individuals in experiments indicated a random mate choice by size and assortative mating by coloration. The most actively copulating males in the experiments had light-colored mesopleuron, sternite, and fore and middle coxae. They were similar in the color pattern and size to resident males, which defend their territories in the habitat. Most P. dominulus females mated only once. In their coloration, those females represented the majority of the individuals in the population. The color variability of the foundresses was shown to change in a cyclic pattern. The possibility that such variability may result from selective or assortative mating is discussed. The color and pattern traits of P. dominulus females and males could serve as markers of their reproductive strategies and their reproductive success on the whole.  相似文献   

15.
Understanding the environmental factors that affect the distribution and abundance of rare and threatened species can help identify priority sites for conservation action such as habitat management. The moth Cucullia lychnitis is identified in UK legislation as a priority species for conservation. Its conspicuous larvae feed on a patchily distributed host plant Verbascum nigrum, but are entirely absent from some host plant patches within the species’ range. Environmental variability among patches was investigated to understand factors affecting (i) patch occupancy by C. lychnitis and (ii) abundance of C. lychnitis, where present. Occupancy of individual V. nigrum plants within occupied patches was also investigated. The likelihood of patch occupancy increased with patch size, and decreased with patch isolation. Abundance of C. lychnitis was negatively correlated with patch isolation and with abundance of the weevil Cionus nigritarsis, which exploits the same host plant and may be a competitor. Within occupied patches, larvae of C. lychnitis were significantly more likely to be found on taller plants with more flower spikes; such plants are typical of established rather than newly-created patches. These results may help to guide efforts to conserve C. lychnitis, highlighting the importance of habitat connectivity and indicating potential management actions to promote features positively associated with larval incidence and abundance.  相似文献   

16.
The life-history traits and population dynamics of species are increasingly being attributed to the characteristics of their preferred habitats. While coral reef fish are often strongly associated with particular habitats, long-term studies establishing the demographic and life-history consequences of occupying different reef substrata are rare and no studies have monitored individuals in situ over their lifetime and determined the fate of their offspring. Here, we documented a quasi-turnover and local reproductive success for an entire population of orange clownfish (Amphiprion percula) from Kimbe Island, Papua New Guinea, by taking bi-annual samples of DNA over a 10-yr period (2003–2013). We compared demographic and life-history traits of individuals living on two host anemone species, Heteractis magnifica and Stichodactyla gigantea, including female size, adult continued presence (a proxy for relative longevity range), early post-settlement growth, the number of eggs per clutch and ‘local’ reproductive success (defined for each adult as the number of offspring returning to the natal population). Our results indicate that while the relative longevity of adults was similar on both host anemone species, females living in H. magnifica were larger than females in S. gigantea. However, despite females growing larger and producing more eggs on H. magnifica, we found that local reproductive success was significantly higher for clownfish living in S. gigantea. Life-history traits also exhibited local spatial variation, with higher local reproductive success recorded for adults living on S. gigantea on the eastern side of the island. Our findings support a ‘silver-spoon’ hypothesis that predicts individuals that are fortunate enough to recruit into good habitat and location will be rewarded with higher long-term reproductive success and will make a disproportionate contribution to population renewal.  相似文献   

17.
A trade-off between flight capability and reproduction is well known in adult females of the wing-dimorphic cricket Velarifictorus ornatus, but it is not clear whether such a trade-off exists in adult males of the species. In the present study, we investigated sexual maturation time, mating frequency, and the fertilization success of spermatophores after sequential mating in long-winged (LW) and short-winged (SW) adult males of V. ornatus to evaluate the potential reproductive advantage of the SW over the LW male morph. We found that the SW males of V. ornatus attained sexual maturity earlier and produced heavier spermatophores during the early stage after adult emergence than their LW counterparts. Additionally, within a 24-h mating period, the SW males showed a higher mating frequency, greater spermatophore weight, and shorter intermating time interval compared with their LW counterparts. Although females copulated with the two male morphs produced eggs of similar size, fertilization success by SW males was significantly higher than by the LW males. These results provide support for a trade-off between dispersal capability and reproduction success in wing-dimorphic males of V. ornatus.  相似文献   

18.
Lifetime fitness is directly influenced by the decision to use resources for either current or future reproduction. Thus, females should weigh the costs and benefits of each reproductive opportunity and allocate resources accordingly. Here, we explore decision-making and the time spent handling hosts of different instars in the parasitoid Haplogonatopus hernandezae, which uses a single planthopper host to either oviposit (i.e., current reproduction) or feed (i.e., future reproduction). Our results indicate that manipulation time in attacks that led to either oviposition and feeding increased with host instar and size. Consequently, attacks were less successful on older host instars than younger ones. Similarly, attack and handling time during oviposition was greater when manipulating fifth instar nymphs compared to younger ones, but oviposition time was similar. Surprisingly, host grasping by the chelate forelegs differed between oviposition and feeding events, and the specific chelate foreleg morphology of H. hernandezae facilitates the specific grasp of the clypeus and gena of the host. We also link this previously undescribed host grasping and differential handling behavior in this species to the final decision to oviposit or feed. Given the differences in handling time and effort among different host instars, we found that older hosts were more often chosen for consumption than younger hosts, and younger hosts were chosen more often for oviposition. Our study suggests that the tradeoff between current and future benefits is influenced by the investment in handling hosts of different instars, and the assessment of host suitability for successful offspring survival.  相似文献   

19.
Conservation of plant species with extremely small populations (PSESP) is a focus of wild plant conservation in China at present. A relevant strategy for PSESP conservation requires improvement from previous programs for rare and endangered plants and national key protected plants. An integrated strategy for PSESP conservation of the Nyssa yunnanensis was initiated and applied over a 7-year period (2009–2015). Here, we reviewed the processes to implement the strategy: resource inventory, formulation of conservation action plan (CAP), in situ conservation, seedling propagation, near situ conservation, ex situ conservation and scientific research. Major concerns and technical requirements for each action are described and further analyzed within a broad scope to conserve PSESPs. A detailed resource inventory that highlights both the change in population status and the participation of local residents is recommended before the formulation of the CAP. Techniques for determination of the area of a mini-reserve is developed for in situ conservation of N. yunnanensis. Near situ conservation is a novel approach whereby establishing new viable population in contiguous areas with a similar climate, habitat and community, in which techniques for seedling preparation, soil preparation, and early management are introduced. A population-based species conservation strategy for N. yunnanensis may aid additional PSESP conservation, so as to contribute to overall wild plant conservation.  相似文献   

20.
We investigated the host suitability of the Mediterranean flour moth Ephestia kuehniella Zeller (Lepidoptera: Pyralidae) for a polyphagous koinobiont endoparasitoid Meteorus pulchricornis (Wesmael) (Hymenoptera: Braconidae), a common natural enemy of various pest lepidopteran larvae. The estimated probability of adult wasp emergence was 80% or higher when eggs were laid in nearly fully grown larvae of E. kuehniella (fresh weight, >?20.0 mg). The body size of emerged adult wasps increased with the initial weight of the host larvae at oviposition. The fresh weight of adult wasps reared on E. kuehniella was approximately 60% of that when reared on a natural host Spodoptera litura (Fabricius) (Lepidoptera: Noctuidae), and the lifetime fecundity of wasps reared on E. kuehniella was approximately half of that when reared on S. litura. Ephestia kuehniella was shown to be a positive host candidate for the mass rearing of M. pulchricornis, but further investigation is needed to increase the body size of wasps for more practical use of this species as a biocontrol agent.  相似文献   

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