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1.
Heritable bacterial endosymbionts are common in aphids (Hemiptera: Aphididae), and they can influence ecologically important traits of their hosts. It is generally assumed that their persistence in a population is dependent on a balance between the costs and benefits they confer. A good example is Hamiltonella defensa Moran et al., a facultative symbiont that provides a benefit by strongly increasing aphid resistance to parasitoid wasps, but becomes costly to the host in the absence of parasitoids. Regiella insecticola Moran et al. is another common symbiont of aphids and generally does not influence resistance to parasitoids. In the green peach aphid, Myzus persicae (Sulzer), however, one strain (R5.15) was discovered that behaves like H. defensa in that it provides strong protection against parasitoid wasps. Here we compare R5.15‐infected and uninfected lines of three M. persicae clones to test whether this protective symbiont is costly as well, i.e., whether it has any negative effects on aphid life‐history traits. Furthermore, we transferred R5.15 to two other aphid species, the pea aphid, Acyrthosiphon pisum (Harris), and the black bean aphid, Aphis fabae Scopoli, where this strain is also protective against parasitoids and where we could compare its effects with those of additional, non‐protective strains of R. insecticola. Negative effects of R5.15 on host survival and lifetime reproduction were limited and frequently non‐significant, and these effects were comparable or in one case weaker than those of R. insecticola strains that are not protective against parasitoid wasps. Unless the benefit of protection is counteracted by detrimental effects on traits that were not considered in this study, R. insecticola strain R5.15 should have a high potential to spread in aphid populations. 相似文献
2.
Christoph Vorburger Pravin Ganesanandamoorthy Marek Kwiatkowski 《Ecology and evolution》2013,3(3):706-713
Host defenses against parasites do not come for free. The evolution of increased resistance can be constrained by constitutive costs associated with possessing defense mechanisms, and by induced costs of deploying them. These two types of costs are typically considered with respect to resistance as a genetically determined trait, but they may also apply to resistance provided by ‘helpers’ such as bacterial endosymbionts. We investigated the costs of symbiont‐conferred resistance in the black bean aphid, Aphis fabae (Scopoli), which receives strong protection against the parasitoid Lysiphlebus fabarum from the defensive endosymbiont Hamiltonella defensa. Aphids infected with H. defensa were almost ten times more resistant to L. fabarum than genetically identical aphids without this symbiont, but in the absence of parasitoids, they had strongly reduced lifespans, resulting in lower lifetime reproduction. This is evidence for a substantial constitutive cost of harboring H. defensa. We did not observe any induced cost of symbiont‐conferred resistance. On the contrary, symbiont‐protected aphids that resisted a parasitoid attack enjoyed increased longevity and lifetime reproduction compared with unattacked controls, whereas unprotected aphids suffered a reduction of longevity and reproduction after resisting an attack. This surprising result suggests that by focusing exclusively on the protection, we might underestimate the selective advantage of infection with H. defensa in the presence of parasitoids. 相似文献
3.
《Evolutionary Applications》2018,11(2):220-230
There is growing interest in biological control as a sustainable and environmentally friendly way to control pest insects. Aphids are among the most detrimental agricultural pests worldwide, and parasitoid wasps are frequently employed for their control. The use of asexual parasitoids may improve the effectiveness of biological control because only females kill hosts and because asexual populations have a higher growth rate than sexuals. However, asexuals may have a reduced capacity to track evolutionary change in their host populations. We used a factorial experiment to compare the ability of sexual and asexual populations of the parasitoid Lysiphlebus fabarum to control caged populations of black bean aphids (Aphis fabae) of high and low clonal diversity. The aphids came from a natural population, and one‐third of the aphid clones harbored Hamiltonella defensa, a heritable bacterial endosymbiont that increases resistance to parasitoids. We followed aphid and parasitoid population dynamics for 3 months but found no evidence that the reproductive mode of parasitoids affected their effectiveness as biocontrol agents, independent of host clonal diversity. Parasitoids failed to control aphids in most cases, because their introduction resulted in strong selection for clones protected by H. defensa. The increasingly resistant aphid populations escaped control by parasitoids, and we even observed parasitoid extinctions in many cages. The rapid evolution of symbiont‐conferred resistance in turn imposed selection on parasitoids. In cages where asexual parasitoids persisted until the end of the experiment, they became dominated by a single genotype able to overcome the protection provided by H. defensa. Thus, there was evidence for parasitoid counteradaptation, but it was generally too slow for parasitoids to regain control over aphid populations. It appears that when pest aphids possess defensive symbionts, the presence of parasitoid genotypes able to overcome symbiont‐conferred resistance is more important for biocontrol success than their reproductive mode. 相似文献
4.
Genotype‐by‐genotype interactions demonstrate the existence of variation upon which selection acts in host–parasite systems at respective resistance and infection loci. These interactions can potentially be modified by environmental factors, which would entail that different genotypes are selected under different environmental conditions. In the current study, we checked for a G × G × E interaction in the context of average temperature and the genotypes of asexual lines of the endoparasitoid wasp Lysiphlebus fabarum and isolates of Hamiltonella defensa, a protective secondary endosymbiont of the wasp's host, the black bean aphid Aphis fabae. We exposed genetically identical aphids harbouring different isolates of H. defensa to three asexual lines of the parasitoid and measured parasitism success under three different temperatures (15, 22 and 29 °C). Although there was clear evidence for increased susceptibility to parasitoids at the highest average temperature and a strong G × G interaction between the host's symbionts and the parasitoids, no modifying effect of temperature, that is, no significant G × G × E interaction, was detected. This robustness of the observed specificity suggests that the relative fitness of different parasitoid genotypes on hosts protected by particular symbionts remains uncomplicated by spatial or temporal variation in temperature, which should facilitate biological control strategies. 相似文献
5.
Dirk Sanders Rachel Kehoe FJ Frank van Veen Ailsa McLean H. Charles J. Godfray Marcel Dicke Rieta Gols Enric Frago 《Ecology letters》2016,19(7):789-799
Animals often engage in mutualistic associations with microorganisms that protect them from predation, parasitism or pathogen infection. Studies of these interactions in insects have mostly focussed on the direct effects of symbiont infection on natural enemies without studying community‐wide effects. Here, we explore the effect of a defensive symbiont on population dynamics and species extinctions in an experimental community composed of three aphid species and their associated specialist parasitoids. We found that introducing a bacterial symbiont with a protective (but not a non‐protective) phenotype into one aphid species led to it being able to escape from its natural enemy and increase in density. This changed the relative density of the three aphid species which resulted in the extinction of the two other parasitoid species. Our results show that defensive symbionts can cause extinction cascades in experimental communities and so may play a significant role in the stability of consumer‐herbivore communities in the field. 相似文献
6.
Piotr &#x;ukasik Margriet van Asch Huifang Guo Julia Ferrari H. Charles J. Godfray 《Ecology letters》2013,16(2):214-218
The importance of microbial facultative endosymbionts to insects is increasingly being recognized, but our understanding of how the fitness effects of infection are distributed across symbiont taxa is limited. In the pea aphid, some of the seven known species of facultative symbionts influence their host's resistance to natural enemies, including parasitoid wasps and a pathogenic fungus. Here we show that protection against this entomopathogen, Pandora neoaphidis, can be conferred by strains of four distantly related symbionts (in the genera Regiella, Rickettsia, Rickettsiella and Spiroplasma). They reduce mortality and also decrease fungal sporulation on dead aphids which may help protect nearby genetically identical insects. Pea aphids thus obtain protection from natural enemies through association with a wider range of microbial associates than has previously been thought. Providing resistance against natural enemies appears to be a particularly common way for facultative endosymbionts to increase in frequency within host populations. 相似文献
7.
The effect of divergent natural selection on the evolution of behavioral traits has long been a focus of behavioral ecologists. Predation, due to its ubiquity in nature and strength as a selective agent, has been considered an important environmental driver of behavior. Predation is often confounded with other environmental factors that could also play a role in behavioral evolution. For example, environments that contain predators are often more ecologically complex and “risky” (i.e., exposed and dangerous). Previous work shows that individuals from risky environments are often more bold, active, and explorative than those from low‐risk environments. To date, most comparative studies of environmentally driven behavioral divergence are limited to comparisons among populations within species that occur in divergent selective environments but neglect comparisons between species following speciation. This limits our understanding of how behavior evolves post‐speciation. The Central American live‐bearing fish genus Brachyrhaphis provides an ideal system for examining the relationship between selective environments and behavior, within and between species. Here, we test for differences in boldness between sister species B. roseni and B. terrabensis that occur in streams with and without piscivorous predators, respectively. We found that species do differ in boldness, with species that occur with predators being bolder than those that do not. Within each species, we found that sexes differed in boldness, with males being bolder than females. We also tested for a relationship between size (a surrogate for metabolic rate) and boldness, but found no size effects. Therefore, sex, not size, affects boldness. These results are consistent with the hypothesis that complex and risky environments favor individuals with more bold behavioral traits, but they are not consistent with the hypothesis that size (and therefore metabolic rate) drives divergence in boldness. Finally, our results provide evidence that behavioral trait divergence continues even after speciation is complete. 相似文献
8.
Coevolution between hosts and parasites may promote the maintenance of genetic variation in both antagonists by negative frequency‐dependence if the host–parasite interaction is genotype‐specific. Here we tested for specificity in the interaction between parasitoids (Lysiphlebus fabarum) and aphid hosts (Aphis fabae) that are protected by a heritable defensive endosymbiont, the γ‐proteobacterium Hamiltonella defensa. Previous studies reported a lack of genotype specificity between unprotected aphids and parasitoids, but suggested that symbiont‐conferred resistance might exhibit a higher degree of specificity. Indeed, in addition to ample variation in host resistance as well as parasitoid infectivity, we found a strong aphid clone‐by‐parasitoid line interaction on the rates of successful parasitism. This genotype specificity appears to be mediated by H. defensa, highlighting the important role that endosymbionts can play in host–parasite coevolution. 相似文献
9.
Bacterial endosymbionts play important roles in ecological traits of aphids.In this study,we characterize the bacterial endosymbionts of A.gossypii collected in Karaj,Iran and their role in the performance of the aphid.Our results indicated that beside Buchnera aphidicola,A.gossypii,also harbors both Hamiltonella defensa and Arsenophonus sp.Quantitative PCR(qPCR)results revealed that the populations of the endosymbionts increased throughout nymphal development up to adult emergence;thereafter,populations of Buchnera and Arsenophonus were diminished while the density of H.defensa constantly increased.Buchnera reduction caused prolonged development and no progeny production.Furthermore,secondary symbiont reduction led to reduction of the total life span and intrinsic rate of natural increase as well as appearance of the deformed dead offspring in comparison with the control insects.Reduction of the secondary symbionts did not affect parasitism rate of the aphid by the parasitic wasp Aphidius matricariae.Together these findings showed that H.defensa and Arsenophonus contributed to the fitness of A.gossypii by enhancing its performance,but not through parasitoid resistance. 相似文献
10.
Bacterial endosymbionts have enabled aphids to adapt to a range of stressors,but their effects in many aphid species remain to be established.The bird cherry-oat aphid,Rhopalosiphum padi(Linnaeus),is an important pest of cereals worldwide and has been reported to form symbiotic associations with Serratia symbiotica and Sitobion miscanthi L-type symbiont endobacteria,although the resulting aphid phenotype has not been described.This study presents the first report of R.padi infection with the facultative bacterial endosymbiont Hamiltonella defensa.Individuals of R.padi were sampled from populations in Eastern Scotland,UK,and shown to represent seven R.padi genotypes based on the size of polymorphic microsatellite markers;two of these genotypes harbored H.defensa.In parasitism assays,survival of H.defensa-infected nymphs following attack by the parasitoid wasp Aphidius colemani(Viereck)was 5 fold higher than for uninfected nymphs.Aphid genotype was a major determinant of aphid performance on two Hordeum species,a modern cultivar of barley H.vulgare and a wild relative H.spontaneum,although aphids infected with H.defensa showed 16%lower nymph mass gain on the partially resistant wild relative compared with uninfected individuals.These findings suggest that deploying resistance traits in barley will favor the fittest R.padi genotypes,but symbiontinfected individuals will be favored when parasitoids are abundant,although these aphids will not achieve optimal performance on a poor quality host plant. 相似文献
11.
Alois Honek Zdenka Martinkova Anthony F.G. Dixon Helen E. Roy Stano Pekr 《Insect Conservation and Diversity》2016,9(3):202-209
- We assessed the changes in abundance and community composition of native species of coccinellids (Coleoptera: Coccinellidae) on deciduous trees that occurred between 1970s and 2010s, in the Czech Republic.
- As the composition of adult communities varies with host plant and season, coccinellids were sampled in May–June from Acer, Betula and Tilia trees using a standardised sweeping method. This was done before (1976–1986) and after (2011–2014) the arrival of Harmonia axyridis in 2006, with interim samples from a period immediately before it arrived in the Czech Republic (2002–2006).
- Twenty‐one native species were identified in the total sample of 2674 adults. The abundance of Adalia bipunctata, Coccinella quinquepunctata and Propylea quatuordecimpunctata decreased over the whole period sampled. Declines in abundance of these species were already evident prior to the arrival of H. axyridis. Recent declines in Adalia decempunctata and Calvia quatuordecimguttata followed the arrival H. axyridis. Their abundance was increasing prior to the arrival of H. axyridis, but decreased following its invasion and the latter species might have affected their decline. The abundance of only one species, Calvia decemguttata, increased. Although the abundance of many species decreased and the frequency of some species varied, the diversity of native coccinellid populations (Shannon index) was similar over the 40 years of this study.
- The changes in species composition can in part be attributed to H. axyridis, the role of other factors (e.g. climate change, habitat degradation) in the long‐term fluctuations in abundance of coccinellids should be considered in future assessments.
12.
Nicolette Zukowski Devin Kirk Kiran Wadhawan Dylan Shea Denon Start Martin Krko&#x;ek 《Ecology and evolution》2020,10(13):6714-6722
Ecological communities are partly structured by indirect interactions, where one species can indirectly affect another by altering its interactions with a third species. In the absence of direct predation, nonconsumptive effects of predators on prey have important implications for subsequent community interactions. To better understand these interactions, we used a Daphnia‐parasite‐predator cue system to evaluate if predation risk affects Daphnia responses to a parasite. We investigated the effects of predator cues on two aspects of host–parasite interactions (susceptibility to infection and infection intensity), and whether or not these effects differed between sexes. Our results show that changes in response to predator cues caused an increase in the prevalence and intensity of parasite infections in female predator‐exposed Daphnia. Importantly, the magnitude of infection risk depended on how long Daphnia were exposed to the cues. Additionally, heavily infected Daphnia that were constantly exposed to cues produced relatively more offspring. While males were ~5× less likely to become infected compared to females, we were unable to detect effects of predator cues on male Daphnia–parasite interactions. In sum, predators, prey, and their parasites can form complex subnetworks in food webs, necessitating a nuanced understanding of how nonconsumptive effects may mediate these interactions. 相似文献
14.
七星瓢虫对麦长管蚜捕食作用及其模拟模型的研究 总被引：4，自引：0，他引：4
实验室内16—21℃的温度下,七星瓢虫雌成虫捕食行为集中在8:00—22:00。瓢虫各龄幼虫及雌成虫对麦长管蚜的功能反应均属Holling Ⅱ型。28℃时,瓢虫雌成虫的攻击率最大,处理时间最短。随温度增加,攻击率减小,处理时间增加。假设:猎物种群在无捕食者存在时,呈Logistic曲线增长;捕食者随机搜寻猎物。对猎物的功能反应为Holling Ⅱ型,捕食者个体间存在相互干扰;捕食者种群存在一个最低死亡率K_0,随种群增大,死亡率增加,增加速率与密度成反比;捕食者取食的猎物转化为自身部分的比例为β。 七星瓢虫-麦长管蚜捕食作用系统模拟模型:较好地描述了当麦长管蚜种群增长到某一数量时,放置一头瓢虫雌成虫后蚜虫种群增长过程。本文对模型平衡点作了局部稳定性分析。 相似文献
15.
The loss of grasslands in southeastern South America has negatively affected grassland birds, leading to marked declines in their populations. However, the extent to which habitat transformation impacts on their reproductive performance, and whether the magnitude of these effects may be modulated by landscape matrices, is unknown. We assessed the effect of fragmentation on grassland bird reproduction by comparing the combined influence of fragmentation and landscape matrix on nesting success, brood parasitism and productivity of the Spectacled Tyrant Hymenops perspicillatus and the Brown‐and‐yellow Marshbird Pseudoleistes virescens. Surveys were undertaken in small grassland patches embedded within different landscape matrices (urban and agro‐ecosystem) and in a large patch within a reserve. Reproductive performance was adversely affected by fragmentation. However, these effects were conditioned by matrix type, and the response was not the same for the two species. For Brown‐and‐yellow Marshbird, fragmentation resulted in higher rates of brood parasitism and lower productivity regardless of the matrix type, whereas for Spectacled Tyrant, we found a negative effect only in an agricultural matrix. The lack of extensive grasslands makes small patches important; however, knowing the effects of different matrix types is critical to predicting the conservation value of grassland patches, and the response of different species is not uniform. 相似文献
16.
Sarah N. Cockburn Tamara S. Haselkorn Phineas T. Hamilton Elizabeth Landzberg John Jaenike Steve J. Perlman 《Ecology letters》2013,16(5):609-616
Facultative symbionts can represent important sources of adaptation for their insect hosts and thus have the potential for rapid spread. Drosophila neotestacea harbours a heritable symbiont, Spiroplasma, that confers protection against parasitic nematodes. We previously found a cline in Spiroplasma prevalence across central Canada, ending abruptly at the Rocky Mountains. Resampling these populations 9 years later revealed that Spiroplasma had increased substantially across the region, resembling a Fisherian wave of advance. Associations between Spiroplasma infection and host mitochondrial DNA indicate that the increase was due to local increase of Spiroplasma‐infected flies. Finally, we detected Spiroplasma west of the Rocky Mountains for the first time and showed that defence against nematodes occurs in flies with a western genetic background. Because nematode infection is common throughout D. neotestacea's range, we expect Spiroplasma to spread to the Pacific coast. 相似文献
17.
18.
PIOTR ŁUKASIK EMILY L. HANCOCK JULIA FERRARI H. CHARLES J. GODFRAY 《Ecological Entomology》2011,36(6):790-793
1. Facultative endosymbiotic bacteria of insects are known to affect life‐history traits of their hosts, and can provide important fitness benefits under certain environmental conditions. While several distinct endosymbiont‐induced effects have been reported, there is no data on whether heritable facultative endosymbionts in any species affect their hosts' performance at low temperatures, something that could have a major effect on insect physiology and survival, and thus population structure and distribution. 2. The original facultative endosymbionts were experimentally removed from five clonal genotypes of the grain aphid, Sitobion avenae Fab., which were then exposed to frost. 3. Aphid genotypes differed considerably in survival following the exposure and in fecundity of the survivors. However, the presence of the facultative symbionts had no overall effect on the studied traits. 4. The results suggest that the facultative symbionts have limited effects on the cold hardiness of their grain aphid hosts. 相似文献
19.
Panisara Pinkantayong Satoshi Suzuki Mamoru Kubo Ken‐ichiro Muramoto Naoto Kamata 《Ecology and evolution》2015,5(3):733-742
Predation by small mammals has been reported as an important mortality factor for the cocoons of sawfly species. However, it is difficult to provide an accurate estimate of newly spun cocoons and subsequent predation rates by small mammals for several reasons. First, all larvae do not spin cocoons at the same time. Second, cocoons are exposed to small mammal predation immediately after being spun. Third, the cocoons of the current generation are indistinguishable from those of the previous generation. We developed a hierarchical Bayesian model to estimate these values from annual one‐time soil sampling datasets. To apply this model to an actual data set, field surveys were conducted in eight stands of larch plantations in central Hokkaido (Japan) from 2009 to 2012. Ten 0.04‐m2 soil samples were annually collected from each site in mid‐October. The abundance of unopened cocoons (I), cocoons emptied by small‐mammal predation (M), and empty cocoons caused by something other than small‐mammal predation (H) were determined. The abundance of newly spun cocoons, the predation rate by small mammals before and after cocoon sampling, and the annual rate of empty cocoons that remained were estimated. A posterior predictive check yielded Bayesian P‐values of 0.54, 0.48, and 0.07 for I, M, and H, respectively. Estimated predation rates showed a significant positive correlation with the number of trap captures of small mammals. Estimates of the number of newly spun cocoons had a significant positive correlation with defoliation intensity. These results indicate that our model showed an acceptable fit, with reasonable estimates. Our model is expected to be widely applicable to all hymenopteran and lepidopteran insects that spin cocoons in soil. 相似文献
20.
James R. Hagler 《Entomologia Experimentalis et Applicata》2016,161(3):187-192
Conventional prey‐specific gut content ELISA (enzyme‐linked immunosorbent assay) and PCR (polymerase chain reaction) assays are useful for identifying predators of insect pests in nature. However, these assays are prone to yielding certain types of food chain errors. For instance, it is possible that prey remains can pass through the food chain as the result of a secondary predator (hyperpredator) consuming a primary predator that had previously consumed the pest. If so, the pest‐specific assay will falsely identify the secondary predator as the organism providing the biological control services to the ecosystem. Recently, a generic gut content ELISA was designed to detect protein‐marked prey remains. That assay proved to be less costly, more versatile, and more reliable at detecting primary predation events than a prey‐specific PCR assay. This study examines the chances of obtaining a ‘false positive’ food chain error with the generic ELISA. Data revealed that the ELISA was 100% accurate at detecting protein‐marked Lygus hesperus Knight (Hemiptera: Miridae) remains in the guts of two (true) primary predators, Hippodamia convergens Guérin‐Méneville (Coleoptera: Coccinellidae) and Collops vittatus (Say) (Coleoptera: Melyridae). However, there was also a high frequency (70%) false positives associated with hyperpredators, Zelus renardii Kolenati (Hemiptera: Reduviidae), that consumed a primary predator that possessed protein‐marked L. hesperus in its gut. These findings serve to alert researchers that the generic ELISA, like the PCR assay, is susceptible to food chain errors. 相似文献