Wolbachia manipulate fitness benefits of olfactory associative learning in a parasitoid wasp.

Upon encountering a host, a female parasitoid wasp has to decide whether to learn positive or negative cues related to the host. The optimal female decision will depend on the fitness costs and benefits of learned stimuli. Reward quality is positively related to the rate of behavioral acquisition in processes such as associative learning. Wolbachia, an endosymbiotic bacterium, often plays an impressive role in the manipulation of its arthropod host's biology. Here, we studied the responses of two natural Wolbachia infected/uninfected Trichogramma brassicae wasp populations to theoretically high- and low-reward values during a conditioning process and the consequences of their responses in terms of memory duration. According to our results, uninfected wasps showed an attraction response to high-value rewards, but showed aversive learning in response to low-value rewards. The memory span of uninfected wasps after conditioning by low-value rewards was significantly shorter than that for high-value rewards. As our results revealed, responses to high-quality hosts will bring more benefits (bigger size, increased fecundity and enhanced survival) than those to low-quality hosts for uninfected wasps. Infected wasps were attracted to conditioned stimuli with the same memory duration after conditioning by both types of hosts. This was linked to the fact that parasitoids emerging from both types of hosts present the same life-history traits. Therefore, these hosts represent the same quality reward for infected wasps. According to the obtained results, it can be concluded that Wolbachia manipulates the learning ability of its host, resulting in the wasp responding to all reward values similarly.

Using demographic characteristics of populations to detect spatial fragmentation following suspected ebola outbreaks in great apes.

OBJECTIVES: Demographic crashes due to emerging diseases can contribute to population fragmentation and increase extinction risk of small populations. Ebola outbreaks in 2002-2004 are suspected to have caused a decline of more than 80% in some Western lowland gorilla (Gorilla gorilla gorilla) populations. We investigated whether demographic indicators of this event allowed for the detection of spatial fragmentation in gorilla populations. MATERIALS AND METHODS: We collected demographic data from two neighbouring populations: the Lokoué population, suspected to have been affected by an Ebola outbreak (followed from 2001 to 2014), and the Romani population, of unknown demographic status before Ebola outbreaks (followed from 2005 to 2014). RESULTS: Ten years after the outbreak, the Lokoué population is slowly recovering and the short-term demographic indicators of a population crash were no longer detectable. The Lokoué population has not experienced any additional demographic perturbation over the past decade. The Romani population did not show any of the demographic indicators of a population crash over the past decade. Its demographic structure remained similar to that of unaffected populations. DISCUSSION: Our results highlighted that the Ebola disease could contribute to fragmentation of gorilla populations due to the spatially heterogeneous impact of its outbreaks. The demographic structure of populations (i.e., age-sex and group structure) can be useful indicators of a possible occurrence of recent Ebola outbreaks in populations without known history, and may be more broadly used in other emerging disease/species systems. Longitudinal data are critical to our understanding of the impact of emerging diseases on wild populations and their conservation.

How Ebola impacts social dynamics in gorillas: a multistate modelling approach.

Emerging infectious diseases can induce rapid changes in population dynamics and threaten population persistence. In socially structured populations, the transfers of individuals between social units, for example, from breeding groups to non-breeding groups, shape population dynamics. We suggest that diseases may affect these crucial transfers. We aimed to determine how disturbance by an emerging disease affects demographic rates of gorillas, especially transfer rates within populations and immigration rates into populations. We compared social dynamics and key demographic parameters in a gorilla population affected by Ebola using a long-term observation data set including pre-, during and post-outbreak periods. We also studied a population of undetermined epidemiological status in order to assess whether this population was affected by the disease. We developed a multistate model that can handle transition between social units while optimizing the number of states. During the Ebola outbreak, social dynamics displayed increased transfers from a breeding to a non-breeding status for both males and females. Six years after the outbreak, demographic and most of social dynamics parameters had returned to their initial rates, suggesting a certain resilience in the response to disruption. The formation of breeding groups increased just after Ebola, indicating that environmental conditions were still attractive. However, population recovery was likely delayed because compensatory immigration was probably impeded by the potential impact of Ebola in the surrounding areas. The population of undetermined epidemiological status behaved similarly to the other population before Ebola. Our results highlight the need to integrate social dynamics in host-population demographic models to better understand the role of social structure in the sensitivity and the response to disease disturbances.

Effect of habitat quality on diet flexibility in Barbary macaques.

Barbary macaques live in extreme temperate environments characterized by strongly seasonal resource availability. They are mainly terrestrial while foraging, harvesting food from the herbaceous layer. These monkeys are threatened mainly because of anthropogenic habitat degradation. We studied the adaptive capacities of wild groups of Barbary macaques that lived in different cedar forests undergoing varying extents of grazing pressure from domestic livestock. In all three sites, diet varied seasonally. Heavy grazing led to a significant decrease in herbaceous production and species richness. As a consequence, the monkeys' diet in this poor habitat showed a decreased plant species richness. Moreover, it incorporated fewer above-ground herbaceous resources, and a greater proportion of subterranean resources (especially hypogeous fungi and subterranean invertebrates such as earthworms, eggs and adults of earwigs, and ant's larvae) than the diet of monkeys inhabiting ungrazed forest. Cedar bark, cedar strobiles, earthworms, and earwigs were part of the monkeys' diet only in grazed forest. Monkeys in heavily grazed forest compensated for a lack of herbaceous foods by eating subterranean foods preferentially to tree and shrub products. The foods they consumed take longer to harvest and process than the seeds or leaves consumed by Barbary macaques in less heavily grazed forest habitats. Our results suggest that monkeys do differ in their diets according to the degree of habitat change induced by human activities. They also highlight the dietary flexibility of Barbary macaques as a key element that allows them to cope with degraded habitats. We later compare the dietary adjustments of Barbary macaques facing environmental change to dietary strategies of other macaques and temperate-zone primates.

Landscape effects on the thermotolerance of carabid beetles and the role of behavioral thermoregulation.

Physiological thermotolerance and behavioral thermoregulation are central to seasonal cold adaptation in ectothermic organisms. For species with enhanced mobility, behavioral responses may be of greater importance in the cold stress response. Employing the carabid beetles as a study organism, the current study compared physiological thermotolerance and behavioral thermoregulation in carabid species inhabiting cereal fields in different landscape contexts, from fine grain heterogeneous "complex" landscapes to homogenous "simple" landscapes. Physiological thermotolerance was determined via measurement of the CTmin and chill coma temperature. Behavioral responses to cold temperature exposure were determined employing a purpose built arena, and thoracic temperature measured to estimate the efficacy of the behavior as a form of behavioral thermoregulation. Results revealed an influence of landscape composition on the cold tolerance of carabid beetles, although species differed in their sensitivity to landscape intensification. A reduced effect of landscape on the thermotolerance of larger carabid beetles was observed, thought to be the consequence of greater mobility preventing local acclimation to microclimatic variation along the landscape intensification gradient. Investigation into behavioral thermoregulation of the 3 largest species revealed burrowing behavior to be the main behavioral response to cold stress, acting to significantly raise carabid body temperature. This finding highlights the importance of behavioral thermoregulation as a strategy to evade cold stress. The use of behavioral thermoregulation may negate the need to invest in physiological thermotolerance, further offering explanation for the lack of landscape effect on the physiological thermotolerance of larger carabids.

Patch leaving rules: a stochastic version of a well-known deterministic motivational model.

A famous motivational model proposed for insect parasitoids by Waage (1979) provides a candidate mechanism for patch-leaving decision rules in foragers. In this model, the animal is supposed to enter a patch of resources with an initial tendency to stay in it, which then regularly decreases. Every encounter with a resource item increases or decreases this tendency, and the forager is supposed to leave the patch when this tendency or motivation falls below a given threshold. Evidence of such increases and drops in this tendency to stay were often obtained by analyzing experimental data with a Cox (1972) proportional hazards model. The Waage (1979) model is purely deterministic and predicts a fixed departure time for a fixed set of encounters with foraging items. On the other hand, empirical data show a large variability of departure times under fixed conditions. We present a fully stochastic version which overcomes this problem and gives a quasi close form expression for the distribution of patch residence times as well as a statistical procedure to estimate its parameters. Two examples of the model fitting on experimental data sets are provided. This novel model, although more complicated than Waage (1979) model, improves its realism and provides a stochastic interpretation of motivation as a proximal mechanism leading foragers to optimality.

Physiological adaptations to climate change in pro-ovigenic parasitoids.

Temperature increase can affect physiological and behavioural constraints. Here, we use a stochastic dynamic modelling approach to predict changes in physiological adaptations and behaviour in response to temperature increase of pro-ovigenic parasitoids (i.e., parasitoids that mature all of their eggs before emergence). Adults of most species of parasitoids, are not capable of de novo lipogenesis. The allocation of lipids accumulated during the larval stage determines adult lifespan and fecundity. In females, lipids can be allocated either to egg production or to adult lipid reserves leading to a trade-off between fecundity and lifespan. Our results show that selection by an increase in ambient temperature, favours a smaller initial egg load and a larger amount of lipids for maintenance. The cost of habitat exploitation increases with temperature because the rate of lipid consumption increases. Hence, lifetime reproductive success decreases. When the optimal activity rate shifts to match the higher ambient temperature, these effects become less pronounced.

Carbon dioxide narcosis modifies the patch leaving decision of foraging parasitoids.

Gleaning information is a way for foragers to adjust their behavior in order to maximize their fitness. Information decreases the uncertainty about the environment and could help foragers to accurately estimate environmental characteristics. In a patchy resource, information sampled during previous patch visits is efficient only if it is retained in the memory and retrieved upon arrival in a new patch. In this study, we tested whether the braconid Asobara tabida, a parasitoid of Drosophila larvae, retains information gleaned on patch quality in the memory and adjusts its foraging behavior accordingly. Females were anesthetized with CO(2) after leaving a first patch containing a different number of hosts and were allowed to visit a second patch containing only kairomones. CO(2) is known to erase unconsolidated information from the memory. We show that in the absence of a short CO(2) narcosis, females responded according to their previous experience, whereas anesthetized females did not. The anesthetized females stayed a given time in the second patch irrespective of what they encountered before. CO(2) narcosis had no effect on the residence time of the non-experienced females in a patch containing hosts or only kairomones in comparison with the non-anesthetized females that had a previous foraging experience. We conclude that CO(2) narcosis erases the effect of the previous patch quality, perhaps due to a memory disruption. Direct information processing is likely to be involved in parasitoid decision making through retention of the information on the previous patch quality into a CO(2) sensitive memory.

The advantage of sex: Reinserting fluctuating selection in the pluralist approach.

The advantage of sex, and its fixation in some clades and species all over the eukaryote tree of life, is considered an evolutionary enigma, especially regarding its assumed two-fold cost. Several likely hypotheses have been proposed such as (1) a better response to the negative frequency-dependent selection imposed by the "Red Queen" hypothesis; (2) the competition between siblings induced by the Tangled Bank hypothesis; (3) the existence of genetic and of (4) ecological factors that can diminish the cost of sex to less than the standard assumed two-fold; and (5) a better maintenance of genetic diversity and its resulting phenotypic variation, providing a selective advantage in randomly fluctuating environments. While these hypotheses have mostly been studied separately, they can also act simultaneously. This was advocated by several studies which presented a pluralist point of view. Only three among the five causes cited above were considered yet in such a framework: the Red Queen hypothesis, the Tangled Bank and the genetic factors lowering the cost of sex. We thus simulated the evolution of a finite mutating population undergoing negative frequency-dependent selection on phenotypes and a two-fold (or less) cost of sexuality, experiencing randomly fluctuating selection along generations. The individuals inherited their reproductive modes, either clonal or sexual. We found that exclusive sexuality begins to fix in populations exposed to environmental variation that exceeds the width of one ecological niche (twice the standard deviation of a Gaussian response to environment). This threshold was lowered by increasing negative frequency-dependent selection and when reducing the two-fold cost of sex. It contributes advocating that the different processes involved in a short-term advantage of sex and recombination can act in combination to favor the fixation of sexual reproduction in populations.

Poor adult nutrition impairs learning and memory in a parasitoid wasp.

Animals have evolved cognitive abilities whose impairment can incur dramatic fitness costs. While malnutrition is known to impact brain development and cognitive functions in vertebrates, little is known in insects whose small brain appears particularly vulnerable to environmental stressors. Here, we investigated the influence of diet quality on learning and memory in the parasitoid wasp Venturia canescens. Newly emerged adults were exposed for 24 h to either honey, 20% sucrose solution, 10% sucrose solution, or water, before being conditioned in an olfactory associative learning task in which an odor was associated to a host larvae (reward). Honey fed wasps showed 3.5 times higher learning performances and 1.5 times longer memory retention than wasps fed sucrose solutions or water. Poor diets also reduced longevity and fecundity. Our results demonstrate the importance of early adult nutrition for optimal cognitive function in these parasitoid wasps that must quickly develop long-term olfactory memories for searching suitable hosts for their progeny.

Assessment of neuropeptide binding sites and the impact of biostable kinin and CAP2b analogue treatment on aphid (Myzus persicae and Macrosiphum rosae) stress tolerance.

BACKGROUND: Neuropeptides are regulators of critical life processes in insects and, due to their high specificity, represent potential targets in the development of greener insecticidal agents. Fundamental to this drive is understanding neuroendocrine pathways that control key physiological processes in pest insects and the screening of potential analogues. The current study investigated neuropeptide binding sites of kinin and CAPA (CAPA-1) in the aphids Myzus persicae and Macrosiphum rosae and the effect of biostable analogues on aphid fitness under conditions of desiccation, starvation and thermal (cold) stress. RESULTS: M. persicae and M. rosae displayed identical patterns of neuropeptide receptor mapping along the gut, with the gut musculature representing the main target for kinin and CAPA-1 action. While kinin receptor binding was observed in the brain and VNC of M. persicae, this was not observed in M. rosae. Furthermore, no CAPA-1 receptor binding was observed in the brain and VNC of either species. CAP2b/PK analogues (with CAPA receptor cross-activity) were most effective in reducing aphid fitness under conditions of desiccation and starvation stress, particularly analogues 1895 (2Abf-Suc-FGPRLa) and 2129 (2Abf-Suc-ATPRIa), which expedited aphid mortality. All analogues, with the exception of 2139-Ac, were efficient at reducing aphid survival under cold stress, although were equivalent in the strength of their effect. CONCLUSION: In demonstrating the effects of analogues belonging to the CAP2b neuropeptide family and key analogue structures that reduce aphid fitness under stress conditions, this research will feed into the development of second generation analogues and ultimately the development of neuropeptidomimetic-based insecticidal agents. © 2019 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Interspecific competition among aphid parasitoids: molecular approaches reveal preferential exploitation of parasitized hosts.

When a guild of species exploit the same limited resources, interspecific competition induces the exclusion of inferior competitors, in which case, interspecific recognition mechanisms are needed. Here, we address resource partitioning and interspecific competition among three main solitary parasitoid species attacking the same host resource, the aphid Sitobion avenae in wheat fields. Optimal host acceptance models predict that parasitoid species should prefer attacking unparasitized hosts when they are available in order to maximize their fitness, as already parasitized hosts are less valuable for laying eggs, especially for inferior competitors. Therefore, we expected the level of competition (multiparasitism) in the field to increase at low host density. By using a combination of taxonomical (determination) and molecular (PCR-based) approaches, we assessed the species of all parasitoid adults and immature stages within aphid hosts. Our results demonstrate that, early in the season, the multiparasitism rates were low, whereas they were high in the mid-late season, corresponding to an aphid density decrease over time. Moreover, parasitoid species could not have been exploiting host resources randomly and the better competitor, Aphidius ervi, seemed to be foraging preferentially on hosts already parasitized by the inferior competitor A. rhopalosiphi, even when unparasitized hosts were still available. This could be due to differences in their host detection capability, as species with a narrow host range may be better at detecting their hosts in comparison with species with a greater host range, such as A. ervi, with a greater host range within the guild. Our study suggests differences in the host exploitation of two prevalent parasitoid species through the main period of aphid colonization, which still allowed the coexistence of a third inferior competitor (A. rhopalosiphi) within the assemblage, in spite of some negative interactions (multiparasitism) and redundancies.

Disease avoidance, and breeding group age and size condition the dispersal patterns of western lowland gorilla females.

Social dispersal is an important feature of population dynamics. When female mammals occur in polygynous groups, their dispersal decisions are conditioned by various female-, male-, and group-related factors. Among them, the influence of disease often remains difficult to assess. To address this challenge, we used long-term monitoring data from two gorilla populations (Gorilla gorilla gorilla) affected by infectious skin disease lesions. After controlling for other potentially influential factors, we investigated to which extent disease avoidance drives the dispersal decisions of gorilla females. We showed that the infection of a silverback of a breeding group by the skin disease increased the probability of adult females to emigrate. Moreover, adult females avoided breeding groups with a high prevalence of skin disease by emigrating from them and immigrating into healthier ones. Age of the breeding group was also an important factor. Adult females left older groups, near the end of a male tenure, to join younger ones led by younger fully grown silverbacks that could be of high reproductive and protective value. Our study highlights that, although females select for high-quality males, disease avoidance is a critical driver of their dispersion decision.

The effect of landscape complexity and microclimate on the thermal tolerance of a pest insect.

Landscape changes are known to exacerbate the impacts of climate change. As such, understanding the combined effect of climate and landscape on agroecosystems is vital if we are to maintain the function of agroecosystems. This study aimed to elucidate the effects of agricultural landscape complexity on the microclimate and thermal tolerance of an aphid pest to better understand how landscape and climate may interact to affect the thermal tolerance of pest species within the context of global climate change. Meteorological data were measured at the landscape level, and cereal aphids (Sitobion avenae, Metopolophium dirhodum and Rhopalosiphum padi) sampled, from contrasting landscapes (simple and complex) in winter 2013/2014 and spring 2014 in cereal fields of Brittany, France. Aphids were returned to the laboratory and the effect of landscape of origin on aphid cold tolerance (as determined by CTmin ) was investigated. Results revealed that local landscape complexity significantly affected microclimate, with simple homogenous landscapes being on average warmer, but with greater temperature variation. Landscape complexity was shown to impact aphid cold tolerance, with aphids from complex landscapes being more cold tolerant than those from simple landscapes in both winter and spring, but with differences among species. This study highlights that future changes to land use could have implications for the thermal tolerance and adaptability of insects. Furthermore, not all insect species respond in a similar way to microhabitat and microclimate, which could disrupt important predator-prey relationships and the ecosystem service they provide.

Weakly aggressive behaviour towards nymphs in the cockroach Schultesia nitor (Blattaria: Zetoborinae).

This paper describes aggressive behaviour in the cockroach Schultesia nitor, a tropical forest species living in bird nests. Young S. nitor nymphs are known to show active dispersal while old nymphs and adults are contrastingly strongly gregarious, a combination of features never observed in other cockroach species. Our laboratory experiments using video recording of confrontations between pairs show that aggressive behaviour towards conspecific nymphs is not exhibited towards nymphs of the species Phoetalia pallida, and thus can be considered species specific in S. nitor. But, it is not kin oriented: the mother and all adults of both sexes in different physiological states exhibit this behaviour as well. Six types of aggressive interactions were discriminated, occurring in age-symmetric pairs of nymphs and adults. Even more frequent aggression was exhibited by adults and last instar nymphs towards younger nymphs of all instars. The frequency of aggressive acts and types of aggressive interactions varied according to sex and size of the two interacting individuals. The possible function and evolution of this behaviour is discussed, with emphasis on the difficulty of interpreting obvious but weak and not kin-biased aggression.

Decrease of memory retention in a parasitic wasp: an effect of host manipulation by Wolbachia?

Several factors, such as cold exposure, aging, the number of experiences and viral infection, have been shown to affect learning ability in different organisms. Wolbachia has been found worldwide as an arthropod parasite/mutualist symbiont in a wide range of species, including insects. Differing effects have been identified on physiology and behavior by Wolbachia. However, the effect of Wolbachia infection on the learning ability of their host had never previously been studied. The current study carried out to compare learning ability and memory duration in 2 strains of the parasitoid Trichogramma brassicae: 1 uninfected and 1 infected by Wolbachia. Both strains were able to associate the novel odors with the reward of an oviposition into a host egg. However, the percentage of females that responded to the experimental design and displayed an ability to learn in these conditions was higher in the uninfected strain. Memory duration was longer in uninfected wasps (23.8 and 21.4 h after conditioning with peppermint and lemon, respectively) than in infected wasps (18.9 and 16.2 h after conditioning with peppermint and lemon, respectively). Memory retention increased in response to the number of conditioning sessions in both strains, but memory retention was always shorter in the infected wasps than in the uninfected ones. Wolbachia infection may select for reduced memory retention because shorter memory induces infected wasps to disperse in new environments and avoid competition with uninfected wasps by forgetting cues related to previously visited environments, thus increasing transmission of Wolbachia in new environments.

Why is there no impact of the host species on the cold tolerance of a generalist parasitoid?

For generalist parasitoids such as those belonging to the Genus Aphidius, the choice of host species can have profound implications for the emerging parasitoid. Host species is known to affect a variety of life history traits. However, the impact of the host on thermal tolerance has never been studied. Physiological thermal tolerance, enabling survival at unfavourable temperatures, is not a fixed trait and may be influenced by a number of external factors including characteristics of the stress, of the individual exposed to the stress, and of the biological and physical environment. As such, the choice of host species is likely to also have implications for the thermal tolerance of the emerging parasitoid. The current study aimed to investigate the effect of cereal aphid host species (Sitobion avenae, Rhopalosiphum padi and Metopolophium dirhodum) on adult thermal tolerance, in addition to sex and size, of the aphid parasitoids Aphidius avenae, Aphidius matricariae and Aphidius rhopalosiphi. Results revealed no effect of host species on the cold tolerance of the emerging parasitoid, as determined by CTmin and Chill Coma, for all parasitoid species. Host species significantly affected the size of the emerging parasitoid for A. rhopalosiphi only, with individuals emerging from R. padi being significantly larger than those emerging from S. avenae, although this did not correspond to a difference in thermal tolerance. Furthermore, a significant difference in the size of male and female parasitoids was observed for A. avenae and A. matricariae, although, once again this did not correspond to a difference in cold tolerance. It is suggested that potential behavioural thermoregulation via host manipulation may act to influence the thermal environment experienced by the wasp and thus wasp thermal tolerance and, in doing so, may negate physiological thermal tolerance or any impact of the aphid host.

Potential Host Manipulation by the Aphid Parasitoid Aphidius avenae to Enhance Cold Tolerance.

During parasitoid development, the immature parasitoid is confined to the host species. As a result, any potential to modify the physiology or behaviour of the host could play an important role in parasitoid fitness. The potential for host manipulation by the aphid parasitoid Aphidius avenae to increase cold thermotolerance was investigated using the aphid host species Metopolophium dirhodum and Sitobion avenae. Aphids were parasitized at L3/L4 instar stage (5 d old) and allowed to develop into pre-reproductive adults (10 d old) containing a 5 d old parasitoid larva. A control group was created of non-parasitized pre-reproductive adults (10 d old). The inherent physiological thermotolerance (LT50) and potential behavioural thermoregulation (behaviour in a declining temperature regime) of parasitized and non-parasitized aphids were investigated. Results revealed no effect of parasitism on the physiological thermotolerance of S. avenae and M. dirhodum. Significant differences in the behaviour of parasitized and non-parasitized aphids were observed, in addition to differences between host species, and such behaviours are discussed in view of the potential for host manipulation.

Adaptive value of host discrimination in parasitoids: when host defences are very costly.

Host acceptance decision in parasitic wasps strongly depends on the parasitism status of the encountered host. In solitary species, a host only allows the development of a single parasitic larva and then, any oviposition in an already parasitised host leads to larval competition and loss of offspring. Females of many parasitoid species are able to discriminate between parasitised hosts and healthy ones. However, the host discrimination process may require more time than oviposition, exposing the wasp to high risks when the host has efficient defences. Consequently, depending on the degree of success of the host defence, the cost of host inspection for discrimination can outweigh the benefit of superparasitism avoidance. In the present paper, a theoretical approach was developed for determining how host defences may affect optimal host acceptance behaviour in parasitoids. The present model compares the lifetime reproductive success over the strategy used, discrimination and no-discrimination: a discriminating wasp sets a relatively greater value in its current oviposition, while a non-discriminating female sets a greater value in its own survival and future reproduction. The model predicts that depending on physiological state variables and environmental state variables, the optimal policy is not discriminating. Our results suggest that the low discriminating ability observed in some parasitic wasps could probably be an evolutionary response to host defences pressure.

Phenotypic Plasticity in Reproductive Traits of the Perennial Shrub Ulex europaeus in Response to Shading: A Multi-Year Monitoring of Cultivated Clones.

Phenotypic plasticity may be advantageous for plants to be able to rapidly cope with new and changing environments associated with climate change or during biological invasions. This is especially true for perennial plants, as they may need a longer period to respond genetically to selective pressures than annuals, and also because they are more likely to experience environmental changes during their lifespan. However, few studies have explored the plasticity of the reproductive life history traits of woody perennial species. This study focuses on a woody shrub, Ulex europaeus (common gorse), and on the response of its reproductive traits to one important environmental factor, shading. The study was performed on clones originating from western France (within the native range of this invasive species) and grown for seven years. We compared traits of plants grown in a shade treatment (with two successive shade levels) vs. full natural light. The traits monitored included flowering onset, pod production and seed predation. All traits studied responded to shading, exhibiting various levels of plasticity. In particular, dense shade induced a radical but reversible decrease in flower and pod production, while moderate shade had little effect on reproductive traits. The magnitude of the response to dense shade depended on the genotype, showing a genetically based polymorphism of plasticity. The level of plasticity also showed substantial variations between years, and the effect of environmental variations was cumulative over time. This suggests that plasticity can influence the lifetime fitness of U. Europaeus and is involved in the capacity of the species to grow under contrasting environmental conditions.