Ants dominate terrestrial ecosystems through living in complex societies whose organization is maintained via sophisticated communication systems. The role of acoustics in information exchange may be ...underestimated. We show that Myrmica schencki queens generate distinctive sounds that elicit increased benevolent responses from workers, reinforcing their supreme social status. Although fiercely defended by workers, ant societies are infiltrated by specialist insects that exploit their resources. Sounds produced by pupae and larvae of the parasitic butterfly Maculinea rebeli mimic those of queen ants more closely than those of workers, enabling them to achieve high status within ant societies. We conclude that acoustical mimicry provides another route for infiltration for ~10,000 species of social parasites that cheat ant societies.
In natural ecosystems, relationships between organisms are often characterised by high levels of complexity, where vulnerabilities in multi-trophic systems are difficult to identify, yet variation in ...specific community modules can be traceable. Within the complex community interactions, we can shed new light on dynamics by which co-evolutionary outcomes can inform science-led conservation. Here we assessed host-ant use in six populations of the butterfly Phengaris (=Maculinea) rebeli, an obligate social parasite of Myrmica ants and a model system in evolutionary and conservation ecology. Starting from the initial distribution of eggs, we estimated the survival of the parasite in the wild in nests of seven Myrmica ant species, and analysed the chemical cues evolved by the parasites to subvert its host defences. We found local variations in host specificity that are consistent with similarities found in the chemical profiles of hosts and parasites on different sites. At some sites, only one ant species is successfully exploited; at others, multiple-host populations are used. Understanding how stable or adaptable these associations are is essential knowledge when devising conservation measures to maintain keystone species of ant and locally adapted populations of Phengaris butterfly species, which are rare, threatened and a high priority for conservation worldwide.
Maculinea (=Phengaris) are endangered butterflies that are characterized by a very complex biological cycle. Maculinea larvae behave as obligate parasites whose survival is strictly dependent on both ...particular food plants and species-specific Myrmica ants. In this interaction, Maculinea caterpillars induce Myrmica workers to retrieve and rear them in the nest by chemical and acoustic deception. Social insect symbiotic microorganisms play a key role in intraspecific and interspecific communication; therefore, it is possible that the Maculinea caterpillar microbiome might be involved in the chemical cross-talk by producing deceptive semiochemicals for host ants. To address this point, the microbiota of Maculinea alcon at different larval stages (phytophagous early larvae, intermediate larvae, carnivorous late larvae) was analyzed by using 16S rRNA-guided metabarcoding approach and compared to that of the host ant Myrmica scabrinodis. Structural and deduced functional profiles of the microbial communities were recorded, which were used to identify specific groups of microorganisms that may be involved in the chemical cross-talk. One of the most notable features was the presence in all larval stages and in the ants of two bacteria, Serratia marcescens and S. entomophila, which are involved in the chemical cross-talk between the microbes and their hosts.
According to the Convention on Biological Diversity, by 2020 invasive alien species (IAS) should be identified and their impacts assessed, so that species can be prioritized for implementation of ...appropriate control strategies and measures put in place to manage invasion pathways. For one quarter of the IAS listed as the “100 of the world's worst” environmental impacts are linked to diseases of wildlife (undomesticated plants and animals). Moreover, IAS are a significant source of “pathogen pollution” defined as the human‐mediated introduction of a pathogen to a new host or region. Despite this, little is known about the biology of alien pathogens and their biodiversity impacts after introduction into new regions. We argue that the threats posed by alien pathogens to endangered species, ecosystems, and ecosystem services should receive greater attention through legislation, policy, and management. We identify 10 key areas for research and action, including those relevant to the processes of introduction and establishment of an alien pathogen and to prediction of the spread and associated impact of an alien pathogen on native biota and ecosystems. The development of interdisciplinary capacity, expertise, and coordination to identify and manage threats was seen as critical to address knowledge gaps.
Insect galls are dramatic examples of extended phenotypes: although composed of host plant tissues, their development is largely controlled by insect genes. Adaptive explanations for gall traits ...should thus be expressed in terms of impacts on insect fitness, but the extent to which interspecific variation in gall structure is adaptive, and the possible selective pressures driving diversification in gall form remain controversial. In colonial aphids and thrips, gall structures probably diversified in response to selection for enhancement of the surface area available for feeding. In other taxa, such as gall wasps and gall midges, diversity is expressed predominantly in non-nutritive tissues, particularly those on the gall surface. All natural enemies attack the occupants of closed galls by penetrating gall tissue, and modifications that reduce enemy attack rates should thus be favoured. Recent studies of intraspecific variation in gall form strongly support a defensive role for several traits, but, to date, there is little empirical support for enemies as a cause of interspecific variation in gall form. Selection imposed by enemies nevertheless remains the most probable adaptive explanation for the evolution of diversity. We suggest that this hypothesis has yet to be tested explicitly, and discuss the requirements for an appropriate cross-species analysis.
Oak gall wasps (Hymenoptera: Cynipidae, Cynipini) are characterized by
possession of complex cyclically parthenogenetic life cycles and the ability to
induce a wide diversity of highly complex ...species- and generation-specific
galls on oaks and other Fagaceae. The galls support species-rich, closed
communities of inquilines and parasitoids that have become a model system in
community ecology. We review recent advances in the ecology of oak cynipids,
with particular emphasis on life cycle characteristics and the dynamics of the
interactions between host plants, gall wasps, and natural enemies. We assess
the importance of gall traits in structuring oak cynipid communities and
summarize the evidence for bottom-up and top-down effects across trophic
levels. We identify major unanswered questions and suggest approaches for the
future.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, UILJ, UKNU, UL, UM, UPUK
Many insect species are under threat from the anthropogenic drivers of global change. There have been numerous well‐documented examples of insect population declines and extinctions in the scientific ...literature, but recent weaker studies making extreme claims of a global crisis have drawn widespread media coverage and brought unprecedented public attention. This spotlight might be a double‐edged sword if the veracity of alarmist insect decline statements do not stand up to close scrutiny.
We identify seven key challenges in drawing robust inference about insect population declines: establishment of the historical baseline, representativeness of site selection, robustness of time series trend estimation, mitigation of detection bias effects, and ability to account for potential artefacts of density dependence, phenological shifts and scale‐dependence in extrapolation from sample abundance to population‐level inference.
Insect population fluctuations are complex. Greater care is needed when evaluating evidence for population trends and in identifying drivers of those trends. We present guidelines for best‐practise approaches that avoid methodological errors, mitigate potential biases and produce more robust analyses of time series trends.
Despite many existing challenges and pitfalls, we present a forward‐looking prospectus for the future of insect population monitoring, highlighting opportunities for more creative exploitation of existing baseline data, technological advances in sampling and novel computational approaches. Entomologists cannot tackle these challenges alone, and it is only through collaboration with citizen scientists, other research scientists in many disciplines, and data analysts that the next generation of researchers will bridge the gap between little bugs and big data.
The focus on global insect declines puts insect conservation firmly on the public agenda but could become a double‐edged sword if population trend estimates do not withstand increased scrutiny.
Here, we identify seven key challenges in drawing robust quantitative inference about insect population declines, reflecting errors of baseline, trend estimation and resulting population level inference.
We present a forward‐looking prospectus for the future of insect population monitoring, highlighting opportunities for more creative exploitation of existing baseline data, technological advances in sampling and novel computational approaches.
Galls are plant tissues whose development is induced by another organism for the inducer's benefit. 30,000 arthropod species induce galls, and in most cases the inducing effectors and target plant ...systems are unknown. Cynipid gall wasps are a speciose monophyletic radiation that induce structurally complex galls on oaks and other plants. We used a model system comprising the gall wasp Biorhiza pallida and the oak Quercus robur to characterise inducer and host plant gene expression at defined stages through the development of galled and ungalled plant tissues, and tested alternative hypotheses for the origin and type of galling effectors and plant metabolic pathways involved. Oak gene expression patterns diverged markedly during development of galled and normal buds. Young galls showed elevated expression of oak genes similar to legume root nodule Nod factor-induced early nodulin (ENOD) genes and developmental parallels with oak buds. In contrast, mature galls showed substantially different patterns of gene expression to mature leaves. While most oak transcripts could be functionally annotated, many gall wasp transcripts of interest were novel. We found no evidence in the gall wasp for involvement of third-party symbionts in gall induction, for effector delivery using virus-like-particles, or for gallwasp expression of genes coding for plant hormones. Many differentially and highly expressed genes in young larvae encoded secretory peptides, which we hypothesise are effector proteins exported to plant tissues. Specifically, we propose that host arabinogalactan proteins and gall wasp chitinases interact in young galls to generate a somatic embryogenesis-like process in oak tissues surrounding the gall wasp larvae. Gall wasp larvae also expressed genes encoding multiple plant cell wall degrading enzymes (PCWDEs). These have functional orthologues in other gall inducing cynipids but not in figitid parasitoid sister groups, suggesting that they may be evolutionary innovations associated with cynipid gall induction.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
The chestnut gall wasp Dryocosmus kuriphilus is a global pest of chestnut (Castanea spp). Established as a pest in the mid-twentieth century in Japan, Korea and North America, this species was first ...reported in Europe in 2002. Following the successful release of a biological control agent Torymus sinensis in Japan, this parasitoid species has been released in Italy since 2005. Here we discuss the potential of T. sinensis as a viable management option for the biological control of D. kuriphilus in central Europe. We suggest that more consideration should be given to determining, (i) the conditions under which T. sinensis may attack alternative native gall wasp hosts and (ii) the likelihood of hybridization of this species with native Torymus. Both issues are central to predicting unassisted range expansion by released T. sinensis, and to assess the environmental risks associated with a more widespread release of this species in Europe.
Tree health declines can be caused by interactions between pests and pathogens and many studies have shown a reduction in their damage in mixed species forests compared to monocultures. Yet few ...authors have considered tree diversity effects on both groups simultaneously. Moreover, it is unclear whether diversity effects on tree pests and pathogens are robust to changes in abiotic conditions, such as drought.
We addressed tree diversity effects on foliar insect herbivory, oak powdery mildew and their interaction under contrasting water regimes in a large-scale tree diversity experiment in SW France. Using an irrigation treatment that alleviated drought conditions, we were able to experimentally assess the effects of tree diversity under contrasting abiotic environments. We surveyed plots along a richness gradient from one to four tree species, in which a focal study species of oak (Quercus robur) was mixed with other oak species (Q. pyrenaica and Q. ilex) and a taller, broadleaved species (Betula pendula).
Increasing tree species richness lowered leaf miner abundance, leaf chewer damage and oak powdery mildew infection, consistent with a protective effect of resource dilution. However, richness effects on leaf miners were stronger in irrigated compared to non-irrigated blocks, indicating that environmental conditions can modulate diversity effects. Separate from the effect of tree species richness, the presence of birch in a plot increased damage by leaf chewers and powdery mildew, but lowered leaf miner damage, suggesting additional tree neighbour identity effects potentially linked to modulation of microclimate. We found a negative association between leaf miner abundance and oak powdery mildew, consistent with antagonism between oak damage agents.
Synthesis. Overall, our study illustrates the importance of considering both tree diversity and composition (neighbour identity) in designing forests more resistant to pest and pathogen damage.
This study from a large‐scale tree diversity in SW France investigates the simultaneous effects of tree diversity and drought on tree pest and disease damage. In addition to providing support for associational resistance in mixed forests to both insect herbivores and a specialist pathogen, we show that the identity of neighbouring species can impact upon associational effects. Moreover, we found that the effect of tree diversity on leaf miners was contingent on water availability, suggesting bottom‐up effects of water relations on tree growth that impacted associational effects.
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