Olfaction is a major sense in
Varroa destructor
. In natural conditions, it is known that this honey bee parasite relies on kairomones to detect its host or to reproduce. Yet, in artificial ...conditions, the parasite is able to feed and survive for a few days even though most honey bee pheromones are lacking. Other key cues are thus probably involved in
V. destructor
perception of its close environment. Here, we used several artificial feeding designs to explore the feeding behaviour of the parasite when it is deprived of olfactory cues. We found that
V. destructor
is still able to feed only guided by physical cues. The detection of the food source seems to be shape-related as a 3D membrane triggers arrestment and exploration more than a 2D membrane. The tactile sense of
V. destructor
could thus be essential to detect a feeding site, although further studies are needed to assess the importance of this sense combined with olfaction in natural conditions.
L’olfaction est un sens prépondérant chez
Varroa destructor
. En conditions naturelles, ce parasite de l’abeille domestique dépend en effet de kairomones qui lui permettent de détecter son hôte ou de se reproduire. Pourtant, lorsqu’il se retrouve en conditions artificielles, le parasite se nourrit et survit plusieurs jours malgré l’absence de la majorité des phéromones émises par l’abeille. Des indices clés autres qu’olfactifs sont donc très probablement impliqués dans la perception de l’environnement de
V. destructor
. Dans cette étude, plusieurs dispositifs d’alimentation artificielle ont été testés afin d’explorer le comportement de nourrissage du parasite lorsqu’il est privé d’indices olfactifs. Les résultats montrent que
V. destructor
est tout à fait capable de se nourrir en étant uniquement guidé par des indices physiques. En l’occurrence, la détection de la source nutritive semble être liée à sa forme puisqu’une membrane 3D provoque des comportements exploratoires plus prononcés qu’une membrane plane (2D). Le sens du toucher serait donc essentiel à
V. destructor
pour trouver son site de nourrissage. Des études complémentaires permettraient néanmoins d’évaluer les importances relatives des sens olfactif et tactile en conditions naturelles.
Beekeepers can use a variety of treatments against Varroa destructor, the parasitic mite of Apis mellifera. However, sustainable and easy-to-use solutions are still scarce, considering the complexity ...of reaching the parasite alone. Current treatments involve soft acaricides, although their mechanism of action is not well understood. We investigated the effects of organic acids such as tartaric, lactic, formic, and citric acids on the attachment abilities of V. destructor under laboratory conditions. Preventing parasites from gripping or holding on to their hosts is a crucial target for mite control strategies. We challenged grip skills through the Rotavar setup after the direct application of acids to mites’ arolia. We also tested the potential for mites to fall off honeybees after bee treatment. We found that tartaric, citric, and lactic acids were good candidates to impair the attachment of V. destructor twenty-four hours post-treatment. However, lactic acid remained the only candidate at a reasonable concentration to destabilise mites after the honey bee’s treatment without reducing their lifespan. While we conducted these experiments under artificial conditions, our results improved our comprehension of the organic acids’ potential impact on V. destructor. They can also help with the development of new methods for hive application for beekeepers worldwide.
, a major ectoparasite of the Western honey bee
, is a widespread pest that damages colonies in the Northern Hemisphere. Throughout their lifecycle,
females feed on almost every developmental stage ...of their host, from the last larval instar to the adult. The parasite is thought to feed on hemolymph and fat body, although its exact diet and nutritional requirements are poorly known. Using artificial Parafilm™ dummies, we explored the nutrition of
females and assessed their survival when fed on hemolymph from bee larvae, pupae, or adults. We compared the results with mites fed on synthetic solutions or filtered larval hemolymph. The results showed that the parasites could survive for several days or weeks on different diets. Bee larval hemolymph yielded the highest survival rates, and filtered larval plasma was sufficient to maintain the mites for 14 days or more. This cell-free solution therefore theoretically contains all the necessary nutrients for mite survival. Because some bee proteins are known to be hijacked without being digested by the parasite, we decided to run a proteomic analysis of larval honey bee plasma to highlight the most common proteins in our samples. A list of 54 proteins was compiled, including several energy metabolism proteins such as Vitellogenin, Hexamerin, or Transferrins. These molecules represent key nutrient candidates that could be crucial for
survival.
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•Many traits are involved in the survival of honey bee populations towards Varroa.•Honey bee survival with Varroa infestations is largely explained by resistance mechanisms.•No common ...molecular pathways for resistance and tolerance were identified.•Understanding of the potential link between the different traits is needed.•Finding proxies of complex traits will facilitate phenotyping for honey bee survival against Varroa.
The ectoparasitic mite Varroa destructor is the most significant pathological threat to the western honey bee, Apis mellifera, leading to the death of most colonies if left untreated. An alternative approach to chemical treatments is to selectively enhance heritable honey bee traits of resistance or tolerance to the mite through breeding programs, or select for naturally surviving untreated colonies. We conducted a literature review of all studies documenting traits of A. mellifera populations either selectively bred or naturally selected for resistance and tolerance to mite parasitism. This allowed us to conduct an analysis of the diversity, distribution and importance of the traits in different honey bee populations that can survive V. destructor globally. In a second analysis, we investigated the genetic bases of these different phenotypes by comparing ’omics studies (genomics, transcriptomics, and proteomics) of A. mellifera resistance and tolerance to the parasite. Altogether, this review provides a detailed overview of the current state of the research projects and breeding efforts against the most devastating parasite of A. mellifera. By highlighting the most promising traits of Varroa-surviving bees and our current knowledge on their genetic bases, this work will help direct future research efforts and selection programs to control this pest. Additionally, by comparing the diverse populations of honey bees that exhibit those traits, this review highlights the consequences of anthropogenic and natural selection in the interactions between hosts and parasites.
Recent studies about mutualism consider the complexity and versatility of the relationship, in addition to highlighting the importance of the cost/benefit balance between the two protagonists. ...Because species interactions are highly dependent on the environment, the climate changes foreseen for the coming years are expected to have significant impacts on the evolution of mutualistic interactions. Among mutualisms, the aphid–ant interaction is well documented, partly explained by the pest status of aphids. This literature review focuses on the impact of climate change (particularly atmospheric carbon dioxide concentration and temperature) on aphid biology and the potential consequences with respect to their mutualistic interactions with ants. We provide an overview of the published reports concerned with the effects of temperature and carbon dioxide on aphids, for which a positive, a negative or no effect has been highlighted. We then discuss how climatic changes can alter four major components of aphid biology that are shaping their interaction with ants: (i) aphid population growth; (ii) aphid behaviour and mobility; (iii) honeydew production and composition; and (iv) semiochemistry. Finaly, we discuss the limitations of such studies on aphid–ant mutualism, as well as the information that is still needed to predict how climate change might impact this type of relationship.
Interspecific interactions are highly dependent on the environmental conditions
We discuss the impact of climate change on aphid biology and the potential consequences on aphid–ant mutualism.
We focus on the effects of temperature and carbon dioxide on aphid (i) population growth; (ii) behaviour; (iii) honeydew; and (iv) semiochemistry.
1. Climate change will likely affect the association between species interacting at different trophic levels. However, studies focusing on the impact of an elevation of temperature on ant‐hemipteran ...mutualism remain scarce.
2. In the present study we investigated, in laboratory conditions, the foraging behaviour of the ant Lasius niger and its mutualistic interaction with the aphid Aphis fabae under three conditions of temperatures (i.e. 20°C, 23°C, and 26°C), as predicted by climatic scenarios.
3. Aphids were more mobile but as likely to release honeydew droplets at higher temperatures. As regards the ants, a moderate 3°C increase of temperature positively impacted their mutualistic interaction with aphids. Such reinforcement was achieved through an increase in the walking speed of ant foragers, in the number of mobilised ants as well as in the total amount of honeydew harvested by the colony.
4. A further elevation of temperature to 26°C reduced the benefits gained by the aphid‐tending ants, in terms of lower amount of collected honeydew.
5. Based on our results, we hypothesise that, in temperate regions, a moderate increase of ambient atmospheric temperature by 3°C will benefit to the L. niger ‐ A. fabae mutualistic interaction. A more marked elevation of 6°C may represent a threshold thermal value above which a switch of partners or a disruption of the interaction may occur under the temperatures predicted for the end of the century. These results demonstrate the fragility of mutualistic interactions, and more particularly their sensitivity to temperature increases predicted by realistic forecast models.
The impact of warming on ant‐hemipteran interactions is little studied. In this study, the behavioural interactions between aphids and ants are compared under three temperatures (20°C, 23°C, and 26°C).A moderate 3°C increase of temperature reinforces the aphid‐ant mutualism. A further elevation of temperature to 26°C attenuates the benefits gained by each partner.Ant‐aphid mutualism is highly sensitive to temperature whose elevation may first reinforce the ant interaction with their trophobionts then lead to a disruption of this interaction.
Chemical communication via infochemicals plays a pivotal role in ecological interactions, allowing organisms to sense their environment, locate predators, food, habitats, or mates. A growing number ...of studies suggest that climate change‐associated stressors can modify these chemically mediated interactions, causing info‐disruption that scales up to the ecosystem level. However, our understanding of the underlying mechanisms is scarce. Evidenced by a range of examples, we illustrate in this opinion piece that climate change affects different realms in similar patterns, from molecular to ecosystem‐wide levels. We assess the importance of different stressors for terrestrial, freshwater, and marine ecosystems and propose a systematic approach to address highlighted knowledge gaps and cross‐disciplinary research avenues.
Chemical communication plays an essential role in ecosystems as it enables organisms to sense their environment, locate predators, food, habitats, or mates and interact with each other. We show that climate change can affect every single step of this fundamental way of communicating from the molecules to ecosystem‐wide interactions. Combined examples from terrestrial, freshwater and marine systems provide an overview across different realms and reveal universal patterns of impact, which help to identify the key aspects that we urgently need to understand to grow our ability to predict future effects and reliably inform ecosystem management efforts.
Invasive species events related to globalization are increasing, resulting in parasitic outbreaks. Understanding of host defense mechanisms is needed to predict and mitigate against the consequences ...of parasite invasion. Using the honey bee Apis mellifera and the mite Varroa destructor, as a host-parasite model, we provide a comprehensive study of a mechanism of parasite detection that triggers a behavioral defense associated with social immunity. Six Varroa-parasitization-specific (VPS) compounds are identified that (1) trigger Varroa-sensitive hygiene (VSH, bees' key defense against Varroa sp.), (2) enable the selective recognition of a parasitized brood and (3) induce responses that mimic intrinsic VSH activity in bee colonies. We also show that individuals engaged in VSH exhibit a unique ability to discriminate VPS compounds from healthy brood signals. These findings enhance our understanding of a critical mechanism of host defense against parasites, and have the potential to apply the integration of pest management in the beekeeping sector.
Beekeepers can use a variety of treatments against Varroa destructor, the parasitic mite of Apis mellifera. However, sustainable and easy-to-use solutions are still scarce, considering the complexity ...of reaching the parasite alone. Current treatments involve soft acaricides, although their mechanism of action is not well understood. We investigated the effects of organic acids such as tartaric, lactic, formic, and citric acids on the attachment abilities of V. destructor under laboratory conditions. Preventing parasites from gripping or holding on to their hosts is a crucial target for mite control strategies. We challenged grip skills through the Rotavar setup after the direct application of acids to mites’ arolia. We also tested the potential for mites to fall off honeybees after bee treatment. We found that tartaric, citric, and lactic acids were good candidates to impair the attachment of V. destructor twenty-four hours post-treatment. However, lactic acid remained the only candidate at a reasonable concentration to destabilise mites after the honey bee’s treatment without reducing their lifespan. While we conducted these experiments under artificial conditions, our results improved our comprehension of the organic acids’ potential impact on V. destructor. They can also help with the development of new methods for hive application for beekeepers worldwide.
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