FEDERICO CAPPA - Academia.edu (original) (raw)
Papers by FEDERICO CAPPA
Science of The Total Environment
Insects
Cuticular hydrocarbons (CHCs) cover insects’ bodies and play important roles in chemical communic... more Cuticular hydrocarbons (CHCs) cover insects’ bodies and play important roles in chemical communication, including nestmate recognition, for social insects. To enter colonies of a social host species, parasites may acquire host-specific CHCs or covertly maintain their own CHC profile by lowering its quantity. However, the chemical profile of small hive beetles (SHBs), Aethina tumida, which are parasites of honey bee, Apis mellifera, colonies, and other bee nests, is currently unknown. Here, adults of SHB and honey bee host workers were collected from the same field colonies and their CHC profiles were analysed using GC-MS. The chemical profiles of field-sampled SHBs were also compared with those of host-naive beetles reared in the laboratory. Laboratory-reared SHBs differed in their CHC profiles from field-sampled ones, which showed a more similar, but ten-fold lower, generic host CHC profile compared to host workers. While the data confirm colony-specific CHCs of honey bee workers, ...
Science of The Total Environment
Biopesticides have been gaining increased attention to develop more sustainable methods for pest ... more Biopesticides have been gaining increased attention to develop more sustainable methods for pest management in agriculture. • Current risk-assessment protocols fail to evaluate the detrimental effects of biopesticides non-target pollinators. • Literature revision demonstrates that biopesticides cause a plethora of sublethal effects on insect pollinators. • Research and policies gaps and future perspective are summarized.
Entomologia Generalis
Understanding the major mechanisms that allow an alien species to become invasive is crucial for ... more Understanding the major mechanisms that allow an alien species to become invasive is crucial for limiting the impact of such species, and individual immunity seems to be a crucial trait for their large range colonization when introduced to a new area. Indeed, a high resistance to pathogens and parasites could favour the establishment and proliferation of an alien species in a newly colonized region. A striking example of recent successful invasion is represented by the Asian hornet, Vespa velutina nigrithorax, which has invaded Western Europe threatening bees and beekeeping activities. Investigating the biology of this species is fundamental to understand how V. velutina nigrithorax has become invasive in Europe and this knowledge could be crucial for limiting its impact. Here, by performing bacterial challenge bioassays, we compare the immune competence of different castes and sex of a population of the invasive Asian hornet, V. velutina nigri thorax, and of the native European hornet, V. crabro. Our results demonstrate that the two species differ in their immunocompetence with respect to caste: a higher level of immunocompetence was found in the reproductive females of the Asian hornet which were resistant to bacterial challenge when compared to workers and males of both species and to reproductive females of the native European hornet. The high pathogen resistance in reproductive females of the Asian hornet, might therefore represent a key factor contributing to the ecological success and spread of this invader.
Social recognition represents the foundation of social living. To what extent is social recogniti... more Social recognition represents the foundation of social living. To what extent is social recognition hard determined by early-life experience or flexible and influenced by social context of later life stages is a crucial question in animal behaviour studies. Social insects have represented classic model to investigate the subject, and the acknowledged idea is that relevant information to create the referent template for nest-mate recognition (NMR) is usually acquired during an early sensitive period in adult life. Experimental evidence, however, highlighted that also other processes may be at work in creating the template and that such a template may be updated during adult life according to social requirements. However, currently, we lack an <i>ad hoc</i> experiment testing the alternative hypotheses at the basis NMR ontogeny in social insects. Thus, to investigate the mechanisms underlying the ontogeny of NMR in <i>Polistes</i> wasps, a model genus in recogn...
Vespa velutina Lepieltier, 1836 (Hymenoptera: Vespidae) is an invasive predator of honeybees acci... more Vespa velutina Lepieltier, 1836 (Hymenoptera: Vespidae) is an invasive predator of honeybees accidentally introduced into Europe from eastern Asia. It was observed for the first time in southwest France in 2004 and in the following years it rapidly spread almost all over the country. In 2013 it was officially reported in Italy, in the region Liguria, near the border with France. In three years it invaded the whole province of Imperia and it was occasionally reported also in the South Western of Piedmont and in one locality in South Eastern Piedmont. The VELUTINA project was funded in 2014 by the Italian Ministry of Agriculture, with the aim of finding effective control methods against the predator. It includes both research and surveillance: adult and nest monitoring; development of methods for nest detection; development of protocols for nest destruction; studies on wasp chemical communication. Adult monitoring was performed in 5 Italian regions – the two where the hornet is alread...
ABSTRACTPhenotypic plasticity is the capacity of a single genotype to exhibit different phenotype... more ABSTRACTPhenotypic plasticity is the capacity of a single genotype to exhibit different phenotypes, and can be an adaptive response to specific environmental and social conditions. Social insects are particularly well-suited to study plasticity, because the division of labor amongst females and the different life histories of males and females are associated with specific sensory needs. Here, we take advantage of the social wasp Polistes dominula to explore if brain plasticity is influenced by caste and sex, and the exploitation by the parasite Xenos vesparum. Within sexes, males had proportionally larger optic lobes, while females, regardless of caste, had larger antennal lobes, which is consistent with sensory needs of sex-specific life histories. Within castes, reproductive females had larger calyces, as predicted by their sensory needs for extensive within-colony interactions and forming winter aggregations, than workers who spend more time foraging for nest material and prey. S...
Scientific Reports, 2021
In social wasps, female lifespan depends on caste and colony tasks: workers usually live a few we... more In social wasps, female lifespan depends on caste and colony tasks: workers usually live a few weeks while queens as long as 1 year. Polistes dominula paper wasps infected by the strepsipteran parasite Xenos vesparum avoid all colony tasks, cluster on vegetation where parasite dispersal and mating occur, hibernate and infect the next generation of wasp larvae. Here, we compared the survival rate of infected and uninfected wasp workers. Workers’ survival was significantly affected by parasite sex: two-third of workers parasitized by a X. vesparum female survived and overwintered like future queens did, while all workers infected by a X. vesparum male died during the summer, like uninfected workers that we used as controls. We measured a set of host and parasite traits possibly associated with the observed lifespan extension. Infected overwintering workers had larger fat bodies than infected workers that died in the summer, but they had similar body size and ovary development. Further...
PLOS ONE, 2020
Paper wasps (Polistes dominula), parasitized by the strepsipteran Xenos vesparum, are castrated a... more Paper wasps (Polistes dominula), parasitized by the strepsipteran Xenos vesparum, are castrated and desert the colony to gather on plants where the parasite mates and releases primary larvae, thus completing its lifecycle. One of these plants is the trumpet creeper Campsis radicans: in a previous study the majority of all wasps collected from this plant were parasitized and focused their foraging activity on C. radicans buds. The unexpected prevalence and unusual feeding strategy prompted us to investigate the influence of this plant on wasp behavior and physiology through a multidisciplinary approach. First, in a series of laboratory bioassays, we observed that parasitized wasps spent more time than non-parasitized ones on fresh C. radicans buds, rich of extra-floral nectaries (EFNs), while the same wasps ignored treated buds that lacked nectar drops. Then, we described the structure and ultra-structure of EFNs secreting cells, compatible with the synthesis of phenolic compounds. S...
Scientific Reports, 2020
The significant risk of disease transmission has selected for effective immune-defense strategies... more The significant risk of disease transmission has selected for effective immune-defense strategies in insect societies. Division of labour, with individuals specialized in immunity-related tasks, strongly contributes to prevent the spread of diseases. A trade-off, however, may exist between phenotypic specialization to increase task efficiency and maintenance of plasticity to cope with variable colony demands. We investigated the extent of phenotypic specialization associated with a specific task by using allogrooming in the honeybee, Apis mellifera, where worker behaviour might lower ectoparasites load. We adopted an integrated approach to characterize the behavioural and physiological phenotype of allogroomers, by analyzing their behavior (both at individual and social network level), their immunocompetence (bacterial clearance tests) and their chemosensory specialization (proteomics of olfactory organs). We found that allogroomers have higher immune capacity compared to control be...
Scientific Reports, 2020
The entomopathogenic fungus Beauveriabassiana is a widely used biopesticide that is considered as... more The entomopathogenic fungus Beauveriabassiana is a widely used biopesticide that is considered as an effective alternative to classical agrochemicals. B. bassiana is thought to be safe for pollinators although little is known about its side-effects on pollinators’ behaviour and cognition. Here, we focused on honey bees and used the proboscis extension response (PER) protocol to assess whether B. bassiana affects individual sucrose responsiveness, non-associative and associative olfactory learning and memory. Fungus-treated bees displayed an enhanced sucrose responsiveness, which could not be explained by metabolic alterations. Strikingly, exposed bees were twice as inconsistent as controls in response to sucrose, showing PER to lower but not to higher sucrose concentrations. Exposed bees habituated less to sucrose and had a better acquisition performance in the conditioning phase than controls. Further, neither mid- nor long-term memory were affected by the fungus. As sucrose respon...
Science of The Total Environment, 2020
• Vespa velutina is an alien hornet of high ecological and economic concern in Europe. • Its gut ... more • Vespa velutina is an alien hornet of high ecological and economic concern in Europe. • Its gut microbiome has been characterized through meta-genomics. • We investigated the effect of ontogeny, phenotype and similarity with environment. • Fungal and bacterial community's abundance depends on ontogeny and phenotype. • Microbiome characterization is a springboard for management strategies.
Frontiers in Ecology and Evolution, 2019
Philosophical Transactions of the Royal Society B: Biological Sciences, 2020
Social recognition represents the foundation of social living. To what extent social recognition ... more Social recognition represents the foundation of social living. To what extent social recognition is hard-wired by early-life experience or flexible and influenced by social context of later life stages is a crucial question in animal behaviour studies. Social insects have represented classic models to investigate the subject, and the acknowledged idea is that relevant information to create the referent template for nest-mate recognition (NMR) is usually acquired during an early sensitive period in adult life. Experimental evidence, however, highlighted that other processes may also be at work in creating the template and that such a template may be updated during adult life according to social requirements. However, currently, we lack an ad hoc experiment testing the alternative hypotheses at the basis of NMR ontogeny in social insects. Thus, to investigate the mechanisms underlying the ontogeny of NMR in Polistes wasps, a model genus in recognition studies, and their different role...
Ethology Ecology & Evolution, 2020
Eusocial insect colonies represent some of the most extreme examples of specialized division of l... more Eusocial insect colonies represent some of the most extreme examples of specialized division of labor. Ageing in workers is often associated with a temporal polyethism in the tasks performed both inside and outside the colony. Such behavioral transition is sometimes linked to a gradual reduction in individual immunity. Here, we studied the immune ability of Apis mellifera guard bees, which represent an intermediate stage between house bees working inside the nest and foragers collecting resources outside, to assess if their specific task is associated with an immune specialization. Through immune challenge with Gram-negative bacteria Escherichia coli, we compared the guards ability to clear bacterial cells from their haemolymph with respect to house bees and foragers. Our findings demonstrate that guards do not show an immune specialization linked to their task but seem to represent a transition also in terms of immunity, since their anti-bacterial response appears intermediate between house bees and foragers.
Insect Science, 2019
Parasites and pathogens can follow different patterns of infection depending on the host developm... more Parasites and pathogens can follow different patterns of infection depending on the host developmental stage or sex. In fact, immune function is energetically costly for hosts and trade-offs exist between immune defences and life history traits as growth, development and reproduction and organisms should thus optimize immune defence through their life cycle according to their This article is protected by copyright. All rights reserved. developmental stage. Identifying the most susceptible target and the most virulent pathogen is particularly important in the case of insect pests, in order to develop effective control strategies targeting the most vulnerable individuals with the most effective control agent. Here, we carried out laboratory tests to identify the most susceptible target of infection by infecting different stages of the red palm weevil Rhynchophorus ferrugineus (larvae, pupae, male and female adults) with both a generic pathogen, antibiotic-resistant Gram-negative bacteria Escherichia coli XL1-Blue, and two specific strains of entomopathogenic nematodes (EPNs), Steinernema carpocapsae ItS-CAO1 and Heterorhabditis bacteriophora ItH-LU1. By evaluating bacterial clearance, host mortality and parasite progeny release, we demonstrate that larvae are more resistant than adults to bacterial challenge and they release less EPNs progeny after infection despite a higher mortality compared to adults. Considering the two EPN strains, S. carpocapsae was more virulent than H. bacteriophora both in terms of host mortality and more abundant progeny released by hosts after death. The outcomes attained with unspecific and specific pathogens provide useful information for a more efficient and sustainable management of this invasive pest.
Frontiers in Microbiology, 2019
Trained immunity is the enhanced response of the innate immune system to a secondary infection af... more Trained immunity is the enhanced response of the innate immune system to a secondary infection after an initial encounter with a microorganism. This non-specific response to reinfection is a primitive form of adaptation that has been shown to be conserved from plants to mammals. Insects lack an acquired immune component and rely solely on an innate one, and they have expanded it upon traits of plasticity and adaptation against pathogens in the form of immune priming. The recent discoveries of the role of Saccharomyces cerevisiae in the insect's ecology and the ability of this yeast to induce trained immunity in different organisms suggest that insects could have developed mechanisms of adaptation and immune enhancing. Here, we report that two yeast strains of S. cerevisiae, previously shown to induce trained immunity in mammals, enhance resistance to Escherichia coli infection in the paper wasp Polistes dominula. The reduction of injected E. coli load by S. cerevisiae strains was statistically significant in future foundresses but not in workers, and this occurs before and after hibernation. We thus investigated if the effect on E. coli was mirrored by variation in the gut microbiota composition. Foundresses, showing immune enhancing, had statistically significant changes in composition and diversity of gut bacterial communities but not in the fungal communities. Our results demonstrate that S. cerevisiae can prime insect responses against bacterial infections, providing an advantage to future foundress wasps to carry these microorganisms. Understanding the mechanisms involved in the generation of specific and long-lasting immune response against pathogenic infections in insects and the influence of the induction of trained immunity on the commensal gut microbiota could have a major impact on modern immunology.
Ecological Entomology, 2018
1. Invasive alien species are a major threat to biodiversity. In addition to predation and parasi... more 1. Invasive alien species are a major threat to biodiversity. In addition to predation and parasitism, native species might suffer from competition when invasive alien species occupy a similar ecological niche.2. This study focused on the potential interspecific interaction between two hornets: the Asian yellow‐legged hornet, Vespa velutina, a high‐concern invasive alien species recently arrived in Europe; and the native European hornet, Vespa crabro. The two species share a similar ecological niche and V. velutina is rapidly expanding across Europe, which suggests that V. crabro might suffer from competition.3. Under laboratory‐controlled conditions, two life‐history traits that might cause the two species to compete were investigated: (i) the ability of workers to find food sources and their flexibility in exploiting them (through individual food item choice tests and exploration assays); and (ii) the worker resistance to pathogens (through immune challenge tests).4. The results s...
PLOS ONE, 2018
The parasitic insect Xenos vesparum induces noticeable behavioral and physiological changes-e.g. ... more The parasitic insect Xenos vesparum induces noticeable behavioral and physiological changes-e.g. castration-in its female host, the paper wasp Polistes dominula: parasitized putative workers avoid any colony task and desert the colony to survive in the nearby vegetation, like future queens and males do. In this long-term observational study, we describe the spectacular attraction of parasitized workers towards trumpet creeper bushes (Campsis radicans) in early-summer. Two thirds of all wasps that we sampled on these bushes were parasitized, whereas the parasite prevalence was much lower in our study area and most wasps sampled on other nearby flowering bushes were non-parasitized. First, we describe the occurrence and consistency of this phenomenon across different sites and years. Second, we evaluate the spatial behavior of parasitized wasps on C. radicans bushes, which includes site-fidelity, exploitation and defense of rich extra-floral nectaries on buds and calices. Third, we record two critical steps of the lifecycle of X. vesparum on C. radicans: the parasite's mating and a summer release of parasitic larvae, that can infect larval stages of the host if transported to the host's nest. In a nutshell, C. radicans bushes provide many benefits both to the parasite X. vesparum and to its host: they facilitate the parasite's mating and bivoltine lifecycle, a phenomenon never described before for this parasite, while, at the same time, they provide the wasp host with shelter inside trumpet flowers and extrafloral gland secretions, thus likely enhancing host survival and making it a suitable vector for the infection.
Biological Invasions, 2019
Vespa velutina Lepeletier, 1836 (Hymenoptera: Vespidae), the yellow-legged hornet, is a social wa... more Vespa velutina Lepeletier, 1836 (Hymenoptera: Vespidae), the yellow-legged hornet, is a social wasp native to North of India, China and tropical and subtropical areas of Southeast Asia. Adults are predators of a wide variety of arthropods, including honey bees. Vespa velutina has been unintentionally introduced in southwestern France before 2004 and its widely spreading across the country was followed by an impressive colonization of several areas within mainland Europe and overseas. In Italy, V. velutina has been officially reported in June 2013 in Imperia province, Liguria region (northern Italy) and is now well established in the western part of this region and occasionally reported in Piedmont region. More recently, it has been spotted in Veneto, Lombardy and Tuscany regions. In order to investigate the phylogenetic relationships and the origin of Italian V. velutina nigrithorax specimens, we performed a phylogenetic analysis of thirty-three samples, collected in 2012, 2016, 2017 and 2018 from different sites (Veneto, Piedmont and Liguria regions) based on mitochondrial cytochrome c oxidase subunit 1 (cox1) gene sequence analysis. The phylogenetic analysis as well the haplotypes study confirmed the placement of 33 Italian specimens within a cluster containing the other European samples plus Chinese specimens collected in Jiangsu and Zhejiang. Our results strongly supported the view that the Italian specimens of V. velutina nigrithorax derived from the spreading southward of the V. velutina nigrithorax population initially established in France, which is also moving northward
Science of The Total Environment
Insects
Cuticular hydrocarbons (CHCs) cover insects’ bodies and play important roles in chemical communic... more Cuticular hydrocarbons (CHCs) cover insects’ bodies and play important roles in chemical communication, including nestmate recognition, for social insects. To enter colonies of a social host species, parasites may acquire host-specific CHCs or covertly maintain their own CHC profile by lowering its quantity. However, the chemical profile of small hive beetles (SHBs), Aethina tumida, which are parasites of honey bee, Apis mellifera, colonies, and other bee nests, is currently unknown. Here, adults of SHB and honey bee host workers were collected from the same field colonies and their CHC profiles were analysed using GC-MS. The chemical profiles of field-sampled SHBs were also compared with those of host-naive beetles reared in the laboratory. Laboratory-reared SHBs differed in their CHC profiles from field-sampled ones, which showed a more similar, but ten-fold lower, generic host CHC profile compared to host workers. While the data confirm colony-specific CHCs of honey bee workers, ...
Science of The Total Environment
Biopesticides have been gaining increased attention to develop more sustainable methods for pest ... more Biopesticides have been gaining increased attention to develop more sustainable methods for pest management in agriculture. • Current risk-assessment protocols fail to evaluate the detrimental effects of biopesticides non-target pollinators. • Literature revision demonstrates that biopesticides cause a plethora of sublethal effects on insect pollinators. • Research and policies gaps and future perspective are summarized.
Entomologia Generalis
Understanding the major mechanisms that allow an alien species to become invasive is crucial for ... more Understanding the major mechanisms that allow an alien species to become invasive is crucial for limiting the impact of such species, and individual immunity seems to be a crucial trait for their large range colonization when introduced to a new area. Indeed, a high resistance to pathogens and parasites could favour the establishment and proliferation of an alien species in a newly colonized region. A striking example of recent successful invasion is represented by the Asian hornet, Vespa velutina nigrithorax, which has invaded Western Europe threatening bees and beekeeping activities. Investigating the biology of this species is fundamental to understand how V. velutina nigrithorax has become invasive in Europe and this knowledge could be crucial for limiting its impact. Here, by performing bacterial challenge bioassays, we compare the immune competence of different castes and sex of a population of the invasive Asian hornet, V. velutina nigri thorax, and of the native European hornet, V. crabro. Our results demonstrate that the two species differ in their immunocompetence with respect to caste: a higher level of immunocompetence was found in the reproductive females of the Asian hornet which were resistant to bacterial challenge when compared to workers and males of both species and to reproductive females of the native European hornet. The high pathogen resistance in reproductive females of the Asian hornet, might therefore represent a key factor contributing to the ecological success and spread of this invader.
Social recognition represents the foundation of social living. To what extent is social recogniti... more Social recognition represents the foundation of social living. To what extent is social recognition hard determined by early-life experience or flexible and influenced by social context of later life stages is a crucial question in animal behaviour studies. Social insects have represented classic model to investigate the subject, and the acknowledged idea is that relevant information to create the referent template for nest-mate recognition (NMR) is usually acquired during an early sensitive period in adult life. Experimental evidence, however, highlighted that also other processes may be at work in creating the template and that such a template may be updated during adult life according to social requirements. However, currently, we lack an <i>ad hoc</i> experiment testing the alternative hypotheses at the basis NMR ontogeny in social insects. Thus, to investigate the mechanisms underlying the ontogeny of NMR in <i>Polistes</i> wasps, a model genus in recogn...
Vespa velutina Lepieltier, 1836 (Hymenoptera: Vespidae) is an invasive predator of honeybees acci... more Vespa velutina Lepieltier, 1836 (Hymenoptera: Vespidae) is an invasive predator of honeybees accidentally introduced into Europe from eastern Asia. It was observed for the first time in southwest France in 2004 and in the following years it rapidly spread almost all over the country. In 2013 it was officially reported in Italy, in the region Liguria, near the border with France. In three years it invaded the whole province of Imperia and it was occasionally reported also in the South Western of Piedmont and in one locality in South Eastern Piedmont. The VELUTINA project was funded in 2014 by the Italian Ministry of Agriculture, with the aim of finding effective control methods against the predator. It includes both research and surveillance: adult and nest monitoring; development of methods for nest detection; development of protocols for nest destruction; studies on wasp chemical communication. Adult monitoring was performed in 5 Italian regions – the two where the hornet is alread...
ABSTRACTPhenotypic plasticity is the capacity of a single genotype to exhibit different phenotype... more ABSTRACTPhenotypic plasticity is the capacity of a single genotype to exhibit different phenotypes, and can be an adaptive response to specific environmental and social conditions. Social insects are particularly well-suited to study plasticity, because the division of labor amongst females and the different life histories of males and females are associated with specific sensory needs. Here, we take advantage of the social wasp Polistes dominula to explore if brain plasticity is influenced by caste and sex, and the exploitation by the parasite Xenos vesparum. Within sexes, males had proportionally larger optic lobes, while females, regardless of caste, had larger antennal lobes, which is consistent with sensory needs of sex-specific life histories. Within castes, reproductive females had larger calyces, as predicted by their sensory needs for extensive within-colony interactions and forming winter aggregations, than workers who spend more time foraging for nest material and prey. S...
Scientific Reports, 2021
In social wasps, female lifespan depends on caste and colony tasks: workers usually live a few we... more In social wasps, female lifespan depends on caste and colony tasks: workers usually live a few weeks while queens as long as 1 year. Polistes dominula paper wasps infected by the strepsipteran parasite Xenos vesparum avoid all colony tasks, cluster on vegetation where parasite dispersal and mating occur, hibernate and infect the next generation of wasp larvae. Here, we compared the survival rate of infected and uninfected wasp workers. Workers’ survival was significantly affected by parasite sex: two-third of workers parasitized by a X. vesparum female survived and overwintered like future queens did, while all workers infected by a X. vesparum male died during the summer, like uninfected workers that we used as controls. We measured a set of host and parasite traits possibly associated with the observed lifespan extension. Infected overwintering workers had larger fat bodies than infected workers that died in the summer, but they had similar body size and ovary development. Further...
PLOS ONE, 2020
Paper wasps (Polistes dominula), parasitized by the strepsipteran Xenos vesparum, are castrated a... more Paper wasps (Polistes dominula), parasitized by the strepsipteran Xenos vesparum, are castrated and desert the colony to gather on plants where the parasite mates and releases primary larvae, thus completing its lifecycle. One of these plants is the trumpet creeper Campsis radicans: in a previous study the majority of all wasps collected from this plant were parasitized and focused their foraging activity on C. radicans buds. The unexpected prevalence and unusual feeding strategy prompted us to investigate the influence of this plant on wasp behavior and physiology through a multidisciplinary approach. First, in a series of laboratory bioassays, we observed that parasitized wasps spent more time than non-parasitized ones on fresh C. radicans buds, rich of extra-floral nectaries (EFNs), while the same wasps ignored treated buds that lacked nectar drops. Then, we described the structure and ultra-structure of EFNs secreting cells, compatible with the synthesis of phenolic compounds. S...
Scientific Reports, 2020
The significant risk of disease transmission has selected for effective immune-defense strategies... more The significant risk of disease transmission has selected for effective immune-defense strategies in insect societies. Division of labour, with individuals specialized in immunity-related tasks, strongly contributes to prevent the spread of diseases. A trade-off, however, may exist between phenotypic specialization to increase task efficiency and maintenance of plasticity to cope with variable colony demands. We investigated the extent of phenotypic specialization associated with a specific task by using allogrooming in the honeybee, Apis mellifera, where worker behaviour might lower ectoparasites load. We adopted an integrated approach to characterize the behavioural and physiological phenotype of allogroomers, by analyzing their behavior (both at individual and social network level), their immunocompetence (bacterial clearance tests) and their chemosensory specialization (proteomics of olfactory organs). We found that allogroomers have higher immune capacity compared to control be...
Scientific Reports, 2020
The entomopathogenic fungus Beauveriabassiana is a widely used biopesticide that is considered as... more The entomopathogenic fungus Beauveriabassiana is a widely used biopesticide that is considered as an effective alternative to classical agrochemicals. B. bassiana is thought to be safe for pollinators although little is known about its side-effects on pollinators’ behaviour and cognition. Here, we focused on honey bees and used the proboscis extension response (PER) protocol to assess whether B. bassiana affects individual sucrose responsiveness, non-associative and associative olfactory learning and memory. Fungus-treated bees displayed an enhanced sucrose responsiveness, which could not be explained by metabolic alterations. Strikingly, exposed bees were twice as inconsistent as controls in response to sucrose, showing PER to lower but not to higher sucrose concentrations. Exposed bees habituated less to sucrose and had a better acquisition performance in the conditioning phase than controls. Further, neither mid- nor long-term memory were affected by the fungus. As sucrose respon...
Science of The Total Environment, 2020
• Vespa velutina is an alien hornet of high ecological and economic concern in Europe. • Its gut ... more • Vespa velutina is an alien hornet of high ecological and economic concern in Europe. • Its gut microbiome has been characterized through meta-genomics. • We investigated the effect of ontogeny, phenotype and similarity with environment. • Fungal and bacterial community's abundance depends on ontogeny and phenotype. • Microbiome characterization is a springboard for management strategies.
Frontiers in Ecology and Evolution, 2019
Philosophical Transactions of the Royal Society B: Biological Sciences, 2020
Social recognition represents the foundation of social living. To what extent social recognition ... more Social recognition represents the foundation of social living. To what extent social recognition is hard-wired by early-life experience or flexible and influenced by social context of later life stages is a crucial question in animal behaviour studies. Social insects have represented classic models to investigate the subject, and the acknowledged idea is that relevant information to create the referent template for nest-mate recognition (NMR) is usually acquired during an early sensitive period in adult life. Experimental evidence, however, highlighted that other processes may also be at work in creating the template and that such a template may be updated during adult life according to social requirements. However, currently, we lack an ad hoc experiment testing the alternative hypotheses at the basis of NMR ontogeny in social insects. Thus, to investigate the mechanisms underlying the ontogeny of NMR in Polistes wasps, a model genus in recognition studies, and their different role...
Ethology Ecology & Evolution, 2020
Eusocial insect colonies represent some of the most extreme examples of specialized division of l... more Eusocial insect colonies represent some of the most extreme examples of specialized division of labor. Ageing in workers is often associated with a temporal polyethism in the tasks performed both inside and outside the colony. Such behavioral transition is sometimes linked to a gradual reduction in individual immunity. Here, we studied the immune ability of Apis mellifera guard bees, which represent an intermediate stage between house bees working inside the nest and foragers collecting resources outside, to assess if their specific task is associated with an immune specialization. Through immune challenge with Gram-negative bacteria Escherichia coli, we compared the guards ability to clear bacterial cells from their haemolymph with respect to house bees and foragers. Our findings demonstrate that guards do not show an immune specialization linked to their task but seem to represent a transition also in terms of immunity, since their anti-bacterial response appears intermediate between house bees and foragers.
Insect Science, 2019
Parasites and pathogens can follow different patterns of infection depending on the host developm... more Parasites and pathogens can follow different patterns of infection depending on the host developmental stage or sex. In fact, immune function is energetically costly for hosts and trade-offs exist between immune defences and life history traits as growth, development and reproduction and organisms should thus optimize immune defence through their life cycle according to their This article is protected by copyright. All rights reserved. developmental stage. Identifying the most susceptible target and the most virulent pathogen is particularly important in the case of insect pests, in order to develop effective control strategies targeting the most vulnerable individuals with the most effective control agent. Here, we carried out laboratory tests to identify the most susceptible target of infection by infecting different stages of the red palm weevil Rhynchophorus ferrugineus (larvae, pupae, male and female adults) with both a generic pathogen, antibiotic-resistant Gram-negative bacteria Escherichia coli XL1-Blue, and two specific strains of entomopathogenic nematodes (EPNs), Steinernema carpocapsae ItS-CAO1 and Heterorhabditis bacteriophora ItH-LU1. By evaluating bacterial clearance, host mortality and parasite progeny release, we demonstrate that larvae are more resistant than adults to bacterial challenge and they release less EPNs progeny after infection despite a higher mortality compared to adults. Considering the two EPN strains, S. carpocapsae was more virulent than H. bacteriophora both in terms of host mortality and more abundant progeny released by hosts after death. The outcomes attained with unspecific and specific pathogens provide useful information for a more efficient and sustainable management of this invasive pest.
Frontiers in Microbiology, 2019
Trained immunity is the enhanced response of the innate immune system to a secondary infection af... more Trained immunity is the enhanced response of the innate immune system to a secondary infection after an initial encounter with a microorganism. This non-specific response to reinfection is a primitive form of adaptation that has been shown to be conserved from plants to mammals. Insects lack an acquired immune component and rely solely on an innate one, and they have expanded it upon traits of plasticity and adaptation against pathogens in the form of immune priming. The recent discoveries of the role of Saccharomyces cerevisiae in the insect's ecology and the ability of this yeast to induce trained immunity in different organisms suggest that insects could have developed mechanisms of adaptation and immune enhancing. Here, we report that two yeast strains of S. cerevisiae, previously shown to induce trained immunity in mammals, enhance resistance to Escherichia coli infection in the paper wasp Polistes dominula. The reduction of injected E. coli load by S. cerevisiae strains was statistically significant in future foundresses but not in workers, and this occurs before and after hibernation. We thus investigated if the effect on E. coli was mirrored by variation in the gut microbiota composition. Foundresses, showing immune enhancing, had statistically significant changes in composition and diversity of gut bacterial communities but not in the fungal communities. Our results demonstrate that S. cerevisiae can prime insect responses against bacterial infections, providing an advantage to future foundress wasps to carry these microorganisms. Understanding the mechanisms involved in the generation of specific and long-lasting immune response against pathogenic infections in insects and the influence of the induction of trained immunity on the commensal gut microbiota could have a major impact on modern immunology.
Ecological Entomology, 2018
1. Invasive alien species are a major threat to biodiversity. In addition to predation and parasi... more 1. Invasive alien species are a major threat to biodiversity. In addition to predation and parasitism, native species might suffer from competition when invasive alien species occupy a similar ecological niche.2. This study focused on the potential interspecific interaction between two hornets: the Asian yellow‐legged hornet, Vespa velutina, a high‐concern invasive alien species recently arrived in Europe; and the native European hornet, Vespa crabro. The two species share a similar ecological niche and V. velutina is rapidly expanding across Europe, which suggests that V. crabro might suffer from competition.3. Under laboratory‐controlled conditions, two life‐history traits that might cause the two species to compete were investigated: (i) the ability of workers to find food sources and their flexibility in exploiting them (through individual food item choice tests and exploration assays); and (ii) the worker resistance to pathogens (through immune challenge tests).4. The results s...
PLOS ONE, 2018
The parasitic insect Xenos vesparum induces noticeable behavioral and physiological changes-e.g. ... more The parasitic insect Xenos vesparum induces noticeable behavioral and physiological changes-e.g. castration-in its female host, the paper wasp Polistes dominula: parasitized putative workers avoid any colony task and desert the colony to survive in the nearby vegetation, like future queens and males do. In this long-term observational study, we describe the spectacular attraction of parasitized workers towards trumpet creeper bushes (Campsis radicans) in early-summer. Two thirds of all wasps that we sampled on these bushes were parasitized, whereas the parasite prevalence was much lower in our study area and most wasps sampled on other nearby flowering bushes were non-parasitized. First, we describe the occurrence and consistency of this phenomenon across different sites and years. Second, we evaluate the spatial behavior of parasitized wasps on C. radicans bushes, which includes site-fidelity, exploitation and defense of rich extra-floral nectaries on buds and calices. Third, we record two critical steps of the lifecycle of X. vesparum on C. radicans: the parasite's mating and a summer release of parasitic larvae, that can infect larval stages of the host if transported to the host's nest. In a nutshell, C. radicans bushes provide many benefits both to the parasite X. vesparum and to its host: they facilitate the parasite's mating and bivoltine lifecycle, a phenomenon never described before for this parasite, while, at the same time, they provide the wasp host with shelter inside trumpet flowers and extrafloral gland secretions, thus likely enhancing host survival and making it a suitable vector for the infection.
Biological Invasions, 2019
Vespa velutina Lepeletier, 1836 (Hymenoptera: Vespidae), the yellow-legged hornet, is a social wa... more Vespa velutina Lepeletier, 1836 (Hymenoptera: Vespidae), the yellow-legged hornet, is a social wasp native to North of India, China and tropical and subtropical areas of Southeast Asia. Adults are predators of a wide variety of arthropods, including honey bees. Vespa velutina has been unintentionally introduced in southwestern France before 2004 and its widely spreading across the country was followed by an impressive colonization of several areas within mainland Europe and overseas. In Italy, V. velutina has been officially reported in June 2013 in Imperia province, Liguria region (northern Italy) and is now well established in the western part of this region and occasionally reported in Piedmont region. More recently, it has been spotted in Veneto, Lombardy and Tuscany regions. In order to investigate the phylogenetic relationships and the origin of Italian V. velutina nigrithorax specimens, we performed a phylogenetic analysis of thirty-three samples, collected in 2012, 2016, 2017 and 2018 from different sites (Veneto, Piedmont and Liguria regions) based on mitochondrial cytochrome c oxidase subunit 1 (cox1) gene sequence analysis. The phylogenetic analysis as well the haplotypes study confirmed the placement of 33 Italian specimens within a cluster containing the other European samples plus Chinese specimens collected in Jiangsu and Zhejiang. Our results strongly supported the view that the Italian specimens of V. velutina nigrithorax derived from the spreading southward of the V. velutina nigrithorax population initially established in France, which is also moving northward