Aebi, Alexandre

2017-4-3, Zindel, Renate, Ofek-Lalzar, Maya, Aebi, Alexandre

There is an increasing awareness of the importance of the microbiome of arthropods to understand their host’s biology. In the bulb mite, Rhizoglyphus robini, associated bacteria have been found to be involved in its chitinolytic abilities. The bulb mite, a plant pest feeding on below- ground parts of mostly Liliaceae crops, prefers fungus- infested plants. Moreover its fitness is higher when feeding on a fungal food source than when feeding on non-infected plants. In this study we isolated a chitinolytic bacterium from mite homogenate and identified it molecularly as Serratia marcescens (Bizio 1823), which is a model organism for chitin degradation. Precise identification of the bacterium can be important for the development of biological control programs of the mite as well as for further studies investigating Serratia marcescens and its chitinolytic machinery.

2013, Thomas, A. P., Trotman, J., Wheatley, A., Aebi, Alexandre, Zindel, Renate, Brown, Peter M. J.

. 1. The harlequin ladybird, Harmonia axyridis, is an invasive alien species that arrived in Britain in 2003 and has spread across most of the country. 2. This spread has been accompanied by a decline in some native coccinellid species, in particular, the two spot ladybird Adalia bipunctata and the ten spot ladybird Adalia decempunctata. One reason for this decline could be intraguild predation (IGP) of the Adalia species by H. axyridis. 3. A DNA-based approach was used to look for evidence of coccinellid IGP in the wild. Adalia bipunctata- and A. decempunctata-specific Polymerase chain reaction primers were developed to analyse the gut contents of field collected H. axyridis larvae for the presence of Adalia DNA. Harmonia axyridis larvae (156) were collected from lime trees at four sites in eastern England over 3 years. 4. Adalia bipunctata DNA was detected in 7.7% and A. decempunctata DNA in 4.5% of H. axyridis larvae. DNA from both Adalia species was detected in two larvae. 5. This is the first demonstration of specific IGP interactions between H. axyridis and other coccinellid species in wild populations in Britain.

, Thomas, Alison P, Trotman, Jamie, Wheatley, Angela, Aebi, Alexandre, Zindel, Renate, Brown, Peter M.J

1. The harlequin ladybird, Harmonia axyridis, is an invasive alien species that arrived in Britain in 2003 and has spread across most of the country.
2. This spread has been accompanied by a decline in some native coccinellid species, in particular, the two spot ladybird Adalia bipunctata and the ten spot ladybird Adalia decempunctata. One reason for this decline could be intraguild predation (IGP) of the Adalia species by H. axyridis.
3. A DNA-based approach was used to look for evidence of coccinellid IGP in the wild. Adalia bipunctata- and A. decempunctata-specific Polymerase chain reaction primers were developed to analyse the gut contents of field collected H. axyridis larvae for the presence of Adalia DNA. Harmonia axyridis larvae (156) were collected from lime trees at four sites in eastern England over 3 years.
4.  Adalia bipunctata DNA was detected in 7.7% and A. decempunctata DNA in 4.5% of H. axyridis larvae. DNA from both Adalia species was detected in two larvae.
5. This is the first demonstration of specific IGP interactions between H. axyridis and other coccinellid species in wild populations in Britain.

, Zindel, Renate, Ofek, Maya, Minz, Dror, Palevsky, Eric, Zchori-Fein, Einat, Aebi, Alexandre

The biology of many arthropods can only be understood when their associated microbiome is considered. The nutritional requirements of the bulb mite Rhizoglyphus robini Claparede (Acari: Astigmata: Acaridae) in the laboratory have been shown to be very easily satisfied, and in the field the mites prefer fungus-infected over uninfected plants. To test whether symbiotic bacteria facilitate the survival of R. robini on a temporarily nutritionally unbalanced diet, we investigated the composition of its microbiome. Using 454 pyrosequencing of 16S rRNA gene fragments, 3 genera were found to dominate the bacterial community: Myroides (41.4%), Serratia (11.4%), and Alcaligenes (4.5%); the latter 2 are known to include chitinase-producing species. Laboratory experiments demonstrated that mite fecundity is significantly higher (2 times) on fungus than on controls (sterilized potato dextrose agar and filter paper). Also, when mite homogenate was applied to a chitin layer, the halo produced through degradation was clearly visible, while the saline control did not produce a halo. We thus concluded that R. robini utilizes fungal chitin, at least to a certain extent, as a food source with the help of its associated bacteria. This information supports the general concept of multigenome organisms and the involvement of bacteria in the mite's nutritional ecology.

2013, Zindel, Renate, Ofek, M., Minz, D., Palevsky, E., Zchori-Fein, E., Aebi, Alexandre

The biology of many arthropods can only be understood when their associated microbiome is considered. The nutritional requirements of the bulb mite Rhizoglyphus robini Claparede (Acari: Astigmata: Acaridae) in the laboratory have been shown to be very easily satisfied, and in the field the mites prefer fungus-infected over uninfected plants. To test whether symbiotic bacteria facilitate the survival of R. robini on a temporarily nutritionally unbalanced diet, we investigated the composition of its microbiome. Using 454 pyrosequencing of 16S rRNA gene fragments, 3 genera were found to dominate the bacterial community: Myroides (41.4%), Serratia (11.4%), and Alcaligenes (4.5%); the latter 2 are known to include chitinase-producing species. Laboratory experiments demonstrated that mite fecundity is significantly higher (2 times) on fungus than on controls (sterilized potato dextrose agar and filter paper). Also, when mite homogenate was applied to a chitin layer, the halo produced through degradation was clearly visible, while the saline control did not produce a halo. We thus concluded that R. robini utilizes fungal chitin, at least to a certain extent, as a food source with the help of its associated bacteria. This information supports the general concept of multigenome organisms and the involvement of bacteria in the mite's nutritional ecology.-Zindel, R., Ofek, M., Minz, D., Palevsky, E., Zchori-Fein, E., Aebi, A. The role of the bacterial community in the nutritional ecology of the bulb mite Rhizoglyphus robini (Acari: Astigmata: Acaridae). FASEB J. 27, 1488-1497 (2013). www.fasebj.org

2011, Aebi, Alexandre, Brown, Peter M. J., De Clercq, Patrick, Hautier, Louis, Howe, Andy, Ingels, Brecht, Ravn, Hans-Peter, Sloggett, John J., Zindel, Renate, Thomas, Alison

, Zindel, Renate, Gottlieb, Yuval, Aebi, Alexandre

1. Arthropods are important players in biological control as pests, control agents and transmitters of invertebrate diseases. Arthropods are frequently infected with one or several micro-organisms, serving as micro-ecosystems in which multiple interactions can take place. These micro-organisms include disease agents and symbiotic micro-organisms. The latter are usually vertically transmitted and can have a broad spectrum of effects on their hosts, ranging from reproductive manipulations to protection against natural enemies. These interactions may directly or indirectly alter the biology of many arthropods in agriculturally, medically and ecologically relevant ecosystems.
2. Symbiotic micro-organism-induced reproductive manipulations such as cytoplasmic incompatibility and parthenogenesis induction can substantially affect the rearing of biological control agents. Many insects, and recently also mites and nematodes, have been found to be infected, displaying a wide range of effects. We discuss examples of arthropod-micro-organism interactions and effects, which could have consequences for the practical application of arthropods in biological control.
3. Symbiotic micro-organisms can also be involved in host protection against natural enemies such as parasitoids, pathogenic bacteria, fungi and viruses.
4. Symbiotic bacteria can influence the vectorial capacity of disease-vectoring arthropods and may be very helpful in decreasing the transmission of disease agents.
5. Synthesis and applications. The effect of micro-organisms on the outcome of biological control programmes is usually not considered in risk assessments and failure analyses. This review emphasizes the importance of endosymbiotic micro-organisms in comprehensive biological control programmes and provides recommendations on how to recognize, avoid or benefit from these influential tenants.

2013, Aebi, Alexandre, Zindel, Renate

2011, Zindel, Renate, Gottlieb, Y., Aebi, Alexandre

1. Arthropods are important players in biological control as pests, control agents and transmitters of invertebrate diseases. Arthropods are frequently infected with one or several micro-organisms, serving as micro-ecosystems in which multiple interactions can take place. These micro-organisms include disease agents and symbiotic micro-organisms. The latter are usually vertically transmitted and can have a broad spectrum of effects on their hosts, ranging from reproductive manipulations to protection against natural enemies. These interactions may directly or indirectly alter the biology of many arthropods in agriculturally, medically and ecologically relevant ecosystems. 2. Symbiotic micro-organism-induced reproductive manipulations such as cytoplasmic incompatibility and parthenogenesis induction can substantially affect the rearing of biological control agents. Many insects, and recently also mites and nematodes, have been found to be infected, displaying a wide range of effects. We discuss examples of arthropod-micro-organism interactions and effects, which could have consequences for the practical application of arthropods in biological control. 3. Symbiotic micro-organisms can also be involved in host protection against natural enemies such as parasitoids, pathogenic bacteria, fungi and viruses. 4. Symbiotic bacteria can influence the vectorial capacity of disease-vectoring arthropods and may be very helpful in decreasing the transmission of disease agents. 5. Synthesis and applications. The effect of micro-organisms on the outcome of biological control programmes is usually not considered in risk assessments and failure analyses. This review emphasizes the importance of endosymbiotic micro-organisms in comprehensive biological control programmes and provides recommendations on how to recognize, avoid or benefit from these influential tenants.

, Aebi, Alexandre, Brown, Peter M. J, De Clercq, Patrick, Hautier, Louis, Howe, Andy, Ingels, Brecht, Ravn, Hans-Peter, Sloggett, John J, Zindel, Renate, Thomas, Alison

The process of biological control carries a distinct risk that an alien biological control agent (BCA) will become established as an invasive alien species with an associated threat to the local ecosystem biodiversity. It is imperative that a wide-ranging environmental risk assessment (ERA) is performed before the release of any BCA. This should include considering various potential but difficult to observe ecological interactions between the BCA and members of the native community, including disruption of intraguild relationships. Detection of intraguild predation (IGP) events involving predatory arthropods in the field can be done by analyzing their gut contents. Polymerase chain reaction (PCR) is a sensitive and specific tool to identify target prey DNA within a predator’s gut. This paper reviews the efficiency of a DNA based approach for detecting IGP in the field, compared with detection by the use of monoclonal antibodies or gas chromatography. Prey specificity, detection times after prey consumption, capacity for quantification, multiple prey targeting and the time and costs involved in developing and using the different methods are considered.