Aebi, Alexandre

2014, Sandau, Nadine, Rohr, Rudolf P., Naisbit, Russell E., Fabian, Yvonne, Bruggisser, Odile T., Kehrli, Patrik, Aebi, Alexandre, Bersier, Louis-Félix

2013, Ingels, Brecht, Aebi, Alexandre, Hautier, Louis, Van Leeuwen, T., De Clercq, Patrick

Several studies have demonstrated that the invasive ladybird Harmonia axyridis is a strong intra-guild predator of native species of ladybird. Laboratory studies have shown that H. axyridis can be an intra-guild predator of aphid predators other than coccinellids, including the hoverfly Episyrphus balteatus and lacewing Chrysoperla carnea. However, little is known about the effect of intra-guild predation (IGP) by H. axyridis on hoverfly and lacewing populations in the field. In the present study molecular analyses were used to detect the DNA of E. balteatus and C. carnea in the gut contents of H. axyridis. Primers for the syrphid and chrysopid prey were designed and feeding experiments performed to determine how long prey DNA remains detectable in the guts of this ladybird. DNA detection was influenced by the life stage of the predator and species of prey. Meal size did not affect detection time, except when fourth instar individuals of H. axyridis were fed 10 eggs or one second instar of C. carnea. Predator weight, sex and morpho-type (melanic/non-melanic) did not influence DNA detection. The half-life of the time for which the DNA of the prey remained detectable was calculated for each predator-prey combination, and ranged from 8.9 to 52.4 h. This method can be used to study the ecological importance of IGP by H. axyridis on aphidophagous predators other than coccinellids in the field.

2013, Aebi, Alexandre, Zindel, Renate

2012, Fabian, Yvonne, Sandau, Nadine, Bruggisser, Odile T., Kehrli, Patrik, Aebi, Alexandre, Rohr, Rudolf P., Naisbit, Russell E., Bersier, Louis-Félix

2013-3-31, Ingels, Brecht, Aebi, Alexandre, Hautier, Louis, Van Leeuwen, Thomas, De Clercq, Patrick

Several studies have demonstrated that the invasive ladybird Harmonia axyridis is a strong intra-guild predator of native species of ladybird. Laboratory studies have shown that H. axyridis can be an intra-guild predator of aphid predators other than coccinellids, including the hoverfly Episyrphus balteatus and lacewing Chrysoperla carnea. However, little is known about the effect of intra-guild predation (IGP) by H. axyridis on hoverfly and lacewing populations in the field. In the present study molecular analyses were used to detect the DNA of E. balteatus and C. carnea in the gut contents of H. axyridis. Primers for the syrphid and chrysopid prey were designed and feeding experiments performed to determine how long prey DNA remains detectable in the guts of this ladybird. DNA detection was influenced by the life stage of the predator and species of prey. Meal size did not affect detection time, except when fourth instar individuals of H. axyridis were fed 10 eggs or one second instar of C. carnea. Predator weight, sex and morpho-type (melanic/non-melanic) did not influence DNA detection. The half-life of the time for which the DNA of the prey remained detectable was calculated for each predator-prey combination, and ranged from 8.9 to 52.4 h. This method can be used to study the ecological importance of IGP by H. axyridis on aphidophagous predators other than coccinellids in the field.

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.

2012, Bacon, Steven James, Bacher, Sven, Aebi, Alexandre

2013, Rey, Olivier, Estoup, Arnaud, Facon, Benoit, Loiseau, Anne, Aebi, Alexandre, Duron, Olivier, Vavre, Fabrice, Foucaud, Julien

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

2012, Aebi, Alexandre, Vaissière, Bernard E, van Engelsdorp, Dennis, Delaplane, Keith S., Roubik, David W, Neumann, Peter