Diversity of endosymbiontic bateria in harmonia axyridis and Halyzia sedecimguttata
Publication Date
July 18, 2023
Creator
Abstract
Ladybirds are economically important insects that can be used as beneficial control agents against pests such as aphids and powdery mildew management in the agricultural industry, due to their aphidophagous and mycophagous nature. With the emergence of resistance to insecticides in recent years, using beneficial agents may be the best choice for farmers, a situation that could increase the commercial demand for ladybirds. Ladybird species are also of interest to study because they are known to be infected with a range of bacterial endosymbiont species that alter the biology of their host. Sex-ratio distortion caused by male-killer endosymbionts is one such example of altered host biology, which might also prove to be a limiting factor for the rapid and commercial multiplication of ladybirds. However, there are also many examples of beneficial endosymbionts that provide useful services to their host. In this project, we tried to understand the diversity of bacterial community in two ladybird species, Harmonia axyridis and Halyzia sedecimguttata, which are found widely in the UK but that differ in their ecologies. We used 16S rDNA sequences cloned and amplified from bacteria followed by comparison with known sequences on Genbank to characterise sequences of bacteria. Phylogenetic analysis was also used to identify other related microorganisms that might provide insights into the roles the bacteria might play in their ladybird hosts. Novel bacteria from 10 different classes, including those closely related to bacteria previously reported from invertebrate hosts, were identified. Of these 10 Classes, 7 were found in H. axyridis and 8 were found in H. sedecimguttata. Alphaproteobacteria, Betaproteobacteria, Gammaproteobacteria, Bacilli and Actinobacteria were identified in both ladybird species. Flavobacteriia and Terriglobia were only found in H. axyridis whereas Cytophagia, Chitinophagia and Hydrogenophilia were only found in H. sedecimguttata.
H. axyridis were commercially available ladybird before being banned due to the negative impact on the indigenous species. However, understanding the function of identified bacteria might help to engineer microbiome or endosymbionts in the native ladybirds in the future to make them a better pest regulator. In addition to this beneficial effect, it might also help us understand the interaction between microbes and invertebrate hosts and therefore tell us more about how populations of ladybirds are influenced by these microbes.
Item Type
ethesis
Thesis Type
PhD
Supervisors
Subjects (LC)
Associated Schools / Departments
School of Life Sciences
eprints ID
73909
UoN Repository URI
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