Evaluation of feeding behaviour of Acyrtosiphon Pisum Harris (Aphididae) clones according to changes of plant growth promoting Rhizobacteria occurrence on host plant in Chile

Abstract

The pea aphid (Acyrthosiphon pisum Harris) is known to be a pest of significant economic importance and is widely dispersed in Chile. Nowadays, the pest management is oriented to a limited utilisation of synthetic insecticides and by this way avoid the development of insect resistances. There are many alternatives to achieve this objective such as the biological control. The plant growth-promoting rhizobacteria (PGPR) are soil organism that increase rates of plant growth but which can also have an effect of biological control on pest insects. The objective of this thesis is to assess if the PGPR-induced plant defence’s has an effect on different APA populations (Acyrthosiphon pisum with alfalfa host-plant). The population parameters, and the feeding behaviour were studied. Moreover, the plant responses were also measured (hormone profile analysis, and photosynthesis and morphological parameters). For all the experiments, broad bean (Vicia faba L.) plants were previously inoculated with the PGPR Bacillus amyloliquefaciens FZB42. Seven-days inoculated plants were infested with the two clones of APA, different between them by the occurrence of the secondary endosymbiont Hamiltonella defensa. At the end of all experiments, it was highlighted that the aphid without the secondary endosymbiont seems to be negatively impacted by the PGPR. Contrary, the clone with the endosymbiont seems to be, in a first time, favoured by this Bacillus but this effect did not remain until the end of the experiment.