MPI-CE_Ernst Stahl Seminar

Abstract:
Nutritional requirements of animals are multidimensional and change qualitatively and quantitatively over time. In parallel, the nutritional environment is frequently highly variable both in space and time and food sources are composed of a wide array of nutrient molecules in various ratios and concentrations combined with non-nutritive molecules. Finally, plants are known to rapidly respond to herbivore attacks by reconfiguring their primary and secondary metabolism in order to reduce herbivore food acquisition. While endophagous insects by their feeding habit secure their nutrition and shelter, they also have to adopt specific feeding strategies allowing them to meet their energetic requirements, to face variations in food composition and nutritional needs, and to counteract plant defensive mechanisms. Recently, insect endosymbiotic bacteria have emerged as key players in plant-insect interactions mediating directly or indirectly fundamental aspects of insect nutrition such as insect feeding efficiency or their ability to manipulate the plant physiology to overcome food nutritional imbalances.

Our results on the Malus domestica/Phyllonorycter blancardella plant-leaf mining system show the ability of leaf-miner insects to manipulate their host plant physiology and to create an “optimal” nutritional micro-environment through cytokinin production by their endosymbiotic partners. This symbiotic association impacts not only nutrient acquisition but also the feeding behavior of leaf miner insects. A close investigation at the interspecific level also shows a strong correlation between the presence of the endosymbiotic bacteria Wolbachia and the induction of green-islands suggesting that insect symbionts most probably played a major role in the evolution and/or radiation of the endophagous feeding mode. Emerging data also strongly suggest converging strategies between gall-inducer and leaf-miner arthropods.

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