Genetics and biology of the mango blossom gall midge, Procontarinia mangiferae, a pest with highly adaptable life strategies

The development of Integrated Pest Management (IPM) on mango requires the knowledge of the biological cycle of the main pests and of their relationships with the mango tree. Among them, the mango blossom gall midge, Procontarinia mangiferae (Felt), is a monophagous invasive pest of mango, causing economic damage by attacking inflorescences. The objective of this study was to improve our knowledge on the biology of this species in the subtropical Reunion Island (i) by describing its genetic diversity and ecological abilities in order to evaluate the determinants of its genetic structure, (ii) by carrying out field and controlled experiments to understand the diapause strategies involved in maintaining populations from one flowering season to another, (iii) by modeling the female dispersion within and between orchards in relation to the mango phenological stages and their flight capacity. Our results showed that P. mangiferae was the only mango midge species feeding on both inflorescences and young leaves, present all year round at all of the sampled sites on the island, regardless of the climatic and cultural conditions. Secondly, diapause mechanisms allowed a developmental arrest at the final larval instar, lasting between six weeks to more than one year. Thirdly, female gall midges were able to colonize all trees of an orchard from external sources, but they were attracted differently by trees within the orchard in relation to the abundance and the phenology of the susceptible organs. These results illustrated the ecological plasticity of P. mangiferae. Consequences of these results to elaborate IPM strategies against the mango blossom gall midge are discussed. (Résumé d'auteur