Grassflies of genus Meromyza (Diptera, Chloropidae) and grasses: the evolution of host plant preference

The present and literature data showed that Meromyza flies developed on grasses from 5 tribes: Poeae, Triticeae, Bromeae, Nardeae, Arundinarieae. The preference of host plants for 25, mainly Western Palaearctic species of Meromyza flies was analyzed: 11 species developed on grasses of the tribe Poeae, 4 – on Triticeae, 9 – on grasses from different tribes, 1 species developed on bamboo. A phylogenetic tree based on the mtDNA CO1 gene locus was constructed in the BEAST for 28 species of Meromyza flies, for 8 species of Drosophila and Campiglossa pygmaea . The host plants were known for 19 species Meromyza flies out of 28 studied species. An overview of the evolution of grasses is given. By the possible time of the genus Meromyza origin (not earlier than the middle of the Miocene), based on the known evolutionary scale of Drosophila , the Pooideae grasses had already been isolated and division into tribes occured. The features of non-specialized phytophage-oligophage (except M. acuminata ) confirmed by the wide spectrum of host plants have been supposed for species close to ancestral haplotypes ( M. nigriseta , M. pratorum , M. saltatrix , M. variegata ) or representing independent branches in their clusters ( M. acuminata , M. mosquensis , M. nigriventris ). The differentiation of Meromyza genus with formation of new species with narrow oligophagy or monophagy was associated with adaptation to other wild grasses following the formation and increase in the abundance of “core pooids” (Triticodae + Poodae) grasses and the spread of herbal biomes in the Miocene. Oligophages M. nigriventris , M. nigriseta , M. variegata and monophages M. acuminata , M. grandifemoris damage cereal cultivars.