Mating patterns of the European grapevine moth, Lobesia botrana (Lepidoptera: Tortricidae) in sympatric and allopatric populations

Phytophagous insects have been at the heart of investigations of ecological speciation, and it is clear that adaptation to different host plant species can promote host race formation and insect speciation. However, the evolution of host races has typically been studied at the plant species scale, using sympatric populations of insects that are specialized on particular plant species. Because many crop pest species are adapted to various plant varieties selected from a single plant species, it is of interest to establish whether reproductive barriers could evolve at this much smaller geographical scale, between individuals exploiting different plant varieties. To assess this we evaluated premating and postmating prezygotic barriers among sympatric populations of the European grapevine moth Lobesia botrana originated from different cultivars of the same plant species (Vitis vinifera), and between allopatric populations originated from different geographical sites. We found weak reproductive isolation for sympatric populations of L. botrana, but marked reproductive isolation among allopatric populations. In sympatric populations, the only effect was on the latency period prior to mating, which was longer for heterotypic partners that originated from different cultivars than for homotypic partners originated from the same cultivar. In allopatric populations, reproductive isolation was evident in both premating barriers and postmating prezygotic barriers. In summary, we did not find any trend for sympatric host race formation in L. botrana, but the occurrence of non-random mating patterns between different allopatric populations suggests the beginning of reproductive isolation, which could lead to the evolution of cryptic species of L. botrana. (C) 2016 The Linnean Society of London.