Differences in nutritional quality of parts of Vitis vinifera berries affect fitness of the European grapevine moth

The European grapevine moth, Lobesia botrana (Denis & Schiffermuller) (Lepidoptera: Tortricidae), is a major grapevine pest in Europe. The larva is polyphagous and able to develop on more than 25 plant species, several of them being more suitable than Vitaceae for the fitness of L. botrana. Larvae normally eat the pulp of the berry, but may also consume the seeds according to the development stage of the berry and the larval density per bunch. Understanding the effect on individual fitness of such feeding behaviour is important to assess how suitable the different berry tissues are for this insect. We offered to the larvae either entire berries, seeds, or pulp with skin of the variety Vitis vinifera cv. 'Cabernet Sauvignon' as larval food in order to assess several life history traits from egg hatching to adult death. Two control groups were raised on semisynthetic diets, offering a low (no plant material) or a higher (with corn flour) nutritive value medium. The larvae performed differently when fed on diets containing different parts of berries. The larvae fed on a diet containing grape berry seeds had a prolonged development time and showed higher mortality. The females emerging from these larvae had a lower fecundity and mating success than the females emerging from larvae fed on diets containing other parts of the berries. However, their longevity was greater in comparison to the other groups. We conclude that seeds of Cabernet Sauvignon are not toxic to larvae but affect the reproductive life history traits in L. botrana.