Fruit set is moderately dependent on insect pollinators in strawberry and is limited by the availability of pollen under natural open conditions

Abstract

Modern strawberry (Fragaria x ananassa Duch.) cultivars are hermaphrodite and have fertile flowers, with the anthers releasing viable pollen. Cultivars are self-compatible and do not require cross-pollination. Studies supporting managed or wild insects are based on a few reports and there are problems with the methods used to assess pollination. This review examined the role of pollination in strawberry. The mean (± s.d. or standard deviation) pollinator dependence (PD) for yield (self-pollination versus open- or insect-assisted pollination) was 0.36±0.26 (P<0.001, N=52 studies). The yields of plants exposed to supplementary insects were higher than those exposed to pollinators under natural open conditions, with a calculated pollen limitation (PL) of 0.20±0.17 (P<0.001, N=20 studies). Fields close to semi-natural habitats, wildflowers, grass or hedges can have more pollinators and a greater diversity of pollinators than fields further away. However, a greater abundance of pollinators does not always lead to higher fruit set. Yield is dependent on insect pollinators (moderate pollinator dependence) and is limited by the availability of pollen under natural open conditions (moderate pollen limitation).