A new brood-pollination mutualism between Stellera chamaejasme and flower thrips Frankliniella intonsa

Background Brood pollination mutualism is a special type of plant-pollinator interaction in which adult insects pollinate plants, and the plants provide breeding sites for the insects as a reward. To manifest such a mutualism between Stellera chamaejasme and flower thrips of Frankliniella intonsa, the study tested the mutualistic association of the thrips life cycle with the plant flowering phenology and determined the pollination effectiveness of adult thrips and their relative contribution to the host's fitness by experimental pollinator manipulation. Results The adult thrips of F. intonsa, along with some long-tongue Lepidoptera, could serve as efficient pollinators of the host S. chamaejasme. The thrips preferentially foraged half-flowering inflorescences of the plants and oviposited in floral tubes. The floral longevity was 11.8 +/- 0.55 (mean +/- se) days, which might precisely accommodate the thrips life cycle from spawning to prepupation. The exclusion of adult thrips from foraging flowers led to a significant decrease in the fitness (i.e., seed set) of host plants, with a corresponding reduction in thrips fecundity (i.e., larva no.) in the flowers. Conclusions The thrips of F. intonsa and the host S. chamaejasme mutualistically interact to contribute to each other's fitness such that the thrips pollinate host plants and, as a reward, the plants provide the insects with brooding sites and food, indicating the coevolution of the thrips life cycle and the reproductive traits (e.g., floral longevity and morphology) of S. chamaejasme.

Automated summary

The adult thrips of Frankliniella intonsa and the host Stellera chamaejasme interact mutually to contribute to each other's fitness, with the thrips pollinating host plants and the plants providing the insects with breeding sites and food. The thrips preferentially forage in half-flowering inflorescences and oviposit in floral tubes, and the floral longevity precisely accommodates the thrips life cycle. Excluding adult thrips from foraging flowers results in a significant decrease in host plant fitness and thrips fecundity in the flowers.