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

Abstract

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.

Pleistocene glaciation advances the cryptic speciation of Stellera chamaejasme L. in a major biodiversity hotspot

“…Pollinator interactions in S. chamaejasme may not rely on floral color, suggesting that common Lepidopterans (butterfly and moths) have a limited role in cryptic speciation (Zhang et al, 2011b). Conversely, a distinct brood-pollination mutualism with Frankliniella intonsa (Trybom) highlights how specialized pollinator relationships contribute to reproductive isolation and genetic differentiation (Zhang et al, 2021a). Furthermore, self-incompatibility and flower specialization stress the need for specific habitats for effective pollination and reproduction, fostering population isolation and evolutionary divergence (Zhang et al, 2011b).…”

“…Speciation here is often driven by historical geographic or environmental factors, leading to allopatric divergence. Yet, the unclear morphological differences and presence of relatively low supports of species delimitation among the four color morphs (RW, PP, YW, and YY) of S. chamaejasme , along with recent divergence (Hu et al, 2022) and less mobile pollinators (Zhang et al, 2011b; Van der Niet et al, 2014; Zhang et al, 2021a), suggest they do not fully meet traditional criteria for distinct biological species. Pollinator interactions in S. chamaejasme may not rely on floral color, suggesting that common Lepidopterans (butterfly and moths) have a limited role in cryptic speciation (Zhang et al, 2011b).…”

Plant-animal below-ground interaction modifies plant phenotype and its above-ground interaction: a review and new case study

“…For example, Frankliniella intonsa (Trybom, 1895) thrips pollinate Stellera chamaejasme L. plants where they also find brooding sites and food for their offspring. This close relationship drives a coevolution process that fits the life cycles of both species (Zhang et al 2021).…”