by João Farm
Plants often evolve flowers with particular shapes, colours, or scents
that match the preferences of the animals that pollinate them. These recurring
patterns are known as pollination syndromes. However, applying this idea to
fly-pollinated plants is challenging because different groups of flies have markedly
different behaviours and preferences. This study examines the plant Succisella
microcephala (from the teasel family), which initially appears to be a
generalist capable of attracting many kinds of insects. Yet preliminary field
observations suggest it may be pollinated predominantly by tachinids, a group
of parasitic flies. Some populations bear flowers with darker colours and
stronger contrast between floral parts, and these darker flowers were visited
mainly by tachinids—especially in high-elevation sites where these flies were
most abundant. These sites also supported a grass species that hosts the moth
larvae on which many tachinid species depend, helping to explain their local
prevalence. The emerging pattern suggests that darker floral colours may
enhance attraction for tachinids. Similar traits in other European plants
visited by tachinids (e.g. the burnt-tipped orchid) support this hypothesis.
Additionally, the plant’s developing fruiting structures are dark red and
visually resemble the dark, globular floral elements found in other species
associated with tachinid pollination. This raises the possibility that these
fruiting structures may also contribute to attracting pollinators, not only the
flowers. Overall, the observations indicate that dark-coloured floral or
fruiting structures may characterise a previously undescribed pollination
syndrome linked to tachinid flies. Succisella microcephala therefore
offers a promising system for exploring how plants evolve traits shaped by the
sensory ecology and preferences of specific pollinating fly groups. 
Succisella
microcephala: flower & developing fruit
