The cockroach: a largely overlooked pollinator

Abstract

T he parasitic plant Balanophora tobiracola is characterized by unusual mushroom-shaped inflorescences that emerge just above the ground. As it lacks chlorophyll and therefore is unable to photosyn-thesize, B tobiracola draws its nourishment from the roots of other living plants. Owing to its non-photosynthetic habit, B tobiracola can tolerate the shadiest of forest floors, which are characterized by relatively few herbaceous angiosperms and their typical pollinators such as bees and butterflies. B tobiracola's largely atypical morphology and habitat suggest that it may rely on atypical pollinators. On Yakushima Island, in Japan's Ōsumi archipelago, we observed cockroaches (Margattea satsumana) frequently visiting and pollinating B tobiracola. The insects bustled rapidly over inflorescences as they fed on pollen and nectar, and consequently, their mouthparts were covered in large quantities of pollen. To date, cockroaches have been largely disregarded as potential pollinators; indeed, there are few studies on cockroach pollination systems. Nonetheless, cockroaches have a nearly ubiquitous distribution , and several species consume floral resources. As cockroaches are generally nocturnal, their interactions with plants are usually cryptic to humans. Therefore, a reevaluation of cockroaches as pollinators is required. Although many consider cockroaches among Earth's most despised creatures, their important roles in our ecosystems should not be ignored. The cockroach-mediated pollination observed here suggests that pollination systems involving unusual and unexpected taxa may be more widespread than previously believed.