How many species of arthropods visit flowers?

Abstract

The majority of living plant species are pollinated by insects, and this interaction is thought to have played a major role in driving the diversification of modern angiosperms. But while flower-insect interactions have been well studied from the perspective of plants in the form of pollination biology, few studies have been carried out from an entomological perspective, where flowers are resources to exploit. As a consequence, it remains unknown how many insect species actually utilise floral resources, especially since many flower-visitors do not carry out pollination and may therefore be widely ignored in pollination studies. In this review, I attempt to present an overview of the taxonomic range of flower-visiting invertebrates and estimate the proportion of described species that regularly utilise flowers. The flower-visiting habit has likely evolved independently hundreds of times across more than a dozen modern invertebrate orders. I speculate, based on reviewing the literature and discussions with experts, that *30 % of arthropod species ([350,000 described species) may regularly utilise flowers to feed, find a mate, or acquire other resources. When extrapolated to the estimated global diversity of the phylum Arthropoda, perhaps more than a million species regularly visit flowers. However, generating more accurate estimates will require much more work from the perspective of flower-visiting insects, including the often-ignored species that do not pollinate host plants. In particular, sampling techniques in addition to traditional observation protocols should be encouraged to ensure that all flower-visitors are recorded. Greater efforts to identify flower-visiting species beyond the level of order or family will also enhance our understanding of flower-visitor diversity.

Overlooked flower-visiting Orthoptera in Southeast Asia

“…The last known report by Schuster (1974) listed merely seven orthopteran species visiting six flowers from Peru and Panama from two years of sampling which may also have underestimated the diversity of flower-visiting orthopterans. Wardhaugh (2015) suggested that orthopterans are rare flower-visitors but we showed that there are more flower-visiting species than previously known.…”

“…Orthopterans are only some of the many invertebrates that visit flowers (Wardhaugh 2015). To our best understanding, we provide here the first documentation of flower-visiting orthopterans from Southeast Asia and the most extensive one from the tropical region.…”

“…, Frame 2003, McCall and Irwin 2006. While we have estimates for flower pollinator-insect species (Bawa et al 1985, Ollerton et al 2011) and for folivore-insect species (Ødegaard 2000, Novotny et al 2006, Dyer et al 2007), we do not have a good estimate of the number of insect species that feed on flowers (Wardhaugh 2015).…”

“…Nonetheless, few records of orthopterans visiting flowers have been published (see e.g. Schuster 1974, Rentz and Clyne 1983, Rentz 2010, Wardhaugh 2015, Krenn et al 2016) and none of these involve Southeast Asian orthopterans. This is not surprising since even studies on the taxonomy of orthopterans in Southeast Asia remain incomplete and fragmentary (Tan et al 2017a).…”

Arthropod fauna recorded in flowers of apomictic Taraxacum section Ruderalia

“…All dandelion microspecies included in this study were apomictic; therefore, pollination is not important for their life cycle. This specifi c fact deserves to be accentuated because pollination is an important facet of plant-insect relationships, and one of the factors driving their co-evolution (Schiestl & Johnson, 2013;Wardhaugh, 2015).…”