No “global” trend: utilising taxonomic collections for assessing the global pollination crisis

Posted by Darren Ward @nzhymenoptera

There is increasing concern about the decline of pollinators worldwide. However, despite reports that pollinator declines are widespread, data are scarce and often geographically and taxonomically biased. These biases limit conclusions about any potential pollinator crisis.

Natural history museums have the potential to transform the field of global change biology. However, museum specimens are underused and could be better utilised to reveal patterns that are not observable from other data sources. Specimens historically collected and preserved in museums provide information on where, and when, species were collected, but also contain other ecological information such as species interactions and morphological traits.

In a recent paper we provide a global synthesis of how researchers have used historical data to identify long-term changes in pollination services. We show that scientific information on the status and trends of most pollinators is poor, if not absent. For example, although a wide variety of countries have recent records of pollinators, they lack historical data. Thus, greater emphasis should be placed on the digitisation of specimens already held in natural history museums.

Furthermore, changes in pollinator communities are context specific, and ‘global trends’ need to be assessed with caution, especially when most of the globe is not assessed!

In Spain, a hot-spot for bee diversity, data analyses showed there were a reduced number of bee species, however, this trend was highly site-specific. Declines in species were clustered around certain types of bees, such as the ground-nesting bees (especially Andrenidae), suggesting a pattern of winners and losers, where some groups of bees are more sensitive to disturbance than other groups.

In New Zealand there are relatively few native bee species, however, they are well studied, and therefore museum records can be used to identify trends in pollinator communities. In contrast to Spain, we found that 11 out of 27 bee species increased in relative occurrence over time, 13 species were stable, and only three bee species declined in relative occurrence.

A greater number of long-term datasets from different countries are needed in order to provide a robust and truly global assessment of trends in pollinator communities. Natural history museums play a central role in assessing the extent of the global pollination crisis, because they are the source which can serve as a baseline.


Bartomeus I, Stavert JR, Ward D, Aguado, O. 2019. Historic collections as a tool for assessing the global pollination crisis. Philosophical Transactions of the Royal Society B. 374, issue 1763.

From a themed issue, ‘Biological collections for understanding biodiversity in the Anthropocene’.


New Zealand bee collection records were gathered from multiple sources, including university, research institute, museum and private collections. Collection records from the New Zealand Arthropod Collection (NZAC) and are freely available online (

Darren Ward is an entomologist, Head Curator at the New Zealand Arthropod Collection at Landcare Research, and a senior lecturer at the School of Biological Sciences, University of Auckland.

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