Diverse artificial nest substrates may provide essential habitat for cavity nesting bee groups across a gradient of landscape intensity

Diverse and abundant assemblages of bee groups may be essential for optimal pollination services. Yet, recent declines in both wild and managed bees have been cause for serious concerns particularly in agricultural systems that require or benefit from these ecological services. Habitat augmentation may be one means to provide artificial nest substrate for specific groups of bees, and increase pollination services in pollinator poor environments. We constructed cavity nests with a diversity and abundance of nesting substrates. These nests were placed along a gradient of urbanization in 12 smallholder diversified farms and urban gardens. We found that bee groups preferentially nested based on the dimension of the cavity. Moreover, structure occupancy shifted greatly across landscape intensity. These results indicate that nesting structures may be a useful tool to measure the diversity and abundance of specific cavity nesting bee groups. In addition, these structures may be one means of providing essential habitat for cavity nesting bee groups in areas affected by urbanization or agricultural intensification. It is still unknown if artificial nests could be used to increase in-field diversity and abundance of these bee groups, and if these nests can affect pollination services, although, both wild and managed bees are an essential part of our food system. Therefore, we should leave no stone unturned in the search for appropriate and sustainable management techniques for these unique and essential organisms.