A preliminary assessment of bumble bee (Hymenoptera: Apidae) habitat suitability across protected and unprotected areas in the Philippines

Abstract

The Philippines is a biodiversity hotspot and is home to thousands of endemic species, including at least two understudied bumble bee species: Bombus flavescens Smith, 1952 and Bombus irisanensis Cockerell, 1910. Since the 1990s, there have been virtually no studies published on the biology, ecology, and taxonomy of Philippine bumble bees—evidence of the dearth of basic entomological investigations on these important insects. In this preliminary study, our objective is to briefly summarize the geographic distribution of bumble bee habitat suitability (HS) in the Philippines across protected and unprotected areas. Maximum entropy species distribution models (SDMs) of B. flavescens and B. irisanensis were constructed using 19 unique occurrence records and 11 bioclimatic variables to estimate HS in the Philippines. Our SDMs estimated that minimum HS for B. flavescens and B. irisanensis covers ~28,066 and ~24,603 km2 of the 114 protected land parcels in the Philippines, respectively. Across unprotected areas, our SDMs estimated that minimum HS for B. flavescens and B. irisanensis covers ~146,063 and ~156,674 km2, respectively. As predicted, high-elevation habitats have the highest HS relative to low-elevation habitats (r = 0.61, P = 0.003). While our SDMs predicts an extensive distribution of both species across both protected and unprotected areas, it is important to note that nearly 80% of the Philippines is deforested. Our study identifies high-elevation protected areas as places where bumble bees may still thrive, and survey effort should be prioritized to these places to determine the status of Philippine bumble bees.