HABITAT AND FORAGING OBSERVATIONS ON AN ORIENTAL BUMBLE BEE (HYMENOPTERA APIDAE)

Bombus baguionensis is found above about 1400 m on Mt Banahaw, Luzon, Philippines. Only two other social bees and very few solitary bees were observed at these elevations. Around the end of the dry season, bumble bees were found foraging at seven species of flowering plants, of which three accounted for all but a very few visits. Behavioral observations and analysis of pollen loads show Melastoma polyanthum (Melastomataceae) as the almost exclusive pollen source. Hedyotis elmeri (Rubiaceae) appears to be the main nectar source, with Rubus rosaefolius (Rosaceae) inferred as a secondary nectar source. Bees also drank human urine on fallen leaves, presumably as a source of salts. The period of foraging activity on a northwest-facing slope was closely congruent with the period of daylight, about 05:30-18:00. Data from a nectar-plant patch and a predominantly pollen-plant patch are consistent with a gradual switch from pollenforaging to nectar-foraging throughout the day. © 1990 Taylor & Francis Group, LLC.