The Ramírez Lab

University of California - Davis

Speciation and Evolution of Reproductive Barriers in Orchid Bees

We are investigating how bees detect, integrate and process chemical stimuli relevant to mating and social organization. In particular, we are interested in studying the chemical, genetic, and neurophysiological basis of mate recognition in Euglossa orchid bees.

Unlike most insects, male orchid bees do not produce their own pheromones, but instead gather and accumulate fragrance compounds found in flowers, fungi, and other sources, to subsequently present to females during courtship display. Previous work done in collaboration with Thomas Eltz (U. Bochum, Germany) showed that male-gathered fragrances are stereotyped, species-specific, and divergent among closely related taxa. These findings suggest that fragrances could play a role in maintaining reproductive isolation among sympatric orchid bee lineages.

Using neuroethological approaches, we are investigating how male bees acquire their chemical profiles from the environment. To this end, we are working with the Central American green orchid bee, Euglossa dilemma, a species that was naturalized recently in southeastern United States (Florida). We are applying diverse methodologies, including Gas Chromatography-Mass Spectrometry (GC-MS), electroantennogram recordings (EAG), and high throughput DNA sequencing to elucidate how chemical information is encoded in the bee brain and how such information flows from the antennae to higher-level integration centers. Ongoing comparative studies are focused on recently diverged, reproductively isolated species.