Suction feeding in orchid bees (Apidae: Euglossini)

Area of Science:

• Zoology
• Biomechanics
• Insect physiology

Background:

• Nectar feeding energy flux is maximized at intermediate sugar concentrations.
• Optimal sugar concentration varies with feeding apparatus morphology and fluid feeding modality.
• Biomechanical models predict lower optimal sugar concentrations for suction feeders compared to lapping feeders.

Purpose of the Study:

• To determine if orchid bees (Apidae: Euglossini) are suction feeders.
• To experimentally assess the feeding optimum for the orchid bee species Euglossa imperialis.
• To compare the feeding optimum of orchid bees with that of lapping bee taxa.

Main Methods:

• Observation and analysis of the feeding apparatus morphology of four major orchid bee genera.
• Experimental determination of the optimal sugar concentration for nectar feeding in Euglossa imperialis.
• Comparison of experimental results with biomechanical predictions and data from lapping bee taxa.

Main Results:

• The four major genera of orchid bees were confirmed to be suction feeders.
• The feeding optimum for Euglossa imperialis was found to be at a lower sugar concentration than predicted for lapping bees.
• Experimental evidence supports the biomechanical model's prediction of a shift in optimal sugar concentration with feeding modality.

Conclusions:

• Orchid bees' suction feeding mechanism results in a lower optimal nectar sugar concentration.
• Feeding apparatus morphology and feeding modality are critical factors determining energy optimization during nectar feeding.
• This study provides empirical support for theoretical models of fluid feeding in insects.