Title: Thermoperiodism in the cavity nesting alfalfa leafcutting bee, Megachile rotundata Authors
Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: June 18, 2012
Publication Date: November 11, 2012
Citation: Rinehart, J.P., Yocum, G.D., Kemp, W.P. 2012. Thermoperiodism in the cavity nesting alfalfa leafcutting bee, Megachile rotundata [Abstract]. Entomological Society of America Annual Meeting. Paper No. D0254. Interpretive Summary: The alfalfa leafcutting bee, Megachile rotundata is the most intensively managed solitary bee, and is the third most used pollinator in the United States. This study characterized how this agriculturally important insect matches adult emergence with the daily cycle of its environment. This is especially interesting because this is a cavity nesting insect, spending the majority of its life in locations where daily light cues may not be detectable. Our data show that while these bees emerge throughout the day when incubated at constant temperature, varying the temperature by as little as 2°C caused incubation to be concentrated in the warming period of the day (and therefore generally associated with morning in a natural environment). This may be especially important to commercial rearing of this species, because they are normally incubated at a constant temperature prior to being released, and the correct timing of emergence can dramatically affect survival in the field.
Technical Abstract: The alfalfa leafcutting bee, Megachile rotundata is the most intensively managed solitary bee, and is the third most used pollinator in the United States. Previous studies have indicated that while the eclosion pattern of this cavity nesting bee is unaffected by photoperiod, a thermoperiod can give rise to rhythmicity. This study further characterizes the relationship between eclosion rhythmicity and thermoperiod. Our results indicate that while this bee is arrhythmic when incubated at constant temperature, a thermoperiod of as little as 2°C caused eclosion to be concentrated during the transition from cryophase to thermophase. This is especially relevant to commercial rearing of this species, in which development from the prepual to adult stages is completed under constant temperature incubation.