How is time sense behavior accomplished? Is it through Endogenous or Exogenous mechanisms?
In 1955 Max Renner trained bees in Paris by consistently giving them food at the same time every day. He then flew these bees to New York, in a constantly illuminated environment to see if time sense (coming back to the same spot in 24 hour intervals) could happen without constant exogenous factors, i.e. external factors like sunlight or temperature. The experiment examined whether the change in geographic latitude and different time zones impacted what time the bees would come back for food. He found that bees returned to the same place in roughly 24 hour intervals even in the new location, indicating the presence of an endogenous clock, that is, a regulator intrinsic to the organism independent of the environment.[3]
The next experiment looked at whether the exogenous contributions had an effect on the exogenous clock, looking specifically at how it might have impacted how often bees returned to the same spot. The experiment was conducted by training bees in Long Island, New York and then translocating them to Davis California. This was not done in constant light, to ensure that the position sunlight was not regulating the bee's behavior.[4] There were two time periods where the maximum number of bees returned to the spot after arriving in Davis. Numerous bees returned after of 24 hours, but numerous bees also returned at another time point illustrating an interaction between exogenous and endogenous factors. Max Renner concluded that if the two contributors, internal and external regulators, were in phase they reinforced each other and if they were off phase they competed with one another and impacted behavior.
Is astronomical orientation time compensated?
Max Renner wanted to examine how animals use the position of the sun to orient themselves. He used the experiment of translocating bees from Long Island to Davis to see how bees changed their orientation angle due to the position of the sun even when it was not consistent with their original time zone. He found that bees oriented themselves to figure out what direction to first fly using the sun-azimuth, which takes into account the change in sun speed as it changes position throughout the day.[3]
With Klaus Schonitzer, another zoologists at the University of Munich, Renner described the antenna cleaning activity of the worker honey bee (Apis mellifica). He discovered they have a structure on their forelegs that they used to clean their antennae with. With a single stroke and only one antenna at a time, these bees used the ipsilateral foreleg to clean the antennae.[5]
In another paper, “The significance of the secretion of the glandular glands for the attractiveness of the bee queen against young workers,” Renner assayed the biological significance of the terit gland secretion of the queen honey bee. He found that worker bees were attracted to the abdominal gland secretion, but it was only effective in conjunction with mandibular gland secretion, at distances over several centimeters. Together they were found to be responsible for the attraction effect.[6]
Renner, along with the chronobiologists before him, built a foundation that allowed Collin Pittendrigh to describe the biological clock of Drosophila, and come up with a model of entrainment of circadian rhythms, on the basis of which Pittendrigh was named the father of modern chronobiology.[4]
Some of Renner's other work gave valuable insights into maintenance and behavior of a honey bee, allowing for advancements in beekeeping.
