Vibrational communication between adults and larvae in the social paper wasp

(Polistes dominulus).

 

Bernard J. Brennan

Department of Neurobiology & Behavior

Cornell University, Ithaca NY 14853

bjb7@cornell.edu

 

It looks like wasps talk to their babies about food using vibratory signals.

 

Adult paper wasps (Polistes dominulus) have a conspicuous behavior of rapidly wagging their abdomen from side to side when they are on their nest with their young (larvae).  I used tiny accelerometers inside nest cells to record the vibrations produced by this abdominal wagging (AW), as "heard" by the larvae.

 

By comparing video and vibratory recordings, I discovered that not all AW produces loud vibratory signals.  It is necessary for the wagging abdomen to contact and scrape against the nest surface to make much sound.  However, most (80% avg.) AW does contact the nest and produce large vibrations. 

 

If larvae are the intended receivers of the vibratory signal then their presence should effect abdominal wagging. To test this I removed all larvae from the nest for an hour and then replaced them.  Sure enough, abdominal wagging completely stopped when larvae were absent, and started immediately when they were returned.  (I should note that I was working with naturally occurring single foundress colonies.  So there were no other possible adult receivers present.) 

 

Finally, I manipulated food resources at the nest by starving the colony for a day and then replacing their food.  I found that abdominal wagging rate increased during starvation, and fell to its lowest level following feeding.

 

Conclusions

·        This is the first time the vibratory signals associated with AW's have been directly recorded.

·        In contrast to previous descriptions, P. dominulus adults make contact with the nest substrate during a majority of abdominal wagging behaviors. 

·        It is this contact that accounts for the loud vibratory sound associated with AW's.

·        The presence of larvae in the nest is necessary for the production of AW's.

·        Manipulation of food availability causes a significant change in the rate of abdominal wagging.

 

These findings are consistent with the hypothesis that abdominal wagging functions as a vibratory signal, between adults and larvae, related to food availability at the nest. 

 

But what exactly do AW's mean to adult senders and larval receivers?  My work continues with these social wasps to discover the precise function of this novel communication system.