Meeting Abstract
In and around ant nests such called ‘myrmecophilous’ animals try to overcome their hosts defense. For those who succeed, the companionship with their host guarantees powerful protection and access to food. As ant defensive behavior is mainly mediated by chemicals – for instance species specific cuticular hydrocarbons (CHCs) or alarm pheromones – ant-associated parasites can either crack their hots chemical code by modifying their own CHC-profiles or use pro-active strategies like chemical weaponry for distraction and repellency. While the chemistry of many ant-parasite interactions has been detailed recently, the chemical mediators of the rare association of ants and ant-resembling Heteropterans are mostly unknown. That is why I studied the mirid bug Pamillia behrensii which has been reported to live associated with velvety tree ants (Liometopum occidentale) an ecologically dominant and aggressive ant species native to the Southwest. More specifically I used behavioral, chemical and molecular approaches to disentangle the relationship of P. behrensii and its host ant. Chemical profiling of cuticular hydrocarbons of both bugs and ants revealed no chemical mimicry, yet additional GC/MS analysis of volatile compounds of the bugs metathoracic glands as well as feeding trials with armed and artificially disarmed bugs showed a defensive function of the gland exudates. Further field observations and first molecular evidence suggest that P. behrensii might be a Batesian mimic. In summary, the bugs mainly live loosely associated directly next to ant nests and are regularly aggressed by ants (CHC mismatch). Yet, bugs usually survive and escape these attacks by releasing their defensive chemical as repellents against (host) ants. Hence, the use of chemical weaponry rather than a chemical code-cracking perfume enables P. behrensii to get along and live close by its host ant.
