Sponsored Projects for Undergraduate Research

As the earliest and most wide-spread form of communication, chemical signaling has permeated and prevailed through the whole tree of life to varying degrees. Particularly insects have exploited chemical signaling as their primary communication mode. Cuticular hydrocarbons (CHC), the dominant fraction of the waxy lipid layer located on the insect epicuticle and primarily functioning as desiccation barrier, form the basis for a wide range of different chemical signaling modalities. In eusocial insects, characterized by reproductive division of labor, cooperative brood care, and nest-living with overlapping generations, CHC have been shown to play pivotal roles in nestmate recognition, demonstrated most prominently in ants, where the discrimination between nest and non-nestmates can be a question of life or death.

The invasive Argentine ant, Linepithema humile, displays an extreme form of eusociality, known as unicoloniality, in which entire populations who have been introduced from their native range in Argentina will behave cooperatively with one another, regardless of individual colony-affiliation. In combination with largely increased human travel activity in the last century, this has led to an unparalleled invasive expansion with vast super colonies partially spanning multiple continents, whose colony members retain the capability to recognize each other as nestmates. Uniformity of CHC signals within invasive Argentine ant populations is believed to be the key factor of their success. However, CHC profile uniformity would largely conflict with the primary CHC function, i.e. the provision of desiccation protection, which is expected to display considerable flexibility while adapting to the vastly different environments and humidity conditions these populations encounter in their expanded range.

To shed light on these seemingly contradictory selective pressures on CHC profile divergence in Argentine ant super colonies, the Tsutsui lab attempts to decipher the particular CHC profile properties enabling constant nestmate recognition over vast geographical distances in relation to the more flexible CHC profile variations ensuring desiccation resistance despite considerable environmental fluctuations. Integrating chemical, genetic and behavioral methods, we are striving to obtain a holistic view on the underlying mechanisms governing the maintenance of a common, unambiguous and universally accepted chemical language within super-colonies while simultaneously providing sufficient flexibility for successfully adapting to a wide range of different habitats.