Authors: Sylvia Lee, Ainsley Parkins, Rodolfo S Probst
Mentors: Rodolfo S Probst
Insitution: University of Utah
Mutualisms between ants and plants are ubiquitous interactions and have been evolving for over 100 million years. Studies have been done on systems wherein the plants provide nutritional resources for ants, but the dynamics of mutualistic interactions in environments where host plants do not provide obvious nutritional rewards continue to remain elusive, raising questions about their co-evolutionary histories. In these circumstances, associated fauna, such as mealybugs and soft scales (Hemiptera: Coccoidea: Pseudococcidae and Coccidae), serve as intermediaries of the association, providing honeydew (enhanced plant sap) as a main food source to their host ants. However, the identity of the insects involved in these associations and their co-evolutionary history with ants is poorly understood. By focusing on samples collected in Costa Rica from 33 colonies of the Neotropical plant-ant genus Myrmelachista (Formicinae: Myrmelachistini), we sequenced DNA barcodes (cytochrome oxidase subunit 1 [CO1]) using Oxford Nanopore Technology and employed Next-Generation Sequencing (NGS) for both the Myrmelachista ants and their associated fauna. We aimed to identify their taxonomy, phylogenetic relationships and identify unique interactions between ants and their associated fauna. We recovered DNA barcodes for eleven Myrmelachista species and seven putative species of mealybugs (n=5) and soft scales (n=2). For the seven putative species of Coccoidea, our DNA barcodes, when compared to available sequences from the NCBI database, recovered an average of 85% match similarity. The closest matches associated our putative species to Old World Coccoidea taxa, reinforcing the need for taxonomic studies of this superfamily for the Neotropical region. Each putative species of soft scales was found uniquely associated with two Myrmelachista species (M. flavoguarea and M. cooperi). For all eleven Myrmelachista species, five were associated with two putative mealybug species. One putative mealybug species was associated with five different Myrmelachista species; one was uniquely associated with M. nigrocotea. Same associations were found between the associated fauna of M. flavocotea and M. lauropacifica; M. haberi and M. RSP027; M. plebecula, M. meganaranja, and M. osa, respectively. These results suggest that there may be unique associations between some Myrmelachista species and their Coccoidea associates, unconstrained by the ant phylogeny. Our findings also provide insights on Coccoidea taxonomy, emphasizing NGS DNA barcoding as a tool to illuminate how ant-plant associations might have evolved.