The sister-species approach in entomology and its importance in disentangling genomics physiology and ecology of species

Current entomology makes use of a large array of analytical tools taken from different disciplines such as ecology, neurobiology, microbiology, genetics, and genomics; this interdisciplinary approach can generate robust knowledge to clarify the biology of a certain insect species. There is however one crucial aspect often neglected: the comparison between an insect and its closest related sister-species ( i.e. the closest species or group of species on a phylogenetic tree). In the absence of a sister-species, any type of comparison cannot discriminate characters that are unique to the pest from those shared with other members of its clade. In the presence of the closest available sister-species, these characters can be instead polarised into the phylogeny to reveal for example: unique chemosensory genes useful for chemical ecological applications, estimate age of speciation and evolutionary patterns for paleo-ecological reconstructions, identify with more accuracy typical physiological and behavioural characters. Because of budget and/or logistic reasons, this knowledge is too often impaired by a certain species being compared only with distantly related species. Here we present the rationale behind the sister-species concept and provide some successful example of the benefit of comparing an insect biology with that of the closer related species. We advocate that entomology would benefit from taking into account the sister species concept by modifying current research agendas.