Bridging the morphological and biological species concepts: studies on the Bactrocera dorsalis (Hendel) complex (Diptera: Tephritidae: Dacinae) in South-east Asia

Abstract

Defining species accurately is a critical need in fundamental disciplines such as ecology and evolutionary biology and in applied arenas such as pest management. The validity of species designations depends on agreement of different methods of species diagnosis for unique biological species. The Bactrocera dorsalis complex of fruit flies provide an excellent opportunity for such a test of the congruence of different techniques (e.g. morphological, molecular, host-plant based, chemotaxonomy) used for species diagnosis. The complex contains a large number of closely-related species, is distributed over a wide geographical range in South-east Asia and considerable information has been compiled on some species. In the present study, the morphological and biological species boundaries were compared using new data from morphometric analyses of reproductive and body parts, together with a review of data on morphology, chemistry of male pheromones that are important in courtship and mating, molecular analyses, and endemic rainforest host plants. For the populations studied (Bactrocera carambolae, Bactrocera dorsalis, Bactrocera occipitalis, Bactrocera papayae, Bactrocera philippinensis, Bactrocera kandiensis and Bactrocera invadens) there appears to be significant congruence between the morphological and biological species boundaries.