Morphological and Molecular Identification of Jamun Gall Whitefly Rusostigma eugeniae (Maskell)

Whiteflies have become increasingly devastating in the horticultural sector due to the changing climate. Globally, the whitefly genus Rusostigma comprises four species; out of which only Rusostigma eugeniae (Maskell) is known from India. Present study reports herein a comprehensive morphological and molecular identification of R. eugeniae collected from Syzygium cumini in Madurai, Tamil Nadu, India. The puparium exhibited distinctive tracheolar and caudal folds with typical reticulate polygonal markings and invaginated tooth-like structures along the margin. The distinguishing characters seen in adults included, antennae with flap-like sensoria, male aedeagus with a well-projected horn and the female cement gland had concentric rings (rattle-shaped) which are unique for R. eugeniae. These features on puparium and adult thus confirm the morphological identity of R. eugeniae. No phenotypic plasticity for puparium was observed. Furthermore, the partial nucleotide sequence (597 bp) of the COI gene of R. eugeniae, was characterized and deposited in the NCBI database as OQ162225.1. Phylogenetic analysis explicitly distinguished the genus Rusostigma from Dialeurodes, corroborating its distinct morphological identity. Notably, OQ162225.1 is the first nucleotide sequence accession for the genus Rusostigma in the GenBank repository. Pictorial presentation of life stages of the pest along with morphological features form a reference guide for researchers, extension personnel and farmers.