Genetic Diversity, Population Structure and Species Delimitation of Trialeurodes vaporariorum (Greenhouse whitefly)

Genetic diversity within Trialeurodes vaporariorum (Westwood, 1856) remains largely unexplored, particularly within regions of Sub-Saharan Africa. In this study, T. vaporariorum samples were obtained from three locations in Kenya: Katumani, Kiambu and Kajiado counties. DNA extraction, PCR and Sanger sequencing were carried out on ~750 bp fragment of the mitochondria cytochrome c oxidase I (COI) gene from individual whiteflies. In addition, global populations were assessed and 19 haplotypes were identified, with three main haplotypes (Hp_19, Hp_10, Hp_011) circulating within Kenya. Measures of genetic diversity among T. vaporariorum populations resulted in haplotype diversity of 0.411, nucleotide diversity 0.00096, and Tajimas D -0. 30315, (P>0.10). Analysis of population structure across global sequences using Structurama indicated one population globally, with posterior probability of 0.72. Bayesian and maximum likelihood phylogenetic analysis gave support for two clades (Clade I = an admixed global population and Clade II = subset of Kenyan and 1 Greek sequence). Species delimitation between the two clades was assessed by four parameters; posterior probability, Kimuras two parameter (K2P), Rodrigos P (Randomly distinct) and Rosenbergs reciprocal monophyly (P(AB). The two clades within the phylogenetic tree showed evidence of distinctness based on; Kimura two parameters (K2P) (p = -1.21E-01), Rodrigos P (RD) (p =0.05) and Rosenbergs P(AB) (p = 2.3E -13). Overall, low genetic diversity within the Kenyan samples is a likely indicator of recent population expansion and colonization with this region and plausible signs of species complex formation in Sub-Saharan Africa.