Morphometric and molecular characterization of iroko gall bug, Phytolyma species (Hemiptera: Psyllidae) from eastern and western Nigeria

Abstract

Iroko gall bug, Phytolyma species is a major pest of Milicia excelsa which has hindered the establishment of Milicia plantations in many West African countries. To date, the genus Phytolyma consists of Phytolyma lata (Scot), Phytolyma fusca (Walker) Phytolyma minuta (Hollis) and Phytolyma tuberculata (Alibert). In Nigeria, there is no clear record of the Phytolyma spp found in the country. This has become a major concern due to irregularities in researchers’ report of species present in Nigeria. This further hampers proper deployment of management strategies of the pest in affected regions. Hence, this study used morphometry and DNA barcoding to delineate Phytolyma species in three regions of Nigeria. The Principal component analysis yielded 19 components which correspond to the 19 morphometric measurements. The first two principal components resulted to 54.6% and 68.8% of the total variation in males and in females, respectively. However, the first two canonical variates showed partial separation for males and full separation of females. Phylogenetic analyses inferred through Maximum Likelihood method yielded a monophyletic clade with two distinct branches. Due to limited taxonomic information on the pest in Nigeria coupled with lack of genetic information at the GenBank on Phytolyma spp, this study reports on the creation of a first DNA barcode reference library of Phytolyma fusca

Keywords: Phytolyma, Species identification, morphometry, DNA barcoding