Identity and genetic structure of eggplant fruit and shoot borer, Leucinodes orbonalis Guenée (Lepidoptera:Crambidae) populations in the Philippines inferred from morphological traits and COI sequence data

Abstract

Abstract Morphological and molecular analysis of 15 Philippine populations of eggplant fruit and shoot borer (EFSB), Leucinodes orbonalis Guenee were conducted to determine if these populations are constituted singly by L. orbonalis or by different species and to assess the level of variability among them. Morphometric analysis of five genital traits of 850 male adult EFSB from field populations and analysis of the COI gene sequence of 879 F1 EFSB larvae from 15 main eggplant-producing provinces identified all individuals as belonging to L. orbonalis. Principal Component Analysis of five morphometric genital characters revealed high similarity among the EFSB populations regardless of geographic location. Thirteen (13) sequence variants (haplotypes) were identified, with one haplotype predominant and widespread throughout the country. The remaining haplotypes occurred rarely and differed from the widespread haplotype by one mutation. Overall, the EFSB populations from Philippines exhibited low nucleotide and haplotype diversity, indicating low genetic diversity. Topologies from a maximum likelihood tree indicate all thirteen haplotypes cluster in a single clade with EFSB populations from India and other South-East Asian countries. Further analysis with the Generalized Mixed Yule Coalescent (GMYC) method classified the different haplotypes into a single GMYC entity. Combined with morphometric analysis, differences between haplotypes are not suggestive of any subspecies. Negative values of Tajima's D and Fu's Fs tests combined with the phylogenetic analysis and overall low genetic diversity of Philippine populations support the hypothesis that EFSB is not endemic but introduced to the Philippines.