Describing the Wing Shape of three local populations of BrontispaLongissima Using Elliptic Fourier Analysis | Abstract
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Annals of Biological Research


Describing the Wing Shape of three local populations of BrontispaLongissima Using Elliptic Fourier Analysis

Author(s): Bryan George Belleza and Cesar G. Demayo

Species morphology has always been considered an important factor that affects the patterns of inter- and intraspecific competition in ecological communities. Difference in the phenotype of different populations of insects has been hypothesized to provide possible evidence of genetic differentiation or local adaptation towards their host plant thus is believed to be occurring in Brontispalongissima, a serious pest of coconut and other palms. This study was therefore conducted to determine variability in this pest by quantitatively describing the left and right wing shape variations between sexes and among geographical populations of the insect pest by applying the tools of elliptic Fourier analysis (EFA). Chain coding technique which relied on a contour representation to code shape informationwas used. The set of possible movement depends on the type of contour representation, a pixel based contour representation were used in this study. Normalized elliptic Fourier descriptors (EFD) obtained from the chain codes was calculated using elliptic Fourier transformation. Normalization of data obtained from chain codes used the first harmonic ellipse as a basis corresponding to the first Fourier approximation and utilized the 20 harmonics number to be calculated. Results showed significant variations on the shape among the three populations of B. longissima gathered from different locations. Based on the canonical variance analysis (CVA) and multivariate analysis of variance (MANOVA), the three populations were shown to differ in the costal, apex and posterior margins of the wing.While it was observed that the left and right wing shape differ the different geographical populations, variations were also detected to occur between sexes. Results of the study showed the use of Elliptic Fourier Analysis proved to be useful in quantitatively describing even subtle shape variations that may aide in understanding the nature of B. longissima. The significant variation in the shape of the inner wings between sexes within and between geographical populations in terms of the curvature in the costal, apex and posterior margin of the wings may be attributed to genetic differentiation, habitat preference, wind dispersal and host-plant relationship