Study on Geometric Morphometric Analysis of the Head, Pronotum and Elytra of Brontispa longissima (Gestro) Collected in Selected Provinces in the Philippines

Background: Using Cluster Analysis, Relative Warp Analysis coupled with box plot and histograms, and Procustean Analysis, this study was conducted to explain variations in the shapes of the elytra, head, and pronotum of populations of adult Brontispa longissima (Gestro) infesting coconut farms from selected areas in the Philippines.
Form residuals captured using the landmark based geometric morphometrics approach were included in the data used in this analysis.

Objective : The goal of this study was to use Cluster Analysis, Relative Warp Analysis with box plots and histograms, and Procustean Analysis to describe variations in the shapes of the elytra, head, and pronotum of populations of adult Brontispa longissima (Gestro) infesting coconut farms from selected areas in the Philippines.

Results: Cluster analyses based on average elytra, head, and pronotum shapes indicate no clear pattern of similarity between and within five populations of B. longissima. When RWA was used to summarise variations using two relative warps in the shape of the elytra, the results revealed that RWA was only effective in summarising variations using two relative warps in the shape of the elytra, with the first two warps containing 86.29 percent of the female variations and 85.48 percent of the male variations. The first two relative warps captured less than half of the total difference in the head and pronotum. When the shapes of the frequency histograms were examined, it was discovered that they all followed a unimodal distribution. There are no clear findings in the box plots.

Only the elytra were more durable and consistent than the head and pronotum among the three characters tested, and Tandag differed from the other overlapping populations. Procustean Analyses, on the other hand, showed that both male and female elytra were more widely distributed in the posterior region. The head and pronotum coordinates were uniformly distributed. Variability was exaggerated in the right side of the elytra and the posterior sections of the head and pronotum in the overlapping consensus configurations. Females had more expansion in their elytra, while males had more compression. For males, expansion occurs in the posterior part of the elytra; however, findings revealed asymmetry in the distribution of expansion areas in the female head, with expansion occurring in the right postero-lateral aspect. Conclusion: The overall findings indicate that they may all belong to the same operational taxonomic unit, ecotype, or biotype. It’s possible that geography isn’t the driving force behind B. longissima population differentiation. Other critical considerations could include the type of coconut host and other environmental parameters. Future research will be needed to confirm this.

Author (s) Details

Professor Dr. Ana Marie T. Acevedo
Surigao del Sur State University, Cantilan, Surigao del Sur, Philippines.

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