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ISHS Acta Horticulturae 1183: XI International Mango Symposium

Localization of populations of Scirtothrips dorsalis Hood collected from various mango-growing areas in the Philippines

Authors:   C.D.R. Medina, J.J.G. Apolinario
Keywords:   morphometrics, internal transcribed spacer 2 (ITS2) region, chilli thrips
DOI:   10.17660/ActaHortic.2017.1183.44
Morphological data and DNA sequences from the internal transcribed spacer 2 (ITS2) region of nuclear ribosomal DNA (rDNA) were analysed to determine evidence of variation among local populations of Scirtothrips dorsalis Hood collected from various mango-growing areas in the Philippines. The local collection sites included Zambales, Bulacan, Laguna, Palawan, and Davao. For the morphometric analysis, 25 characters including the setal distances were measured. The ratios of characters against the head, metanotal, and abdominal length were computed to eliminate population differences due to nutrition. Discriminant and cluster analysis showed that Davao and Zambales specimens were most similar (77.9%) while the Palawan population was the least similar to all the local groups (9.7%). The similarity of the Zambales population to the cluster of from Bulacan and Davao was 75.4%, while similarity between these three groups and the Laguna population was 74.3%. These results suggest that the local populations of S. dorsalis from the five growing areas of mango in the Philippines did not exhibit distinct differences when compared using the morphometric study of all the quantitative characters used. On the other hand, ITS2 DNA sequences from different local populations were aligned using the Basic Local Alignment Search Tool (BLAST) and were found to be 100% identical with the S. dorsalis ITS2 sequences submitted by Farris et al. (2010). The evolutionary divergence and phylogenetic relationship of the local populations were consistent with this sequence identity. Other genes must be explored to evaluate further if there is an interspecific variation among these local populations. Moreover, behavioural studies must be conducted to verify the results of this study.

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