Parallel genetic divergence of the coconut scale insect Aspidiotus rigidus Reyne (Hemiptera:Diaspididae) and its host-specific parasitoid Comperiella calauanica Barrion et al. (Hymenoptera:Encrytidae) in the Philippines
2019
Ishitani, N. | Serrana, J. | Carvajal, T.M. | Almarinez, B.J.M. | Barrion, A.T. | Amalin, D.M. | Watanabe, K.
The Philippines faced coconut scale insect (CSI), Aspidiotus rigidus Reyne, outbreaks in CALABARZON [Cavite, Laguna, Rizal, Quezon, Philippines] from 2009-2014, and in Basilan and Zamboanga recently. From 2009, infestation only reached manageable status in early 2017 mainly due to the parasitoid Comperiella calauanica Barrion et al. this encrytid was discovered during the outbreak in Calauan, Laguna, with a highly successful 80% parasitization specific to CSI. The introduction of CSI into the Philippines was believed to be either by wind or accidentally through imported infested palms. However, inferring from the source population, the route and mechanism of spread of CSI need further evidence. The history of geographic origin of an invading population can be traced by characterizing genetic variation using molecular markers. Sequences of cytochrome oxidase (COI) gene and the nuclear protein encoding gene elongation factor 1a (EF-1a) were utilized to investigate the genetic structure and diversity of CSI from localities with documented outbreaks from 2014-2017. Both COI and Ef-1a markers and all approaches revealed two distinct genetic groups, separating the Luzon outbreak population from those in Mindanao. Two mitochondrial, and four nuclear haplotypes (one from Luzon, and three from Mindanao) exists. In addition, parallel genetic divergence among C. calauanica populations was observed, with two distinct populations from Luzon and Mindanao. These could provide critical information for designing and implementing quarantine strategies, and defining and testing ecological and evolutionary studies to understand the invasion success and decline of outbreak populations.
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