Detection of bloodworm larvae (Diptera: Chironomidae) in the golden apple snail Pomacea canaliculata (Lamarck, 1819) (Gastropoda: Ampullariidae) in Metro Manila

Abstract

Background: Pomacea canaliculata (Lamarck, 1819) is an invasive freshwater snail in the Philippines that damages crops but is consumed as food. It is known to harbor parasites, some of which are pathogenic to humans.

Objectives: The objective of this study is to examine P. canaliculata individuals present in Metro Manila for
parasite infection and identify the parasites and other organisms associated with the snail using molecular
identification.

Methodology: P. canaliculata were collected from rivers and marketplaces in Metro Manila. Individuals were
crushed and digested in Ash's digestive fluid and observed under a microscope. Collected parasites were subjected to DNA barcoding of the COI gene for putative identification.

Results: A total of 462 snails were gathered from 15 sites, eight of which were market areas that sourced the snails from outside Metro Manila. No known parasites were found. Two snails were found to contain insect larvae in the mantle (0.43% infection). The closest BLAST matches for the two insect larvae were the chironomid fly Nilodorum tainanus (91.0% identity) from a snail in Sucat, Muntinlupa, and another chironomid Parachironomus sp. (92.8% identity) found in a snail originally from Cavite and brought to Calumpang, Marikina.

Conclusion: This study is the first report of the presence of chironomids in Philippine P. canaliculata. This could have an impact on the allergenic status of these mollusks if consumed while containing these chironomids. The absence of infection of other medically important parasites is possibly due to the patchy distribution of the snails and few interactions with the definitive hosts of known parasites.