Distribution of Parmarion cf. martensi (Pulmonata: Helicarionidae), a New Semi-Slug Pest on Hawai‘i Island, and Its Potential as a Vector for Human Angiostrongyliasis

Authors: Hollingsworth, Robert; KANETA, RACHEL - FORMER ARS EMP; SULLIVAN, JAMES - CDC; BISHOP, HENRY - CDC; QVARNSTROM, YVONNE - CDC; DA SILVA, ALEXANDRE - CDC; ROBINSON, DAVID - APHIS

Submitted to: Pacific Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/9/2007
Publication Date: 10/1/2007
Citation: Hollingsworth, R.G., Kaneta, R.K., Sullivan, J.J., Bishop, H.S., Qvarnstrom, Y., Da Silva, A.J., Robinson, D.G. 2007. Distribution of Parmarion cf. martensi (Pulmonata: Helicarionidae), a New Semi-Slug Pest on Hawai‘i Island, and Its Potential as a Vector for Human Angiostrongyliasis. Pacific Science. 61: 457-467

Interpretive Summary: A new species of semi-slug was discovered on the island of Hawaii in 2004. The species has been tentatively identified as Parmarion martensi. This species is very common in some areas of eastern Hawaii island, and it may be out-competing the Cuban slug, Veronicella cubensis, which is usually the most common large slug species on the island at lower elevations. A survey in the summer of 2005 showed that semi-slugs are present primarily at lower elevations in the Puna area of Hawaii island. We found an isolated population in Kailua-Kona (western Hawaii island). People participating in the survey reported that this semi-slug species is a pest of lettuce and papaya in home gardens. People considered this semi-slug a pest because of its tendency to climb on structures where it deposits its feces, and because of its potential to transmit disease. Individual semi-slugs were found to carry large numbers of infective third stage larvae of the nematode Angiostrongylus cantonensis (Chen, 1935), the causative agent of rat lungworm disease. Using a newly developed PCR (polymerase chain reaction) test, we found that 77.5% of P. martensi semi-slugs collected at survey sites were infected with A. cantonensis, compared to 24.3% for Cuban slugs sampled from the same areas. The probability that semi-slugs will transmit rat lungworm disease to humans may be higher than for other slug and snail species because a high percentage of semi-slugs are infected, and the habits of semi-slugs increase the chance of contact with humans.

Technical Abstract: The semi-slug, Parmarion cf. martensi Simroth, 1893, was first discovered on Oahu, Hawaii in 1996 and then on the island of Hawaii in 2004. This species has become abundant in eastern Hawaii island, reportedly displacing the Cuban slug, Veronicella cubensis (Pfeiffer, 1840) in some areas. A survey in the summer of 2005 found P. martensi primarily in the lower Puna area of Hawaii island, with an isolated population in Kailua-Kona (western Hawaii island). Individuals participating in the survey reported P. martensi as a pest of lettuce and papaya in home gardens. Survey respondents considered P. martensi a pest also because of its tendency to climb on structures where it deposits its feces, and because of its potential to transmit disease. Individuals of this species were found to carry large numbers of infective third stage larvae of the nematode Angiostrongylus cantonensis (Chen, 1935), the causative agent of human angiostrongyliasis and the most common cause of human eosinophilic meningoencephalitis. Using a newly developed PCR test, 77.5% of P. martensi collected at survey sites were found infected with A. cantonensis, compared to 24.3% for V. cubensis sampled from the same areas. The transmission potential of this species would appear higher than that for other slugs and snails in Hawaii because of the high prevalence of infection, worm burdens, and its greater association with human habitations, increasing the possibility of human-mollusk interactions.