Observations on the life history of Achatina fulica, a intermediate host of Angiostrongylus cantonensis, in the Amami Islands

Abstract

Seasonal fluctuations in the egg production of the giant African snail, Achatina fulica, the growth of the snail and the rate of infection with Angiostrongylus cantonensis in relation to the size of the snail were studied on the Amami Islands. Two clear peaks in the egg production were observed in June and in October/December. Almost all the eggs and infants produced in the latter period died from the cold. The effective reproduction season, therefore, was assumed to be around June. Infant snails grew rapidly to 50-70 mm in shell height and then leveled off. The infection rate with A. cantonensis rose rapidly in snails over 50 mm in shell height, namely from 11.7 (20-49 mm) to 67.9% (50-89 mm).newline˜AS ADDITIONAL ABSTRACT: Seasonal fluctuations in egg production and growth of Achatina fulica and the rate of infection with Angiostrongylus cantonensis were studied in the Amami Islands. 2 distinct peaks of egg production were observed in June and October/November. However, egg and infant snail mortality was very high during the latter period, and it was concluded that the reproductive season was around June. Infant snails grew rapidly to 50-70 mm in shell height and showed little change thereafter. The prevalence of infection with A. cantonensis increased rapidly in snails > 50 mm (shell height), from 11.7 (20-40 mm) to 67.9% (50-89 mm).