Abstract
1) The molluscicidal effect of 10 agricultural chemicals which are commonly usedby farmers in Saitama Prefecture was tested experimentally against A. ollula in the laboratory. The snails were made to contact with chemical solution for 48 hrs. at 23-25°C, then transferred to new containers with fresh water. The death rate was observed after 1 more hr.
LC50 value of Saturn emulsion (Benthiocarb 50%), Saturn-S granule (Benthiocarb 7%, Simetryne 1.5%), MO emulsion (CNP 20%), NIP emulsion (NIP 25%), Sumithion emulsion (MEP 50%), Baysid emulsion (MPP 50%), Disiston granule (Ethylthiometon 5%), Bassa emulsion (BPMC 50%), Kitasin-Pemulsion (IBP 4%), and Lime nitrogen granule (CaNCN 21%) were 13.0, 92.5, 24.8, more than 50, 16.5, 13.5, more than 500, more than 50, more than 50 and 360 ppm. respectively, all figures were far larger than the doses in practical use for each chemicals. So it can not be expected that these chemicals would be effective against the snail in the ordinally practice.
2) Themolluscicidal effect of Lime nitrogen granule was also investigated with the snail in the paddy field where this fertilizer had been applied at an ordinally dose that is 2 Kg per are., 5 days prier to the test. The snails were introduced into the paddy and the mortality rate was observed 1, 2 and 3days after the introduction. The mortality rates of the snails at each day were 7.5%, 11.0% and 12.9% respectively. In the untreated field these figures were 7.0%, 14.9% and 4.4%.
It was concluded that Lime nitrogen granule was not effective against the snail at the ordinally dose for the use for fertilizer.
