LARVAL DEVELOPMENT OF MUELLERIUS CAPILLARIS (NEMATODA, PROTOSTRONGYLIDAE) IN EXPERIMENTALLY INFECTED CERNUELLA (XEROMAGNA) CESPITUM ARIGONIS (MOLLUSCA, HELICIDAE)

The larval development of Muellerius capillaris was studied in samples of 1200 Cernuella (X.) cespitum arigonis. The molluscs, distributed in groups of 100, were infected in the laboratory at monthly intervals (for one year) with 200 L-I and kept, together with the same number of controls, under controlled conditions on an experimental farm. The snails were killed every 7 or 15 days p.i. In the parasitological study we considered: the total number of larvae (I + II + III), of L-III per mollusc and their respective percentages, as well as the days on which the first L-II and L-III were obtained and when all of them reached the third stage. In general, it was observed that the average and percentage of the total number of larvae were similar in the infections carried out in the coldest, wettest months (October–March) and in the wannest, driest months (April–September), but the average and percentage of the total L-III were lower in the first case. The shortest period before observing the third larval stage for the first time corresponded with the infections carried out from June to October. The total numbers of L-III and their percentage are, in general, positively related to the thermal integral and not to the average relative humidity. There are no statistically significant differences between the mortality rate of infected molluscs and that of the controls