LARVAE OF EQUINE STRONGYLIDS - DEVELOPMEN T, TRANSLATION AND SURVIVALIN A NATURAL-ENVIRONMENT IN VALDIVIA, CHILE

15 fresh equine faeces samples were placed, every week, on a field in Valdivia, from March 1991 to March 1992. The number of strongylid eggs per gram (epg) was determined. After 1, 2, 3, 4, 6, 8, 10, 12, 16, 20 , 24, 28 and 32 weeks of permanence of the faecal samples in the envir onment, the number of larvae III in the faeces and in the surrounding grass was recorded. The flora and fauna over and under the faeces was also determined. Daily temperature and rainfall were obtained from a n earby meterological station. The average number of eggs in fresh faece s fluctuated between 210 and 740 epg in winter and 1.630 and 2.850 epg in summer. The development from egg to larvae III was influenced by t he average temperature during the first three weeks of permanence of t he faeces in the environment as follows: there was no development at a mean temperature below 8.7-degrees-C, a moderate development between 8.9-degrees-C and 12.5-degrees-C and an optimum developed between 13-d egrees-C and 18-degrees-C. The development was delayed during a period with temperature above 18-degrees-C without rainfall. The permanence of larvae III in the faeces depended on the integrity of the faecal un it. Larvae III were found on the grass after a week, increasing in num ber in week 3. Maximum number of larvae was observed after 16 weeks in the summer and 12 weeks in the spring; thereafter exhibiting a gradua l reduction. Rainfall helped the translation of the larvae to the gras s. Flies were observed on the faeces only on the day the faeces were p laced on the field. Subsequently, collembola, acari and fungus appeare d over the faeces, but mainly during spring and summer. During autumn, earthworms and gastropods were observed under the faeces. In general, there was practically no disintegration of the faecal unit caused by the arthropodic local fauna.