THE SEASONAL ABUNDANCE OF ORIBATID MITES (ACARI, CRYPTOSTIGMATA) ON AN IRRIGATED KIKUYU GRASS PASTURE

The seasonal abundance of oribatid mites, the intermediate hosts of an oplocephaline cestodes, was studied on an irrigated Kikuyu grass pastu re in Transvaal, South Africa. The following species were consistently present: Galumna nuda, Galumna rasilis, Scheloribates elsi and Tectoc epheus sarekensis. The mean total number of mites on the herbage peake d in January (3.7 mites g-1 dry herbage) and correlated positively wit h temperature, relative humidity, rainfall and soil moisture on the da y of collection. The mean total number of mites on the herbage includi ng the top 5 cm of soil peaked in April (3.757 mites m-2) and May (3.7 61 mites m-2), and these numbers correlated positively with radiation on the day of collection. There was a significant decline in the numbe r of mites on the herbage at midday and in the afternoon, but there wa s no difference in the number on the herbage including the top 5 cm of soil at different times of day. The trends in abundance are also disc ussed separately for each of the four species.