Author : Franciscus Xaverius Kusharto

Summary : Seasonal fluctuation of the number of buffalo flies was monitored throughout a one-year period at several places in the vicinity of Los Ba¤os and at the Dairy Training and Research Institute, University of the Philippines at Los Ba¤os. Effort was exerted to correlate the abundance of buffalo flies with several components of climate, namely: temperature, humidity, and rainfall. High populations of buffalo flies occurred from July to December and low populations from January to May. The lowest population occurred in March and April. The rainy season, which started in June, accelerated the propagation of flies with peak activity in August. The flies' population declined in October when monthly total rainfall reached more than 400 mm. Excessive rain was detrimental because it inundated and washed the breeding sites. Among the three components of climate, it was noted that humidity and rainfall had a greater correlation with the abundance of flies. However, two combined components of climate such as temperature-humidity and humidity-rainfall gave higher correlation with the fluctuation of fly populations. The low number of buffalo flies coincide with decreasing moisture content of cow dung during the dry season. Lowering of dung moisture content was presumed to influence the number of eggs laid and duration of oviposition of the female flies. The method of manure management method (spreading of manures in the field) created an unfavorable environment for the development of immature stages of buffalo flies. Thus, flies are prevented from developing in the breeding medium. The abundance of parasites of buffalo flies was dependent on the number of available host. However, it is suggested that the rate and extent of parasitism should be investigated further. From all field samples collected, sex ratio favored a large number of female flies. However, the percentage of female flies slightly decreased with the increasing abundance of flies particularly during rainy season.