Studies on Rhinoestrus sp [diptera: Oestridae] larvae infesting donkeys [Equus asinus] in Egypt 1 Incidence and seasonal variations

ABSTRACT

Examination of 144 donkey heads at the postmortem during the period from September 1989 up to the end of August 1990 revealed that 88 [61.11%] donkeys were infested with rhinoestrus purpureus. The larvae were present in the 88 heads examined throughout the year with highest mean larval number during June [57.86]. The larvae were absent during November and December. The monthly prevalence of each 1st, 2nd and 3rd instar larvae was determined. Each larval instar occurred in two peak of infestations; March and June for the 1st and 2nd 1arval stages and March and August for the 3rd larval stage. The size of infestation showed that the percentage of donkeys infested with 1-50, 51-100 and 101-150 1arvae were 50.69, 9.03 and 1.39% respectively. It was concluded that, two generations of R. purpureus occurred during the year and the adult flies were active during two seasons; from mid-January to mid-April and from early June to late September. Two annual treatment of donkeys during March and June were recommended to eliminate most of the 1arvae from infested donkeys