Prevalence and monthly variations of the second and third instars of Cephalopina titillator (Diptera: Oestridae) infesting camels (Camelus dromedarius) in the Eastern Province of Saudi Arabia.

Nine hundred and twenty-three camels slaughtered at Al-Ahsa abattoir, Eastern Province, Saudi Arabia, were examined for infestation with second and third instars of Cephalopina titillator during the period from December 1991 to November 1992. Four hundred and eighty camels (52%) were infested with second and third instars, with an annual mean of 19.29 +/- 1.09 larvae per camel (L/C). The percentage of infested camels and the mean monthly total number of larvae per camel showed two peaks of abundance, during February (96.06% and 25.06 +/- 2.1 L/C) and September (88.90% and 27.50 +/- 3.97 L/C). Variations in the percentage of infestation were inversely correlated with monthly average temperature and positively correlated with relative humidity. Mean numbers of third instars were significantly greater than those of the second instars during each month of the study period. Two peaks of abundance were observed for each of the second (February and September) and third instars (January and October). Infestation levels showed that the percentages of camels infested with 1-10, 11-20 and 21-30 larvae were 47.90%, 19.16% and 12.71%, respectively. Fewer camels were infested with 31-40 (6.25%), 41-50 (4.37%), 51-60 (3.54%) and 61-70 (2.08%). The greatest number of larvae (101-110) was observed in only three camels (0.62%). It is concluded that adult flies appear twice a year, during the period from late March to early May and in December. Twice-annual larvicidal treatment of camels during February and September is recommended to eliminate most of the larvae infesting camels.