Predacious syrphid flies of Brevicoryne brassicae in rapeseed fields of Kermanshah province and study on biology and feeding behavior of Eupeodes corollae

Many species of the family Syrphidae are predators of pests, especially aphids. To study the predacious syrphid species of rapeseed fields of Kermanshah, we assembled a sizable collection of syrphids between 2013-2015. The result showed the existence of 12 species in these fields of which the species Eupeodes corollae F. was found to be the predominant species. The length of growth periods and feeding capability of this species was studied on cabbage aphid (Brevicoryne brassicae) at 3 different temperatures. The growth period means of this fly are 22.45, 18.82 and 15.17 days at 20, 25 and 30oC respectively. The predation rate of E. corollae on third instar nymphs of B. brassicae at 20, 25 and 30°C significantly decreased with increasing temperature with a mean value of 371.07, 283.00 and 253.13, respectively. There were significant differences between daily and total feeding rates of the first, second and third instar larvae of E. corollae at various temperatures. The results suggest that 25ºC was the optimum temperature for both survival and feeding of E. corollae. As the temperature increases of the feeding rate reduces during periods of growth. The lowest mortality rate occurred at 25°C.