Functional Response of Pseudodoros clavatus Fabricius(1) on Aphis nerii Boyer de Fonscolombe(2)

Functional response of Pseudodoros clavatus Fabricius (Diptera: Syrphidae) preying on oleander aphid, Aphis nerii Boyer de Fonscolombe (Hemiptera: Aphididae), on leaves of Cynanchum racemosu var. unifarium was determined during a 24-hour period. Type of functional response was determined by logistic regression analysis that suggested larval stages I, II, and III of P. clavatus had a type II functional response. Handling time decreased with the state of development of the syphid. The attack rate was greater in larval stage I compared to larval stages II and III. Larval stage III had a greater attack rate than did larval stage II of P. clavatus. First, second, and third larval stages of P. clavatus ate an increasing number of A. nerri nymphs as abundance of prey increased.