Larval aggregation and competition for food in experimental populations ofChrysomya putoria (Wied.) and Cochliomyia macellaria (F.) (Dipt., Calliphoridae)

In blowflies, larval aggregation in patches of food can be both intra- and interspecific, depending upon the degree to which competitors are clumped a mong the patches. In the present study, the implications of spatial aggrega tion for larval competition was investigated in experimental populations of the introduced blowfly Chrysomya putoria and the native Cochliomyia macell aria, using data from survival to adulthood in a range of single- and doubl e-species larval cultures. The reduction in C. macellaria survival rate in the presence of C. putoria suggests that the former species is the inferior competitor. The results on survival to adulthood for both species in singl e- and double-species cultures can be explained in the light of the relatio nship between the level of intra- and interspecific aggregation and the eff iciency of the larval feeding process. The possible implications of these r esults for the population biology of both species in natural environments a re discussed.