Larval predation by Chrysomya albiceps on Cochliomyia macellaria, Chrysomya megacephala and Chrysomya putoria

Chrysomya albiceps, the larvae of which are facultative predators of larvae of other dipteran species, has been introduced to the Americas over recent years along with other Old World species of blowflies, including Chrysomya megacephala, Chrysomya putoria and Chrysomya rufifacies. An apparent corre late of this biological invasion has been a sudden decline in the populatio n numbers of Cochliomyia macellaria, a native species of the Americas. In t his study, we investigated predation rates on third instar larvae of C. mac ellaria, C. putoria and C. megacephala by third instar larvae of C. albicep s in no-choice, two-choice and three-choice situations. Most attacks by C. albiceps larvae occurred within the first hour of observation and the highe st predation rate occurred on C. macellaria larvae, suggesting that C. albi ceps was more dangerous to C. macellaria than to C. megacephala and C. puto ria under these experimental conditions. The rates of larvae killed as a re sult of the predation, as well as its implications to population dynamics o f introduced and native species are discussed.