ABSTRACT The classic episode of biological invasion: Cochliomyia macellaria (Fabricius, 1775) versus Chrysomya megacephala (Fabricius, 1794) (Diptera: Calliphoridae) - evaluation of the biotic potential. The biotic of the native fly Cochliomyia macellaria and the exotic Chrysomya megacephala was compared, through the reproductive capacity and longevity. The experiment took place in a climatized chamber, with four repetitions of 15 grouped couples of each species. The posture, egg mass weight, and death of individuals were observed daily. C. macellaria showed an average of longevity of 27.72 days while in C. megacephala the average was 41.96 days. The egg mass weight average per repetition was 0.58 g and 1.22 g, respectively. These results give a better understanding about the population dynamics of these species in nature.

O desenvolvimento pós-embrionário, a produtividade, a taxa de parasitismo e a razão sexual de Nasonia vitripennis (Walker, 1836) criada em pupa de Cochliomyia macellaria (Fabricius, 1775) foram estudados. Densidades diferentes de hospedeiro foram usadas (proporções 1:1, 1:2, 1:3, 1:4 e 1:5) com tempo de exposição de 72 horas, em cada uma delas. Fêmeas nulíparas originárias da colônia estoque foram individualizadas em tubos de teste cobertos com algodão hidrófobo e contendo as pupas hospedeiras. Cada tratamento constituiu-se de 10 repetições. Depois da exposição, as vespas foram descartadas e as pupas hospedeiras foram individualizadas em tubos de teste até a emergência dos adultos de C. macellaria ou N. vitripennis. Amostras das pupas hospedeiras não expostas ao parasitismo e recebendo o mesmo tratamento experimental foram usadas como controle. Os parasitóides mostraram um desenvolvimento mais lento em relação ao aumento da densidade de hospedeiros. Houve uma diminuição na produção de parasitóides por hospedeiro em densidades elevadas. A razão sexual tendeu para um desvio para nascimento de fêmeas com o aumento da densidade do hospedeiro. Os índices de parasitismo mostraram uma diminuição quando o parasitóide foi exposto a mais de duas pupas hospedeiras.

The post-embryonic development, productivity, rate of parasitism and sexual ratio of Nasonia vitripennis (Walker, 1836) reared in pupae of Cochliomyia macellaria (Fabricius, 1775) were studied. Different densities of the host were used (proportion 1:1, 1:2, 1:3, 1:4, and 1:5) and the exposition in each one lasted 72 hours. Nulliparous females originating from the stock colony were individualized in test tubes covered with hydrophobic cotton and containing the host pupae. Each treatment was constituted by 10 repetitions. After the exposition, the wasps were discarded and the host pupae were individualized in test tubes until the emergence of the adults of C. macellaria or N. vitripennis. Samples of host pupae not exposed to parasitism and receiving the same experimental treatment were used as control. The parasitoids showed a slower development in relation to the increase of host density. There was a production decrease of parasitoids per host in elevated densities. The sexual ratio tended towards a deviation for the birth of females with the increase of the density of host. The rate of parasitism showed a decrease when the parasitoid was exposed to more than two host pupae.