Influência do aumento do número de pupas hospedeiras de Cochliomyia macellaria (Diptera, Calliphoridae) no desenvolvimento do parasitóide Nasonia vitripennis (Hymenoptera, Pteromalidae) em laboratório

Abstract

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.