Parasitismo e superparasitismo de Trichogramma pretiosum Riley (Hymenoptera : Trichogrammatidae) em ovos de Sitotroga cerealella Oliver (Lepidoptera : Gelechiidae)

Abstract

During the parasitism process many factors can lead to host rejection by the parasitoid. Thus, it was evaluated bio-ecological aspects of Trichogramma pretiosum Riley (Hym.: Trichogrammatidae) parasiting Sitotroga cerealella Oliver (Lep.: Gelechiidae) eggs. The study was conducted in free-choice test, alternating parasitized and unparasitized eggs, and no-choice test, using only parasitized eggs. For the parasitism study, mated females of T. pretiosum 12 to 24h-old were used. And, parasitized eggs of S. cerealella 24, 72 and 120h-old were used as host. To evaluate the biological characteristics of T. pretiosum superparasitism, S. cerealella eggs were exposed to the parasitism by one or more parasitoid females aiming oviposition of one or two eggs of the parasitoid per host. The parasitism rejection on 72 e 120h previously parasitized S. cerealella eggs was approximately 100% in relation to the 24h-parasitized eggs (ca. 71.3%). On the other hand, the contact time of the female on 24h-parasitized eggs was around twice longer than on 72 and 120h-parasitized eggs. The offspring produced from single egg laid per host werelarger, exhibited no deformation and greater capacity of parasitism, and in contrast of those produced from two eggs laid per host. We concluded that T. pretiosum exhibited ability inrecognizing eggs previously parasitized and that the superparasitism resulted in reduction of reproductive success of the parasitoid.