Parasitismo de Palmistichus elaeisis (Hymenoptera: Eulophidae) em hospedeiro alternativo sobre plantas de eucalipto em semi-campo

The success of programs of biological control with parasitoids depends on applied research and therefore it was estimated the optimal number of females Palmistichus elaeisis Delvare & LaSalle, 1993 (Hymenoptera: Eulophidae) for release in eucalyptus plantations, for the control of lepidopterans defoliators. In each replicate were used thirty-six alternative host pupae of Anticarsia gemmatalis Hubner, 1818 (Lepidoptera: Noctuidae) with 24 to 48 hours old that were identified in traps made of nylon with mesh and fixed in branches of trees of Eucalyptus grandis in thirds upper, middle and bottom, in the proportion of 33.33% (12 traps). After setting the traps, the trees were covered individually with a cage of 7.0 x 7.0 x 2.5 m made with organza fabric and subsequently released, 36; 72; 144, 288; 576 or 1,152 females of P. elaeisis, representing one, two, four, eight, 16 or 32 parasitoids per pupae and for the witness there was no release of the parasitoid. Each proportion was considered a treatment, installed six replicates itself and allowed the parasitism for 96 hours. The number of pupae of A. gemmatalis parasitized increased with the increase of the number of parasitoids released, regardless of the third of the plant considered, adjusting to a quadratic function with point of maximum close to 25 females per pupae. In the density of 32 females/ pupae was no significant increase in the number of parasitized pupae, suggesting 25 females of P. elaeisis by pupa as density closer to ideal for release of this parasitoid in eucalyptus plantations.