Multiplicação de Tetrastichus howardi (Hymenoptera: eulophidae) em pupas de Tenebrio molitor (Coleoptera: tenebrionidae) e de Diatraea saccharalis (Lepidoptera: crambidae)

Abstract

Tetrastichus howardi (Olliff, 1893) (Hymenoptera: Eulophidae) is a pupal and larval endoparasitoid, gregarious and cosmopolitan, mainly of Lepidoptera species that has been studied as a potential biological control agent. The objective was to obtain information abought the biology and rearing of T. howardi pupa in the alternative host Tenebrio molitor (Linnaeus, 1758) (Coleptera: Tenebrionidae) aimed at multiplying its mass scale to be used in biological control programs, especially for control of Diatraea saccharalis (Fabricius, 1794) (Lepidoptera: Crambidae) . For this, the following works have been developed in the Laboratory of Entomology / Biological Control (LECOBIOL), Faculty of Agricultural Sciences, Federal University of Grande Dourados in Dourados, Mato Grosso do Sul, Brazil. In the first study “Reproduction of T. howardi in pupae of T. molitor depending on the density of the parasitoid”. Female T. howardi were exposed to parasitism of pupae of T. molitor at densities 1:1, 7:1, 14:1, 21:1, 28:1 and 32:1, parasitoid-host, respectively. The densities of 7, 14 and 21 females of T. howardi by pupae of T. molitor were the most suitable for the creation of this parasitoid. Influence of age of pupae T.molitor progeny of T. howardi. Therefore, females of T. howardi at densities of 7:1, parasitoid host, respectively, were exposed to parasitism of pupae of T. molitor, at ages 12, 24, 48, 72, 96 and 120 hours. The age of 24 hours was more appropriate for rearing of T. howardi. Reproductive performance of T. howardi in the natural host D. saccharalis after three generations in alternative host T. molitor. To conduct this study, two groups of T. howardi were multiplied separately by three generations, a group on alternative host T. molitor and the other in the natural host D. saccharalis. Subsequently, 50 pupae of D. saccharalis were exposed for 72 hours to parasitism of females of T. howardi, rearing earlier in pupae of T. molitor and D. saccharalis. The rearing of three successive generations of T. howardi in alternative host did not affect the number of parasitized pupae and pupal parasitoids emergence of the natural host D. saccharalis and contributed to the increase of progeny per pupa, with larger longevity of females and males. The sex ratio found was the same in both conditions tested. It was concluded that in general T. howardi can be rearing in alternative host T. molitor for three generations, without compromising their reproductive performance in natural host D. saccharalis.