Interações biológicas entre Tetrastichus howardi (Hymenoptera: eulophidae) e Cotesia flavipes (Hymenoptera: braconidae) no parasitismo de Diatraea saccharalis (Lepidoptera: crambidae) em cana-de-açúcar

Abstract

Cotesia flavipes (Cameron) (Hymenoptera: Braconidae) is a larval endoparasitoid effective in control of sugarcane borer Diatraea saccharalis (Fabricius) (Lepidoptera: Crambidae) and Tetrastichus howardi (Olliff) (Hymenoptera: Eulophidae) is a larval and pupal endoparasitoid with the potential to be used to control lepidopteran pests. The general objective was to compare the biological reproductive T. howardi and C. flavipes multiplied in larvae and pupae D. saccharalis and ability to locate and parasitize caterpillars of this insect in the internode of sugarcane in the laboratory and field. The experiments were conducted at the Laboratory of Entomology/Biological Control (LECOBIOL ), Faculty of Agricultural Sciences, Federal University of Grande Dourados, and in the experimental area of Monteverde Factory Agro-Energética S/A in Dourados, Mato Grosso do Sul , Brazil. In Chapter I, we evaluated the development of T. howardi and C. flavipes in larvae of D. saccharalis exposed to different densities and periods of parasitism. In Chapter II, there was the development of T. howardi in pupae of D. saccharalis exposed to different densities and periods of parasitism. And in Chapter III, we analyzed the efficiency of T. howardi and C. flavipes to locate and parasitize larvae of D. saccharalis in sugarcane. Concluded generally that the parasitoids T. howardi and C. flavipes parasitized third instar D. saccharalis all combinations of densities of females (one and three) and periods of parasitism ( 0.016, 0.5, 1 , 12, 24 , 48, 72 and 96 hours). The highest rate of emergence of progeny of T. howardi was from the increase of the period of parasitism. The number of descendants of C. flavipes by third instar caterpillar of D. saccharalis decreased with the increase of the period of parasitism and the reverse was observed for the parasitoid T. howardi. Three females of T. howardi within 96 hours of parasitism and three C. flavipes with thirty minutes of parasitism in third instar larvae of D. saccharalis combinations are most appropriate for multiplication by these parasitoids provide the more number of descendent per female parasitoid. The parasitoid T. howardi parasitized and developed into pupae of D. saccharalis all combinations of densities of females (one, three and seven) and periods of parasitism (24, 48, and 72 hours). The production of descendent T. howardi was proportional to the density increase (one, three and seven) parasitoid females. The number of female produced by female T. howardi per pupa of D. saccharalis was inversely proportional to the density increase females. Seven females of T. howardi with 24 hours of parasitism in pupae of D. saccharalis was the combination most appropriate for multiplication of this parasitoid for providing the more number of descendent per female parasitoid. The parasitoid C. flavipes and T. howardi located and parasitized third instar D. saccharalis in internodes of sugarcane in the laboratory and fiel. Attributes such as longevity, sex ratio coupled with the ability to parasitize host two stages (larvae and pupae) and ease of multiplication in large quantities are peculiarities of parasitoid T. howardi that enable and justify the possibility of being associated with C. flavipes in biological control programs of D. saccharalis.