Parasitism and Emergence ofTetrastichus howardi(Hymenoptera: Eulophidae) onDiatraea saccharalis(Lepidoptera: Crambidae) Larvae, Pupae and Adults

Abstract

Tetrastichus howardi Olliff (Hymenoptera: Eulophidae) parasitizes the larvae, pupae and adults of Diatraea saccharalis, and therefore seems to be a suitable candidate for the biological control of D. saccharalis in commercial sugarcane in Brazil and other industries where this stem borer is an important pest. The aim of our study was to analyze the biological characteristics of this natural enemy on sugarcane borer. The research was conducted in the Laboratory of Entomology/Biological Control (LECOBIOL) at the “Faculdade de Ciências Agrárias” of the “Universidade da Grande Dourados (UFGD)” in Dourados, Mato Grosso do Sul State, Brazil. Ten of each of the following life stages: 24-h old egg masses, fifth instar larvae, pupae and adults of D. saccharalis were isolated and exposed to parasitism by seven T. howardi parasitoids females. Parasitism rates by T. howardi of the adult, fifth instar larva and pupal stages of D. saccharalis were 2%, 56% to 68%, respectively. Emergence rates of 14%, 100% and 100% were recorded for adult, fifth instar larvae, and adults, respectively. The duration of each life cycle (egg to adult) of T. howardi on the pupae, fifth instar larvae and adults of D. saccharalis were 20 ± 0.03, 27.00 ± 0.01, 33 ± 0.00 days, respectively. Fecundity and the female-based sex ratio of T. howardi were greatest in the pupae of D. saccharalis, at 70.44 ± 5.22 and 0.85 ± 0.41, respectively. Parasitism and the emergence of T. howardi from the fifth instar larvae, pupae and adults of D. saccharalis revealed the ability of this natural enemy to establish itself in culture, even in the absence of host pupae.