Biological quality of Tetrastichus howardi (Hym.: Eulophidae) reared with Tenebrio molitor (Col.: Tenebrionidae) pupae after storage at low temperatures for different periods

Abstract

Introduction: The endoparasitoid Tetrastichus howardi (Olliff, 1893) (Hymenoptera: Eulophidae) can be reared with the alternative host Tenebrio molitor (Linnaeus, 1758) (Coleoptera: Tenebrionidae). Host storage at low temperatures can regulate parasitoid production and demand in biological control programs. Material and Methods: The life-cycle (egg-adult), parasitism and emergence percentage, number of parasitoids emerged per host pupae, sex ratio and longevity of the T. howardi offspring per T. molitor pupa were evaluated after low temperature storage of this host for different periods and its immature (pupae) in T. molitor pupae for five periods at 10.3 ºC. Tenebrio molitor pupae stored at 0.5 ± 0.09 °C and 2.7 ± 0.11 °C for 10 and 20 days, respectively, were adequate to produce T. howardi. Results: The biological characteristics of this parasitoid were better with T. molitor pupae stored at 0.5 ± 0.09 °C and 2.7 ± 0.11 °C for 10 and 20 days. Tetrastichus howardi immature (pupae) can be stored in T. molitor pupae for 10, 20, 30, 60 and 90 days at 10.3 ºC, preferably in pupae of this host for 10 days to produce these adults of this parasitoid for biological control programs. Discussion: These results contribute to overcoming one of the difficulties encountered in the massive production of parasitoids which is to obtain large numbers of suitable hosts when they are needed. Therefore, the possibility of conserving T. molitor pupae to rear T. howardi will be useful to use this natural enemy in biological pest control programs. Keywords: Biological control, Cold storage, Parasitoids, Progeny.