E. E. STOIANOVA1, J. C. HERNANDEZ2 and P. E. CABALLERO2
1 Plant Protection Institute, BG - 2230 Kostinbrod, Bulgaria
2 Laboratorio de Entomologia Agricola y Patologia de Insectos, Departamento de Produccion Agraria Universidad Publica de Navarra, 31006 Pamplona, Spain
STOIANOVA, E. E., J. C. HERNANDEZ and P. E., CABALLERO, 2007. Ovipositional discrimination by Euplectrus plathypenae (Howard) (Hymenoptera:Eulophidae) between healthy and nucleopolyhedrovirus-infected Spodoptera exigua and Spodoptera fugiperda larvae (Lepidoptera: Noctuidae). Bulg. J. Agric. Sci., 13: 07-13
Parasitoid behavior was monitored to investigate the ability of Euplectrus plathypenae (Howard) (Hymenoptera: Eulophidae) to distinguish between
healthy and infected with nucleopolyhedroviruses Spodoptera exigua (Hubner) and Spodoptera frugiperda (J. E. Smith) (Lepidoptera: Noctuidae) larvae. Third and fourth instars (L3 and L4) of both Noctuidae species were used in the present study. When E. plathypenae females were given choice between healthy and virus-infected S. exigua and S. frigiperda hosts, the adult females exhibited marked preference (P < 0. 05) for the healthy hosts of the both instars of the two species. The ovipositional discrimination study also showed that the correlation between the percent parasitism of healthy and virus-infected L3 larvae was significantly higher than the correlation between parasitized healthy and virus-infected L4 S. frugiperda larvae. In S. exigua larvae the oposite correlation between the two instars has been observed.
The results proved that E. plathypenae females and the multiple-enveloped nucleopo-lyhedroviruses of S. exigua (SeMNPV-SP2) and S. frugiperda (SfMNPV) did not significantly compete for the same type of host larvae and are, generally, compatible. Since the healthy and virus-infected larvae were different in a number of ways, several factors may have contributed to the behavioral discrimination evidenced.