Pre-release evaluation of Semielacher petiolatus (Hymenoptera: Eulophidae) in quarantine for the control of citrus leafminer: Host discrimination, relative humidity tolerance, and alternative hosts

To evaluate the potential benefits and risks associated with releasing Semielacher petiolatus Girault (Hymenoptera: Eulophidae) in a classical biological control project directed against the citrus leafminer Phyllocnistis citrella Stainton (Lepidoptera: Gracillariidae) in Florida, we evaluated the ability of S. petiolatus females to discriminate between hosts previously parasitized by Ageniaspis citricola Logvinovskaya (Hymenoptera: Encyrtidae) and unparasitized hosts. In laboratory trials, S. petiolatus females did not discriminate between hosts previously parasitized and oviposited and fed on each host category equally. Hatch rate of S. petiolatus eggs on hosts previously parasitized by A. citricola was normal and development time was not different. However, mortality of immatures was significantly higher on previously parasitized hosts when compared to hosts that were not parasitized by A. citricola, and size of adult females reared on hosts previously parasitized was reduced. The relative survivorship of S. petiolatus adults compared with adults of P. citrella and another parasitoid, A. citricola, under three relative humidities (RHs) (55, 76, and 95% at 28 °C) indicated that S. petiolatus survives longer than A. citricola at all RHs tested, but did not survive as long as the citrus leafminer. Finally, the leafminer Liriomyza trifolii Burgess (Diptera: Agromyzidae) was evaluated as a possible host for S. petiolatus but no progeny were produced in choice and no-choice tests. The lack of discrimination raises the concern that S. petiolatus could disrupt the efficacy of A. citricola, which is already established in Florida, without providing substantial reduction of citrus leafminer populations during early spring.