Evaluation of key factors for mass rearing the egg parasitoid Telenomus remus Nixon (Hymenoptera: Scelionidae)

Abstract

Abstract Background Telenomus remus is an egg parasitoid used as a biocontrol agent to control the invasive pest Spodoptera frugiperda. The use of high-quality factitious hosts is needed for efficient mass rearing of high-fitness parasitoids for biological control releases. To improve the efficiency and quality of parasitoid production for mass rearing, we evaluated host perference, supplemental nutrition, ultraviolet (UV) irradiation, parasitoid density, and exposure duration. Quality control for the mass rearing of Te. remus has not been conducted previously. This study determined the conditions and quality control factors necessary for the effective mass rearing of Te. remus. Methods The preferred host of Te. remus was determined and the effects of supplemental nutrition on Te. remus adults, as well as those of ultraviolet (UV) irradiation on host eggs were evaluated. The subsequent impact on the quality of Te. remus were also assessed. The optimal parasitoid-to-host eggs ratio and exposure duration were studied. Results Telenomus remus preferred S. frugiperda eggs as the host. Nutrition supplementation prolonged female longevity and increased fecundity of Te. remus. UV irradiation caused S. frugiperda eggs to shrivel, having a negative effect on Te. remus reproduction. When the ratio of Te. remus to S. frugiperda eggs ranged from 1:4 to 1:10 and the exposure duration was 48 h, a lower wizened egg rate, higher emergence rate, and greater female proportion was obtained. Conclusions The use of S. frugiperda eggs as the host for mass rearing of Te. remus was indicated, and it was found Spodoptera litura eggs could sever as an alternative host. Nutrition supplementation and non-UV-irradiated S. frugiperda eggs should be provided. The suitable ratio of Te. remus to S. frugiperda eggs ranges from 1: 4 to 1:10, and the exposure duration should be 48 h, as determined by the ratio of parasitoid to host eggs.