Parasitism of Telenomus remus Nixon on Spodoptera frugiperda J.E. Smith and acceptability of Spodoptera littoralis Boisduval as factitious host

•A single T. remus female was able to parasitize about 100 S. frugiperda eggs.•The optimal parasitism was obtained releasing one T. remus female on 70 S. frugiperda.•In a choice scenario, T. remus females did not parasitize any 3-day old eggs.•T. remus sex-ratio is generally in favor of females.•T. remus can be mass reared on the eggs of S. littoralis. The egg parasitoid Telenomus remus has emerged as one of the potential candidates for use in biological control of the of the fall armyworm, Spodoptera frugiperda in Africa. However, its uses in biological control require a better understanding of its biology and the development of a cost-effective mass production. We firstly determined how T. remus reacts to an increasing S. frugiperda egg density. Subsequently we identified its preference for parasitism as a function of S. frugiperda egg age. Finally, we assessed the acceptability of Spodoptera littoralis as a factitious host for T. remus rearing. The number of eggs parasitized by T. remus increased as the egg density increased. Competition between T. remus females resulted in a male-biased sex ratio. Regarding host-eggs age, T. remus females prefer 1-day-old eggs over 2- or 3-day-old eggs. With respect to host acceptability, T. remus was shown to parasitize S. littoralis eggs and produce viable offspring. Although, T. remus tended to parasitize fewer S. littoralis than S. frugiperda eggs it can be used as a factitious host for the mass multiplication of T. remus in a biological control program.