Host Egg Preference and Density-Dependent Parasitism of Telenomus remus in Spodoptera litura and Spodoptera frugiperda Eggs.

Abstract

Successful biological control requires accurate knowledge of the host preference of the released parasitoid. Telenomus remus Nixon (1973) is an effective parasitoid of Spodoptera frugiperda (J.E. Smith) in many regions, but S. frugiperda is not ideal for mass rearing due to cannibalism and high feeding costs. This study evaluated the efficacy of T. remus by assessing parasitization and emergence rates on eggs of S. frugiperda and Spodoptera litura (Fabricius). Host preference was tested through choice and non-choice experiments using parasitoids reared on both hosts, and various host-parasitoid ratios were tested to assess density-dependent parasitism. Results showed that T. remus had higher parasitism and emergence rates on S. litura eggs, regardless of the rearing host. The highest parasitism was observed on S. litura (94.63%) from T. remus reared on S. litura eggs and the highest emergence rates was also on S. litura eggs from T. remus reared on S. frugiperda (88.03%). The lowest emergence rate (52.29%) was observed on S. frugiperda eggs under no-choice conditions. Parasitoids reared on S. frugiperda achieved the highest parasitism on S. litura eggs (98.11%) in host-parasitoid ratio tests, while the lowest emergence rate (55.02%) occurred when reared and tested on S. frugiperda. These results suggest that S. litura is a more suitable host for mass rearing T. remus, enhancing its potential as a biological control agent in the field.