Evaluating the Potential of Using Spodoptera litura Eggs for Mass-Rearing Telenomus remus, a Promising Egg Parasitoid of Spodoptera frugiperda

Abstract

Although <i>Telenomus remus</i>, a promising parasitoid of <i>Spodoptera frugiperda</i>, had been successfully reared on the eggs of <i>Corcyra cephalonica</i> in some countries, reports from China have argued that it is infeasible. Notably, studies from China have indicated that <i>Spodoptera litura</i> eggs could be a candidate host. Therefore, to further evaluate the potential of using <i>S. litura</i> eggs as hosts, we compared the development and parasitism of <i>T. remus</i> on the eggs of <i>S. frugiperda</i> and <i>S. litura</i> at temperatures between 20-32 °C. Our results showed that <i>T. remus</i> developed successfully on both host eggs at all of the tested temperatures, and the developmental duration and thermal requirements at each stage were similar between the two host species. The number of parasitized eggs was greater for <i>S. litura</i> than for <i>S</i>. <i>frugiperda</i>. Meanwhile, the emergence rate exceeded 86.6%, and it was significantly higher for <i>S. litura</i> than that for <i>S</i>. <i>frugiperda,</i> except at 29 °C. This study is the first time estimating the thermal requirements of <i>T. remus</i> at each stage. Moreover, we also recorded the morphological characteristics of <i>T. remus</i> at each stage. Our results demonstrate that <i>S. litura</i> eggs are more suitable than <i>S. frugiperda</i> eggs as an alternative host for the mass-rearing of <i>T. remus</i> in China. Understanding the thermal requirements and biological parameters contributes greatly to predicting the generation time and providing a reference for the mass-rearing and storage of the parasitoid.