In Egypt, the early plantation (September) in the two seasons of sugar beet suffers from major
economic losses by Spodoptera littoralis larvae; e.g. Significant defoliation and small roots which causes a
shortage of sugar crop. Looking at the associated parasitoids, there is Exeristes roborator. This parasitoid’s
parasitism ability to Spodoptera littoralis larvae was not estimated. Thus, the present study was conducted during
two successive seasons 2017/2018 and 2018 / 2019 for the first time in Egypt. Also, estimate the reduction in the
parasitoid numbers resulting from application of two groups of insecticides represented in ecdysone agonists and
conventional ones against Spodoptera littoralis larvae. The parasitoid Individuals associated with the cotton
leafworm larvae was identified as Exeristes roborator. It is a larval ectoparasitoid. Concerning its parasitim
ability, the results indicated that the maximum parasitism percentage was 50%. The total parasitism percentage
was 21.33% in 2017/2018 season. While the maximum of parasitism percentage reached 100% and the total
parasitism percentage was 20.59% in 2018/2019 season. Statistical analysis demonstrated that a significant
correlation between S. littoralis larvae and this parasitoid during the two seasons. As for the total reductions in
parasitoid numbers due to applied ecdysone agonists ranged between 17.72 to 21.67% and 14.57 to 21.52% in
2017/2018 and 2018/2019 seasons, respectively. However, the total reductions due to applied conventional
insecticides reached the maximum; 98.39 to 100% in the first season and 98.82 to 100% in the second season.
These previously data indicated that the ecdysone agonists (IGRs) are the preferred pesticides to retain the
parasitoid.