Biology and predation of assassin bug (Sycanus dichotomus) on fall armyworm (Spodoptera frugiperda) larvae

The experiment was conducted during 2023 and 2024 at the Sungai Burung, Tanjung Karang, Selangor, Malaysia to investigate the life cycle and predation ability of assassin bug (S. dichotomus) on fall armyworm (S. frugiperda) larvae. Results revealed that S. dichotomus laid eggs in a cluster of 34–116 eggs, and the mean egg incubation period was 18.50 ± 0.27 days with a 12–25 days range. The nymph passed through five instars, and the respective mean nymphal durations of females and males were 107.16 ± 0.94 days and 106.13 ± 1.07 days. Adult female longevity was 55.18 ± 0.41 days, and adult male longevity was 55.12 ± 0.51 days. The predation ability of the nymphal and adult stages of S. dichotomus varied with the different larval categories of S. frugiperda. Where all the nymphal and adult stages of S. dichotomus have the ability to attack 1st category larvae of S. frugiperda, conversely, the 1st instar nymph of S. dichotomus was unable to prey on the 2nd category larvae of S. frugiperda. Additionally, the 1st, 2nd, and 3rd nymphs of S. dichotomus were unable to attack the 3rd larval category of S. frugiperda. Results on the predation potentiality of S. dichotomus revealed the adult females and males showed significantly higher (p<0.05) performances than their nymphal stages, with the adult females the most voracious. Thus the adults of S. dichotomus could be an efficient biocontrol for S. frugiperda.