2.4. Behavior measurement
Briefly, nematodes were captured for videos by dissecting microscope (XTL-BM-9TD, Shanghai BM optical instruments manufacture co., Ltd) equipped with an industrial digital camera (UCMOS05100KPA). The head swing, body bending frequency, reversal movement and Omega turns in videos were counted for each individual for one minute (Yu et al., 2011). A slow-playing mode was employed to facilitate the counting and recording of the pharyngeal pumping times within 10 s (Luo et al., 2022). The satiety quiescence referred to the time when nematodes did not move for more than 5 s within 1 min, and the satiety quiescence duration was also recorded (Luo et al., 2022). Each group was consisted of at least 6 replicates.