2.2 BPH Bioassays
The choice test was conducted as follows (Li et al., 2023): two rice
plants were potted side-by-side in the same plastic container, and each
plant was placed in glass cylinders (2 cm diameter × 8 cm height), which
surrounded the basal stem of each plant. One was infested with 20 gravid
BPH female adults, and the other was used as an un-infected control.
After 24 hours of infestation, BPHs were removed and one pair of plants
was confined in a glass cylinder (4 cm diameter × 8 cm height) into
which 15 fifth-instar nymphs or gravid BPH female adults were released
in the middle of the two plants. Afterwards, BPHs settling on each plant
were counted at 2, 4, 8, 12, 24, and 48 hours, respectively. The
experiment was repeated 12 times with 15 insects per replicate.
In the survival rate and honeydew measurement tests, the gravid BPH
females pre-infested and control plants were prepared using the same
method as above. Third-instar BPH nymphs were allowed to feed on rice
plants, stems of rice plants (one plant per pot) were confined
individually within glass cylinders, into which 15 third-instar BPH
nymphs were released (Ji et al., 2017). The number of surviving BPH
nymphs in each cylinder was recorded every day. The experiment was
repeated four times. The honeydew was measured as follows (Ji et al.,
2021): a brachypterous newly emerged BPH female adult was placed into a
small Parafilm bag (6×5 cm), which was then fixed on the stem of a rice
plant. The amount of honeydew excreted by a female adult was weighed (to
an accuracy of 0.1 mg) at 24 hours after the start of the experiment.
The experiment was replicated 18 times.