Fig 1.
Location map of survey sites.
Fig 2.
Canopy trap and helicopter-towed net trap.
a. Canopy trap over wheat plants. Laodelphax striatellus flew directly up into the acrylic box, or insects flew onto the plastic sheet and then walked into the box. b. Helicopter-towed net trap in the air. The photo was taken from the cabin looking below the helicopter. The trap has two gates at the tail of the mesh net. The tail gate was closed when sampling started at about 260 m high, and the front gate closed when the sampling ended. The helicopter maintained its flight speed (65 km/h) and height for 20 min during each sampling.
Table 1.
Canopy trap settings at Dongtai, Jiangsu province, China.
Table 2.
Monitoring methods and parameters.
Fig 3.
The number of L. striatellus trapped in the net trap at Tongzhou, Jiangsu Province, China.
a. The daily number of insects trapped. b. The number of insects trapped at three-hour intervals on June 8 and 9, 2012. c. The sex of insects trapped on June 8 and 9, 2012 as shown in a.
Fig 4.
The number of L. striatellus trapped in the canopy traps at Dongtai, Jiangsu Province, China.
The number of insects trapped at twelve-hour intervals from June 1 to June 6, 2012.
Fig 5.
The number of L. striatellus entering canopy traps at hourly intervals.
a. The total number of insects entering canopy traps at two sites, CT1 and CT2. Insects were counted by viewing recorded video images of the trap’s entrance hole. b. The sex of trapped insects as shown in a. Insects of undetermined sex were excluded. For example, 1700 h CST corresponds to the number of insects entering the trap from 1600 to 1700 h CST.
Fig 6.
One- or two-hour profiles of numbers of L. striatellus caught in several types of traps located in Saga Prefecture, Japan.
a. S1 site in 2012, b. S2 site in 2012, c. S1 site in 2013, and d. S2 site in 2013. The survey parameters of the traps are shown in Table 2. The number of the insects caught in the light traps is not shown due to their small numbers.
Fig 7.
Summary of the Japanese survey.
a. The total number of L. striatellus caught in traps located at both S1 and S2 for each survey year. b. The catch number of L. striatellus female caught in the 10-m net trap at S1, the suction trap at S2 in 2012, and in the 10- and 5-m net traps and the suction trap at S1 in 2013. These traps were selected because their total numbers were large (> 100) and only days when the daily catch number was more than 10 were used to make the graph. c. The catch number of L. striatellus male caught in the five traps listed above.
Fig 8.
Proportion of L. striatellus at bi-hourly intervals.
Solid bars indicate mean value of the proportion of L. striatellus (sum of the number of females and males trapped in each time category/daily total number of females and males) for the five traps (the 10-m net trap at S1, the suction trap at S2 in 2012, and in the 10- and 5-m net traps and the suction trap at S1 in 2013) and the two years (2012 and 2013). Error bars indicate the S.E. Different letters indicate significant differences (Tukey-Kramer HSD test, P<0.05).
Fig 9.
Examples of L. striatellus’s migration simulation for selected dates during the survey periods in 2012 and 2013.
a. May 30, 2012, b. May 24, 2013, c. June 3, 2013 and d. June 4, 2013. These dates are when a small number of L. striatellus was captured by the net trap at the Isahaya Plant Protection Station, western Japan. In the simulation, L. striatellus took off in Jiangsu Province on the previous day at 1800 h CST, and grey areas in each figure indicate the relative aerial density of the insect (arb. unit), or the area of migrating insects 24 hours after their take-off.
Table 3.
Migration simulation results during the survey periods in Japana.