Chinese Journal of Entomology (1990) 10, 1-25

C.H. Cheng (1990)
Studies on population dynamics and forecasting of population abundance of brown planthopper, Nilaparvata lugens in Chia-Nan area
Chinese Journal of Entomology 10 (1), 1-25
Abstract: The population changes of brown planthopper, Nilaparvata lugens (Homoptera:Delphacidae) in paddy fields were investigated for the first and second rice crops in Chianan area from 1982 to 1988. The results revealed that the immigration of brown planthopper in the initial stage of the first rice crop in most cases could not be traced due to low immigrant. The first generation adults used to appear during the end of April to the beginning of May, and the hopper took about one month to complete one generation up to the time of harvest of the crop in the end of June. The highest population peak in this crop season ranged from 0.60 to 10.2 with an average of 1.33 per hill, which appeared mostly during 1-2 weeks before harvest of the crop. Analysis of the factors affecting to abundance of the hopper in the first rice crop indicated that the density of over-winter population was the most important (y² = 0.984). Besides, the number of days with the lowest day-temperature below 10°C during December to March, and the number of rainy day in April were also the factors affecting the population abundance to a certain extend. On the contrary, the population of the hopper in the second rice crop was high. The immigrant invaded into paddy fields soon after rice planting, and the peak of immigration appeared mostly during 2 to 3 weeks after rice planting. Initial population was varied from year with a range from 0.006 to 0.27 female adults per hill. The population increased from 46.6 to 2071 folds through 2 to 3 generation's multiplication to reach its highest population peak in the range of 0.6 to 450.6 per hill. The population abundance of the hopper in this crop season was highly correlated with the density of immigrant and the rainfall in September. High temperature over 34°C in August was also an important factor in reducing the population abundance in this crop season. Several regression equations had been established for predicting the population abundance of the hopper both in the first and second rice crop in this area. The coefficience of determination of the regressions were higher than 0.986, indicating that they were likely to be used practically. The population characteristics of the hopper in each crop season and on ratoon rice in this area are also discussed in the paper.
(The abstract is excluded from the Creative Commons licence and has been copied with permission by the publisher.)

Research topic(s) for pests/diseases/weeds:
population dynamics/ epidemiology
environment - cropping system/rotation

---

Pest and/or beneficial records:

Beneficial	Pest/Disease/Weed	Crop/Product	Country	Quarant.
	Nilaparvata lugens	Rice (Oryza)	Taiwan