SAMPLING DESIGN FOR ESTIMATING THE POPULATION OF THE SOUTHERN GREEN STINK BUG, NEZARA VIRIDULA (PENTATOMIDAE, HEMIPTERA) IN THE PADDY FIELD

• Published in: JAPANESE JOURNAL OF ECOLOGY Vol. 12; no. 6; pp. 228 - 235
• Main Authors: HOKYO, Nobuhiko, KIRITANI, Keizi
• Format: Journal Article
• Language: Japanese
• Published: The Ecological Society of Japan 1962
• ISSN: 0021-5007; 2424-127X
• DOI: 10.18960/seitai.12.6_228

sampling design for estimating the population density of successive states is discussed from analysis of the data which were obtained every other day as the entire distribution maps of the insect. Censuses were conducted in the two plots, each containing 500 rice plants, that were arranged in the paddy field of late planting rice. Analysis of the data was made along two lines. First, by the method which was proposed by BEALL (1939), and the effect of stratification of the plot, relative efficiency of various sampling units, and sampling size required for securing a given degree of accuracy were examined. As regards stratification, there was no detectable improvement in raising the sampling efficiency. Sampling unit type III' which was taken parallel to the direction of columns was somewhat more excellent in relative efficiency than the other types for the stage egg to the first instar, while for the second instar sampling unit type III which is equal in size out differs in from with type III showed more excellency. For less the third instar sampling unit type I with minimum unit size (one stump of rice plant) revealed stable excellency. Sampling size to secure a given degree of accuracy, e.g. α=0.20,using the most effective sampling unit, is 33〜50 per cent of the slot for the stage egg to the third instar, but 15〜20 per cent is enough for less the fourth instar. Secondly, using random numbers, samples with different sample size were drwwn from the distribution maps for each stage of the insect and sampling variation of estimates was examined. From this procedure there can be detected that C.V. of the estimates of population mean becomes small and stable not less than 40 per cent sampling for the stages egg to the second instar, not less than 20 per cent and 10 per cent for the stages of the third and the fourth instar, respectively. These results were elucidated from the viewpoints of behaviour of the insect relative to egg laying and dispersal. Sampling design-field plot lay out and determination of census date- was recommended for the estimation of Nezara population. Determination of the census date for each developmental stage can be made by using the incidence curve of the eggs and the average developmental period of each stage.