SAWADA Hiroichi Shiga Prefectural University, Department of Environmental Sciences, Associate Pr, 環境科学部, 助教授 (90259391)
TAKAFUJI Akio Kyoto University, Graduate School of Agridulture, Professor, 農学研究科, 教授 (50026598)
|Budget Amount *help
¥3,900,000 (Direct Cost : ¥3,900,000)
Fiscal Year 1996 : ¥1,000,000 (Direct Cost : ¥1,000,000)
Fiscal Year 1995 : ¥2,900,000 (Direct Cost : ¥2,900,000)
We newly developed a binomial sequential sampling scheme for making control decision based on the proportion of sample units in which the pest number reaches or exceeds the predetermined control threshold (CTBS) and examined its efficacy based on the density-average samplingcost relationship. The scheme seems to be recommendable for decision making surveys in many IPM systems, especially of such insect pests that control threshold densities are fairly high, distribution patterns are highly aggregated, and yet precise number counting in the field requires much labor. For, under these conditions it usually requires much less labor or cost in total, as compared with the usual number-counting census. On the other hand, we explored the applicability of this labor-saving monitoring technique to the three important agricultural pests all known to have aggregated distribution pattems, the brown planthopper on rice (BPH), the two spotted spider mites on rose (TSM), and the Kanzawa spider mite on pear (KSM). Based on extensive field data taken in both Japan (BPH,TSM,KSM) and Indonesia (BPH), we showed that the degrees of aggregation in these species are not only high in general, but also are quite unstable, varying widely from place to place or time to time. The practical effectiveness of this technique for these pests are then analyzed on the basis of density-average cost relationship specified for assumed value ranges of cost function parameters and to control threshold, leading to the conclusion that our new CTBS method, as compared with the usual number-counting census, is quite promising for actual use in decision making in management systems of these pests.