New approach for estimating egg parasitism of white-backed planthopper
1994
Zeng-Rong Zhu | Jiaan Cheng | Xiu Chen (Zhejiang Agricultural Univ., Hangzhou, Zhejiang 310029 (China). Plant Protection Dept.)
Results showed that the number of parasitized WBPH [whitebacked planthopper] can be estimated using the function X = 1.3761 (Y-1) + 1. Mean number of WBPH eggs/egg mass laid within tillering Guangluai 4 plants under different constant temperatures was measured in other independent experiments: 17 deg C: 7.94 plus or minus 0.68 (17); 23 deg C: 9.40 plus or minus 1.00 (35); 26 deg C: 7.93 plus or minus 0.60 (341); 30 deg C: 6.04 plus or minus 0.61 (25). The parabolic relationship of number of WBPH egg/egg mass against temperature is M = 13.9722 + 2.1149 T-0.0484 T2 (r = 0.9764, P0.01). A practical way to estimate egg parasitism is to collect WBPH-infested hills of rice on day t, and observe them in the laboratory for about 1 wk for parasitoid emergence. Number of WBPH egg masses and parasitoid emergence holes can be counted under a stereomicroscope or magnifying glass. Parasitism then can be calculated as P(percent)
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