玉米螟卵期寄生性天敌调查

在玉米螟卵期的寄生性天敌中，玉米螟赤眼蜂占93．51％，其它寄生蜂仅占6．49%．玉米螟赤眼蜂是卵期的优势蜂种。年度之间玉米螟卵的被寄生草差异较大。逐步回归分析表明，第2代玉米螟卵的被寄生率与第1代玉米螟卵发生量(X1)，6月份温雨系数(X2)，第2代玉米螟卵发生量(X2)，7月上旬雨量(X4)和7月中旬雨量(X3)有极显相关(X1、X4为主要影响因于)。第3代玉米螟卵的被寄生率与7月上旬雨量(X2)、7月下旬雨日(X2)、8月上旬气温(X3)，8月上旬雨量(X4)和8月下旬雨量(X5)有极显相关。由此可见，第1代卵发生量大，上代次卵发生期多雨，当代次卵发生期前少雨，当代次卵发生期多雨，有利于赤眼蜂寄生，玉米螟卵被寄生率提高。

Investigation on parasitoids of egg stage of Ostrinia furnacalis

The eggs of Ostrinia furnacalis have the following parasitoids, namely Trichogramma ostrinia (93.51%),the dominant species, and a few others (6.49%). The parasitic rate of eggs varied in different years. The parasitic rate of the second generation egg, by progressive regression, was found to be most significantly related to the egg amount of the first generation (X 1),temperature-rain coefficient in June (X 2), the egg amount of the second generation (X 3), precipitation of first ten -day in July (X 4) and precipitation of second ten-day in July (X 5), in which X 1 and X 4 were the main affecting factors. The parasitic rate of the third generation egg was indicated to be most significantly related to precipitation of first ten-day in July (X 1),rain day of last ten-day in July (X 4),temperature of first ten-day in August (X 3), precipitation of first ten-day in August (X 4) and precipitation of last ten-day in August (X 5). Thus, the large amount of eggs in the first generation, heavy precipitation in egg stage of the last generation,small precipitation before egg stage of the occurring generation, and heavy precipitation in egg stage of the occurring generation were advantageous for parasitizing of trichogramma with high parasitic rate.