Study on influencing factors of predation efficiency of Eocanthecona furcellata on Spodoptera litura in taro field

To evaluate the effects of external factors on the predation efficiency of Eocanthecona furcellata (Wolff) and improve its field biocontrol on Spodoptera litura (Fabricius) populations, a quadratic general rotation combination design was employed to examine the influence of three experimental factors on the predation efficiency of E. furcellata, including the density of S. litura larvae (X₁), the release quantity of E. furcellata nymphs (X₂), and the number of taro plants (X₃). Based on the predation rates of E. furcellata against S. litura under varing treatments, a regression model was established to describe the relationship between the predation efficiency (Y) and the three factors: Y = 71.8751593 - 4.74158206X₁ + 12.83546961X₂ + 1.249219611X₃ + 0.1022956216X₁² - 0.518515769X₂² - 1.076015769X₃² - 0.1667500000X₁X₂ - 0.0832500000X₁X₃ + 0.416250000X₂X₃. Single-factor effect analysis revealed the relative importance of the three experimental factors on predation rate in descending order as follows: the density of S. litura larvae (X₁), the release quantity of E. furcellata nymphs (X₂), and the number of taro plants (X₃). Through the fitting analysis of each factor when the highest index was taken in the established quadratic polynomial regression model and drawing of single-factor and interaction effects of the three factors, the optimal ratio for maximizing predation efficiency was determined to be 7∶5∶1.That was, the density of 7 S. litura larvae (X₁), the release quantity of 5 E. furcellata nymphs (X₂), and the number of 1 taro plant (X₃) could achieve a maximum predation rate of 90.83%.