[Control effect of parasitic Metaphycus parasaissetiae on host Parasaissetia nigra].

A laboratory test was conducted to study the control effect of parasitic Metaphycus parasaissetiae on its host Parasaissetia nigra. The functional reactions of the parasitism conformed to the Holling Type II Equation, but the parameters of the functional reactions varied with temperature. Taking the ratio of instant attack rate to preying time (a/T(h)) as an evaluation index, the preying efficiency at 30 degrees C was the highest, with a/T(h) being 23.4211. There was a stronger interference effect in the functional reactions of the parasitism within M. parasaissetiae populations. With the increase of the population density, the amounts of parasitism decreased gradually. Hassell Equation (E = QP(-m)) could describe the relationships between the searching efficiency of M. parasaissetiae and its population density much precisely within the range of 21 degrees C - 33 degrees C. The interference increased with temperature within the range of 21 degrees C - 27 degrees C, and the interference coefficient reached the highest (0.6626) at 27 degrees C. When the temperature was raised to 30 and 33 degrees C, the interference coefficient decreased to 0.6161 and 0.5916, respectively. In the prophase of egg-laying, the parasitized P. nigra could be entirely controlled by M. parasaissetiae. However, when a few larvae were crawling out, the control effect was declined to 81.4%.