Efficacy of the Ladybird Beetle Cryptolaemus montrouzieri Mulsant for Control of Saccharicoccus sacchari (Cockerell)

摘要

The lady beetle Cryptolaemus montrouzieri (Coleoptera: Coccinellidae) is an important predator of the mealybug Saccharicoccus sacchari (Hemiptera: Pseudococcidae), a pest sugarcane (Saccharum species hybrid) in China. To efficiently use this predator in biological control of mealybugs, predation parameters of C. montrouzieri on S. sacchari were studied. The prey feeding by C. montrouzieri of the 1st instar of S. sacchari nymphs was observed in the laboratory every 2 day. The functional response of C. montrouzieri to the 1st instar S. sacchari nymphs was determined as well as the prey feeding under different mealybug densities: 75, 150, 300, 600 and 1200. In addition, the populations of S. sacchari were observed in a greenhouse following the release of C. montrouzieri at the rate of one adult/plant and another with 2nd instar larva/plant, respectively, and were compared to situations where no predators were released. There was a significant difference between the average consumption per day of the 1st instar S. sacchari nymph by female and male adults of C. montrouzieri with 324.35, 303.10 mealybugs/day, respectively. The functional responses of female and male adults of C. montrouzieri on S. sacchari nymphs were determined as Holling type II. The Holling type II model for C. montrouzieri adults was Na = 1.2716NT/(1 + 0.001132N) for females and Na = 1.2252NT/(1 + 0.001482N) for males. The search rate (a) of C. montrouzieri females (1.2716) on the 1st instar nymphs of S. sacchari was higher than that of males (1.2252), while the handling time (Th) of females (0.00089) was shorter than that of males (0.00121). The results showed that S. sacchari population on sugarcane decrease from 12.90, 42.70 and 25.50 individuals/plant to 0.50, 4.50 and 7.30 individuals/plant, respectively, after released the predators for 20 days. The results from this study indicated that C. montrouzieri is a highly efficient predator of S. sacchari, and therefore, it could be tested further for possible use as a biocontrol agent for management of sugarcane mealybug.