The importance of Cryptolaemus montrouzieri Mulsant (Col., Coccinellidae) in the control of the citrus mealybug Planococcus citri (Hom., Coccoidea) under specific conditions.
Experiments were conducted in greenhouses in Greece from November 1991 to January 1992 under normal conditions to assess the effects of Cryptolaemus montrouzieri for the control of Planococcus citri on potted orange trees. The predator was released in 3 predator:prey ratios, 1:10, 1:15 and 1:30. These effects were also compared with experiments in a greenhouse under controlled conditions of 25-30°C and 55-70% RH, where the efficacy of Nephus reunioni, C. montrouzieri and an application of the insecticide methidathion was assessed against P. citri on pumpkins. Five adults of of each predator were released per test plant and methidathion was applied at a concn of 0.1%. In the 1st experiment, C. montrouzieri significantly reduced the number of P. citri, although there was no overall significant difference between the predator:prey ratios. C. montrouzieri also significantly reduced P. citri populations in the experiment on pumpkins under controlled conditions, especially in comparison with N. reunioni. In most cases, significant differences were not detected between C. montrouzieri and treatment with methidathion. The efficacy of N. reunioni may have been affected by the relatively low temperature of the controlled conditions compared to the temperatures of its normal active period in the field, March to June. C. montrouzieri was also thought to have been affected by the low temperature in December, during the 1st experiment.