Efficiency of Cryptolaemus montrouzieri Mulsant (Coleoptera: Coccinellidae) to control Planococcus citri Risso (Hemiptera: Pseudococcidae) in citrus orchards in Tunisia

Abstract: The study of the efficiency of the predatory ladybird Cryptolaemus montrouzieri against Planococcus citri was conducted in two Citrus orchards variety “Maltaise” in the region of Mornag and “Maltaise douce” in the region of El Gobba in northern Tunisia. This study revealed that C. montrouzieri, which was introduced and multiplied in Tunisia since 2006, is capable of controlling the populations of P. citri and maintain them at an economically tolerable threshold one month after their releases. Indeed, the density of eggs of P. citri decreased by 85% compared to the initial populations in El Gobba and 89% in Mornag orchard. After a period of approximately three months of the first releases of adults of C. montrouzieri, the population structure of P. citri was composed of 7.67% of eggs, 0% L1, 7.56% of L2, 4.86% of L3 and 10% of females in the orchard of El Gobba. By contrast, in Mornag, the population of P. citri was maintained at a relatively higher level with 11.27% of eggs, 14.56% of L1, 24% of L2, 18.42% of L3 and 13% of females. Thus, we can conclude that C. montrouzieri can be considered as an effective biocontrol agent against P. citri in Tunisia.