POPULATION DYNAMICS OF CITRUS PSYLLA, Diaphorina citri Kuwayama (Hem.Psyllidae) and Exochomus nigromaculatus (Cole., Coccinelidae) ON CITRUS PLANTS.

Diaphorina citri Kuwayama (Hem.: Psyllidae) has been recognized as a serious pest of citrus in Asia for many years. In Iran, the pest has spread in Hormozgan, Sistan- Baluchestan and Kerman Provinces. Both nymph and adult stages are phytophagous and sucks plant sap and able to transferring the Liberobacter asiaticum Greening bacteria which is considered as the most serious disease of citrus in the world. In this survey, population fluctuation of D. citri and Exochomus nigromaculatus in Kohgiluyeh and Boyerahmad province were studied during 2010–2011. Results show that the citrus psylla was found on sweet orange and citrus plants at every occasion during the study. In contrast, the predator, E. nigromaculatus was found only on the potted sweet orange plants (Citrus sinensis) where pruning and insecticide application was not practiced. Not only did the flushing condition appear to regulate the psylla population, but also rainfall, the only one climatic factor that significantly influenced the psylla population fluctuation. The results implied that E. nigromaculatus could establish well only in the stable habitat. Hence, in practice, it may be utilized as a biological control agent against D. citri when releasing this predator is carried out on the plants neither pruned nor sprayed with insecticide.

Fluctuation, Citrus psylla, Kohgiluyeh, Citrus