Seasonal Fluctuation and Spatial Distribution of the Parasitolds Eretmocerus Mundus and Encarsia Acaudaleyrodis Natural Enemies of Bemisia tabaci on Fall Cucumber in Mollasani Area

Cotton whitefly, Bemisia tabaci Gennadius, is considered as one of the most important pests of fall cucumber in Khouzestan province. Seasonal dynamics and spatial distribution of Eretmocerus mundus Mercet and Encarsia acauda leyrodis Hayat natural enemies of cotton whitefly were studied weekly during 2006 and 2007 on fall cucumber in Mollasani area. In both years, pupae of both parasitoids first appeared on the plants in middle of September. In 2006, peak population of E.mundus and E.acaudaleyrodis were observed on 5th of October (1.9 pupa) and 12th of October (0.6 pupa) in 2 cm2 leaf, respectively. In 2007, peak population of two aforementioned parasitoids were observed on 27th of September (4.5 pupa) and 4th of October (0.9 pupa) in 2 cm2 leaf area, respectively. In both years, the population of both parasitoids reached zero in late October. Special distribution of both parasitoid were studied using Taylor power law. The slopes of regression lines (b) of two aforementioned parasitoids were 1.274 and 1.447 (2006) and 1.745 and 1.302 (2007), respectively. Spatial patterns of the pupae of both parasitoids on cucumber leaves were aggregated.