Comparing Three Methods of Calculation Economic Threshold and Injury Levels for Land Snail Monacha cantiana (Montagu) on Sugarbeet in Nubaryia, Egypt

Abstract

This investigation is the first to determine Monacha cantiana's EIL and ETL. This study was accomplished during two seasons to identify EIL and ETL of M. cantiana in West Nubaryia region in Egypt. Four infested techniques (SnP, SnM, ILnP and ILnP %) and three methods (i.e. 1WRB, Chi-square and the equation of Pedigo et al. 1986) were applied to calculate EIL and ETL. Generally, at SnP, SnM, ILnP and ILnP%, the EIL values for RWL and RYL ranged from 5.0 to 6.4, 35.1 to 44.7, 14.9 to 18.3 and 48.4 to 55.0, respectively. The EIT values for SYL at the techniques infested above ranged from 5.9 to 8.7 SnP, 41.4 to 58.7 SnM, 16.7 to 26.7 ILnP and 53.1 to 73.1 ILnP%. For RWL and RYL, range ETL values were 3.8 to 5.3, 22.4 to 38.4, 8 to 14.6 and 32.5 to 44.0 at SnP, SnM, ILnP and ILnP%, respectively. Nonetheless the corresponding values for RYL were 4.4-5.1, 22.4-35.8, 8-11.9 and 32.5-38.7. On the other hand, the aforementioned SYL treatment values were 4.0 to 7.0, 26.8 to 46.9, 10.3 to 21.4 and 37.0 to 58.0, respectively. Chi-square were only significant for root weight and their losses, therefore, it was neglected. The ranges in SnP expression were very closely. So, It could be inferred that SnP with Pedigo et al. 1986) or 1WRB is an effective technique for EIL or ETL determination.