MODEL DESIGN TO ESTIMATE THE ECONOMIC THRESHOLD LEVEL OF LESSER DATE MOTH BATRACHEDRA AMYDRAULA Meyrick IN CENTRAL IRAQ

Abstract

The study was conducted in date palm orchards in Tarmiia, provenance of Baghdad during the 2003 growing season in order to estimate the Economic level (ETL) for lesser date moth B. amydraula on two cultivar of date palm Phoenix dectylifera L. Zahdi and Khastawe. The damage yield function and the relationship between the number of fallen fruits as well as infested fruits and the number of larvae were calculated. The model which designed was based on two criteria, first: the number of larvae/100 fallen fruits and second: a percent of fruit infested in fallen fruits .It was found that the fallen fruits contains a number of larva with different stages and there was a positive relationship between the number of larvae and the percent of fruits infestation. The high number of larvae in Zahdi cultivar was 12.76 larvae100 infested fallen fruits when the percent of infestation was 45.60% in the second half of June, while in Khastawe cultivar was 32.02 larvae100 infested fallen fruits when the percent of infestation was 94.20% in the first week of July. The data showed that each larva in the fallen fruit equel to 4.18,3.08 infested fallen fruits in Zahdi and Khastawe respectively. The Economic Threshold level was found to be 3, 1 larvae/100 fallen fruits or when a percent of infestation was 14.05%, 5.42% in Khastawe and Zahdi respectively. The damage yield function was (Y = - 0.2768 X+146.4513) in Zahdi and(Y = - 1.70914 +127.58) in Khastawe.