Studying the effect of environmental conditions in the seasonal abundance of lesser date moth (Batrachedra : Amydraula : Meyrick) on date palm, Phoenix dactylifera L. in Central and Southern Iraq

Abstract

A field study was conducted for the 2019/2020 season, which included a field survey to determine the infestation percentages and determine the sensitivity of some date palm varieties to the infestation with the lesser date moth (B.amydraula M.). Besides, determining the date of insect appearance and its population density is based on temperatures, relative humidity, and thermal accumulation. The study showed that infestation with the lesser date moth includes all areas planted with palm trees and the infestation percentages range between medium and severe, especially in dense orchards, and according to the prevailing environmental conditions. Basra Governorate / Abu Al-Khaseeb district gave a severe infection in the total infestation percentage of 67.00%, while the lowest infestation percentage was recorded in Babylon Governorate, Al-Madhatia district, at a percentage of 17.66 %, which considered a weak infection. The study also gave a clear indication that all date varieties were infested with lesser date moths at varying percentages, where the Al - Zahdi cultivar recorded the highest infestation percentage of 58.71%, while Al - Halawi cultivar recorded the lowest infestation percentage amounted to 39.97%. The study recorded the first appearance of the insect adults at the beginning of the second week of March in both Basra and Babylon governorates, with a population density of (2.80, 2.80) insect/in2 respectively at an average temperature (14.26, 15.20) ºC, respectively, and average humidity of (49.86, 51.67) % respectively. The study showed that the insect has three overlapping generations during the year, starting from the beginning of March to the beginning of March of the next season, as the duration of the first and second generations was one month each, while the duration of the third generation extends to approximately nine months. The insect has three peaks in which the insect population density increases significantly. In Basra, the increase reached its peak at the beginning of the second week of April and during the second week of May and June, with a population density of (7.71, 7.39 and 6.88) insect/in2 respectively, and an aggregate temperature of (445.20, 665.52 and 814.65) thermal units, respectively. However, in Babylon, the seasonal abundance of the insect reached its peak at the end of the first week of April and the second week of May and during the third week of June, with a population density of (6.71, 6.40, and 6.60) insect/in2 and a thermal accumulation of (358.08, 418.56 and 586). 08) thermal unit.