Population dynamics of the mite, Tetranychus urticae Koch (acarina: tetranychidae) under acaricide treatment on two varieties of peach and one variety of nectarine in the province of El-Hajeb (Morocco)

The population dynamics of Tetranychus urticae Koch on two varieties of peach (Prunus persica var. Royal Majestic, and Prunus persica var. Kaweah) and one variety of nectarine (Prunus persica var. nucipersica var. Zephyr) were monitored for three years from 2019 to 2022. The results of this study showed that over the course of these three years, infestation peaks occurred in March and declined later in October. For all three varieties, the infestation profile varied from year to year. The Royal Majestic variety was the most infested by T. urticae, with average infestation percentages of 57.06%, 44.11%, and 50.97%, respectively during the three years. As for the two other varieties, the infestation was less pronounced during the three years with average infestation percentages of 31%, 15.42%, and 15.50% on Kaweah and 5.31%, 29.21%, and 26.06% on Zephyr. The results of intra-plant infestation showed that during that during this study periods, the lower stratum was the one with the highest average infestation percentages, with average infestation percentages of 57.29%, 26.08%, and 28.37% respectively on the Royal Majestic, Zephyr, and Kaweah varieties. Concerning the middle stratum, the percentages of infestation are 53.19%, 19.42%, and 19.96% respectively for the Royal Majestic, Zephyr, and Kaweah varieties. For the upper stratum the percentages of infestation are 47.87%, 11.56%, and 9.54% respectively for the Royal Majestic, Zephyr, and Kaweah varieties.