Population Dynamics of Tetranychus urticae Koch. and Associated Predators in Relation to Certain Ecological Factors in Sweet Potato Fields

Abstract

The two spotted spider mite, Tetranychus urticae is a highly polyphagous sap sucking pest, without a hibernation period, efficacy all the year round. He is destructive pest of important and fields and vegetable crops. This investigation was carried out at Beheira Governorate during 2023 and 2024 seasons, to monitor the population fluctuations of the spider mite and their predators; Stethorus gilvifrons Mulsant, Coccinella undecimpunctata L., Chrysoperla carnea Steph and Scymnus interruptus Goeze. In the first season, the infestation of T. urticae started on sweet potato plants at low numbers, the population increased gradually to reach its highest peak during 22nd July (19.75±1.98 individ.). This peak was followed by a relatively high population of the four predators, S. gilvifrons (4.75±1.57 individ.), C. undecimpunctata (5.00±1.60 individ.), Ch. carnea (8.00±1.58 individ.) and Sc. interuptus. (5.00± individ.). The second peak of T. urticae was detected on 14th Aug. (48.00±2.91 individ.), synchronized with the peaks of the four predators. During 2024, the first incidence of the mite was recorded on 22nd July. (44.25±3.76 individ). This peak was associated with the peak of the four predators. The second peak of T. urticae was observed on 14th Aug. (25.75±3.01 individ.), it coincided with the peaks of the four predators. The infestation of T. urticae and their predators were highly significantly correlated with weather factors (Max., Min°C and RH). From the found data in this experiment, advise that together predators could be effectively application as biological control agents for T. urticae management.