Effect of selected pesticides on the orientation of entomopathogenic nematodes (Rhabditida: Heterorhabditidae and Steinernematidae)

Abstract

Entomopathogenic nematodes (EPNs) play a crucial role in biological control, but they can be also applied together with pesticides. Therefore, the compatibility of pesticides with EPNs and the influence on their behavior significantly affect field success. This study investigated how selected pesticides (Deltamethrin, Imidacloprid, Pendimethalin, 2,4-D, and Boscalid + Pyraclostrobin) affect the orientation behavior of three commercial EPN species. Trials were conducted using steel olfactometers followed by the assessment of EPN dispersal ratios after 24 hours. The study was conducted in the Laboratory of the Plant Protection Department, Faculty of Agriculture and Natural Sciences, Bilecik Seyh Edebali University between 2022 and 2023. According to the results, while nearly all pesticides exhibited a significant impact on the dispersal behavior of EPNs, the most notable effects were observed in the trials involving 2,4-D and Imidacloprid. These two pesticides demonstrated both repellent and attractive effects on different EPN species. The impact of other pesticides was comparatively negligible. All EPN species exhibited higher orientation towards larvae than the control application. The orientation behavior displayed variations depending on the pesticide type and the EPN species involved. It is expected that this study will contribute to our understanding of the relationship between EPNs and pesticides, and ultimately enhancing the efficacy of EPNs.