Agricultural researchers are intrigued by the possible use of biological copper nanoparticles (BCuNPs) as fungicides, insecticides, and fertilizers. Bacillus subtitles AM18 strain, identified molecularly by MALDI-TOF as Bacillus subtilis ssp. subtilis DSM 5660 DSM was a new isolate utilized in this study that biosynthesized BCuNPs. This strain can withstand copper concentrations up to 12 mM and eliminates copper by synthesizing BCuNPs. BCuNPs were characterized by UV-VIS (Ultraviolet–visible spectroscopy), Dynamic Light Scattering (DLS), Zeta potential, Fourier transform infrared (FTIR), and Transmission Electron Microscopy (TEM) devices. BCuNPs produced were polydisperse, spherical, and devoid of aggregation. They varied in size from 15 to 45 nm, with an average particle size of 23 nm, as measured by TEM and DLS. According to their zeta potential of 16.2 mV, BCuNPs were highly stable. FTIR spectra supernatant was predominantly responsible for the reduction and stability of BCuNPs. C on forming the nematocidal activity of produced BCuNPs, in vitro and in vivo plant studies were conducted to assess the toxicity of BCuNPs on eggs and J2 of M. incognita and the effect of repeated applications of BCuNPs and time on reproduction and populations of Phytonematodes inflected of cucumber. Ovicidal and larvicidal of BCuNPs against eggs and J2 of M. incognita increased with 0.1RC of abamectin compared with negative control (distilled water) and positive control (each alone). In vitro, tests revealed toxicity of BCuNPs concentrations in solo application against galling and reproduction (galls numbers, "RGI", egg mass numbers "EI") of M. incognita and population’s density (IJs/100 g soil), besides 250 ppm of BCuNPs, was the most toxic concentration. Varied efficacy was obtained due to factors of tested material such as chicken manure and bio-agents (rhizobacteria and fungi). Toxicity of repeated applications against plant parasitic nematodes by BCuNPs not companied with proper plant growth of cucumber plants to announce harmfully or exceeded application rate. Another in vivo test provides more information about the toxicity of BCuNPs against Tylenchorhynchus spp., Pratylenchus spp., and Helicotylenchus spp., infected Cucumis sativus L. under greenhouse test and documented effect of BCuNps concentrations on Phytonematodes communities in pot soils reflected on their RF. Our findings provide important insights into the time-resolved interactions between efficacy and toxicity BCuNPs on phytonematodes communities and plant growth features.