Usage of copper nanoparticles as a nematicidal agent for root-knot nematodes in naturally infested open-field pepper

Root-knot nematodes (Meloidogyne spp.) cause significant economic losses and have a profound impact on the agricultural sector, while commercial chemical nematicides have been found to cause pollution and are harmful to human health. The unique qualities and possible advantages of metal-based nanoparticles have gained considerable interest in plant disease control. This study synthesized, described, and evaluated CuONPs against the M. incognita nematode in terms of female biological cycle arrest, reduction of egg hatchability, and second juvenile mortality in pepper plants. It was done in both in vitro and open-field trials. Copper nanoparticles tested concurrently in graded concentrations (100, 75, 50, 25, and 12.5%) were evaluated. CuO nanoparticles were revealed to be effective nematode agents in the in vitro assay against eggs and second juvenile stages (J2s) of M. incognita, with a 100% concentration after 48 h of exposure, causing 87.9% larval mortality and 57.5% egg hatchability reduction. The open field experiment on pepper CuONPs application in direct irrigation showed 100% results with a concentration of 100%, an 84.4% decrease in egg masses/plant, a 92% decrease in J2s/100 g soil, and ultimately, an effect on the female's life cycle with an 83% decrease in number and an 89.6% reduction in galls/plant. Furthermore, pepper plants treated with CuONPs showed fresh and dry weights for the shoots and roots in open field trials. Finally, the safety effect of CuONPs on the growth of normal human cells was evidenced by its higher safety on normal human lung and skin cell lines (WI-38 and HFB4, respectively). CuONPs exhibited significantly effective growth parameters and strong nematicidal effects against nematodes, so they could be considered a safe and potential nanofertilizer and nematicide agent.