In this study, after converting raw chitosan to Chitosan Nanoparticles CNPs for utility as a biological alternative to insecticides and nematicides, the laboratory results for three pests were recorded. Egyptian cotton leafworm and desert locust showed that the highest mortality rate was 29% at a concentration of 500ppm and 22% at a concentration of 2000ppm after a week of treatment for each of them, respectively, which were somewhat low rates, but the following results of the development were severe of each of them. According to the S. littoralis, the longevity of larvae and the pupae and the hatchability of eggs was recorded as highly significant inhibition and the incompleteness of the L. migratoria nymphs. As it was evident from the enzymatic studies of insects, the reason for the CNPs had a very large effect in increasing the enzymatic activity of both the enzyme chitinase and the protease but the decrease in the enzymatic activity of the enzyme alkaline phosphatase. In accord with M. incognita, In laboratory assays, the nematode mortality was significantly influenced by exposure times for CNPs concentration. CNPs 2000 ppm was the most effective in killing the nematode of tomato seedlings compared with the untreated control, in a greenhouse bioassay: All concentrations reduced the number of galls/root system, the number of egg mass/root, and the population of the second-juvenile stage (J2) in 250 g soil. Also, CNPs increased