Relative toxicity of two natural compounds compared to abamectin against some soybean pests under period rates

A sustainable pest management in agro-ecosystems requires parallel assessments of pesticide and natural compounds to control target pests. In the present study, a semi-field experiment was conducted to evaluate the relative toxicity of abamectin (Abamax), humic acid, and Chitosan Nano-Particles (C.N.Ps) against four soybean pests: Tetranychus urticae, Eutetranychus orientalis, Bemisia tabaci, and Phenacoccus solenopsis. The experimental treatments were arranged in a split-plot design with three replicates, where treatments were assigned to main plots and pest populations under different periods in the subplots. The obtained results and graphs demonstrated that there were considerable differences between the total numbers of pests after different periods of treatment. Generally, E. orientalis recorded the minimum pest number at all. Different tested compounds demonstrated a considerable correlation between the densities of the pests. T. urticae exhibited a significant correlation with the other three pests (E. orientalis, B. tabaci, and P. solenopsis). E. orientalis did not correlate with B. tabaci and P. solenopsis. The humic acid recorded the best effect on T. urticae after 3 days with a reduction of 85.45% and E. orientalis after 7 days 65.55%. However, Chitosan Nano-Particles (C.N.Ps) was the best for E. orientalis after 14 days (mortality 74.36%). In contrast, abamectin (Abamax) had a general mean of reduction of 91.17% against T. urticae, whenever, these compounds are promising for controlling T. urticae, E. orientalis, B. tabaci, and P. solenopsis. These results may be a supporting method to overcome some soybean pests. The findings are discussed within the context of integrated management of soybean pests under semi-field conditions.