Abstract
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,Eutetranychusorientalis,Bemisia tabaci, andPhenacoccus 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. orientalisrecorded the minimum pest number at all. Different tested compounds demonstrated a considerable correlation between the densities of the pests.T. urticaeexhibited a significant correlation with the other three pests (E. orientalis,B. tabaci, andP. solenopsis).E. orientalisdid not correlate withB. tabaciandP. solenopsis. The humic acid recorded the best effect onT. urticaeafter 3 days with a reduction of 85.45% andE. orientalisafter 7 days 65.55%. However, Chitosan Nano-Particles (C.N.Ps) was the best forE. orientalisafter 14 days (mortality 74.36%). In contrast, abamectin (Abamax) had a general mean of reduction of 91.17% againstT. urticae, whenever, these compounds are promising for controllingT. urticae,E. orientalis,B. tabaci, andP. 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.
Highlights
Reduction percentages were calculated for each treatment, showing the effect of sprayed compounds against movable stages of different pests (T. urticae, E. orientalis, B. tabaci, and P. solenopsis) after 3, 7, and 14 days of treatment under natural conditions (Fig. 1)
The highest effect of humic acid was obtained for T. urticae after a different period and followed by P. solenopsis (73.43%) after 3 days
Abamectin had an efficacy on T. urticae recording values above 90% (96.1, 91.52, and 85.9% after 3, 7, and 14 days, respectively) and for E. orientalis and P. solenopsis (85.6 and 85.5) after 3 days, respectively followed by B. tabaci (88.70) after 14 days
Summary
Soybean (Glycine max) is considered an important oilseed crop that has grown in the world (60% of world oilseed production) (US Soybean Export Council, 2019). Polyphagous pests are wide-ranged on many economic and important crops including soybean (Alakhdar et al, 2015). The two-spotted spider mite Tetranychus urticae Koch, and the oriental red mite Eutetranychus orientalis Klein are piercingsucking pests’ infest soybean plant. This behavior of feeding leads to the appearance of characteristic yellow-chlorate spots on the leaves. The invasive mealybugs Phenacoccus solenopsis is a highly invasive and polyphagous insect responsible for serious damage to crops and plants. It attacks more than 200 plant species including field crops, vegetables, ornamentals, and weeds, bushes, and trees. It attacks more than 200 plant species including field crops, vegetables, ornamentals, and weeds, bushes, and trees. (Arif et al, 2009; Fand and Suroshe, 2015)
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