التقييم الحقلي لبعض عناصر المكافحة المتكاملة في مكافحة مَن اللهانة Brevicoryne brassicae و تقدير متبقيات المبيد Lambda-cyhalothrin

Rp-Evaluation of the efficiency of some integrated pest management elements in controlling the cabbage aphids Brevicoryne brassicae and measuring th

Abstract

A series of field experiments were carried out at the research station of the College of Agriculture, University of Karbala, to investigate the seasonal population dynamics of the cabbage aphid (Brevicoryne brassicae) on two cabbage varieties (Globe Master and Red Globe ). The study further assessed the relative efficacy of selected botanical insecticides (Palizin, Tondexir, and Oxymatrine), a chemical insecticide (Lambdacyhalothrin), a bio-insecticide Amyloland ) Bacillus amyloliquefaciens), and Nano silicon dioxide particles (SiO₂ NPs). Additionally, the research evaluated the insecticidal performance of a nanocomposite consisting of Lambdacyhalothrin loaded onto nano-silica particles (Lambda@sio₂nps) .The study also included an analysis of the dissipation rate of Lambdacyhalothrin residues on cabbage leaves, along with an evaluation of the effectiveness of certain food processing treatments—such as washing with water and soap, soaking in saline solutions, and pickling—in removing pesticide residues.
The study recorded the first appearance of cabbage aphid (Brevicoryne brassicae) nymphs on cabbage plants on November 10, 2024, four weeks after transplanting the seedlings into the field, with a density of 1.66 nymphs per leaf at a temperature of 17.93°C and relative humidity of 46.79%. The highest population density was observed in the fourth week, reaching 7.04 nymphs per leaf at a temperature of 16.62°C and relative humidity of 53.47%. Subsequently, the population declined significantly, reaching 0.08 nymphs per leaf by early December 2025, as the temperature dropped to 10.43°C and relative humidity rose to 71.27%. A noticeable reduction in nymph abundance was observed on the red cabbage variety (Red Globe) compared to the green variety (Globe Master), with a maximum density of 1.33 nymphs per leaf on Red Globe, versus a peak of 7.04 nymphs per leaf on Globe Master.
The results of evaluating the relative efficacy of the botanical insecticides Palizin, Tondexir, and Oxymatrine at a concentration of 3 mL/L indicated that Palizin achieved the highest relative efficacy, reaching 91.28% after 21 days of application. In comparison, Tondexir and Oxymatrine recorded efficacy rates of 72.48% and 73.3%, respectively. The bio-insecticide Amyloland also demonstrated high effectiveness in controlling the target pest. The 3 g/L concentration produced the highest mortality rate, reaching 67.2% after 21 days of treatment, with statistically significant differences compared to the 2 and 2.5 g/L concentrations, which recorded mortality rates of 51.2% and 56.9%, respectively. Furthermore, the 3 g/L concentration exhibited the highest biological efficacy after 21 days, reaching 99.4%, surpassing the 2 and 2.5 g/L concentrations, which achieved efficacy rates of 91.6% and 92.9%, respectively, over the same period.
The results of evaluating the efficacy of the bio-insecticide Amyloland in comparison with nano-silica compound over short time intervals showed that treatments with Amyloland at concentrations of 2, 2.5, and 3 g/L achieved cumulative mortality rates of 40.3%, 59.6%, 86.3%, and 100% at 3, 5, 7, and 9 days after treatment, respectively. In contrast, treatments with nano-silica at concentrations of 0.1, 0.15, and 0.2 g/L resulted in lower mortality rates, recording 36.6%, 50.1%, 70.3%, and 76.6% over the same time intervals, respectively.
The treatment with Karate 5% EC demonstrated high efficacy from the first day, recording a mortality rate of 90.33%, which continued to increase, reaching 100% by the fifth day. In contrast, the results of the nano-silica-loaded formulation indicated a positive correlation between increased concentration and insecticidal efficacy. Specifically, the formulation of the chemical insecticide Lambdacyhalothrin loaded onto nano-silica particles (Lambda@sio₂nps) at a concentration of 0.7 mg/L exhibited a relative efficacy comparable to that of the standard chemical insecticide, achieving 91.67% mortality on the first day and reaching 100% starting from the fifth day.
The dissipation analysis of the lambda-cyhalothrin in cabbage leaves revealed a significant decline in its concentration from 0.700 mg/kg for the recommended dose to 0.0335 mg/kg after 9 days, with no detectable residues observed after 13 days. When using the double dose, the concentration decreased from 0.832 mg/kg to 0.0373 mg/kg after 13 days. The pesticide’s half-life ranged between 3.3 and 3.7 days, with a pre-harvest interval (PHI) of 7 days required to ensure crop safety.
Regarding the effects of food processing treatments on pesticide residue removal, the data showed that washing with tap water and soap resulted in the lowest removal rate at 25.19%. In contrast, soaking in a 5% saline solution achieved a higher removal rate of 68.79%. The most effective treatment was the combination of brining and pickling (soaking in a 50 g/L saline solution for 10 days followed by pickling in synthetic vinegar for 5 days), which resulted in the highest pesticide removal rate of 90.21%.