Estudo da influência da utilização de imidacloprido em alface (Lactuca Sativa L.)

Abstract

Agriculture is highly dependent on the use of substances that may inhibit the action of pests harmful to cultivars. However, although they are highly effective in controlling a variety of insects, studies have shown lethal effects for non-target insects such as pollinating bees and aquatic insects, as well as side effects on birds, fish, and even humans. There is little information available on molecular changes and on the effect on the absorption of minerals caused by the influence of pesticides on vegetables, being these foods part of the day-to-day population. Thus, the objective of this work was to evaluate the development of lettuce in the absence and presence of two different imidacloprid (IMD) insecticide concentrations, using molecular vibration analyzes obtained by near-infrared (NIR), mid-infrared (MIR) spectroscopy, flame atomic absorption spectrometry (FAAS) and a-chlorophyll fluorescence stress analysis (Fchl) through a pulse of modulated amplitude fluorimeter (PAM), as well as to evaluate the cytotoxic and genotoxic potential of IMD in Allium cepa root meristems at the exposure times of 0, 24 and 48 hours. The NIR and MIR spectra were measured on the stem and leaf surface of the lettuces and treated by Principal Component Analysis (PCA). The Ca, K, Fe, Cu, Al and Pb contents were obtained by FAAS. The PAM and FAAS data were statistically treated using ANOVA and Tukey’s test, while the results of cytotoxicity and genotoxicity were obtained by the ShapiroWilk tests and homogeneity of Hartley, Kruskal-Wallis, and post-Dunn test. No statistical differences were found in the mineral analyzes between the groups (with and without insecticide). The results showed that there is a difference between the measurements of NIR when the spectra are obtained from the stem and on the outer surface of the leaves só that the measurement point can influence the results. However, considering only the leaf, it was not possible to differentiate the groups (control, treatment 1 and treatment 2) by using PCA in the NIR, MIR spectroscopy data, as happens in FAAS data. The parameters obtained by Fo, FV, FV/FM and FV/Fo, as well as the NIR and MIR results, did not present significant statistical differences between the groups (with and without pesticide). The two concentrations evaluated caused significant inhibition in cell division mainly after 48 hours of exposure, where the mitotic index was approximately 1.76 and 0.56 for concentration 1 and 2, respectively. The pesticide did induce the formation of a significant number of micronuclei in addition to the number of cells in apoptosis, indicating that IMD has genotoxicity and cytotoxicity. Therefore, it is suggested that the use of IMD should be strictly monitored because, in addition to not being easily differentiated, cultivars produced using IMD may promote toxicity.