Exploring the impact of pesticide exposure on physiological and metabolic dynamics in olive trees infested by key bioagressors

Abstract

Bioaggressors have a detrimental impact on olive trees, affecting both the quantity and quality of their products. While pesticides are commonly used to control these pests, they pose limitations such as soil, water, and air contamination, raising environmental concerns. This study aims to investigate the effects of pesticides on olive leaf health by analyzing parameters including chlorophyll, sugar, protein, and potassium levels, as well as twig growth and photosynthesis. The study employed the olive variety 'Menara' selected from the population variety ‘Picholine marocaine’. Specifically, we focus on pests such as Prays oleae BERN (Lepidoptera: Praydidae), Euphyllura olivina COSTA (Hemiptera: Psyllidae), and Venturia oleaginea (Castagne) Rossman & Crous, using pesticides Dimethon and Oleo-Nordox, and exploring the correlation between olive bioaggressors and the studied parameters. Our findings revealed that infestation led to a reduction in various leaf health indicators and twig growth, while slightly increasing sugar and potassium levels. The treatment reduced the population of Prays oleae and Psyllid by up 35%. Pesticide treatments disrupted olive tree health, resulting in lower sugar (25% drop) and potassium (18.03% drop) levels, while increasing proline (72% increase) and protein (7.88% increase) contents, twig growth (185% increase), stomatal conductance (148% increase), chlorophyll (7.7% increase), and photosynthesis (4.05% increase). The treatment effectively reduced the populations of Prays oleae and olive psyllid by up to 35%, and decreased the incidence of peacock spot disease by up to 61.9%. These changes suggest that treated olive trees experienced stress and activated defense mechanisms in response.