Field evaluation of different eco-friendly alternative control methods against Panonychus citri [Acari: Tetranychidae] spider mite and its predators in citrus orchards

Abstract

Biotic stress caused by pests on citrus trees has become a major problem for ecologists around the world, hence the need to develop ecological approaches to surmount this stress. To evaluate the effectiveness of diverse control methods on the pest Panonychus citri and its predators, Euseius stipulatus, Phytoseiulus persimilis, and Typhlodromus sp. Different treatments were applied in orchards planted by Citrus clementina in the Gharb area of Morocco (T0 = treated by water only, T1 = spirodiclofen (the molecular formula is C21H24Cl2O4). 0.5 L/ha, T2 = 5% black soap 125 L/ha, Its ingredients are: argan oil, olive oil, black olive, salt, water, vegetable potash, without chemicals. T3 = mixture of two detergents; Oni product is composed of the following ingredients (sodium C12-13 parenth sulfate, and sodium C14-17 alkyl sec sulfonate) and Tide product with the following ingredients (sodium C10-16 alkylbenzene sulfonate, propylene glycol and sodium borate). Results obtained during the follow-up period showed that the black soap, spirodiclofen, and two detergent treatments provided a decrease in the P. citri population in comparison with plot treated by water during the whole monitoring period. We found 5,044 mobile forms of P. citri in the plot treated by water only, 1,544 forms in the plot treated with spirodiclofen, 3,002 forms in the plot treated with black soap, and 1,567 mobile forms in the plot treated with two detergents. This study demonstrated that all three treatments had a negative effect on the predators that survived in comparison to the control (T0), while the negative impact of spirodiclofen on beneficial phytoseiid mites was greater than that of black soap and detergents. However, the increase in temperature according to the follow-up weeks showed a significant effect on the evolution of the density of the studied mites. Unfortunately, the chemical products like spirodiclofen used against various citrus pests are considered toxic to phytoseiids and to the agro-ecosystem in general. This comparison aims to detect the effectiveness of black soap and mixtures of two detergents on P. citri and their impacts on its predators: E. stipulatus, P. persimilis, and Typhlodromus sp. to replace the use of pesticides by these alternative methods, which remain effective and environmentally friendly.