Sublethal concentrations of conventional nematicides alter the physiological activities of Meloidogyne incognita and suppress parasitism

Abstract

Reducing nematicide dose rates could be a useful strategy for mitigating their negative effects on health and the environment. In this study, enzymatic activities and the parasitic ability of Meloidogyne incognita after exposure to sub-lethal concentrations (0.25, 1, 2, and 5 ppm) of ethoprophos, fenamiphos, and oxamyl were investigated. Although the tested concentrations did not show nematicidal properties in vitro, they reduced root galls by at least 30% at 0.25 ppm and up to 67% at 5 ppm in pots, besides disrupting nematode fertility. For all three nematicides at 2 ppm, a chemotaxis assay showed that ≤ 11% of the nematode population was successfully oriented to the host roots, compared to 44% in the control. Ethoprophos and fenamiphos at 5 ppm showed poor inhibitory effects on acetylcholinesterase (AChE) activity (5.6% and 12.5%, respectively). In contrast, the same nematicides were shown to be strong ATPase inhibitors, causing 82.4% and 82.8% inhibition, respectively. At the same concentration, oxamyl moderately inhibited AChE and ATPase-specific activities, the inhibition being 22.5% and 35.2%, respectively. This study suggests that the use of very low nematicide concentrations could be a promising strategy for nematode management. Furthermore, it has also highlighted the role of ATPases as a possible target site for suppressing nematode activity in the development of future nematicides.

Zuccagnia punctata Cav., a Potential Environmentally Friendly and Sustainable Bionematicide for the Control of Argentinean Horticultural Crops

“…Some 21 fractions of 10 mL each were obtained. After TLC comparison (silica gel, hexane (H)/ethyl acetate (EtOAc)) 8:2 as the mobile phase, detection under UV light, and after spraying with diphenyl boric acid, ethanolamine complex in MeOH, fractions with similar TLC patterns were combined as follows: 1 (50 mg; fraction 1); 2 (20 mg, fraction 2); 3 (100 mg, fractions 3-4); 4 (78 mg, fractions 5), 5 (314 mg, fractions 6-7); 6 (180 mg, fractions 8), 7 (128 mg, fractions 9), 8 (172 mg, fractions 10), 9 (437 mg, fractions 11-14), 10 (19 mg, fractions [15][16][17][18][19][20][21].…”

“…Over the last decade, there has been an increasing search for new methods of controlling animal and plant parasitic nematodes, using methods less toxic to the environment and to people [ 3 ]. Among these, the search for compounds from natural sources stands out [ 12 , 13 , 14 , 15 ]. In this context, the search for new sources of potential nematicides from unexplored natural products, such as South American flora, has become relevant.…”

Harnessing the dual antimicrobial mode of action with a lipophilic Mn(ii) complex using the principle of the Irving–Williams Series to completely eradicate Staphylococcus aurous

“…It is known that Mn can produce ROS in bacteria through two main pathways. [23][24][25] The first involves redox cycling, which transfers electrons between different oxidation states of Mn, leading to superoxide and hydrogen peroxide generation. The second pathway involves the disruption of metal homeostasis in bacteria due to excess Mn, which can compete with Fe for binding to proteins and enzymes, causing Fe depletion and ROS production.…”