Impact of nematicides on plant-parasitic nematodes: Challenges and environmental safety

Abstract

Plant Parasitic Nematodes (PPNs) are tiny, pseudocoelomate, unsegmented, bilaterally symmetrical vermiform animals that attack plants. Nematicides are chemically synthesized substances that kill or harm nematodes. Between 1940 and 1950, three chemicals with nematicidal properties were discovered: methyl bromide (bromomethane), D-D mixture, and EDB (1, 2-dibromoethane; as ethylene dibromide) which were fumigants. When fumigant compounds are applied to soil, a gas moves through the open spaces between soil particles or into the water film that surrounds soil particles. Fumigants significantly decrease nematode respiration by oxidizing Fe²⁺ centers and alkylated proteins in the cytochrome-mediated electron transport chain. Despite the efficacy of fumigants in nematode, their use was lowered due to the high environmental risk of these products. A new generation of nematicides was introduced: carbamates and organophosphates that served as contact nematicides, which led to the testing and development of other non-fumigant nematicides such as aldicarb, carbofuran, ethoprop, and fenamiphos. The carbamates and organophosphates acetylcholinesterase inhibitory properties prevent normal nerve impulse transmission in the nematode nervous system. Nematicides are typically non-selective pesticides, and their use impacts non-target organisms, humans, and the environment. Since nematicides are toxic to humans, soil, groundwater, and non-target organisms, cautious nematicide selection and application are vital. New compounds that are less aggressive and more specific for PPNs have been developed, making them safer for the producer, consumer, and environment. Crop rotation, cover crops, organic manuring, use of resistant varieties, and other methods must be integrated with nematicides for increased effectiveness.