Table 1.

Some of the most common genera of nematodes in agricultural soils, hosts, methods of attack, and symptoms.

Genus/Host Range	Plant/Crop Host	Method of Attack	Symptoms	Author
Meloidogyne spp. Root-knot nematodes More than 90 host species	Wide horticultural and field crop host range (about 2000 plant hosts worldwide)	Root system	Root galls Dead in young plants	[32]
Nacobbus aberrans False root-knot nematode	Affects a number of economically important crops, e.g., tomato, chilli pepper, beans, potatoes, sugar beets, and crucifers	Migratory/sedentary Endoparasitic nematode Penetrate into plant roots, forming galls	Root galls	[33,34]
Aphelenchoides spp. More than 200 species	Wide host spectrum, including ornamentals. Some species are fungi feeders	Some species endoparasitic in leaves, but also feeds ectoparasitically on leaves and flower buds in some plants	Chlorosis and necrosis of leaves	[35,36]
Heterodera spp. At least 80 species Obligate parasites Affects more than 40 species	A few hosts, including: oatmeal, soybean, alfalfa, corn, and others	Penetrate cortex roots, endodermis, or vascular parenchyma Feeds on root tissues	General debilitation Reduction in the efficiency of the root system Chlorosis, stunted growth, wilting Poor yield	[37,38]
Longidorus spp. More than 160 species Can transmit Nepoviruses	Polyphagous root-ectoparasites of many plants, including various agricultural crops and trees	Damage is caused by direct feeding on root cells, as well as by transmitting Nepoviruses	Chlorosis and stunted growth in forest trees	[39,40,41,42]
Pratylenchus spp. Migratory endoparasites	Possess a wide host range Commonly found in wheat, canola, chickpea, and barley	Provoke plant tissue necrosis because of migration and feeding	Crops show an in-field patchy decline, lack of vigour, chlorosis slower growth, crooked or bushy appearance of tap roots, fleshy tap roots, stunted, stubby small root systems with excessive branching Small roots that are large near the tip Sparse lateral roots Brownish to black spots or streaks or discolored necrotic areas on the roots	[43,44]
Radopholus spp. Burrowing nematodes Two species: R. citrophilus and R. similis	Affects several economically important crops, e.g., banana citrus, coconut, ginger, palm, avocado, coffee, prayer plant, black pepper, sugarcane, tea, vegetables, ornamentals, trees, grasses, and weeds	Attack the root system Migratory endoparasite in all life stages	In banana, provokes toppling disease In pepper, causes the yellows disease In citrus, can spread decline	[45,46]
Xiphinema spp. 39 species have been identified	They have a wide host range that includes common weeds and grasses, strawberries, soybeans, forest trees, orchards, and grapes Can be vectors of viruses, e.g., peach yellow bud mosaic virus in peach, apricot, and plum, cherry rasp leaf virus, and grape yellow vein virus	Attack roots, causing root stunting and tip galling	Necrosis on roots	[47]