Zakaullah Khan

The root-lesion nematode, Pratylenchus subpenetrans , on ginseng ( Panax ginseng ) in Korea

Korean ginseng (Panax ginseng C.A. Meyer), is a deciduous perennial plant belonging to the Araliaceae family and is cultivated mostly in Korea and China. Ginseng root is highly prized for its medicinal properties and, in addition to the root itself, is made into many different kinds of products, including powder, extracts, tablets, capsules, tea, tonic drinks and cosmetics. Ginseng is cultivated under shade for 4-6 years for commercial use, growing for about 1 year in the nursery and the remainder in the field. Initially, ginseng cultivation in Korea was exclusively confined to some mountainous areas where summer temperatures were cooler. However, cultivation has now been extended to lowland areas with the aid of improved cultural techniques such as growing the crop in raised beds. Today, ginseng is grown throughout Korea, the total area of ginseng production in South Korea being ca 13 000 ha (Ministry of Agriculture and Forestry, 2006). Contamination of soil with nematodes and other pests, together with physical and chemical properties of the land, need to be considered for proper site selection. In Korea there is limited information available regarding the nature and extent of nematode disease problems in ginseng. Root-knot nematode Meloidogyne hapla Chitwood, 1949 and potato rot nematode Ditylenchus destructor Thorne, 1945 have been found occurring commonly in ginseng fields (Choi, 1976), the latter being responsible for the root-rot disease of ginseng (Ohh et al., 1983). Although the root-lesion nematode, Pratylenchus penetrans (Cobb,

Biological and Structural Mechanisms of Disease Development and Resistance in Chili Pepper Infected with the Root-knot Nematode

Biological and structural mechanisms of the nematode disease development in chili pepper caused by the rootknot nematode, Meloidogyne incognita, were investigated. Out of 39 chili pepper cultivars/lines tested, six were found resistant, while 33 were susceptible to M. incognita, of which a susceptible cultivar Chilseongcho and three resistant cultivar/lines CM334, 02G132 and 03G53 with different resistance degrees were selected for microscopic studies on the disease development. Gall formation was greatly reduced in the resistant cultivars/ lines. Nematode penetration occurred both in the susceptible and resistant chili pepper roots; however, the penetration rates were significantly lowered in the three resistant peppers compared to the susceptible pepper cv. Chilseongcho. In the susceptible pepper, giant cells were extensively formed with no discernible necrosis around the nematode feeding sites. In the highly resistant pepper cultivar CM334, no giant cell was formed, but extensive necrosis formation was observed around the penetrating nematodes. In the other two resistant pepper lines (02G132 and 03G53), both giant cells and prominent necroses were formed, and the necrotic responses appeared to inhibit the further development of giant cells or accelerate their early degeneration. Although the nematode penetration was retarded significantly in the resistant cultivar/lines, all of the above results suggest that the disease resistance of pepper may be related to post-infectional defense mechanisms (nematode growth and development) more than pre-infectional ones (penetration and establishment). Variations in structural modifications in the resistant cultivar/lines may reflect their genetic differences related to the nematode resistance.

Effects of Inoculum Level and Time of Microcoleus vaginatus on Control of Meloidogyne incognita on Tomato

Abstract Application of Microcoleus vaginatus , a blue-green alga (Cyanobacterium) at different levels along with Meloidogyne incognita , second stage larvae, in the rhizosphere of tomato plants; showed that the plant growth as well as yield of tomato were increased and gall formations and nematode populations decreased with the increase in inoculum level of M. vaginatus. An inoculum level of 20 ml endospores suspension of M. vaginatus (2.4 × 10 6 endospores per ml) per plant was optimum to reduce nematode attack with a population density of 1000 larvae per kg soil. Plant growth and yield of fruits were greatly suppressed and gall formations on roots, and nematode populations in soil were increased when M. incognita larvae added five days prior to M. vaginatus inoculation. On the other hand, when M. vaginatus inoculated ten days before nematode inoculation, suppressive effect of M. incognta on plants was reduced and their population density as well as gall formations were also decreased significantly. The efficacy of simultaneous inoculation of both nematode and M. vaginatus was lied in between two treatments discussed above.

Three new species of actinolaim nematodes from India

Three new species of Actinolaimidae are described, two belonging to Paractinolaimus Meyl, 1957, and one to Westindicus Thorne, 1967. Paractinolaimus aruprus sp.n., is closely related to P. baldus Thorne, 1967 and P. microdentatus (Thorne, 1939) Meyl, 1957 but differs from the former in having a smaller odontostyle, anterior vulva and longer female tail while from the latter it differs in having longer female tail, shorter spicules and fewer ventromedian supplements. Paractinolaimus vulvapapillatus sp.n. is distinctive in being short, the posterior location of vulva and presence of papillae on both sides of vulva, and is closely related to P. indicus Khan & Ganguly, 1988 and P. vigor Thorne, 1967. Westindicus keralaensis sp.n. differs from all the three known species viz. W. brachycephalus Thorne, 1967, W. rapax Hunt, 1977 and W. cinctus (Cobb in Thorne, 1939) Thorne, 1967 in the presence of a comparatively short body, short female tail and many ventromedian supplements.

A Survey for Plant-Parasitic Nematodes Associated with Strawberry (Fragaria ananassa Duch.) Crop in Korea

A survey was conducted during February-March 2003 to determine the occurrence and population density of plant-parasitic nematodes in strawberry (Fragaria ananassa) fields, cultivated under plastic houses in major strawberry growing regions of Gyeongbuk and Chonbuk provinces, Korea. The survey revealed presence of eleven species of plant-parasitic nematodes viz., Aphelenchoides fragariae, Criconemoides morgensis, Ditylenchus dipsaci, Helicotylenchus dihystera, Hirschmanniella imamuri, Meloidogyne arenaria, M. incognita, Pratylenchus penetrans, Psilenchus hilarulus, Tylenchorhynchus claytoni and Xiphinema sp. Frequency and density of each species were highly variable from field to field and within the field. Plant growth was not uniform in the surveyed fields under plastic houses; stunted growth, chlorotic leaves, small curled or crinkled leaves, deformed buds and flowers and wilted plants with fewer fruits were observed in patches.

Observations On the Predation Ability of Aporcelaimell Us Nivalis (Altherr, 1952) Heyns, 1966 (Nematoda: Dorylaimida)

Predation by Aporcelaimellus nivalis depended largely on chance encounters with the prey but the pre-feeding attraction and aggregation of up to 7 predators around an already injured prey at a feeding site is an indication of positive perception of prey body fluids. Prey catching and feeding mechanisms comprised five distinct phases viz., encounter with prey, attack response, attack, salivation/extra-corporeal digestion and ingestion/feeding. Rate of predation remained unchanged over a period of eight days but prey number, temperature, agar concentrations, starvation of the predators, type of the prey etc., determined predation. A. nivalis preferred second stage juveniles of Meloidogyne incognita (Kofoid & White, 1919) Chitwood, 1949 and Heterodera mothi Khan & Husain, 1965 to other species of prey nematodes. No predation took place when Hoplolaimus indicus Sher, 1963, Helicotylenchus indicus Siddiqi, 1963 and Hemicycliophora sp. were used as prey; thick cuticle, body annulations and toxic or unfavourable prey secretions were considered the likely cause. Adult (male and female) A. nivalis killing maximum number of prey nematodes was the most active predator stage.

Description of Dorylaimoides punctatus n. sp. and Paractinolaimus acutus n. sp. (Nematoda: Dorylaimida) from Korea

Abstract Soil samples collected from Taebak Changkunbong and Undal mountains of Kyungbuk Province, yielded two new species of the order Dorylaimida which are described and illustrated below. Dorylaimoides punctatus n. sp. (Nematoda: Dorylaimida) is 1.2–1.4 mm long; b = 5.9–6.9; c = 14.6–17.7; odontostyle 7.3–8.5 μm; spicules 33.5–36.5 μm; ventromedian supplements 5–6 and is characterized by having zig-zag lines on body cuticle, continuous lip region, elongate conoid tail and comes close to Dorylaimoides micoletzkyi (De Man, 1921) Thorne & Swanger, 1936 and Dorylaimoides leptus Husain & Khan, 1968. Paractinolaimus acutus n. sp. (Nematoda: Dorylaimida) is 2.1–2.4 mm long; b = 4.3–4.9; c = 10–12; odontostyle 25–27 μm and characterized by having continuous lip region, longitudinally oval vulva and long filiform tail with acute tip and comes close to Parctinolaimus aruprus Khan et al. , 1994 and Parctinolaimus baldus Thorne, 1967.

Three New Species of Predatory Nematodes (Dorylaimida: Actinolaimoidea) from Korea

Abstract Three new species of predatory nematodes belonging to family Actinolaimidae, superfamily Actinolaimoidea, order Dorylaimida are described and illustrated. Westindicus sanaensis sp. n. has a body 1.9–2.4mm long; b = 3.7–4.3; c = 8.1–8.5; odontostyle 26.5–28.0μm long; spicules 71–74μm long; ventromedian supplements 15 and comes close to Westindicus cheongsongensis Choi et al , 1998 and Westindicus keralaensis Khan et al. , 1994. Egtitus koriensis sp. n. is 1.8–2.0 mm long; b = 3.4–4.1; c = 14–18; odontostyle 20–21 μm, and comes close to Egtitus elaboratus (Cobb, 1906) Thorne, 1967; Egtitus itanagrus Khan et al. , 1994 and Egtitus adhricus Khan & Jairajpuri, 1994. Stopractinca glandulus sp. n. is 2.3–2.4 mm long; b = 4.0–4.1; c = 11–12; odontostyle 26–28μm and differs from other two known species viz., Stopractincta orientalis Khan et al. , 1994 and Stopractincta malnadensis Dhanam et al. , 1994 in having very thick body cuticle and longer cardia, and in the presence of a gland at the base of oesophagus.

Systematic Study of Dorylaimida from Korea# : 4. Four New Species of Dorylaimida from Korea

Abstract Four new species of Dorylaimida from Korea are described and illustrated. Belondira pugwiensis n. sp. is 1.7–1.9 mm long, b = 3.3–4.2, c = 58.1–65.8, V = 35–37, odontostyle = 6.5–7.3 μm and characterized by having a prominent spindle-shaped valve area in the anterior part of oesophagus and long expanded part of oesophagus, occupying 68–70% of total oesophageal length. Lindseyus juwangens sp. n. is 3.5–4.1 mm long, b = 13.3–14.5, c = 11.6, V = 40–40.3, odontostyle = 6.6–7.4 μm and characterized by having a slender body, short odontostyle and longer spicule. Prodorylaimus donghagens sp. n. is 1.7–2.1 mm long, b = 3.9–4.6, c = 5.8–6.3, V = 47–49, odontostyle = 29.2–32 μm and characterized by continuous, truncated lip region and ventrally hooked tail end. Prodorylaimus taebekensis sp. n. is 1.2–1.5 mm long; b = 4.2, c = 5–6, V = 43.3–47.2, odontostyle = 16–19 μm, spicule = 35–46 μm and ventromedian supplements = 5–6 and characterized with slightly set off lip region and long filiform tail with ventrally hooked terminus.

Description of Paractinolaimoides Unicus N. Gen., N. Sp. (Dorylaimida: Actinolaimidae) From India

Paractinolaimoides n. gen. is distinctive in having four sclerotized plates at the level of the onchia in addition to mural denticles arranged in several rows. The new genus is related to Paractinolaimus Meyl, 1957 and Scleroactinolaimus Ahmad et al., 1992 but differs from them in the nature of the cheilostomal armature. The type species Paractinolaimoides unicus n. gen., n.sp. is described and illustrated.