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Phenotypic diversity of five Jordanian populations of cyst nematodes, Heterodera spp. collected from five regions from Jordan (Ar-Ramtha, Madaba, Dana, Al-Karak, and Jerash) was investigated. Soil samples were collected from one representative field in each region. Morphological and morphometrical characteristics revealed that Heterodera latipons is dominated in cereal fields at Ar-Ramtha, Madaba, Dana and Al-Karak regions and Heterodera schachtii in Jerash. Cysts populations from all cereal fields had bifenestrate vulval cone and a strong underbridge. Wherever, cysts of the cabbage population had ambifenestrate vulval cone with long vulval slit. The bullae were absent in Ar-Ramtha, Madaba and Dana populations, but present in Al-Karak and Jerash. Based on 12 morphometrical characters, the first three functions in canonical discriminant analysis accounted 99.3% of the total variation. Distance from dorsal gland duct opening to stylet base, underbridge length, a = L/W (body length/midbody width) and length of hyaline tail tip had strong and significant contributions in the first function. While the second function was strongly influenced by length of hyaline tail, fenestral length, fenestral width and tail length. However, the third canonical discriminate function was found to be influenced by stylet length, fenestral length, a = L/W (body length/midbody width) and underbridge width. The graphical representation of the distribution of the samples showed that the first canonical discriminant function clearly separated H. schachtii from Jerash from other populations. Whereas, H. latipons collected from Madaba and Dana were clearly separated in the second function. The results indicated that differences at morphological and morphometrical levels revealed diverse populations of Heterodera spp. in Jordan.

Two field experiments were carried out to study the efficacy of different biological control agents in controlling certain plant-parasitic nematode species including Meloidogyne javanica, Tylenchorhynchus mediterraneus, Hoplolaimus seinhorsti, Longidorus latocephalus, and Xiphinema elongatum on guava and fig trees under the tropical field conditions of Jazan region, south-west Saudi Arabia during two successive seasons from Feb. 15, 2016 to Jan. 15, 2017. The evaluated bioagents were used in different integrated management combinations of certain fungal species (Trichoderma harzianum, Verticillium chlamydosporium, and Purpureocillium lilacinum), the bacterium Pasteuria penetrans, some organic amendments (cow manure, compost, and chicken manure), urea 46% as a nitrogenous fertilizer, and the nematicide carbofuran 10G for comparison. Results showed that all the tested treatments gradually decreased (P ≤ 0.05) the population densities of plant-parasitic nematodes on guava and fig trees over the study period. The highest reduction of nematode densities occurred at the end of the experiment. Carbofuran 10G was the most effective treatment in suppressing the nematode densities on guava and fig trees. The most effective management combinations, next to carbofuran 10G, in suppressing the nematode densities in the rhizosphere of guava trees were P. lilacinum + P. penetrans + urea 46%, P. lilacinum + P. penetrans + chicken manure, and T. harzianum + P. penetrans + chicken manure (66.54-69.22% nematode reductions). Correspondent combinations in the rhizosphere of fig trees were P. lilacinum + P. penetrans + cow manure, T. harzianum + P. penetrans + cow manure, P. lilacinum + P. penetrans + urea 46%, and V. chlamydosporium + P. penetrans + urea 46% (54.68-57.17% nematode reductions). On the other hand, nematode population densities continued to increase (P ≤ 0.05) in the rhizosphere of guava and fig trees in the absence of nematode management combinations. All the tested treatments significantly increased (P ≤ 0.05) the number of fruits/tree on guava and fig trees. Treatments which included the combinations of fungal and bacterial parasites along with chicken manure gave the highest numbers of fruits/tree, followed by the treatment with the nematicide carbofuran 10G. Regression analysis showed a significant negative linear relationship between the number of nematodes/kg soil and the number of guava and fig fruits/tree.

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Root-knot/charcoal root rot disease complex caused by the interaction of Meloidogyne javanica and Macrophomina phaseolina is a serious disease complex attacking bean crop either in the field or greenhouses. In two different greenhouse tests, the influence of soil texture and moisture on the severity of the root-knot/charcoal root rot disease complex on green beans, Phaseolus vulgaris were examined. Results of the soil texture test indicated that the disease severity (suppression of plant growth and rootknot/charcoal root rot disease index), the nematode reproduction and the fungus growth in soil increased with the increase of sand content in the soil. Results of the soil moisture test showed that the greatest plant damage occurred at the soil of moisture level of 30% of field capacity, and disease severity decreased gradually as the moisture level was increased.

The genus Morus comprises many species (Suttie 2012). The species Morus alba is one of the most popular mulberry species worldwide. In October 2020, numerous mulberry trees presented chlorotic leaves and stunted growth with severe root galling in a private compound in Riyadh region, Saudi Arabia. The infected roots showed galls, which are typical symptoms of infection by root-knot nematodes (RKNs). Infected roots were dissected, and males and females were extracted from roots while second stage juveniles (J2s) were from both soil and eggmasses. Morphological and morphometrical features were documented. Perineal patterns of females, males, and J2s were studied using a compound microscope. The endoparasitic females had pearly shaped bodies with projecting neck. Stylet knobs were rounded and set off and the shape of the cone distinctly curved. The posterior perineal had a dorsally high square arch. Striae patterns were zig-zag or forked along the lateral lines. Males were vermiform and the head cap flat to concave. Mostly conus of stylet was longer than shaft. Stylet knobs were prominent, set off, flat and usually greater width than the length. Males had a bluntly rounded tail, spicules were slightly curved and gubernaculum was crescentic. The J2s were vermiform, and stylet knobs were prominent and rounded shape. The J2s tail had a transparent area with an obtuse tip. The morphological measurements (means and range) of the perineal patterns of females (n = 4) were: length of vulval slit (LVS) = 22.5 (21.5 to 23.4) μm, anus to vulval slit (AVS) = 22 (21.8 to 22.1) μm, and anus length (AL) = 7.7 (7.5 to 7.8) μm. The males (n = 16) measurements were: length (L) = 1136 (1116 to 1159) μm; a (total body length / greatest body width) = 34.8 (33 to 37.1); body width = 32.7 (31.2 to 33.8) μm; stylet length = 25.6 (24.7 to 27.3) μm; dorsal oesophageal gland orifice (DGO) = 2.9 (2.6 to 3) μm, tail length = 7.1 (6.5 to 7.8) μm, c (total body length / tail length) = 161 (143.1 to 175), spicules length = 30.8 (26 to 33.8) μm; gubernaculum = 9.7 (9.1 to 10.4) μm. The J2s (n = 11) measurements were: L = 395 (378 to 405) μm; a = 26.2 (24.3 to 28.4); c = 8.6 (8.2 to 9.2); head end to metacorpus valve = 53 (49.4 to 54.6) μm; excretory pore to head end = 78 (72.8 to 80) μm, stylet length = 10.7 (10.4 to 11.7) μm; body width = 15.1 (14.3 to 15.6) μm; tail length = 45.8 (44.2 to 49.4) μm; hyaline tail terminus length = 12.5 (10.4 to 13) μm. Both the morphological and morphometrical features of the perineal pattern of the females, males, and J2s match the original description of Meloidogyne incognita (Kofoid and White, 1919) Chitwood, 1949 (Eisenback and Hirschmann 1981; Taylor and Netscher 1974). To perform Koch’s postulates, mulberry plants maintained in pots were inoculated with 2,500 J2s and eggs of the original population of M. incognita using five replicates. After two months, all inoculated plants had galled roots typical of RKNs. Reproduction factor value was 6.4. The noninoculated plants did not present galls in the roots. These results confirmed the nematode’s pathogenicity on mulberry. To the best of our knowledge, this is the first report that M. incognita was identified as a parasite of mulberry (Morus alba) in Saudi Arabia and the world, while Meloidogyne hispanica was reported on mulberry trees in Iran (Shokoohi et al. 2016). The importance of this report shed some lights on this new problem to direct the attention of farmers and home gardeners to take actions for the management of this newly identified problem. The authors declare no conflict of interest. Acknowledgments Authors wish to thanks College of Food and Agricultural Sciences, Research Center and Deanship of Scientific Research, King Saud University, Saudi Arabia for supporting this work. References: Eisenback, J. D. and Hirschmann, H. 1981. J. Nematol. 13:513. Shokoohi, E. et al. 2016. Australasian Plant Dis. Notes 11:16. Suttie, J. M. 2012. Food and Agricultural Organization of the United Nations. Taylor D. P., Netscher, C. 1974. Nematologica 20:268.

Ubiquitin expression protein DNA clone (Hl-UBI) was isolated from Heterodera latipons collected from North Jordan. Its sequence of 285 nucleotides was also determined and deposited in the GeneBank. The 285-bp open reading frame coded for 76-amino acid protein having two domains; the ubiquitin domain and the C terminal extension. The first 59 amino acids were predicted with the ubiquitin domain with identity percentages of 78% to ubiquitin of H. schachtii, 77% to polyubiquitin of Globodera pallida, 74% to ubiquitin of Globodera rostochiensis and 72% to ubiquitin of Heterodera glycines. The other domain at the C-terminus, containing 17 amino acids, showed no homology to any known protein. Sequence analysis showed a calculated encoding amino acids molecular weight of 8.77 kDa, theoretical isoelectric point = 4.76, negatively charged residues = 12, positively charged residues = 9, extinction coefficient = 1490, estimated half-life = 30 h, instability index = 32.51 and grand average of hydropathicity = −0.537. The demonstrated subcellular localization analysis of cytoplasm, cell nucleus, mitochondrion, cell skeleton and plasma membrane of Hl-UBI protein occupied about 52.20, 21.70, 17.40, 4.30 and 4.30%, respectively. Sequence, homology and structural analysis confirmed that Hl-UBI gene was highly conserved during evolution and belonged to ubiquitin gene family.

A sum of 218 composite rhizosphere soil samples were collected from around the feeder roots of mango, Mangifera indica growing in Jazan region, the tropical south west corner of Saudi Arabia. Samples were rendered for nematodes extraction using the centrifugal floatation method, and the stylet-bearing nematodes were morphologically identified according to the standardized taxonomical keys. A list of 14 stylet-bearing nematode genera and/or species were found to be associating the roots of mango in this study. Species identification of the most important parasitic nematodes, in this list, was carried-out, based on morphometrics and morphological features. Identification of these species was then molecularly confirmed using the D3 expansion region of 28S ribosomal RNA (rRNA) gene. These nematodes included; Tylenchorhynchus mediterraneus, Hoplolaimus seinhorsti, Hemicriconemoides strictathecatus, Longidorus latocephalus and Xiphinema elongatum. Some new local nematode-host records in Saudi Arabia were recorded including; Aphelenchus sp., H. strictathecatus, L. latocephalus, and T. mediterraneus. Some new world nematode-host records were also reported including; L. latocephalus and T. mediterraneus.