Biotypes and spatial distribution of Tylenchulus semipenetrans in Southern Iran

Citrus producing regions^a	The number of sampling localities by nematode scores^b				Total samples
Citrus producing regions^a	Nematode-free (1)	Nondamaging population (2)	Moderate infection (3)	Damaging population (4)	Total samples
Jahrom	28	8	9	14	59
Darab	6	2	8	13	29
Ghirokarzin	7	6	7	9	29
Fasa	9	0	5	13	27
Kazerun	5	4	6	10	25
Shiraz	6	2	4	8	20
Total samples	61	22	39	67	189

[i] ^aThe listed regions, collectively known as the “citrus belt,” produce more than 94% of the total citrus yield in Fars Province.

[ii] ^bScores 1, 2, 3, and 4 represent nematode densities of 0, <800, 800–3,600, and >3,600 males and J2 per 100 cm soil, respectively.

Table 2

Geographic coordinates, Tylenchulus semipenetrans population densities, and nematode damage scores in citrus orchards in Jahrom County, Fars Province, Iran

Soil Sample codes	GPS location		Nematode counts^a	Nematode population scores^b	Soil Sample codes	GPS location		Nematode counts	Nematode population scores
Soil Sample codes	Latitude (N)	Longitude (€)	Nematode counts^a	Nematode population scores^b	Soil Sample codes	Latitude (N)	Longitude (€)	Nematode counts	Nematode population scores
1	28.669278	53.606233	10,200	4	24	28.657221	53.608646	5,805	4
2	29.035991	52.948343	4,370	4	25	28.685277	53.059892	195	2
3	29.026267	52.989052	8,120	4	26	28.689224	53.135475	30,908	4
4	29.013814	53.041493	3,335	3	27	28.713066	53.118763	11,843	4
5	29.000878	53.044644	75	2	28	28.685308	53.059835	0	1
6	28.995715	53.064851	1,700	3	29	28.646726	53.142337	0	1
7	28.996655	53.081414	10,125	4	30	28.585194	53.191659	1,538	3
8	29.003597	53.110989	2,835	3	31	28.514193	53.402093	1,755	3
9	28.967092	53.135956	730	2	32	28.493349	53.454955	173	2
10	28.980327	53.147542	0	1	33	28.474944	53.494705	750	2
11	28.986850	53.205817	555	2	34	28.444957	53.519854	788	2
12	28.916327	53.257365	2,498	3	35	28.481629	53.499258	0	1
13	28.948801	53.312334	83	2	36	28.500721	53.516178	135	2
14	28.981959	53.184211	0	1	37	28.505358	53.530622	368	2
15	28.966185	53.168300	0	1	38	28.513342	53.533937	735	2
16	28.947530	53.194809	3,023	3	39	28.523522	53.518746	255	2
17	28.962441	53.206915	12,483	4	40	28.535712	53.546095	8,880	4
18	28.868347	53.133130	75	2	41	28.549132	53.509364	0	1
19	28.779141	53.259646	2,325	3	42	28.567053	53.532719	0	1
20	28.770289	53.296342	998	3	43	28.570218	53.457169	83	2
21	28.683328	53.530932	195	2	44	28.618094	53.397301	0	1
22	28.507193	53.612112	2,700	3	45	28.617202	53.362431	0	1
23	28.518237	53.667010	0	1	46	28.524671	53.553364	15	2

[i] ^aA 1-ml aliquot of well-mixed nematode suspension containing males and J2 extracted from 100 cm³ soil was counted three times.

[ii] ^bScores of 1, 2, 3, and 4 correspond to nematode-free (0), nondamaging (<800 males and J2), moderate (800–3,600 males and J2), and damaging (>3,600 males and J2) populations per 100 cm³ soil, respectively.

GIS-based spatial distribution maps of soil potassium, calcium carbonate, magnesium, and copper in citrus orchards of Jahrom County, Fars Province.

GIS-based distribution maps of soil iron, zinc, manganese, and sodium in citrus orchards of Jahrom County, Fars Province.

GIS-based spatial distribution maps of soil pH, organic matter, clay, and silt in citrus orchards of Jahrom County, Fars Province.

Spatial distribution model of *Tylenchulus semipenetrans* in citrus orchard soils of Jahrom County, Fars Province, using the Random Forest (RF) machine learning algorithm.

Relative importance of soil physicochemical properties influencing the distribution of *Tylenchulus semipenetrans* in citrus orchard soils of Jahrom County, Fars Province, based on Random Forest (RF) model. Soil variables included pH, silt, sand, manganese, zinc, EC, magnesium, copper, sodium, calcium, potassium, organic matter, phosphorus, iron, calcium carbonate, and clay. Edge.RF.Exp refers to the experimental RF model used to evaluate the effects of soil properties within the defined study area. “%IncMSE” represents the percentage increase in the mean squared error (MSE) following random permutation of each variable, higher values indicate greater influence on nematode distribution.

Table 3

Reproduction of 19 Tylenchulus semipenetrans populations on differential host plants [olive (Olea europaea), grapevine (Vitis vinifera), sour orange (Citrus aurantium), and trifoliate orange (Poncirus trifoliata] 8 months after inoculation

Population codes	Nematode counts on differential hosts 8 months after inoculation^a
Population codes	Olive	Grapevine	Sour orange	Trifoliate orange
411	0	n.d.	310	0
828	0	n.d.	2,200	0
830	0	n.d.	4,410	0
835	0	n.d.	2,820	0
843	0	n.d.	560	0
898	0	n.d.	1,500	0
908	75	120	2,100	0
921	90	735	9,315	0
942	45	105	5,505	15
969	0	0	220	0
993	30	90	5,115	75
1001	0	70	510	105
1033	0	90	135	0
313 A	0	0	1,550	0
37 A	0	0	780	0
411 A	0	n.d.	3,240	0
42B	0	n.d.	2,460	0
AA-1	75	n.d.	21,160	0
Gre P	0	0	8,220	30

n.d.: No data.

[i] ^aValues are the mean number of nematodes (males and J2) per 100 cm³ soil from four replicated plants.

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DOI: https://doi.org/10.2478/jofnem-2026-0036 | Journal eISSN: 2640-396X | Journal ISSN: 0022-300X

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Language: English

Page range: 598 - 612

Submitted on: Dec 20, 2025

Accepted on: Aug 3, 2026

Published on: Oct 21, 2026

Published by: Society of Nematologists, Inc.

In partnership with: Paradigm Publishing Services

Publication frequency: 1 issue per year

Keywords:

Biotype,

Citrus nematode,

Distribution,

Spatial modeling,

Tylenchulus semipenetrans

Related subjects:

Life sciences,

Life sciences, other

© 2026 Mohammad Rumiani, Akbar Karegar, Habiballah Hamzehzarghani, Hamid Reza Pourghasemi, published by Society of Nematologists, Inc.
This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 License.

Volume 58 (2026): Issue 1 (February 2026)

Biotypes and spatial distribution of Tylenchulus semipenetrans in Southern Iran

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