Lignosae

Helicotylenchus (Tylenchida: Hoplolaimidae) are coiled worms known as spiral nematodes. They’re worldwide and related with plant roots. Most are ectoparasites and feed on root epidermis, whereas some reside half-buried in root tissues. Many species’ damage potential is unknown, however some are global and affect plant growth and yield. Thorsteinson believed that insect host selection is related to taxonomy . Rathore and Lal found that Maruca vitrata only attacks leguminous plants. Rathore and Tiwari observed that whitefly, Bemisia tabaci, preferred certain plants and evolutionary lineage. Rathore and Ali and Rathore and Tiwari found taxonomic correlations in Meloidogyne incognita and 63 Heterodera species. In this review, we investigate Helicotylenchus’ host spectrum.

The review includes 33 Helicotylenchus species with various host ranges.

Hutchinson’s taxonomy was used to investigate Helicotylenchus species’ hostplant relationships. In this classification, angiosperms are divided into dicotyledons and monocotyledons, which are further divided into calyciferae (with distinct calyx and corolla), corolliferae (calyx and corolla are similar), and glumiflorae (perianth is much reduced or represented by lodicules). The plant species described as Helicotylenchus hosts were linked with families and orders using Hutchinson’s approach . The available information on this nematode species’ clades was also discussed. Bernays and Chapman  coined the categories monophagous (feeding on a single genus), oligophagous (feeding on multiple genera within a family) and polyphagous (feeding on a wide range of plant families).

Helicotylenchus 

Helicotylenchus may parasitize 585 plant species, of which 69 percent are dicotyledons and the remainder monocotyledons. Lignosae (woody plants) host 51.6% of host species while 17.6% are herbaceae. Glumiflorae (14.36%) has more parasitized monocotyledons than corolliferae (10.77%) and calyciferae (5.64 percent ). Except for glumiflorae, family and order numbers follow host species trends.

Only 5 species parasitize the Magnoliaceae, Annonaceae, and Lauraceae plant families. Magnoliaceae (Magnolales) is plagued by H. dihystera and H. digonicus; Annonaceae (Annonales) by H. anhelicus, H. concavus, H. dihystera; Lauraceae (Laurales) by H. erythrinaeand H. dihystera. H. dihystera parasitizes allthree families. Only H. californicus parasitizes rare families like Tamaraceae and Juncaceae. Amaranthaceae, Clusiaceae and Pedaliaceae are plagued by H. multicinctus; Typhaceae, Pittosporaceae and Vacciniaceae by H. pseudo robustus; Paeoniaceae and Punicaceae by H. erythrinae, etc.

Poaceae has 11 Helicotylenchus species, followed by Fabaceae with 10, Solanaceae with 9, and Asteraceae, Rosaceae, and Rutaceae with 7 each. These plant groups also have the most host plants, indicating a varied feeding habit.

Species-specific taxonomy and phylogeny

Species-specific nature provides a broader perspective. 7 Helicotylenchus species are monocot-specific. Helicotylenchus brevis and H. varicaudatusparasitize musaceae: H. coomansi from Iridaceae and H. canadensis, H. concavus, H. microcephalus and H. zeidani from Poaceae. The lignosae H. cavenessi parasitizes Annonaceae, Fabaceae, Euphorbiaceae, Euphorbiaceae, Euphorbiaceae, Euphorbiaceae, and Oleaceae exclusively. 5 hostspecific herbceae species. H. densibullatus parasitized Lamiaceae, H. australis, H. dihysteroides, H. tunisiensis, and H. willmottae Solanaceae. All the above species are monophagous since they feed on a single family member.

H. macrostylus is oligophagous while others are polyphagous because they parasitize plants from multiple genera, families, and orders.

H. californicus, H. microlobus, and H. pseudorobustus prefer dicotyledons, with 5, 9, and 21 host families, respectively .Three species’ host plants are distant evolutionaryly.

Helicotylenchus dihystera hosts a wide variety of angiosperms, from gymnosperms to dicots and monocots. It parasitizes Cycus sp. (Cycadaceae), Ginkgo sp. (Ginkgoaceae), Araucaria sp. (Araucaceae),Cupressus sp. (Cupressaceae), Abies sp., Pinus clausa, P. cubiensis,P. echidna, P. elliottis, P. paulastris, P. taed (Polypodiaceae). This worm parasitizes the angiosperm families Magnoliaceae, Annonaceae, and Lauraceae. Angiosperm ancestors separated from gymnosperms in the late Triassic (245-202 million years ago). Bowe et al. found that cycads diverged from gymnosperms first, followed by Ginkgo, and then (Gnetales + Pinaceae) was sister to all other conifer families . It implies gnetophytes and angiosperms are comparable. Hutchinson said that Magnoliaceae derive floral structure from foliage leaves like Pinaceae, Cycads, etc . Any gymnosperm H. dihystera eats could be the progenitor of angiosperms and Magnoliaceae (primitive woodyflowering plants) derived from them. Two phylogenetic relationships are obvious with four taxonomic groups:

1.Magnoliales—Delleniales—Rosales—Hamamelidales—Fagales

Ugandales

2.Magnoliales-Delleniales-Bixales-Tiliales-Malvales-Euphorbiales-Rhamnales-Myrsinales-Ebenales

In both evolutionary branches, no host species has been reported for Delleniales and Bixales. Delleniales reveal a connecting link between Magnoliales andRosales, Bixales, etc.

Taxonomic groups including Rosales-Leguminales, Rosales-Cunoniales-Araliales, salicales, Theales-Ericales, and Loganiales-Rubiales offer many host species.

Saxifragales-Solanales-Personales, Saxifragales-Caryophyllales-Onagrales,Chenopodiales, Polygonales are herbceae lineages. Liliales, a monocot stock, gave rise to Graminales, Iridales, Arales, and Agavales-Palmales. In dicotyledons-lignosae, host plants from several orders are chosen, however in herbaceae, Brassicales and its descendants are rejected. In monocots, orders descended from Alismatales (Ranunculaceae) aren’t parasitized.

parasites 6 gymnosperms (Cupressus, Juniperus, Thuja, Pinus, Sequoia) and 62 angiosperms. 34 species are dicotyledons-lignosae, 9 are dicotyledons-herbaceae, and 19 are monocotyledons (1 calyciferae, 7 corolliferae, and 11 glumiflorae). Parasitized lignosae and herbaceae host species range from primitive to sophisticated in their orders. Rosaceae, Fabaceae, and Poaceae dominate. Paeoniaceae (Ranales) is a counterpart to dicotyledon Magnoliaceae (Magnoliales). Gymnosperms are the progenitor of this category. The evolutionary lineage is:

Gymnosperms-Ranales-Saxifragales-Solanales-Personales.

Liliales are monocots’ base stock and give rise to 6 orders. No host other than Zingiberales is parasitized by Commelinales and Alismatales

Helicotylenchus erythrinae feeds on Cycus sp. and Juniperus sp. It parasitizes 88 host species from 77 genera in angiosperms, including 23, 10, 6, 5 and 1 families in dicots and monocots. In both dicot divisions, infestation begins with primitive families like Lauraceae (Laurales) inlignosae and Paeoniaceae (Ranales) in herbaceae and continues to advanced groups. Rosales, Leguminales,Araliales, Salicales, Hamamelidales, Fagales, Jugandales, and Urticales originated from Rosaceous stock, and Loganiales, Rubiales, Myrtales,Rutales, Celastrales, and Sapindales contributed to host range. Herbaceae also like diverse groups. Liliales dominate 5 families in 5 orders, while Zingiberales contributed 5 families. Poaceae plants are most parasitized.

H. multicinctus lacks evolutionary or phylogenetic relationships. It favoured host plants from multiple orders, including dicotyledons and monocotyledons.

Helicotyenchus phylogenetics Subbotin et al. found many species kinds. Helicotylenchus has 9 clades. H. pseudorobustus occupied Clade I, H. digonicus Clades I, V, and X, H. dihystera Clade II, H. multicinctus Clade III, and H. brevis Clade VII. They considered H. rotundicauda to be a synonym of H. dihystera [16]. Subbotin et al. also consider H. rotundicauda and H. dihystera synonyms. West African H. dihystera grouped with H.muticinctus [17]. These samples contained H. microlobus, according to Bae et al. Sher equatedH. microlobus withH. pseudorobustus [18]. H. dihystera, H. digonicus, H. microlobus, H. multicinctus, and H. pseudorobustus favour dicotyledonous plants. Taxonomy supports synonymy. Clade VII H. brevis parasitizes monocotyledons. It has no Helicotylenchus clademates.

The preceding paragraphs’ taxonomic categories of host species are predictive. In endemic locations, this will aid with variety selection, crop rotation, agronomic techniques, and worm management.

Conclusion

Within the framework of John Hutchinson’s classification scheme, a subdivision of the dicotyledons that contains the families of plants that are mostly composed of wood. Herbaceae is a family that is comprised of plants that are predominately herbaceous. The majority of taxonomists hold the opinion that the divide is artificial because it splits families that are normally considered to be closely related to one another, such as the herbaceous Labiatae and the woody Verbenaceae.