Prevalence of Loranthaceae on fruit trees in cocoa agroforestry systems in Daloa (Center-West, Côte d'Ivoire): diversity and extent of infestation

 Corresponding author: Amon Anoh Denis-Esdras. Copyright © 2025 Author(s) retain the copyright of this article. This article is published under the terms of the Creative Commons Attribution License 4.0. Prevalence of Loranthaceae on fruit trees in cocoa agroforestry systems in Daloa (Center-West, Côte d’Ivoire): diversity and extent of infestation Amon Anoh Denis-Esdras 1, *, Sylla Moussa 1, Kouadio Affoue Roseline 1, Soro Kafana 2 and Soro Dodiomon 3 1 Laboratory for Improvement of Agricultural Production, Agroforestry UFR, Jean Lorougnon Guédé University, Daloa, Côte d’Ivoire. 2 Ecology Research Center, Nangui Abrogoua University, Abidjan, Côte d’Ivoire. 3 Botany Laboratory, Biosciences UFR, Felix Houphouët-Boigny University, Abidjan, Côte d’Ivoire. GSC Advanced Research and Reviews, 2025, 25(02), 441-456 Publication history: Received 18 October 2025; revised on 25 November 2025; accepted on 27 November 2025 Article DOI: https://doi.org/10.30574/gscarr.2025.25.2.0353 Abstract Floristic inventories carried out in cocoa agroforestry systems in the peri-urban zone of Daloa identified three species of Loranthaceae: Phragmanthera capitata, Tapinanthus bangwensis and T. globiferus. These parasites affect a diversity of 60 fruit species, divided into 44 genera and 25 botanical families. T. bangwensis proved to be the most frequent and most infective species. The most heavily parasitized families were the Rutaceae (seven species), followed by the Anacardiaceae, Annonaceae and Myrtaceae (six species each). The density of fruit trees in cocoa plantations is estimated at 44.25 ± 13.86 stems/ha. The average incidence of Loranthaceae was 66 ± 7.07% on fruit trees and 40.07 ± 6.93% on cocoa trees. The average severity of infestation was 34.03 ± 8.07% on fruit trees and 33.89 ± 7.29% on cocoa trees. The results revealed that the diameter and height of fruit trees significantly influence their level of infestation by these parasites. They also help to guide the choice of less susceptible fruit species, with a view to promoting sustainable cocoa agroforestry. Keywords: Cocoa; Loranthaceae; Fruit species; Incidence; Infestation severity; Daloa 1. Introduction Agroforestry cocoa farming systems derived from cultivated clearings are systems in which farmers combine multipurpose trees with crops [1]. In these cocoa plantations, useful trees provide significant food products and/or income supplements for farmers [2]. However, in recent decades, these trees, particularly the fruit trees present in cocoa agroforestry plots, have tended to disappear due to overexploitation and felling [3]. Moreover, these trees, like cocoa trees, due to poor agricultural practices, the expansion of Loranthaceae and the parasitic pressure they exert, particularly on trees grown in cocoa agroforestry systems, threaten both food security and crop sustainability. Loranthaceae, described by Ballé & Halle [3], are small epiphytic, chlorophyllous shrubs that live as hemiparasites on the branches of other wild or cultivated trees and shrubs. These clump-like parasitic plants, once attached to the tree branch, anchor themselves in the wood of the latter by means of a sucker that establishes functional links with the conductive apparatus of the host tree [4]. In this way, they extract the water and mineral salts it needs. Their parasitic lifestyle often causes considerable damage to the many wild and cultivated trees and shrubs they parasitize [5]. In cocoabased agroforestry systems, Loranthaceae are widespread, infesting cocoa trees as well as slash trees and various fruit species such as citrus, avocado, cola tree and guava. Already, Sonké et al. [6], in an article entitled "Parasitism of avocado (Persea americana) by Loranthaceae in the Yaoundé region (Cameroon)," expressed concern about a massive attack on avocado trees by Loranthaceae species. Today, as a result of climate change and the abusive destruction of natural plant GSC Advanced Research and Reviews, 2025, 25(02), 441-456 442 formations, these parasitic plants have become a real threat to crops, especially fruit trees and shrubs [7]. However, studies dealing with the diversity and incidence of parasitic Loranthaceae on fruit trees and shrubs in agrosystems in general and cocoa agrosystems in particular in the peri-urban zone of Daloa are almost non-existent, hence the need to conduct this study. The aim of this study was therefore to gain a better understanding of Loranthaceae in order to assess the extent of their infestation on the fruit species present in the various cocoa orchards. The aim was therefore to identify the Loranthaceae species actually present in the various cocoa farms and to measure their impact on the associated fruit species. 2. Materials and methods 2.1. Study site The study was carried out in cocoa farms in four localities around Daloa: Zépréguhé (06°54′09.27′′ N, 06°21′28. 84′′ W), Toroguhé (06°56′41.01′′ N, 06°27′49.77′′ W), Zakoua (06°48′06.24′′ N, 06°27′07.58′′ W) and Bribouo (06°52′09.88′′ N, 06°30′20.45′′ W). Located in center-west Côte d’Ivoire, 400 km from Abidjan, the economic capital, and 140 km from Yamoussoukro, the political capital, Daloa, our study area, lies between 6°52′ and 6°87′ N latitude and between 6°27′ and 6°45′ W longitude (Fig. 1). The vegetation, once made up of immense, dense forests, is now characterized by a mosaic of various types of plant formations and forest fragments or patches [8]. The climate is sub-equatorial, with average annual rainfall of around 1,200 mm [9]. 2.2. Material The plant material consisted of samples of the various Loranthaceae species and their woody fruit hosts present in the cocoa orchards. The technical equipment consisted of a Garmin GPS, BTP tapes, a 50 m decameter, a digital camera, data collection sheets, newsprint, a Suunto dendrometer and pruning shears. The equipment used for data processing includes Excel 2013 spreadsheets and Statistica software version 7.1. 2.3. Methods 2.3.1. Floristic inventory A floristic inventory by surface survey was carried out in the cocoa agroforestry systems in order to assess the fruitbearing woody flora hosting Loranthaceae. In each of the four study localities, five cocoa plantations were selected. For each of them, a 50 m × 50 m plot, i.e., a surface area of 2,500 m² (Figure 2), was marked out to count cocoa trees and parasitized and non-parasitized fruit-bearing woody plants. GSC Advanced Research and Reviews, 2025, 25(02), 441-456 443 Figure 1 Map of study site Circles represent cocoa trees in the plot (healthy trees in green, parasitized trees in blue). The triangles represent individuals of fruit trees associated with cocoa trees (healthy individuals in white, parasitized individuals in red). Figure 2 Surface survey device To ensure an accurate count of all cocoa trees, parasitized and non-parasitized fruit trees and Loranthaceae clumps, each plot was subdivided using BTP tape into ten 50 m × 5 m strips (Figure 2). Parasitized cocoa trees were marked in blue and parasitized fruit trees in red. To ensure that the data were representative, this method was applied twice to 20 cocoa farms selected according to a randomized Fisher design, for a total of 40 surveys. During the surveys, the number of parasitized and unparasitized cocoa and fruiting woody individuals, the number of Loranthaceae tufts present on the hosts, and the Loranthaceae taxa associated with each host were recorded. Herbarium samples of parasites and GSC Advanced Research and Reviews, 2025, 25(02), 441-456 444 parasitized fruit trees were also collected. The botanical nomenclature used was that adopted by Lebrun & Stork [10]. Itinerant surveys complemented the surface surveys to complete the floristic list. They were carried out in all directions in order to inventory Loranthaceae species and parasitic fruit trees encountered, based solely on their presence [11]. 2.3.2. Species identification The identification of the Loranthaceae species inventoried was carried out using the reference work by Ballé & Halle [3], documents by Boussim [5], Soro [12] and the collection of herbarium samples from the Centre National de Floristique (CNF) in Abidjan. For host fruit taxa, their identification was carried out using the papers by Arbonnier [13], Bongers et al. [14] and Aké-Assi [15]. The validity of scientific names, including specific genus and family levels as well as authors, was verified using recognized botanical databases, notably the International Plant Names Index (IPNI) and Plants of the World Online (POWO). 2.4. Analysis 2.4.1. Analysis of floristic data Floristic composition Floristic composition refers to the number of woody fruit species inventoried and their distribution by family and genus. Density of fruit host taxa The density (D) of a taxon, defined as the number of individuals per unit area [16], was calculated for woody fruit species using the following formula: D = n/S with n - number of host stems; S - total plot area in hectares Structural distribution of host fruit trees For each attacked fruit tree, the circumference was measured and converted into diameter using the formula C = 3.14 × d (where C = circumference and d = diameter). The diameters obtained were then divided into five classes [17]: DC1: ≤ 5 cm; DC2: [6-10 cm[; DC3: [11-15 cm[; DC4: [16-20 cm[ and DC5: > 20 cm. With regard to the heights of host fruit trees, three classes were defined [18]: HC1: ≤ 2 m; HC2: [3-4 m[ and HC3: > 4 m. 2.4.2. Analysis of tree size Estimation of the average number of Loranthaceae clumps The average number of Loranthaceae clumps (AnLc) represents the average number of Loranthaceae clumps on parasitized trees in a given biotope and was estimated according to the following formula: Assessment of the extent of Loranthaceae on cocoa and fruit trees The extent of Loranthaceae on cocoa and woody fruit trees in selected cocoa farms was assessed by the incidence and severity of attack. Incidence of Loranthaceae (IL) was calculated according to the following relationship [19]: GSC Advanced Research and Reviews, 2025, 25(02), 441-456 445 To assess the severity of Loranthaceae parasitism on cocoa and woody fruit trees, 40 cocoa trees and 40 fruit trees per cocoa farm were randomly selected and examined for the presence or absence of parasitic taxa. The number of clumps, as well as the number of parasitized and unparasitized trees, was counted and the severity of parasitism was assessed using a scale from 0 to 4 [20] : Score Description 0 - No infection (no parasites) 1 - 1-5 clumps/tree (low infection) 2 - 6-10 clumps/tree (moderate infection) 3 - 11-15 clumps/tree (severe infection) 4 - ≥ 16 tufts/tree (very severe infection) The severity index (SI) for Loranthaceae parasitism was calculated using the following formula [20, 21]: Where a, b, c, d and e represent the number of trees falling into the categories of increasing infestation 0-4. 2.5. Statistical processing Numerical data were organized and plotted using Microsoft Excel 2013. The analysis of the parameters of the degree of parasitism of cocoa and fruit trees was carried out by a one-factor ANOVA using Statistica 7.1 software. In the event of significant differences between means, the Newman-Keuls test at the 5% threshold is used to compare them. 3. Results 3.1. Loranthaceae species encountered A total of three Loranthaceae species were recorded on cocoa and woody fruit species. These were Phragmanthera capitata (Spreng.) Ballé (Figure 3), Tapinanthus bangwensis (Engl. et K. Krause) Danser (Figure 4) and T. globiferus (A. Rich.) Danser (Figure 5). They are divided into two genera, Phragmanthera and Tapinanthus. Figure 3 P. capitata flowering shoot GSC Advanced Research and Reviews, 2025, 25(02), 441-456 446 Figure 4 T. bangwensis flowering shoots Figure 5 T. globiferus flowering shoot 3.2. Average number of Loranthaeae clumps per parasitized tree Analysis of Loranthaceae parasitism, based on the average number of tufts per tree (Table 1), reveals significant differences between parasitic taxa and host types (cocoa and woody fruit trees). T. bangwensis is the most dominant species, with an average of 4015.33 ± 553.94 tufts on cocoa trees and 191 ± 63.80 tufts on woody fruit trees, for a total average number of 2103.33 ± 308.87 tufts per tree. It is followed by P. capitata (815.50 ± 247.46 tufts) and T. globiferus (172.96 ± 391.65 tufts). The results show significant differences between the three parasitic species (F = 51.36; p = 0.000012). Table 1 Average number of Loranthaceae tufts parasitizing cocoa and fruit species Loranthaceae species Number of clumps Average number of clumps/parasite Cocoa trees Fruit species Phragmenthera capitata 1504.50 ± 412.42b 126.50 ± 82.51b 815.50 ± 247.46b Tapinanthus bangwensis 4015.33 ± 553.94c 191 ± 63.80b 2103.33 ± 308.87c T. globiferus 335.67 ± 780.09a 10.25 ± 3.30 172.96 ± 391.65a Average 1871.75 ± 1765.65 109.25 ± 95.25 1030.59 ± 315.99 In the columns, the means assigned the same letters are not different (Newman-Keuls test, p < 0.05). GSC Advanced Research and Reviews, 2025, 25(02), 441-456 447 3.3. Fruit species inventoried The floristic inventory of woody fruit host species present in cocoa trees in the peri-urban zone of Daloa identified 60 host species, 35 of which are wild or spontaneous trees and shrubs (Table 2). Table 2 Woody fruit host species of Loranthaceae in cocoa orchards Families Species Parasite species Tg Pc Tb Anacardiaceae Anacardium occidentale L. - + + Pseudospondias microcarpa (A. Rich.) Engl. - + - Spondias cytherea Sonn. - - + Spondias mombin L. + + + Spondias purpurea L. - - + Trichoscypha acuminata Engl. - + - Annonaceae Annona muricata L. - + + Annona senegalensis Pers. + + + Annona squarnosa L. - - + Monodora myristica (Gaert.) Dumal - - + Xylopia aethiopica (Dunal) A. Rich. - + + Xylopia parviflora (A. Rich.) Benth. - - + Apocynaceae Calotropis procera (Aiton) W. T. Aiton - - + Landolphia dulcis (Sabine) Pichon - + - Bixaceae Bixa orellena L. - + + Bombacaceae Adansonia digitata L. - - + Burseraceae Dacryodes macrophylla (Oliv.) H. J. Lam - + + Caesalpiniaceae Detarium microcarpum Guill. & Perr. - + + Tamarindus indica L. - + + Clusiaceae Garcinia kola Heckel + + + Combretaceae Terminalia catappa L. - + + Euphorbiaceae Jatropha curcas L. - - + Ricinodendron heudelotii (Baill.) Pierre ex Pax - + + Fabaceae Lonchocarpus sericeus (Poir.) DC. - - + Prosopis africana (Guill. & Perr.) Taub. - - + Pterocarpus santalinoides DC. - - + Irvingiaceae Irvingia gabonensis (Audrey-Lecomte ex O'Rorke) baill. - + + Lamiaceae Vitex simplicifolia - + - Lauraceae Persea americana Mill. + + + Loganiaceae Strychnos spinosa Lam. - + + Malvaceae Cola gigantea A. Cev. var. glabrescens Brenan & keay - - + Cola nitida (Vent.) Schott & Endl. - + + GSC Advanced Research and Reviews, 2025, 25(02), 441-456 448 Meliaceae Azadirachta Indica A. Juss. - + + Carapa procera DC. De Wilde - - + Mimosaceae Parkia bicolor A. Chev. - - + Tetrapleura tetraptera (Schum. & Thonn.) Taub. - - + Moraceae Antiaris toxicaria subsp. welwitshii (Engl.) C. C. Berg. - - + Ficus exasperata M. Vahl - + + Ficus lutea M. Vahl - + + Ficus vallis-choudae Del. - + + Myrtaceae Eugenia jambos L. - - + Eugenia malaccensis L. + + + Eugenia miegeana Aké Assi - - + Eugenia owariensis P. Beauv. - + + Psidium guajava Linn. - + + Syzygium guineense (Willd.) DC; - + + Olacaceae Coula edulis Baill. - + - Rubiaceae Coffea robusta Pierre ex A. Froehner - - + Gardenia erubescens Stapf & Hutch. - - + Morinda lucida Benth. - - + Rutaceae Citrus aurantifolia (Christm.) Swingle - + + Citrus aurantium L. + + + Citrus maxima (Burm.) Merr. - - + Citrus limon Burn. f. - - + Citrus reticulata Blanco - + + Citrus sinensis (L.) Osbeck + + + Zanthoxylum zanthoxyloides Lam. Zep. & T. - - + Sapindaceae Blighia sapida C. Konig. - + + Sapotaceae Baillonella toxisperma Pierre - + - Chrysophyllum albidum G. Don - + + Total 7 37 56 Meaning of abbreviations : Pc - Phragmanthera capitata; Tb - Tapinanthus bangwensis; Tg - Tapinanthus globiferus; (+) - Presence of parasite on host; (-) - Absence of parasite on host These species are distributed across 44 genera and 25 botanical families. The families with the highest number of parasitized species are the Rubiaceae, with seven host species, followed by the Anacardiaceae, Annonaceae and Myrtaceae, each represented by six species. Next comes Moraceae with four species, then Fabaceae (three species), Apocynaceae, Caesalpiniaceae, Euphorbiaceae, Meliaceae, Mimosaceae, Sapindaceae and Sapotaceae, each represented by two species (Figure 6). The remaining eleven families have only one species each. Generic diversity is also high, with a total of 44 genera recorded. The Citrus genus is the most represented with six species (or 10% of host species), followed by the Eugenia genus with four host species (or 6.67%), then the Annona, Ficus and Spondias genera, each represented by three host species (or 5%). Finally, two other genera, Cola and Xylopia, each have two host species (3.33%) (Table 1). Among host species, 57 are parasitized by T. bangwensis, 37 by P cacapitata and only 7 by T. globiferus (Table 1). GSC Advanced Research and Reviews, 2025, 25(02), 441-456 449 Figure 6 Distribution of Loranthaceae host fruit families in cocoa plantations 3.4. Density of host woody fruit species in cocoa plantations The average density of Loranthaceae woody host species in cocoa orchards ranged from 30.20 ± 4.65 stems/ha in Toroguhé to 55.60 ± 4.82 stems/ha in Bribouo (Table 3). The highest densities were observed in Bribouo (55.60 ± 4.82 stems/ha) and Zépréguhé (55 ± 5.24 stems/ha), with a high concentration of Loranthaceae host fruit species. In contrast, the cocoa farms at Toroguhé (30.20 ± 4.65 stems/ha) and Zakoua (33 ± 6.96 stems/ha) have significantly lower densities. Analysis of variance (ANOVA) followed by the Newmann-Keuls test revealed a significant difference between mean densities across sites (F = 31.171; P = 0.000001), highlighting two statistically different groups (a and b). The overall average density of host fruit species recorded in all the cocoa plantations studied was 44.25 ± 13.86 stems/ha. Table 3 Density of woody fruit host species in surveyed cocoa farms Sites Cocoa farms density/fruit species (stems/ha)/ cocoa farm Average density/fruit species (stems/ha) Bribouo Cac 1 60 55.60 ± 4,82b Cac2 57 Cac3 51 Cac4 50 Cac 5 60 Toroguhé Cac 1 31 30.20 ± 4.65a Cac2 35 Cac3 24 Cac4 27 Cac 5 34 Zakoua Cac 1 40 33 ± 6.96a GSC Advanced Research and Reviews, 2025, 25(02), 441-456 456 [14] Arbonnier M. (2002). 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