Botany Research International 6 (1): 01-06, 2013 ISSN 2221-3635 © IDOSI Publications, 2013 DOI: 10.5829/idosi.bri.2013.6.1.503

Plant Parasitic Nematode Communities Associated with Pepper Crops in Aguie Region ( Republic)

1Haougui Adamou, 1 Nouri Kassoum Mamame, 12 Basso Adamou, Doumma Ali and 2 Adam Toudou

1Institut National de la recherche Agronomique du Niger, BP 429 Niger 2Université de Niamey, Faculté des Sciences et Techniques et Faculté d’Agronomie, BP 10896 Niamey Niger

Abstract: Pests and diseases are cited as major biotic constraints to pepper production in Niger. While, insect pests and some diseases are well known, the plant parasitic nematodes communities are ignored. To characterize these communities, a survey was carried out in the Aguie area in the central part of Niger republic (one of the two main pepper growing areas). Soil and root samples were collected from fields and transported into the Laboratory for nematological analyses. Plant-parasitic nematodes belonging to 7 different genera were encountered in soil and roots. High densities of Meloidogyne species up to 45,000 second stage juveniles per gram of roots were recovered from the most affected plants. Tylenchorhynchus sp. and Helicotylenchus sp. were widespread and found in all the sites. But, Xiphinema, Criconemmella, Scutellonema and Tylenchus were found in 3 sites out of 5. The role of plant parasitic nematodes in reducing pepper growth in the Aguie region is discussed.

Key words: Pepper Vegetable Plant parasitic nematodes Niger

INTRODUCTION In sandy soils, plant parasitic nematodes population densities can be very high [3]. For instance Peppers (sweet and hot types) are important in the pepper monoculture system of in the eastern vegetable crops in Niger. They constitute the second part of Niger, sandy soils are heavily infested and yield export vegetable crops after onion. About 5,000 hactares losses are high [4]. In the region of Aguie, peppers are devoted to the crops, with an annual production more production is concentrated in the area of Goulbi Kaaba than 80,000 tons. The main production area is around the which has a long tradition of growing peppers than the Lake Chad in Diffa with nearly 85% of the national other localities. Indeed, this activity dates back nearly 22 production. It is followed by the regions of and years, i.e. since the waters of the river were temporarily Maradi with 6 and 5% respectively [1]. Apart of the detained by Nigeria. In recent years, producers have been production is sold in local markets, but the larger part is facing serious problems caused by an un-identified exported to Nigeria, providing substantial amount of disease [5]. No control measure has been proposed. foreign exchange to the country. The value of this However, all observations made by the extension production now exceeds five billions of FCFA (Boukari, workers tend to incriminate plant parasitic nematodes. INRAN, personal communication). The management of the Kana-Katina-Maradi Project Despite of the importance of the crop to the national has included the resolution of this problem in their economy, rather limited attention is paid to problems program of as a top priority activity. The present study is limiting the production of peppers. In general, plant heath a part of the Kana-Katina-Maradi Project program. Its problems, particularly those caused by nematodes have objective is to characterize the communities of parasitic been neglected. Nematodes are well known as one the nematodes associated with peppers in the Aguie project most important pests limiting vegetable production [2]. area.

Corresponding Author: Haougui Adamou, Institut National de la recherche Agronomique du Niger, BP 429 Niamey Niger. 1 Bot. Res. Intl., 6 (1): 01-06, 2013

Fig. 1: Location of the survey area.

MATERIALS AND METHODS Abundance (A) of a nematode species is the average density per sample in which the nematode Five sites in the KKM project intervention zone, was found and calculated by using the following Golom, Gourjia, Assaya, Birnin Kouka and Jan kouki were formula: selected for the survey in 2009 (Fig. 1). Samples of soil X and roots were taken randomly from the pepper farms in A = ∑ i the rhizosphere of plants, according to the method of [6], e at a depth of 5-20 cm using a trowel. Each sample was composed of three sub-samples (2 kg of wet soil + roots) Where Xi = number of nematodes per liter of soil or gram and was placed in a plastic bag and sent to the of root, e = number of samples in which the given Nematology Laboratory of the Regional Centre for nematode was present. Then the A values were log Agronomic Research of Kollo. transformed. A species is considered abundant and Nematodes were extracted from the soil and frequent when it was present in at least 30% of samples roots by the Seinhorst methods [7, 8]. Soil nematodes with at least 300 individuals per liter of soil or 20 were extracted from 250 cc of soil collected from each individuals per gram of dry root. sample. After extraction of root nematodes, roots were dried and their dry weight was recorded. The importance RESULTS of each species or genus of nematodes has been determined from the Fortuner and Merny Diagram of Parasitic Nematodes Encountered: All five sampled sites Frequency / Abundance of [9]. The frequency (F) is the were infested with plant parasitic nematodes. In this study percentage of samples that contain a given species or seven genera of parasitic nematodes, Meloidogyne, genus. This parameter was calculated by using the Tylenchorynchus, Scurtellonema, Xiphinema, Tylenchus, following formula: Helicotylenchus and Criconemella, were found in the rhizosphere of pepper (Table 1). e F = ×100 These nematodes belong to six different n families, grouped in the orders of Tylenchida and Where e = total number of samples containing a given Dorylaimida. Species of Meloidogyne are sedentary species of nematode and, n = total number of samples at endoparasites while the six others are migratory given site. ectoparasites.

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Table1: Grouping of species of parasitic nematodes found on peppers in the area of Aguie, during a survey conducted in 2009. Orders Families Genera Species Belonolaimidae Tylenchorhynchus T. indicus Criconematidae Criconemella C. curvata Tylenchida Tylenchidae Tylenchus Tylenchus sp Heteroderidae Meloidogyne Meloidogyne spp Hoplolaimidae Helicotylenchus H. dihystera Scutellonema S. clathricaudatum Dorylaimida Longidoridae Xiphinema X. elongatum

Table 2: Genus distribution of parasitic nematodes according to the five sampled sites. Sites Meloidogyne Tylenchorynchus Criconemella Scutellonema Helicotylenchus Xiphinema Tylenchus Golom + + - + + + + Gourjia + + + + + + - Assaya + + + - + + + B.Kouka + + + + + - - J.Kouki + + - - + - + Legends : + = present and - = ab

Fig. 2: Importance of parasitic nematodes at Golom site. Fig. 5: Importance of parasitic nematodes at Birni kouka site.

Fig. 3: Importance of parasitic nematodes at Gourjia site.

Fig. 6: Importance of parasitic nematodes at Jan kouki site. Nematode genus

and Tylenchus sp (Table 2); but only two of them, Meloidogyne sp. and H. dihystera, were both frequent and abundant. Tylenchorynchus was frequent but not abundant. The other three species i.e. Scurtellonema, Xiphinema and Tylenchus were neither frequent nor Fig. 4: Importance of parasitic nematodes at Assaya site. abundant (Fig. 2).

Quantitative Analysis Gourjia: Six species of parasitic nematodes, Soil Nematodes Meloidogyne sp, X. elongatum, T. indicus, H. dihystera, Golom: In this site, six species of plant parasitic S. clathrycaudatum and C. curvata, were also found in nematodes were encountered: Meloidogyne sp, T. this site (Table 2). Meloidogyne and Xiphinema indicus, S. clathrycaudatum, H. dihystera, X. elongatum were frequent and abundant. Tylenchorynchus,

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Table 3: Number of juveniles of Meloidogyne genus in the roots of pepper according to the 5 sampled sites. Sites Abundance (juveniles/gram of root) Frequency (%) Golom 7860 100 Gourjia 45128 50 Assaya 23960 100 Birni Kouka 596 67 Jan kouki 19720 67

DISCUSSION

The results clearly indicate that peppers were seriously infected by nematodes in all the sites of the KKM-Aguie Project. Seven plant parasitic nematode species have been identified. With the recorded number Fig. 7: Structure of parasitic nematodes communities in of nematodes on the pepper, the sites present a relatively the 5 sites. low biodiversity compared to results obtained in the rhizosphere of pepper by other authors in Niger [4, 10]. Helicotylenchus and Scutellonema were common but not In clay-loamy sites and tidal plains of Gabagora abundant. Criconemella was neither frequent nor Kareygorou near Niamey, the first author recorded over abundant (Fig. 3). 15 species infecting pepper and in a study conducted in the major vegetable growing sites of Niger. The second Assaya: Five species of plant parasitic nematodes were author counted up to 20 species of parasitic nematodes. encountered in soil samples taken from this site (Table 2). The low biodiversity means that the nematode community Only Meloidogyne and Xiphinema species were both is dominated by few species of nematodes that appear frequent and abundant. T. indicus and H. dihystera were particularly adapted to the agroecosystem of Aguie. frequent but not abundant while C. curvata is neither According to the frequencies and abundances diagrams, frequent nor abundant (Fig. 4). nematodes appear to be very important and therefore being a limiting factor to pepper production in this area. Birni Kouka: Four species have been found, (Table 2), The group of root-knot nematodes, Meloidogyne sp is the but only Meloidogyne sp was both frequent and most important plant parasitic nematode of the pepper abundant. The others species were all frequent without because it was e ncountered in both soil and roots. being abundant (Fig. 5). They were found in 100% of samples in all sites at very high population levels. These densities are among the Jan Kouki: Like the previous site, only four species were highest in the country. encountered (Table 2). Three of them, Meloidogyne sp, H. The widespread distribution of nematodes dihystera and Tylenchus sp were both frequent and through the area may be due to an exchange of plant abundant while, C. curvata was frequent but not materials from one region to another. Throughout the abundant (Fig. 6). region, trade of seedlings is an activity performed by The nematodes communities’ structures are several farmers. Indeed, seedlings of pepper and onion are presented in Fig. 7. Meloidogyne sp appears to be the subjected to an extensive trade between the villages most dominant parasitic nematodes in the soil. Their concerned by the project and the neighboring villages of relative density varied from 45.51% in Golom to 97.40% in Nigeria. Assaya. The second most important parasitic genus was One most important reason for the persistence of Helicotylenchus in Golom, Birnin kouka and Jan kouki nematodes in the plots is the occurrence of tree species where it’s relative density was respectively 22.80, 20.85 such as Adansonia digitata, Prosopis juliflora and and 31%. Moringa oleifera in the majority of sites. These tree species are known as hosts to many species of Root Nematodes: The extraction of nematodes from root nematodes, but they don’t express any symptom even if revealed only one species, Meloidogyne sp. Results are roots are severely infected. So they are permanent shown in Table 3. sources of proliferation, re-contamination and spread of

4 Bot. Res. Intl., 6 (1): 01-06, 2013 several species of nematodes including root-knot species like Adensonia digitata, Moringa oleifera and nematodes belonging to the genus of Meloidogyne Prosopis juliflora, because they provide hospitality to [11, 12]. many species of parasitic nematodes. On several plots of Gourjia, plants exhibited apparently normal growth. However, in other sites, the ACKNOWLEDGMENTS pepper plants were stunted and strongly chlorotic in correlation with high densities of nematodes. Similarly, in The authors thank the Director General of the some plots at Assaya and Golom, nearly 20% of plants Institute of Agronomic Research Institute of Niger were dead before fruiting and the rate of wilted plants was (INRAN) and the Kano-Katina-Maradi Project 47%. This result is similar to those obtained in the Coordinator for financing the study. Thanks are also due region of Diffa [5]. to Bizo Mahamadou and Abdoul Rachid for helping with Diseased samples were collected for further analysis. the planning and implementing of the sampling. In 60% of the samples, the vascular tissues presented a brown discoloration. This was an indication of the REFERENCES presence of a vascular pathogen, Ralstonia solanacearum (a bacterium) or Fusarium oxysporum 1. Djibey, A., 2012. Caractérisation des communautés (a fungus). The Laboratory analysis confirmed the de nematodes parasites associées au poivron à presence of these two pathogens from the diseased Dosso et Diffa et reaction de deux ecotypes de samples. Thus, the severity of the attack could be poivron et de Pasteuria penetrans vis à vis de attributed to a synergistic interaction between the Meloidogyne javanica. Mémoire d’ingénieur en nematodes and the vascular wilt pathogens, R Protection des Végétaux, Centre Garhymet de solanaceraum and F. oxysporum. This represents a major Niamey, Niger, pp : 55. threat to pepper and other vegetables cropping in the 2. Haougui, A., A. Domma, M. Toufique and A.I. Kollo, area. 2011. Survey of plant parasitic nematodes associated The severity of damage caused by nematodes with sweet potato in Niger. Asian J. Agric. Sci., may have also been accentuated by the sandy texture 3(1): 32-36. and low organic matter content that predispose plants to 3. Noe, J.P. and R.A. Sikora, 1990. Effects of tropical attack by nematodes. Under these conditions, even low climates on the distribution and host-parasite population densities of nematodes could severely damage relationship of plant parasitic nematodes. In: Plant the plants as the mineral supply is hampered [3, 13]. parasitic nematodes in subtropical and tropical Finally, the monoculture of peppers for two decades in agriculture, Eds. Luc M. R.A. Sikora and J. Bridge. this zone has resulted in increased parasitic nematodes CAB International: London, pp: 583-597. population densities, especially those of the root-knot 4. Haougui, A., 1999. Les nématodes parasites des nematode, which greatly exceeded the damage threshold cultures maraîchères au Niger : importance et levels [14]. méthodes de lutte par utilisation de plantes. Thèse de doctorat en zoologie agricole, option CONCLUSIONS nématologie, CARFOP/Université de Dschang, Cameroun, pp: 114. In this survey conducted in the Kana-Katina-Maradi 5. Doumma, A., A. Haougui, B.M. Toufique, I. Adamou Project area of Aguie, the plant-parasitic nematodes and N. Gani, 2008. Phytosanitary diagnostic of sweet associated with pepper have a relatively low biodiversity potato in Niger. UAM project/phase 1 report. since only seven species were found in the rhizosphere of 6. Barker, K.R., 1985. Sampling nematode communities. the plants. The genus of Meloidogyne appears to be the In: An advanced treatise on Meloidogyne, Vol. 2: most important nematodes parasites of pepper in this Methodology, Eds. Barker; R. K. R. Carter, J. N. zone. It is widespread in all the 5 sites of the project area SASSER. North Carolina State University Graphics: with a relatively high abundance. Based on the Raleigh, USA, pp: 3-14. importance of damages caused by these root-knot 7. Seinhrst, J.W., 1950. De beteckenic van de tostand nematodes to pepper, it is important to train farmers with van de gron²d voor het optreden van aan stasing techniques of growing healthy seedlings. They should door het stengelaaltje Dytilenchus dipsaci (Kuln also be trained to avoid planting peppers close to tree filijev).tijidschr. pl/zeikt. 56 : 291-349.

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