African Journal of Natural Sciences 2014, 17, 37 - 47 Njila et. al.: Abundance and distribution of adult and juvenile stages of soil microarthropods along the Western bank ISSN: 1119-1104 ABUNDANCE AND DISTRIBUTION OF ADULT AND JUVENILE STAGES OF SOIL MICROARTHROPODS ALONG THE WESTERN BANK OF RIVER BENUE IN ADAMAWA STATE NORTH-EASTERN NIGERIA 1*Njila, H. L, 2Mwansat, G. S, 3Imandeh, G. N. and 1Onyimba, I. A. 1Department of Science Laboratory Technology and 2Department of Zoology, University of Jos, P. M. B. 2084 Jos, Nigeria 3Department of Biological Sciences, University of Agriculture, Makurdi, Benue State, Nigeria Email: [email protected]; [email protected] (Received January 2014; Accepted August 2014) ABSTRACT Adult and Juvenile stages of microarthropods are important pests of agricultural crops. Thus, this study was aimed at investigating their abundance and distribution in relation to habitat integrity and season along the bank of River Benue in Adamawa State, North-eastern Nigeria. Soil was collected from eighteen villages situated along the river bank between 2008- 2010. Samples were taken from 0-10cm soil depth from three habitat types using a soil corer of diameter 8.5cm. The dry behavioural extraction method using Berlese-Tullgren funnel extractor was used to extract microarthropods from soil and litters. A total of 7,632 microarthropod individuals distributed in 4 classes, 20 orders, 63 families, 70 genera and 26 species were extracted from 540 soil samples. Habitat type had a significant effect (Kruskall- wallis test, df = 2, χ2 = 10.40, P = 0.001) on mean abundance of adult and juvenile stages of microarthropods. The Abundance of adults and juveniles were significantly lower with increasing habitat disturbances, thereby confirming the negative effect of the several anthropogenic activities along the western bank on natural selection. There was also a significant difference (One-way ANOVA for dry season: F1,16 = 17.14, P = 0.05; One-way ANOVA for wet season: F1,17 = 19.42, P = 0.05) in the abundance of adult and juvenile stages of microarthropods during the dry and wet seasons. The highest abundance observed only in the natural uncultivated soil underscores the importance of the western bank of river Benue in Adamawa state for conservation and calls for better protection and management. INTRODUCTION soil inhabiting arthropods in various ways, Microarthropods are an integral part to a the degreee of change on the ecology of the functioning ecosystem and perform such numerous arthropod species in the soil has roles as detritivores, herbivores, prey and hardly been measured ( David and William, predators (Cole et al., 2006 and Njila et al., 2005). The aim of this research work is to 2013). Soil microarthropods aid in establish the seasonal abundance and regulating the rates of nutrient cycling, distribution of adult and juvenile stages of decomposition and energy flow (Stephen et soil microarthropods, in relation to habitat al., 2006). Their disturbance, therefore, can and season along the western bank of River alter or disrupt these essential ecosystem Benue in Adamawa State, North-Eastern processes (Adejuyigbe et al., 2009; Nigeria. Gbarakoro et al., 2010). Even though anthropogenic activities such as agro-horti- silvicultural practices are known to affect 37 African Journal of Natural Sciences 2014, 17, 37 - 47 Njila et. al.: Abundance and distribution of adult and juvenile stages of soil microarthropods along the Western bank MATERIALS AND METHODS Demsa, L.G.As which lie between Latitude Study Area 9029'53.67'' and 9°30'53.80''N and Longitude River Benue is a major river in Adamawa 12051'48.69'' and 12°58'87.52''E (Jen, 2004). State flows from the highlands of Cameroun Villages situated by the river bank in each southward through Lamurde, Numan, L.G.A. were used as sampling sites (Figure Demsa, Fufore and Yola Local Government 1). The criterion for choosing a village was Areas (L.G.A.) of Adamawa state to based on anthropogenic disturbances such as confluence with River Niger at Lokoja, after intensive agricultural activities, grazing and passing through Taraba and Benue states. burning of vegetation. A total of eighteen The study covered only Lamurde, Numan, villages were selected. Figure 1: Map of the Sampling Sites (Source: Nigeria SatX National Remote Sensing, Jos) Collection of Soil Samples collecting samples from dry portions of the Soil samples were collected from 0-10cm river bed (after the water has receded) soil depth for two seasons between 2008- precisely 50 meters away from the 2010 from natural soil (This involved riverbank-It was not surveyed during the wet collecting soil samples from natural and season) using a soil corer of mouth diameter uncultivated soil), cultivated soil (This 8.5cm. All soil samples collected were involved collecting samples from cultivated bagged in polythene bags, labeled according areas) and free river bottom (This involved to locations and conveyed to the laboratory 38 African Journal of Natural Sciences 2014, 17, 37 - 47 Njila et. al.: Abundance and distribution of adult and juvenile stages of soil microarthropods along the Western bank for extraction, identification, quantification 0.02% Smaris species, 0.02% Rabidosa and classification of arthropods. rabida, 0.02%, Nicoletia species, 0.02% Coccinella septempunctata and 0.02% Extraction Procedure Geophilus flavus as species with the least In the laboratory, the Dry Behavioural abundance of adult stages (Table 1). Extraction Method using Berlese-Tullgren Similarly, the checklist of juvenile stages Funnel Extractor (Crossely and Lair, 2001) revealed 12.87% Alaus species, 11.87% was used to extract the microarthropods Paederus species and 5.86% Phlebotomus from soil samples. After full extraction, species as species with the highest which lasted for 72 hours, the abundance of juvenile stages (Table 2). microarthropods collected were sorted, Species with the least abundance of juvenile identified and counted under Dissecting stages were Tetranychus urticae (0.05%), microscope (WILD-MSA WEERBRUGG). Allotrochosina species (0.05%), and They were identified, grouped and classified Urothrips species (0.05%). 35 adults were into orders, families, genus and species identified only to the Family level (Table 1), levels using colored atlas and identification while 281 juvenile individuals majority of keys provided by Evans et al. (1967), which were members of the Family Gizimek (1972), Castner (2000), Norton Curculionidae could not be identified beyond (2000) and Wolley (2000). the family level (Table 2). There is a significant difference (Kruskall- Statistical Analysis 2 Microsoft excel, Statistical Package for wallis test, df = 2, χ = 10.40, P = 0.001) in Social Sciences (SPSS) 2001 506 /id the seasonal abundance of adult and juvenile software and R-console software (version 2. stages in the three habitat types studied as 9. 2) were used for data analyses. The data showed in Figures 2 and 3. Natural was tested with One-sample Kolmogorov- uncultivated soil recorded the highest Smirnov test (Wilkinson, 1990) and the abundance of both adult and juvenile stages Levenne’s test for equality of variances to of microarthropods during the two seasons, satisfy the assumption of test model (Fowler while the free river bottom had the least and Cohen, 1995). Kruskal- Wallis test was abundance in the dry season. There was no used to test Adult and Juvenile abundance free river bottom sample during the wet between the three habitat types. One way season. ANOVA was used to test Adult and Juvenile There is a significant difference (One-way abundance in the dry and wet seasons ANOVA: F , =20.36, P=0.05) in the respectively 1 16 abundance of both adult stages between seasons as shown in Figure 4. The same RESULTS trend was observed in juvenile abundance, A total of 7,632 microarthropods were also shown in Figure 4 (One-way ANOVA: extracted, out of which 5,703 (74.72%) were F , =18.42, P=0.05). Comparison of mean adults (Table 1) and 1,929 (25.28%) were 1 17 abundance of adult and juvenile stages of juveniles (Table 2). The checklist of adult microarthropods within seasons showed stages depicted 20.55% Eremulus species; significant differences (One-way ANOVA 18.50% Messor species and 7.22% for dry season: F , =17.14, P= 0.05; One- Entomobrya confuse as species with the 1 16 way ANOVA for wet season: F , =19.42, highest abundance of adult stages, while 1 17 P=0.05) as shown in Figure 4. 39 African Journal of Natural Sciences 2014, 17, 37 - 47 Njila et. al.: Abundance and distribution of adult and juvenile stages of soil microarthropods along the Western bank Table 1: Checklist of Adult Stages of Soil Microarthropod Biodiversity along the Western Bank of River Benue in Adamawa State North- East Nigeria Order Family Species NS CS FRB Total (%) Acarina Oribatidae Eremulus spp 646 525 1 1172 20.55 Nothrus spp 261 - - 261 4.58 Carabodidae Carabodes spp 17 3 - 20 0.35 Damaeidae Epidamaeus spp 31 21 - 52 0.91 Epilohmannidae Epilohmannia spp 109 46 - 155 2.72 Acaridae Acarus siro 2 142 - 164 2.88 Acarus rhombeus 284 - - 284 4.98 Tetranychidae Tetranychus urticae 32 9 - 41 0.72 Gamasidae Pergamasus crassipes 15 8 - 23 0.40 Smaridiidae Fessonia papillosa 1 - 3 4 0.07 Smaris spp 1 - - 1 0.02 Mesostigmata Trombidiidae Dinothrombium spp 60 39 144 243 4.26 Sarcoptidae Sarcoptes spp 2 5 51 58 1.02 Araneae Thomsidae Sidymella spp 13 4 - 17 0.30 Lycosidae Allotrochosina spp 4 3 - 7 0.12 Rabidosa rabida - - 1 1 0.02 Collembola Entomobryidae Entomobrya spp