ABSTRACT
The study investigated the abundance and diversity of insects in a mulberry plantation of Forestry Research Institute of Nigeria, using water trap and physical observation on the plants for four months (May to August, 2013). Results showed a total of 24 insect species from 9 insect orders to be associated with mulberry plants. They included; Hymenoptera, Coleoptera, Hemiptera, Orthoptera, Diptera, Lepidoptera, Araneae, Mantodea and Thysanoptera. Hymenoptera was the most abundant order (40.0%) with diversity index of 0.163 and highest species richness (7). The highest insect density was recorded in June during the period of study. The damaging insect species was relatively high (36%), therefore there is need to embark on routine insect control measures in mulberry plantation to ensure quality and mass production of mulberry leaves which is a prerequisite for a successful silkworm rearing.
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URL: https://scialert.net/abstract/?doi=rjf.2015.58.64
INTRODUCTION
Mulberry (Morus alba L.) of family Moraceae is an exotic and hardy perennial plant. It is a deciduous tree variety that is native to China which was brought to the United States for silkworm production (Sanchez, 2002). There are several species of mulberry plant; Morus alba, Morus nigra, Morus indica and Morus bombycis among others. It is a deep-rooted perennial plant, capable of thriving under a variety of conditions ranging from temperate to tropical region. Several varieties of mulberry plant are under cultivation in Nigeria. The mulberry tree can be grown as low bush, high trunk or deep-rooted tree and as such, could be utilized in afforestation of land and anti-erosion programmes (Adeduntan and Oyerinde, 2010).
Mulberry tree is recognized as food plant for silkworm as well as an economic tree (Jaiyeola and Adeduntan, 2002). Its leaves contains high protein and is also used in cattle feed for milk production (Adeduntan and Oyerinde, 2010). The timber is used for furniture, tool handle and the fruits are used for making wine while the seeds are used for making jam, powder of Morus alba leaves have been used to prepare drink by some people as a healthy diet in Japan but its chemical composition was not known (Shimizu et al., 1992).
Mulberry is also appreciated for its fruit (consumed fresh, in juice or as preserved), as a delicious vegetable (young leaves and stems) for it medicinal properties in infusions (mulberry leaf tea) and for landscaping (De Almeida and Fonseca, 2002). Traditionally mulberry fruits have been used as medicinal agents to nourish the yin and blood. It is beneficial to the kidney and treat weakness, fatigue, anemia and premature graying of hair. It is also used to treat urinary incontinence, tinnitus dizziness, constipation in the elderly and the anemic (Dharmananda, 2003) Mulberry contains plenty nutritious elements, such as minerals and vitamins. It can cure chronic diseases of digestive tract, promote gastric juice secretion and strengthen the ability for digestion and assimilation. It also improve appetite and eliminate abdominal distention and constipation (Dharmananda, 2003).
The perennial nature of mulberry in combination with monocultural practices, encourages several pests development and infestation throughout the year with seasonal differences (Santhi and Kumar, 2010). The production of appreciable quantity and quality mulberry leaf is often hampered by insect pests and disease. A number of pests and diseases cause damage to mulberry tree. The noxious insects of mulberry tree include Coleoptera, Lepidoptera, Hemiptera, Thysanoptera, etc.
Several insects have been identified causing most damage to mulberry plants they include Phenococcus hirsutus (sucks sap of stem, leaf or petiole, causing severe curling and crinkling of leaves and swelling and twisting of apical regions), Pseudodendrothrips ornatissima (thrips) and white grubs and termites (Santhi and Kumar, 2010). In addition to insect pests, pathogens (fungi, bacteria, virus) and nematodes causes damage to mulberry plants. They cause arrays of diseases to the plant ranging from foliar to root diseases. They foliar diseases of mulberry include, leaf spot, powdery mildew, leaf rust and sooty mould while the root diseases include root rot and root knot. More so, many wild rodents of the family Muridae may cause damage to mulberry trees especially on the base of branches.
There is currently dearth information on the insect diversity of mulberry plant in Nigeria. Therefore, this study was aimed at determining the insect diversity of mulberry plant in Ibadan South West Nigeria.
MATERIALS AND METHODS
Study area: The study was conducted at mulberry plantation of Forestry Research Institute of Nigeria (FRIN), Jericho Hills Ibadan, Oyo state, Nigeria. The area is located within latitude 7°26N and longitude 3°54E, the climate of the area is tropical type of climate and dominated by rainfall pattern, the mean total rainfall is about 1420.106 mm and mean maximum temperature is 34.46°C minimum is 21.55°C. Mean relative humidity ranges from about 82% from June to September to approximately 60% between December and February.
Insect sampling: The mulberry plantation was divided into three sub plots, from each sub plot, three plants were selected. Raised platforms were constructed with wooden plank to the height of mulberry canopy on each sub plot. Yellow water trap were randomly placed on the platform. The yellow water trap comprises of plastic bowls measuring 8x6 cm. Soap solution was used as the trapping agent. The soap solution was prepared at the ratio of 95:5 ratio of water to liquid. Observation was also made on mulberry leaves to check for insects. No insecticide was applied during the period of the study. The plot was maintained by weeding manually with cutlass at three weeks interval until the end of the study.
Trap placement: The traps were filled to one-quarter level with the soap water solution in order to break the surface tension and to prevent escape of trap insects. The soap water solution was changed at weekly interval after removal of trapped insects.
Data collection: Data on total number of trapped insects were taken at weekly interval for sixteen consecutive weeks. The trapped insects were carefully removed from the water and transferred to vials containing 30% alcohol and they were later identified at Entomology Section of Forestry Research Institute of Nigeria.
Data analysis: Total number of insects collected was subjected to descriptive statistics. The diversity index was calculated using the formula (Beals et al., 1999):
Where:
ni | = | Individual of each species caught |
N | = | Total number of all species caught |
D | = | Diversity index |
The graph of population dynamics of insects was plotted against each month.
RESULTS
Insect diversity in the mulberry ecosystem in Ibadan: The summary of insect diversity and abundance of mulberry plant as encountered during the study is presented in Table 1.
Table 1: | Insect diversity in the mulberry ecosystem in Ibadan |
A total of 24 insect species belonging to 9 insect order were observed in mulberry plantation in Ibadan. The insect order include; Hymenoptera, Coleoptera, Hemiptera, Orthoptera, Diptera, Lepidoptera, Araneae, Mantodea and Thysanoptera. Hymenoptera with diversity index of 0.163 recorded highest species richness (7), followed by Coleoptera (6) with diversity index of 0.353. Lepidoptera, Araneae, Mantodae and Thysanoptera recorded only one insect species each.
Insect relative abundance in the mulberry ecosystem in Ibadan: The insects relative abundance in mulberry plantation is shown in Fig. 1. Insects species associated with mulberry plant were relatively abundant in the study area. Among the nine insect order encountered, Hymenoptera were most abundant, (40.0%) followed by order Diptera (19.9%) while Thysanoptera (0.07%) was the least abundant order.
Population fluctuation of insects on mulberry plants: The monthly population fluctuation of insect species associated with mulberry plant is shown in Fig. 2. The highest density of insects was recorded in June and it belongs to order Hymenoptera. Hymenopteran density was highest all through the four months of the study.
Fig. 1: | Insects relative abundance in the mulberry ecosystem in Ibadan |
Fig. 2: | Population fluctuation of insects on mulberry plants |
Fig. 3: | Insect pests with proven damaging relationship with mulberry plant in Ibadan |
Diptera recorded highest population in May and reduced through August. Coleoptera on the other hand slightly increased from May to June, declined in July and picked up slightly again in August. The population fluctuation of Lepidoptera, Araneae, Mantodea and Thysanoptera followed the same pattern and were at low densities throughout the period of the study.
Insect pests with proven damaging relationship with mulberry plant in Ibadan: Insect pest with proven damaging relationship with mulberry plant is shown in Fig. 3. Nine insect species were found to be causing damage to the mulberry plant in the study area. They include; Maconellicocus hursutus, Peudodendrothrips mori, Crysolagria cuprina, Migdolus fryanus, Empoasca flavensces, Bactrocera invadens, Podagrica malvae, Melanoplus ponderosus and Romalea microptera. Maconellicocus hursutus (Mealy bug) was the most abundant (28.96), followed by Migdolus fryanus (long horn beetle) (27.46%). Podagrica malvae and Pseudodendrothrips mori (0.25%) each were least among them. All the observed destructive insect species apart from Bactrocera invadens were vegetative pests of mulberry plant. Bactrocera invadens is a fruiting pests of mulberry plant.
DISCUSSION
The order Hymenoptera was the most dominant and largest order. Seven Hymenopterans were recorded. They include: Chrysura refulgens, Camponotus pennsylvanicus, Solenops conjurata, Ampulex compressa, Apis meilifera, Sphecius spheciosus, Monomrium minimum. Santhi and Kumar (2010) reported that hymenoptera was the second dominant order in mulberry ecosystem in south India.
Order Coleoptera was the second largest order, six insect species were recorded; Migdolus fryanus, Euphoria sepulcralis, Coccinellidae magnifica, Chauliognathus pennsylvacus, Podagrica malvae and Anthonomus eugenii. Coccinella magnifica in family of Coccinellidae was beneficial among them. They were seen preying on mealy bugs. Joshi et al. (2003) also reported coccinelids were effective predators of soft bodied insects and they also feed on fungal growth of such as powdery mildew.
Hemiptera was the third largest order observed in the study area. Hemiptera has two sub orders: Homoptera and Heteroptera. Two homopterans and one heteropterans were recorded. Maconellicoccus hirsutus of family Pseudococcidae was dominant among members of this order. Santhi and Kumar (2010) also reported that the family Pseudococcidae was the largest family recorded in mulberry ecosystem among the Hemipterans.
Insects of Orthoptera, Diptera, Lepidoptera, Araneae, Mantodea and Thysanoptera were found in mulberry ecosystem in Ibadan southwestern Nigeria. Among them, Peudodendrothrips mori, (thysanoptera) Bactrocera invadens (diptera) are serious pest of mulberry. Sathyaprasad et al. (2000) and Dandin et al. (2001) similarly reported that Pseudodendrothrips is a major pest of mulberry.
CONCLUSION
Insects associated with mulberry plants in Ibadan South western Nigeria were diverse, hymenopterans were the dominant insects in the mulberry ecosystem. The insect diversity was due to the morphology and the chemical constituents of the plants. Weather condition contributed to the fluctuation of the insects. The insects were either defoliators, pollinators, predators or visitors. The damaging insect species was relatively high, therefore there is need to embark on routine insect control procedures in mulberry plantation to ensure a qualitative and quantitative mulberry production which is a prerequisite for a successful silkworm rearing.
REFERENCES
- Adeduntan, S.A. and A.S. Oyerinde, 2010. Evaluation of nutritional and antinutritional characteristics of Obeche (Triplochition scleroxylon scleroxylon) and several Mulberry (Morus alba) leaves. Afr. J. Biochem. Res., 4: 175-178.
Direct Link - Sathyaprasad, K., D. Manjunath, M.V. Rajan and A. Sarkar, 2000. Screening of mulberry germplasm for tolerance to sucking pests. Proceedings of the National Conference on Strategies for Sericulture Research and Development, November 16-18, 2000, Central Sericultural Research and Training Institute, Mysore, India.
- Shimizu, T., M. Yazawa and N. Takeda, 1992. Aromatic amino acids in the leaves of Morus alba and their possible medicinal value. Sericologia, 32: 633-639.
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Victoria I. Chukwujekwu Reply
Good day,
I came accross the great research you did on the Mulberry tree 'Diversity and Abundance of Insects in the Mulberry Ecosystem in Ibadan South Western Nigeria'. Scientists/Researchers like you project Nigeria and our educational system positively to the world.
I like the Mulberry tree/fruits. I need to plant it. How do I get the seeds/stem to plant.
Kindly respond.
Regards,
Victoria Chukwujekwu
Juliana Amaka Ugwu
Thank you for your comments, You can get mulberry parent stock( stem ) for planting in our research Institute- the Forestry Research Institute of Nigeria. Dr. J.A. Ugwu