Evaluation of Four Insecticide Formulations for the Management of Flowering and Post Flowering Insect Pests of Cowpea.
ABSTRACT
Field trials on evaluation of four insecticide formulations for the management of flowering and post flowering insect pests of cowpea were conducted in two locations (IAR Research Farm Samaru, Zaria, Kaduna State (Lat.11o 111N and 7o 381N) and Wase.
In Minjibir local government of Kano State (Lat. 12 100 60.001 and 8 400 0.001 E), under rainfed conditions in the Northern Guinea Savannah and Sudan Savannah of Nigeria respectively. Four insecticide formulations: Chlorpyrifos, Chlorpyrifos plus, Dimethoate and Imidacloprid. There was a standard check (Cyperdicot; 250+30 g a.i./ha) and an untreated control.
The treatments were arranged in a randomized complete block design (RCBD) replicated three times. Population of thrips, Megalurothrips sjostedti Tryb, Maruca. Vitrata and Clavigralla. Tomentosicollis were sampled 24 hours before and after each spray for three weeks between 7.00 and 8.00am.
The damage was assessed by counting the number of aborted flowers/plot; seed damage indices (Sdi) was determined by sorting the seed lot from each plot into 3 categories. The results showed that all the four insecticides effectively reduced the population and infestation of insect pests as well as increased the yields compared to untreated control.
Most of the insecticides differ significantly from the standard check (Cyperdicot). The various levels (concentrations) 0.5, 1.0 and 1.5 l/ha were similar in their performance in reducing insects’ population and infestation, pod and seed damage.
Therefore the lower concentration range of 0.5-1.0 l/ha should be used so as to minimise cost and reduce risk of environmental pollution among other hazards. Application of Imidacloprid at 105 g a. I./ha (1.5 l/ha) with almost hundred per cent reduction was most effective in the control of C. Tomentosicollis at both locations compared with other insecticide treatments.
INTRODUCTION
Cowpea (Vigna unguiculata (L.) Walp.) Is an important grain legume in the tropics and subtropics. It is native to central Africa and belongs to the family Fabaceae (Cobley, 1956). Cowpea is eaten in the form of grain, green pods, and leaves (Adejumo, 1997).
The roots are eaten in Sudan and Ethiopia, and the peduncles and stems are used as source of fibres in Nigeria (Adejumo, 1997). Cowpea is known as vegetable meat due to high amount of protein in the grain with better biological value on dry weight basis (Owolabi et al., 2012).
Cowpea grain depending on varieties, for instance, IAR 48 (SAMPEA 7) contains 26.61 % protein, 3.99 % lipid, 56.24 % carbohydrates, 8.60 % moisture, 3.84 % ash, 1.38 % crude fibre, 1.51 % gross energy, and 54.85 % nitrogen free extract (Owolabi et al., 2012).
Cowpea is mainly grown in tropical and sub tropical regions of the world for vegetable and grain and to a lesser extent as fodder crop. It is a very versatile pulse crop because of its smothering nature, drought tolerant character, soil restoring properties and multi-purpose uses.
More than 11 million hectares are cultivated worldwide, 97 % of which is in Africa. Nigeria alone cultivates 4.5 million hectares annually representing over 60 % of total production (FAO STAT, 2011). The crop can be harvested in three stages; while the pods are young and green, mature and green and dry.
It is mostly grown as an intercrop with sorghum, maize and millet (Asiwe, 2007; Voster et al., 2007). Cowpea is usually preferred by farmers because of its role in increasing soil fertility through nitrogen fixation and production of nutritious fodder for livestock (Blade et al., 1997 and Asiwe et al., 2009). Under sole cropping, the potential grain yield is high (1.5 – 3.0 t ha-1), especially, when insecticide was applied.
REFERENCES
African Agricultural Technology Foundation (AATF), (2012). Maruca- Resistant Cowpea Frequently asked question. Nairobi, Kenya www.aatf-africa.org accessed July,2013.
Abalu, G.O.I. (1976). A Note on Crop Mixture under Indigenous conditions. Journal of Developmental Studies 12: 212-220
Adejumo, T. O. (1997). Identification, incidence, severity and methods of control of the causal organism of false smut disease of cowpea Vigna unguiculata L. Walp. Ph.D.Thesis, University of Ibadan, Ibadan, Nigeria. 236pp
Agyen-Sampong, M. (1978). Pests of cowpea and their control in Ghana. In S R Singh, H F van Emden and T A Taylor (eds). , Pests of grain legumes 63pp.
Alabi, O.Y., Odebiyi, J.A. and Jackai, L.E.N. (2003). Field evaluation of cowpea cultivars (Vigna unguiculata (L) Walp.) For resistance to flower bud thrips (Megalurothrips sjostedti Trybom) Thysanoptera: Thripidae) International Journal of Pest Management. 49 (4), 287-291.
Alao, F. O. And Adebayo, T. A. (2011). Comparative Toxicity of Botanical and Synthetic Insecticides Against Major Field Insect Pests of Cowpea (Vigna unguiculata (L) Walp). Journal of Natural Production and Plant Resources 1(3): 86-95.
StudentsandScholarship Team.
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