Ndam et al.
Greener Journal of Agricultural Sciences Vol. 2 (3), June 2012.
© 2011 Greener Journals
Impact of Insecticide Sprays on Soybean Pests and Natural Enemy Densities at Makurdi, Nigeria.
*1Ndam O.N.; 2Ogunwolu E. O. and 3Manggoel W.
1,3Department of Agricultural Technology, College of Agriculture, Garkawa, Plateau State, PMB, 001, Garkawa, Plateau State, Nigeria.
2 Department of Crop and Environmental Protection, University of Agriculture, Makurdi.
*Corresponding Author’s E-mail: firstname.lastname@example.org
Impact of Chlorpyrifos (50g a.i. /ha), dimethoate (280g a.i./ha), cypermethrin (75g a.i./ha) and cypermethrin + dimethoate (37.5 + 140g a.i./ha) applied at mid – vegetative, 50% flowering and 50% podding on the population of pest and beneficial insect species on soybean was assessed at the Teaching and Research Farm of the University of Agriculture, Makurdi, in 2000 and 2001 cropping seasons. Pest and natural enemy population densities were (i) generally low in both years, and (ii) statistically comparable in sprayed and unsprayed plots. However, in the 2001 cropping season, the number of ants per pitfall trap was significantly (P<0.05) higher under chlorpyrifos than under the control at flowering and podding phases of crop growth. The phytophagous species commonly encountered included Empoasca dolichi Paoli (492 from D-Vac, 3 from pitfall trap), Haliticus tibialis Reut (170 from D-vac, 37 from pitfall trap) and Cicadella nigrifrons Dist. (53 from D-vac, 97 from pitfall trap). Natural enemy species were dominated by ants: Pheidole sp. (7 from D-vac, 1932 from pitfall trap) and Camponotus sp. (1 from D-vac, 80 from pitfall trap). Other predators captured included carabid beetles (72 from pitfall traps only) and spiders. Further studies are needed to confirm low selective pressure of the applied insecticides on beneficial species in soybean.
Keywords: Beneficial insects, phytophagous species, pitfall trap, predators, soybean.