P. K. Kariuki1*, F. J. Toroitich2, G. Ongamo1, J. Nduko3, E. Owino1 and A. King’ori4
1School of Biological Sciences, University of Nairobi, Kenya
2Department of Biological Sciences, Egerton University, Kenya
3Department of Dairy and Food Technology, Egerton University,
4Department of Animal Science, Egerton University, Kenya
*Corresponding Author: firstname.lastname@example.org
Grasshoppers play strategic roles in the ecosystems of recycling of plant nutrients and acting a first order consumers along the trophic food webs. Therefore, their distribution and diversity within an ecosystem signify richness and evenness. Despite their usefulness, very little is known about the diversity, the relative abundance as well as the distribution of Caeliferans in Africa and more so, Kenya. This study was undertaken to understand the species diversity, distribution and abundance of grasshoppers and locusts in the ecological zones of Nakuru County, Kenya. Nakuru County was selected based on having different ecological zones (Forest, grassland and semi-arid for zone I, II and III, respectively) and major economic activity which is agriculture that encompasses both crops and livestock farming. Specimens were captured using a sweep net or by hands and then transferred to a 500 ml Kilner jar, containing a cotton wool soaked with 6.9% diethyl ether concentration for killing. Shannon-Wiener index was used as a measure of species diversity while Simpsons’ index was for species dominance. A total of 456 individuals (Order Orthoptera; sub-order Caelifera) belonging to 2 families and 18 species were recorded during the study period. Acrididae family had six sub-families including Cyrtacanthacridinae, Oedipodinae, Gomphocerinae, Eyprepocnemidinae, Acridinae and Catantopinae while Pyrgomorphidae had one sub family, Pyrgomorphinae. Aiolopusthalassinus species was the most abundant and found in the three ecological zones while Ornithacrispictula, Gastrimagusverticalis and Heteropternis couloniana were the least abundant. Shannon-Wiener diversity index (H’) was recorded at 2.38 overall and 2.45, 1.37 and 1.3 for zone ii, zone iii and zone iv respectively. Simpsons’ abundance index was 0.095, 0.313 and 0.125 for zone ii, zone iii and zone irrespectively. Diversity was found to be significantly different among the three ecological zones at t=0.04 while abundance was not significantly different at t=0.08. Difference in grasshopper diversity between ecological zones was greatly influenced by the difference in range of vegetation available. Therefore, ecological zones affect species abundance and diversity and their conservation is threatened, thus forestry to improve biodiversity conservation should be encouraged.
Keywords: Abundance, Caelifera, diversity, ecological zones, Nakuru County, orthoptera