Diversity of Grasshoppers and Locusts, Life Parameters, Fat and Protein Content of Acanthacris Ruficornis in Nakuru County, Kenya

Abstract

Locusts and grasshoppers in order Orthoptera and suborder Caelifera are indicators of ecosystem quality and an important source of nutrients in the food chain. However, there is limited information on the diversity and distribution of various species in the country. This study evaluated the diversity and distribution of grasshoppers and locust species in the ecological zones of Nakuru County, Kenya. Further, the study assessed life history parameters, fat and protein content of Acanthacris ruficornis, the dominant locust species. Specimens collected were identified to species level. Life history parameters study was done on colony of Acanthacris ruficornis reared in aluminium cages at 30ºC temperature and 30% ±2 relative humidity in the insects’ room, Egerton University. Crude fat was estimated using Soxhlet extraction method while crude proteins were estimated using Kjeldahl’s digestion method. A total of 456 individuals were collected and were found to belong to Acrididae family (93.4%) and Pyrgomorphidae family (6.6%). Aiolopus thalassinus was the most abundant (27.4%) and distributed species. Abundance was highest in zone II (47%) and lowest in zone IV (24.3%). Overall Shannon-Wiener diversity index (Hʹ) was 2.38 while zone II, III and IV had Hʹ=2.44, Hʹ=1.37 and Hʹ=1.3 respectively. Overall Simpson’s dominance index (D-1) was 0.125 while zone II, III and IV had D-1= 0.095, D-1=0.313 and D-1=0.254 respectively. Poisson regression showed that diversity and abundance was not significantly different (P ˃ 0.05) among the ecological zones. Percentage similarity index was highest between zone III and IV (3.30) and lowest between zone II and zone IV (1.23). Acanthacris ruficornis laid an average of 158 ± 2.65 eggs per pod which took an average of 35 ± 1.33 days to hatch with a hatching percentage of 91.78 ± 1.00%. 73.97 ± 1.88% of the total nymphs survived to adulthood taking an average of 36.88 ± 2.48 days to reach pharate stage, 54 vii

± 3.61 days to mate and 62.67 ±1.45 days to lay eggs. In terms of crude protein, second nymphs, third nymphs, fourth nymphs and fifth nymphs had 55.2%, 58.14%, 64.09% and 60.38% respectively with 14.53%, 15.07%, 14.84% and 7.71% of crude fat in the same order. Poisson’s regression showed both crude fat and crude protein were significantly different (P˂ 0.05) between the different nymphal stages. Some of the grasshoppers and locusts in Nakuru County were shown while the amount of crude fat and protein recorded in the instars shows that Acanthacris ruficornis has potential as a source of protein and fat for use as food and animal feed when reared in large numbers.