Bio-ecology of the acridid genus Oxya in selected agro-ecosystems of Southern Rajasthan
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Date
2012
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MPUAT, Udaipur
Abstract
Investigations on the bio-ecology of the acridid genus Oxya in selected agro-ecosystems of Southern Rajasthan were carried out in the Department of Entomology, Rajasthan College of Agriculture, MPUAT, Udaipur, with the following objectives (i) Survey of the acridid fauna in the agro-ecosystems of Southern Rajasthan; (ii) Estimation of the qualitative and quantitative abundance of acridid genus Oxya in paddy; (iii) Studies on the biology, taxonomy and food preference of the dominant Oxya species; (iv) Evaluation of the management strategies for Oxya spp. in paddy nurseries.
Surveys conducted in the five crop ecosystems of Banswara, Chittorgarh, Dungarpur, Pratapgarh and Udaipur districts of Southern Rajasthan during 2008-09 and 2009-10, resulted in the collection of 10 acridid species from paddy, maize, sugarcane and sorghum crop ecosystems; while, 7 acridids from soybean crop ecosystem. Among the surveyed crop ecosystems, the acridid species diversity was maximum in sorghum and sugarcane ecosystem with the Shanon Weiner Diversity Index being 2.219 and 2.199 for sorghum; followed by 2.205 and 2.207 for sugarcane during 2008-09 and 2009-10, respectively. Soybean ecosystem was least diverse with diversity index of 1.827 and 1.767 during 2008-09 and 2009-10, respectively. The acridid monthly mean and relative density values varied considerably among these crop ecosystems. The population of acridids and their biological activity was observed to be maximum from July to October months.
In paddy, the numerical abundance of Oxya spp. was significantly higher during July in both the years; however, their occurrence differed significantly district-wise only during 2008-09. During the present study, six species of the genus Oxya viz., Oxya fuscovittata (Marschall) Oxya intricata (Stål), Oxya rufostriata Willemse, Oxya nitidula (Walker), Oxya ebneri Willemse and Oxya hyla hyla Serville could be recognized.
* Ph. D. Scholar, Department of Entomology, RCA, Udaipur
** Associate Professor, Department of Entomology, RCA, Udaipur
Studies on the biology of rice small grasshopper evinced that the mean development period from egg to adult was 70.15 days and the adult females lived a little longer (40.70 days) than the males (37.50 days). A single female could lay about 2 egg pods with an average of 23 eggs per pod that had a hatchability of 67.46 per cent. The mean duration of different nymphal stages from I through V was 51.85 days where the duration of nymphal stage I was the shortest (7.20 + 0.23), while that of the nymphal stage V was the longest (13.10 + 0.30). Growth and development of Oxya fuscovittata (Marschall) was best on Oryza sativa L. ranking first followed by Cyperus rotundus L. ranking second; resultantly, the developmental period on O. sativa, manifested by hopper duration, was the lowest; the survival was 100 per cent; consequently, the growth index was the highest during both years. The food utilization indices, efficiency of conversion of ingested food (ECI), approximate digestibility (AD) and efficiency of conversion of digested food into body substances (ECD) were the highest when the grasshopper (O. fuscovittata) was fed on O. sativa.
In an effort to evaluate the management strategies for Oxya spp. in paddy nurseries, Fipronil (0.02%) was observed the best treatment when applied on unweeded paths around the paddy nurseries.
Description
Bio-ecology of the acridid genus Oxya in selected agro-ecosystems of Southern Rajasthan
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Citation
Pareek and Sharma, 2012