Diversity, distribution and seasonal variations of grasshopper populations in Sialkot, Punjab, Pakistan

The study was planned to estimate diversity, distribution and seasonal variations of grasshoppers in croplands of Sialkot, Punjab, Pakistan. The seasonal variations were assessed by sampling 16 randomly selected sites fortnightly during 2015-2016. The specimens were collected by hand picking and using sweep net. Adult grasshoppers were sampled from each site between 10:00 and 15:00 PST under sunny conditions. The collected specimens were killed, identified and preserved. Data were subjected to statistical analysis and interpretations which indicate the presence of 18 species representing 14 Genera, 8 subfamilies and 3 families. The collected specimens represented sub-family Acridinae (genus Acrida) which were found to be the most abundant (372) followed by sub-family Oxyinae (genus Oxya) with 330 specimens whereas their population was consistent in all study sites. Data indices calculated showed greater richness and evenness of species in the studied area. The higher value of Shannon Index (2.722) showed that greater richness and the evenness of species in the sampled areas. Simpson Index value (0.927) showed dominance in terms of more species diversity. Oxya hyla, Oxya japónica and Hieroglyphus banian were the most abundant species whereas Mermiria bivittata was the least common species. Maximum populations were recorded during July-November (61.39 %) with an increasing trend in population size during these months indicating seasonal variations in their populations around the year. The study suggested that sampled area has well established grasshopper populations which require well-knitted pest management strategies to avert economic losses and conserve biodiversity.