Effect of Management Practice on ground Beetles (Coleoptera: Carabidae) Assemblages in The Cultivated Land Andorchards of The Kathmandu Valley

Abstract

Carabid community variation wasexamined between agricultural habitats under differentmanagement practices, i.e., organic and conventional. Three cultivated sites, Nagadesh(organic & conventional), Sarswatinagar (Conventional) and Gamcha (Organic) and twoorchards, Kirtipur (Conventional) and Pharping (Organic), all within Kathmandu Valley,were selected for the study. Seasonal variation in carabid abundance and species richnessfor all sites were also studied and compared using pitfall traps. The questions posed were:What is the impact of management practice on carabid beetles between organically andintensively managed cultivated lands and orchards? What are the carabid species living indifferent agricultural habitats within Kathmandu Valley? What is the relation betweentemperature, rainfall and soil variables with carabid abundances? How do these abioticfactors affect the temporal variation in carabid assemblages and abundance? A total of 57 species of carabids were collected during the study and it was found that 18of them wererepresented by just a single specimen and 33 species (58%) by less than 5specimens. Abundance and species richness was higher in organically managed farmsand orchards. Each site had some characteristic species. Least number of species wasrecorded from Kirtipur orchard but non-organic farm at Sarswatinagar had the leastabundance. On the other hand, Organic farm at Nagadesh, not only yielded the largestnumber of species, but also the highest abundance. Habitat specificity was found to behigh among the carabids collected (over 56% unique to a habitat), more in organic farmsand orchards than in their conventional counterparts. Significant positive correlation between abundance and rainfall was found only atPharping orchard while at Nagadesh (non-organic), there was significant correlationbetween abundance and rainfall as well as temperature. For other sites, the correlation ofabundance with both the param was insignificant. In case of various soil param, positivecorrelation was significant only for pH. Carabids were collected throughout the year from most of the habitats, however, theyshowed slight increase in abundance during summer months for organically managedorchard, from August to October for non-organic farms and during February for non-organicorchard, with no records during summer.