Consequences of pesticide pollution upon the population of Collembola (springtails) in Kashmir apple orchard edaphic ecosystem

Studies were conducted in 2005–07 to evaluate the effect of pesticides sprayed to apple trees on Collembola inhabiting edaphic ecosystem. They constitute one of the predominant groups of soil microfauna after acarina, playing an important role in nutrient flow and enriching fertility of soil. Under Kashmir conditions highest population of Collembola comprising mainly of five genera namely Isotoma, Onychiurus, Hypogastura, Folsomia and Tulbergia occurs in August (1731.3/m²) and May and the lowest (201.9/m²) in February (Shah and Rather, 2008). Soil samples were collected after 10 days interval from sprayed and untreated orchards for extraction of Collembola through Berlese funnel as by Al-Assiuty et al.(2000) in the laboratory. The insects so collected were preserved in 70% alcohol, counted per sample and mounted in Hoyer's medium for identification. Data revealed that Mancozeb 75 WP 0.3% and Bitertanol 25 WP 0.05% (fungicides) had a drastic impact on Collembolan population being significantly high in case of Mancozeb. However, Hexaconazole 5EC 0.03% and Captan 50 WP 0.3% when applied separately had a short lived effect. The treatment of diesel oil emulsion 1:10+ Ethion 50 EC 0.05% reduced the population initially (after 2 days), but it quickly regrew and reached higher than in untreated orchard, 12 days post treatment. Similar result was recorded in case of captan 50 WP 0.3% + Chlorpyriphos 20 EC 0.01% which also significantly declined the population after 2 days but outnumbered the one in unsprayed orchard within 12 days period. Bittertanol 25 WP 0.05% + Dicofol 18.5 EC 0.02% reduced the population constantly. Similarly Ziram 80 WP 0.2% proved most lethal to Collembolans. Thus Collembolans responded differently to various pesticides.