Differential impact of pesticides and biopesticides on edaphic invertebrate communities in a citrus agroecosystem

Abstract

Edaphic invertebrate fauna is usually exposed directly or indirectly to a wide range of pesticides in agroecosystems worldwide. Very few studies have assessed the negative effects of these pesticides on the diversity and population dynamics of soil invertebrates. In this study, the effect of most commonly used pesticides viz; bifenthrin (a synthetic pyrethroid), spinosad (a bio-insecticide), Aliette (a synthetic fungicide) and Trichoderma harzianum formulation (30x106 cells mL-1; a bio-fungicide) was assessed on soil invertebrate fauna in a citrus agroecosystem. Secondary objective was to compare the impact of synthetic versus biological pesticides and insecticides versus fungicides. There was a significant effect of all pesticides on the population abundance of springtails (F4,14 = 16.53; p<0.001), mites (F4,14 = 12.07; p<0.001) and ants (F4,14 = 16.28; p<0.001). By and large, soil fauna got recovered after two to three weeks post-treatment. Insecticides were more suppressive for soil invertebrates than fungicides. Overall, biological pesticides i.e. spinosad and T. harzianum formulation were less disruptive to soil invertebrate fauna than synthetic conventional pesticides. Hence, keeping in view the key role of soil invertebrates in soil sustainability and crop productivity, the utilization of biopesticides should be encouraged.

Keywords

• bio-pesticides
• fungicides
• insecticides
• population abundance
• soil invertebrates