Impact of Pesticides on Diversity and Abundance of Predatory Arthropods in Rice Ecosystem

Abstract

Rice (Oryza sativa) is one of the most important cereal crops with a diverse set of pests and natural enemies. Rice fields often support a high diversity of arthropods which contribute significantly to productivity. This diversity is frequently threatened due to indiscriminate applications of pesticides. Our aim was to emphasize on the predator diversity in agrochemical exposed rice field as well as on the impact of surrounding vegetation on beneficial insect diversity. Natural enemies’ data were recorded from randomly selected 10 quadrates by visual observation from each treatment. A total of 5,590 individuals of predators were observed during the study period which included 27 species belonging to 16 families from five orders of arthropods during the kharif season of rice. Statistically, there were no significant differences between the population of general natural enemies such as Odonata, Coleoptera, Hymenoptera, and Araneae in plots with insecticide and control during the different growth stages of rice cultivation. Diversity indices were almost similar in fields where pesticide was sprayed and not sprayed. Our study concluded that natural enemies are conserved by ensuring crop heterogeneity, growing insect-friendly plants (with high levels of nectar and pollen) as border crops, and judicious application of granule insecticide like cartap hydrochloride in a rice agro-ecosystem.