Species composition of parasitoids and predators in two rice agro-farming systems—effect of ecological intensification

Abstract

Ecological intensification through organic farming is known to have an influence on plant communities and diversity of insects associated with them. The comparative abundance of natural enemies was studied in organically as well as conventionally (chemical control) grown aromatic rice at farmer’s field during 2015–2016 and 2016–2017. Different life stages, i.e., egg, larvae and pupae of rice stem borer, and leaf folder, were collected and brought to the laboratory to record natural parasitism in both organic and conventional fields. The population of predators was recorded through sweep nets. The population of spiders was recorded using pitfall traps and sweep net. A total of nine parasitoid species including 3 egg parasitoids (T. chilonis, T. japonicum, and Telenomus sp.), 3 larval parasitoids (Stenobracon nicevillei, Bracon sp., and Cotesia sp.), and 3 pupal parasitoids (Tetrastichus sp., Brachymeria sp., and Xanthopimpla sp.) were recorded. However, the natural parasitism by these parasitoids was significantly higher in organic than conventional rice. Similarly, the population of predators like spiders, dragonflies, and damselflies was significantly higher in organic fields than in conventional fields. The study highlights the significance of conservation of these natural enemies for a sustainable system of rice insect pest management.