Please take a look at the following RG links and PDF attachments.

Article Ecological engineering cropping methods for enhancing predat...

Article Managing Tropical Rice Pests Through Conservation of General...

Article Flora surrounding rice fields as a source of alternative pre...

Rice (Oryza sativa L.) is the important cereal crops of the world and forms the staple food for more than 65 per cent of the world population. Rice production decrease, among various reasons of low production of rice, insect pest complex are one of the major factors for lowering down the yield. Out of nearly 800 insect pest species recorded on paddy, only 18–20 species are major pests in tropical Asia. Of the several management options available, by and large, only pesticides still dominate and serve as the primary component. The largest proportion of the world paddy market is affected by insecticides. There is a rich complex of natural enemies in tropical Asia. These arthropod natural enemies have existed in this environment for thousands of years and have contributed to keep the pest species below damaging levels. Most paddy farmers apply their first insecticide spray 40 days after crop establishment which is aimed to control early season foliage feeding insect pests. Biological control is an important component of integrated pest management programme. It exists as a naturally occurring phenomenon. A large number of biocontrol agents have been recorded on rice pests. Many minor or sporadic pests today probably are kept in check by the action of natural enemies. Biological control is primarily ecology based and therefore, ecofriendly. They are highly host specific natural enemies such as parasitoid and the general feeders like predators, Egg parasitoid Trichogramma japonicum and T. Chilonis, Egg-larval parasitoids Platygaster oryzae (cameron), Among the predacious orders, coleopteran and family coccinelidae (Micraspis hirrashimai & Harmonia octamaculata) is exclusively predacious on rice pests. Dragon flies and damsel flies are amongst the most conspicuous predators associated with irrigated rice fields.

https://www.ijcmas.com/special/7/Munna%20Yadav2,%20et%20al.pdf

Article Predator-prey interactions in rice ecosystems: Effects of gu...

http://krishikosh.egranth.ac.in/bitstream/1/85204/1/th10299.pdf

Here is another article that might be helpful and specifically relates to irrigated rice ecosystems:

Article Conservation biological control: Improving the science base

In which condition Simpson Index, Dominance Simpson Index and Reciprocal Simpson Index are used?