Phitsanulok Rice Research Center, Thailand
In the crop seasons of 2009/2010, Thailand’s rice bowl in the Central Plains suffered huge damages caused by the brown planthopper and the two virus diseases it transmits. An estimated 3.1 million ha were seriously damaged and about 1.1 million tons of rice lost. The government provided US$ 22 million in pesticide subsidies, US$ 28 million as incentives for farmers to delay planting and US$ 3.3 million for farmers to change varieties. In addition, about US$ 275 million might have been lost in export revenues and government spent about US$ 60 million in subsidies, compensations, campaigns and control activities. Thousands of farmers went into debt because of crop failures and loans. (Read: Outbreaks of planthoppers and virus diseases in 2009).
Pitsanulok was among one of the provinces that suffered heavy losses. (Read: Ragged stunt and grassy stunt virus infection in northern provinces of central Thailand). Rice fields were subjected to heavy planthopper attacks because they were vulnerable to invading hopper adults. The lack of essential ecosystem services, like natural biological control elements, made rice fields vulnerable and often this is due to excessive use of insecticides, particularly pyrethoids, in the early season (Read: Spraying for leaffolders increases crop vulnerability). One way to restore biodiversity and ecosystem services is through ecological engineering techniques to increase natural enemy biodiversity.
In Pitsanulok Rice Research Center, we have introduced several species of flowers along rice fields to restore biodiversity. These flowers can serve as food and refuge resources to pollinators such as bees and syrphids and natural enemies of rice pests such as parasitoids. We have grown a total of 200 metres of these flowers along the farm road, the bunds and other non rice areas in the 32 ha farm. Insecticide use has been reduced. We now use only one insecticide application and only when needed. Preliminary monitoring of arthropods showed that there is an increase in bees, syrphids , ladybird beetles, dragonfly, earwigs, spiders and hymneopteran parasitoids and very low planthoppers. However, virus infected plants, although very low numbers, had persisted. We are continuing to monitor planthoppers and other arthropods to conduct a comprehensive assessment of the ecological engineering approach to reduce insecticide use and restore ecosystem services.