Field-evolved resistance to imidacloprid and ethiprole in populations of brown planthopper, Nilaparvata lugens, collected from across South and East Asia

Rice is the major staple crop for around 50% of the world’s population. Currently one of the most important pests of rice is the brown planthopper (Nilaparvata lugens Stål). This pest has only a very few natural enemies, therefore control has mainly relied upon the application of insecticides. Rice ecosystems across Asia are presently being put at severe risk due to over-reliance on certain insecticides, mainly imidacloprid (neonicotinoid) and ethiprole (phenylpyrazole), which the pest is now showing widespread resistance against. This is not sustainable for the future and much needs to be done to control this destructive pest.

Here we report on the status of insecticide resistance in the brown planthopper across the whole of South and East Asia over the period 2005-2012. Monitoring of field samples showed that resistance to imidacloprid has reached 220-fold in certain strains, and ethiprole resistance 223-fold, (compared with a laboratory susceptible strain). Also most field strains are resistant to both compounds, as well as to pyrethroid insecticides. Monitoring is ongoing in the laboratory to see if this resistance is maintained in the population even in the absence of insecticide selection pressure.

An update will be provided on the resistance mechanisms that have been linked with causing insecticide resistance against imidacloprid and ethiprole.  How this knowledge can be implemented in a more sustainable control strategy will also be discussed.