Biology︱Dr Tomohisa Fujii Untangling cross resistance patterns in the Using long-term monitoring of susceptibilities

In many countries, rice is a ests within the food industry resistance to one pesticide, imidacloprid staple crop within people’s can lead to great economic (a type of neonicotinoid) varies diets. There are many Ploss. Pesticides such as nerve- throughout countries. By uncovering pests to rice. Of these pests, altering neonicotinoids are used to how imidacloprid resistance can lead to one of the most devastating exterminate the pests and reduce the cross resistance of other neonicotinoids, to crops is the brown risk of yield loss. But resistance and they hope to contribute to effective planthopper. Recently, in Asia, cross resistance are core issues within insecticide resistance management. the brown planthopper has the industry; how does resistance become resistant to various to one pesticide affect the resistance THE BROWN PLANTHOPPER pesticides, including the Rice is a staple crop for people around to another? Patterns of cross resistance The brown planthopper is an insect pest the world. frequently used imidacloprid. are not always clear. of rice (Oryza sativa). It lives in temperate Dr Tomohisa Fujii from and tropical zones of Asia. When these Kyushu Okinawa Agricultural The effectivity of pesticides used target a rice plant the plant loses also make the pest resistant to other and combined this with their own lab from fields that had not been treated Research Center, NARO and to combat the brown planthopper its golden glow and turns brown before , often from a similar type. experiment and field experiment (Fujii by pesticides. The insecticide his colleagues used data ( lugens) has recently been dying. This results in a yield loss which Developing resistance to one substance et al., 2019). Although helpful, field susceptibility was monitored against from three different sources fluctuating in Asia, and Dr Tomohisa can have implications for the farmers, through exposure to a similar substance studies do not allow for the stringent five neonicotinoids: imidacloprid, (datasets, experiments and Fujii and his colleagues wanted to the economy, and people’s diets. is known as cross resistance. manipulation of variables which are thiamethoxam, clothianidin, the field) to discover patterns discover why. They set about collecting The brown planthopper also acts as outside of the farmer’s control. These dinotefuran, and nitenpyram. of cross resistance between long term data about the brown a bridge or ‘vector’ between rice and Neonicotinoids work by targeting the include the external temperature A pesticide (fipronil) from a different imidacloprid and other pesticides from the same class: planthopper’s insecticide susceptibilities two viruses: the rice ragged stunt virus central nervous system (CNS) of insects. of the environment and the genetic class of pesticide (phenylpyrazole) neonicotinoids. and collated them with data from field and the rice grassy stunt virus. Vectors If a mutation occurs that changes the material of the pests themselves. was used as a comparison. and experimental trials to discover the help transmit a virus to its host – in this CNS to make it resistant, it is likely patterns of cross resistance. The team way the brown planthopper has a dual that the insect will become resistant The researchers aimed to see the LAB EXPERIMENT were particularly interested in how effect on plant health. to other CNS-altering insecticides. This “bigger picture” to detect how Laboratory-selected strains of brown has occurred between imidacloprid resistance works within neonicotinoid planthopper which were resistant Like many ailments, prevention is better (a neonicotinoid) and thiamethoxam (and cheaper!) than cure. So farmers (another neonicotinoid). spray their fields with insecticides. Clearly, the relationship between Neonicotinoid and phenylpyrazole INSECTICIDE SUSCEPTIBILITY insecticides have been successful Insecticide susceptibility is a series of pesticides and the brown planthoppers since the 1990s in preventing tests which ensures that pest control that are targeted by them is complex. invasion from the brown planthopper. treatment is still working. If it isn’t However, the effectiveness of some working, it means new, more effective pesticides. They used both field to imidacloprid were produced. neonicotinoids has begun to fluctuate. drugs must be created or farmers and laboratory experiments to make The team applied imidacloprid should change their methods. The this picture as clear and accurate as following the previously developed INSECTICIDE RESISTANCE quantity needed of a certain strength possible. Insects from the Philippines topical application method (Matsumura Resistance occurs when a mutation of pesticide to kill half of the and Vietnam were used due to et al., 2014). This method involves (a change in genetic material) means in an experiment is calculated. The their vastly contrasting genetic anaesthetising females with long wings,

that the insecticide no longer affects result is known as the LD50 level. backgrounds (selection pressures and then applying the substance to the pest being controlled against – this are different in different countries). their thorax. Different concentrations mean the insecticide fails to diminish of the insecticides were tested. The The brown planthopper (Nilaparvata THE SOLUTION lugens) damages and kills rice plants. the numbers of the pest. The mutation Dr Tomohisa Fujii and his colleagues FIELD EXPERIMENT number of brown planthoppers that which leads to the resistance will gathered already existing data Brown planthoppers were gathered had died was recorded after 24 hours.

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Research Objectives References

Dr Fujii examines the effect of neonicotinoids Fujii, T., et al. (2019). Long term field insecticide on the brown planthopper. susceptibility data and lab experiments reveal evidence for cross resistance to other neonicotinoids in the imidacloprid-resistant brown planthopper (Nilaparvata SkyNet33/Shutterstock.com lugens). Pest Management Science, 76, pp.480-486. Detail doi:10.1002/ps.5533 Pesticides are widely used throughout the world to protect crops. 2421 Suya Matsumura M, et al. (2014) Insecticide susceptibilities in Koshi populations of two rice planthoppers, Nilaparvata lugens resistance is tied to nitenpyram and Kumamoto prefecture and furcifera, immigrating into Japan in the period dinotefuran resistance. The researchers 861-1192 2005–2012. Pest Management Science, 70, pp.615–622. The Colorado potato beetle has developed resistance to neonicotinoids... hypothesise that either enzyme activity Japan or chemical structures are causing the differences in resistance. Although Bio Personal Response The adult females that don’t die are The laboratory studies showed the insecticides are all neonicotinoids, Dr Fujii is a researcher at Kyushu Okinawa Agricultural placed into rearing boxes along with that imidacloprid resistance has the chemical structures can alter the Research Center, National Agriculture and Food Do you know whether any affected non-target species some male insects. Mating occurs, a significant effect on insecticide cross resistance. Activity of a particular Research Organization (NARO). To understand have also developed resistance to neonicotinoids? the genes for resistance are passed resistance to thiamethoxam and enzyme, P450, may also influence delaying development of insecticide resistance I do not have any information of non-target species on and a new laboratory-selected clothianidin. Cross resistance to the imidacloprid resistance. and virulence to resistant crops, his studies focus related to neonicotinoid resistance. I know other insect strain is produced. To create a control thiamethoxam and clothianidin is on insecticide susceptibilities and the virulence to pests have developed neonicotinoid resistance. For strain (important so that researchers influenced by imidacloprid resistance. CONCLUSION resistance rice cultivars of the brown planthopper. example, Colorado potato beetle, diamondback moth, can be sure another variable isn’t So, although resistance is a great brown sting bug, cotton , small brown planthopper, and sweet potato have all developed resistance changing behaviour) a similar approach Clearly, the relationship between problem in Asia, the researchers have Funding to neonicotinoids including imidacloprid. The resistance was followed using acetone. pesticides and the brown planthoppers created a series of trials which have A grant from the Genomics-based Technology to neonicotinoids of insect pests is a concern for food that are targeted by them is complex. suggested an achievable and realistic for Agricultural Improvement, PRM06 in the Ministry security in various countries. Monitoring insecticide RESULTS way to help combat it and slow it of Agriculture, Forestry and Fisheries of Japan. susceptibility is important to avoid the risks of overusing In the field, resistance to imidacloprid WHY IS THIS HAPPENING? down. Where there are insects resistant insecticides and developing resistance. was closely tied to thiamethoxam Imidacloprid resistance clearly to imidacloprid and/or thiamethoxam, Collaborators and clothianidin resistance. increases the risk of resistance then dinotefuran and nitenpyram Drs Sachiyo Sanada-Morimura, Masaya Matsumura, Akira However, resistance to imidacloprid to thiamethoxam and clothianidin. can still be used as they will not Otuka, Shoji Sonoda, Dinh Van Thanh, Ho Van Chien, didn’t have much of an effect on However, there is little evidence be influenced by the imidacloprid Phan Van Tuong, Phung Minh Loc, Le Quoc Cuong, Ze- dinotefuran, nitenpyram and fipronil. to suggest that imidacloprid resistance. If resistance increases Wen Liu, Zeng-Rong Zhu, Jian-Hong Li, Gang Wu, Shou- further, policies can be created, Horng Huang, Gerardo F. Estoy, Jr., and Gaku Akiduki. The chemical structure of imidacloprid – it affects the central nervous system of insects. and marketing strategies established to ensure insecticide resistance management is efficient and effective.

Furthermore, more research should be pursued which analyses the bodily processes of the resistant insects. Enzymes in the insects should be further studied, to assist with the management of insecticide-resistant brown planthoppers. In the future, researchers should aim to investigate the cross-contamination patterns of multiple

Source: PubChem https://pubchem.ncbi.nlm.nih.gov PubChem Source: pesticides against multiple species.

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