Pharmacological Properties Of Serotonin System Involved In Feeding Behaviour Of Nilaparvata Lugens St(?)l(Hemiptera:Delphacidae)

Serotonin also known as 5-hydroxytrptamine(5-HT)is monoamine neurotransmitter which is an important regulator of many behavioral and physiological processes in both plant and animal kingdom and ubiquoustly present in the central nervous system.Nilaparvata lugens is still proving difficult to control despite of synthesis of improved insecticides,integrated pest management(IPM)strategies and changes in farming practices.Five distinct waveforms were observed during the feeding process of brown planthopper on sucrose diet using electrical penetration graph technique.Serotonin significantly increased the time of first insertion of stylet into the diet in both 100ppm(26.97±6.07 min)and 1000ppm(89.90±28.97 min).No significance differences were observed in average and total time of ingestion while feeding on serotonin.5-HT receptor antagonist Ketanserin,Mianserin hydrochloride and Yohimbine hydrochloride shows significant increase in non-probing duration in 100ppm dose.Ketanserin caused significant increase in average and total non-probing duration in 25ppm and 100ppm.Mianserin hydrochloride and Yohimbine hydrochloride shows significant decrease in mean percentage of ingestion.About 25%and 31%decrease in ingestion was observed in 200ppm of mianserin hydrochloride and Yohimbine hydrochloride respectively.Methyldopa is the inhibitor of aromatic L-amino acid decarboxylase enzyme which help in synthesis of 5-HT.In 200ppm concentration,mean total non-probing duration was increased and total ingestion duration was decreased during the feeding.29%increased in total time of non-probing was observed as compared to control.Significant duration was increased in first insertion of stylet by brown plant hopper while feeding on 5-HT(1000ppm),Ketanserin(25ppm,100ppm),mianserin hydrochloride(200ppm,400ppm),Yohimbine hydrochloride(200ppm,400ppm)and Methyldopa(100ppm,200ppm).Percent feeding by brown planthopper on Yohimbine revealed that only 25%insects were feed on 200 and 400ppm concentrations.Feeding behaviour of brown plant hopper using electrical penetration graph revealed the role of serotonin system in feeding inhibition of BPH.We conclude from the present study that serotonin system have important role in the feeding of N.lugens.