Effects Of Near-zero Magnetic Field On The Development,Phototaxis And Flight Behaviours Of Two Rice Planthoppers

Many insects have the ability to perceive magnetic field,they can gain the orientation information by using the geomagnetic field(GMF),or make specific biological responses to changes in magnetic field.Previous researches have showed that changes in magnetic field intensity can not only affect orientation behaviour of animals,but can also exert bio-effects on physiology,metabollism and other behaviour of organisms.Insects,as being the largest animal group on earth,are interacting with their surrounding environment.Based on Insect Ecology,it can offer new insight into the magnetoreception and magnetic response mechanisms for insects through exploring the effects of magnetic field strength changes on insects.In this research,we chose the white-backed planthopper,Sogotalla furcifera and brown planthopper,Nilaparvata lugens as the model insect and near-zero magnetic field(NZMF)(vs.GMF)as the environmental factor,to explore NZMF-triggered magnetic field effects on physiological development,phototaxis and flight behaviour.This study reveals magnetic response and adaptative strategy of migratory rice planthoppers to changes in magnetic field intensity,and has filled the gap in magnetobiology of rice planthoppers.The main results of this study are as follows:1.Effects of NZMF on development and reproduction of rice planthoppersWith S.furcifera and N.lugens as model insects,the biological effects on the development and reproduction induced by NZMF(vs.GMF)were studied.Compared with the GMF,the results showed that NZMF significantly extended the developmental periods of eggs and nymphs.Moreover,NZMF significantly reduced the longevity of female adults but significantly extended that of male adults for both S.furcifera and N.lugens.2.Effects of NZMF on wing dimorphism of rice planthoppersIn order to explore the adaptative strategy of S.furcifera and N.lugens to NZMF(vs.GMF),the biological effects on the wing dimorphism induced by NZMF were studied.Compared with the GMF,the results showed that NZMF significantly increased the proportion of brachypterous adult female.furcifera.Also,NZMF significantly increased the proportion of brachypterous adult female and male N.Lugens.3.Effects of NZMF on phototaxis and flight behaviour of rice planthoppersIn this part,with artificial magnetic field-rice planthopper as the research system,the effects of NZMF(vs.GMF)on phototaxis and flight behaviour of macropterous adult S.furcifera and N.Lugens were studied.Compared with the GMF,for the phototaxis behaviour of S.furcifera exposed to magnetic fields for generations,the NZMF significantly increased the percentage of adult females and males that moved towards the light for the first time during the first 2 days.Similar trends has been marginally(but not significantly)found in S.furcifera exposed to magnetic fields in real time.For the phototaxis behaviour of N.Lugens exposed to magnetic fields for generations,the NZMF significantly increased the percentage of adult females that moved towards the light for the first time during the first 2 days.Similar trends has been marginally(but not significantly)found in N.Lugens exposed to magnetic fields in real time.For the flight behaviour,we found that NZMF significantly prolonged flight distance and flight duration,but significantly reduced flight speed of the 2-day-old macropterous female adult S.furcifera.Meanwhile,NZMF significantly shortened the flight duration,marginally increased flight distance,but significantly enhanced flight speed of the 2-day-old macropterous male adult S.furcifera.In the NZMF,the flight duration of male adults is significantly lower than that of female adult S.furcifera,while the flight speed of males is significantly higher than that of females.For N.Lugens,NZMF significantly reduced flight duration of the 2-day-old macropterous female and male adults N.Lugens,but significantly increased their flight speed.In the NZMF,the flight duration of male adult N.Lugens is significantly higher than that of female adults,while the flight speed of males is marginally lower than that of females.