Abstract: 【Aim】 Organisms (including migratory insects) on the earth are constantly affected by the geomagnetic field (GMF). The migratory insects can have a long distance migration, and there is a perceptible difference in the GMF intensity between the emigration and immigration regions, which affects the population fitness of migratory insects. This study was carried out to clarify the magnetobiological effect on migratory insect populations so to help predict the occurrence of migratory insect pests. 【Methods】 The GMF intensities of the spring emigration (Guangzhou city, GMF 45 μT) and immigration (Nanjing city, GMF 50 μT) regions of the brown planthopper, Nilaparvata lugens, a migratory pest, were simulated by the DC-type helmholtz coils, respectively, and the changes in the growth, development and reproduction of N. lugens in response to the GMF intensity change between the emigration and immigration regions were investigated. 【Results】 The results showed that in the immigration region (GMF 50 μT), the egg duration of N. lugens was slightly shortened (0.50%), the egg hatching rate was significantly enhanced (6.11%), the developmental duration of female and male nymphs was lengthened by 5.26% and 2.37%, respectively, the body weight of the newly emerged female and male adults was increased by 0.66% and 9.56%, respectively, and the developmental duration of female and male adults was shortened by 35.34% and 26.15%, respectively, as compared with those in the emigration region (GMF 45 μT). Moreover, the fecundity of female adults was significantly enhanced (30.13%) and the relative transcription level of Vg was significantly enhanced (259.25%). Furthermore, compared with the GMF intensity 45 μT, the GMF intensity 50 μT significantly decreased the egg duration (2.52%) and significantly increased the egg hatching rate (10.83%) of the F₁ generation of N. lugens. 【Conclusion】 The results suggest that the GMF intensity of the region where N. lugens is located after northward migration in spring is positive for its migration to enhance the population fitness, further advantageous for the population occurrence and increasing the risk of population outbreak and damage in the immigration regions in spring.

Key words: Nilaparvata lugens; geomagnetic field intensity, migratory insect, emigration, immigration, magnetobiological effect