Abstract: Cotton bollworm (Helicoverpa armigera Hubner) is one of the most serious agricultural pests in Northern China, while magnetic field may have significant effects on the growth and development of H. armigera. In this paper, three intensities of magnetic field (zero magnetic field, high magnetic field, and natural magnetic field) were installed to observe the development and reproduction of H. armigera. Zero magnetic field increased the duration of larvae markedly, with a range of 0.4-1.7 d, while high magnetic field had minor effects. The larval survival rate, pupal weight, eclosion rate, egg laying amount, and egg hatching rate were less affected by magnetic field. It was suggested that zero magnetic field could delay the development of H. armigera larvae, but have minor effects on the reproduction of the pest. Since the intensity of high magnetic field in this study was only 4 Gs, whether the more high intensity magnetic field could affect H. armigera needs to be further studied.

Key words: land use type, ecological security baseline, ecosystem service value, food security.