Abstract: In order to clarity the effects of photoperiod on the growth, development and reproductive behaviours of Spodoptera exigua, three different photoperiods (12L:12D, 16L:8D, 20L:4D) were set up in the study. The results showed that, at 20 h of light duration, the hatching rate of S. exigua was only 74.0%; the larval during was shortened to 11.5 d, the survival rate of larvae was reduced to 57.8%, the pupation rate was only 57.8%, the pupal weight was reduced to 0.1905 g and the adult life span was shortened to 6.3 d. Under the condition of sex ratio of 1:1, the reproductive behavioral parameters were observed continuously in seven scotophases. In the third scotophase, the length of time between the onset of courtship and the scotophase was four times longer for S. exigua in 12 h treatment (212.4 min) than in 20 h treatment (51.4 min), the number of courtships under 12L:12D, 16L:8D and 20L:4D were 47.7, 37.9 and 25.5, respectively, and all three treatments were significantly different from each other, the mating initiation time was shortened or reduced with the increase of light time. Egg production at 12 h light (855.0) was approximately 2.5 times that at 20 h light (301.6). The results of this study preliminarily revealed the influence of photoperiod on the growth, development and reproductive behavior of S. exigua, which can provide data for indoor artificial breeding or field management of S. exigua.

Key words: Spodoptera exigua, photoperiod, growth and development, reproductive behavior