The fall armyworm, Spodoptera frugiperda (Lepidoptera, Noctuidae), is a notorious migratory pest. After invading China in 2019, the species has established as a year-round breeding population in most of the southern provinces. The area of winter corn in this region has been increasing due to the huge demand of fresh corn consumption which is potentially at risk from this invasive, although S. frugiperda growth and development under changing climate in this region is unclear, particularly the rising temperature during night period. Here we used highest daily temperatures of 27℃, 24℃, 20℃ and night temperatures that were 2℃, 4℃, 6℃ lower giving three daily temperature treatments reflective of winter conditions; GroupⅠ: 27-21℃, 27-23℃, 27-25℃, Group Ⅱ: 24-18℃, 24-20℃, 24-22℃, and Group Ⅲ: 20-14℃, 20-16℃, 20-18℃; to evaluate the effect of increasing night temperature on growth and development of S. frugiperda. Results show that the survival rate of larvae and pupae significantly declined with the daily temperature declining and the night temperature range increasing. Significant developmental effects were observed in all day-night temperature treatment, except for adults, with significant interaction effects for all stages except egg and generation time. Development rate accelerated along with the increasing daily temperature and night temperature, except for the intermediate treatments (Group Ⅱ). The uniformity of pupation and emergence times are higher in high daily temperatures and night temperature. Predictions of FAW development and warnings to local farmers need to be adjusted to take into account the more rapid development. These results will support decision makers to develop long-term management strategies for FAW in southern China.

Irrigation with water containing a variety of microcystins (MCs) may pose potential threat to normal growth of agricultural plants. The mechanism of microcystin-LR (MC-LR) induced phytotoxicity in rice (Oryza sativa L.) at environmental concentrations is still unknown. Rice seedlings were exposed to MC-LR at concentrations of 0.10, 1.0, 10.0 and 50.0 μg·L−1 in hydroponic nutrient solutions for 7, 15, 20, and 34 days in the current study. The absorption and accumulation in leaf and root tissues, as well as a series of key physio-biochemical process changes in leaves of rice at different exposure time points were measured. Results showed that MC-LR could be detected in rice leaves and roots in all exposure groups, however, a significant accumulation trend of MC-LR in plants (BCF > 1) was only found in the lowest group (0.10 μg·L−1). The time-course study revealed a biphasic response of O2•- levels in rice leaves to the exposure of MC-LR, which was more pronounced in higher concentration groups, which could be attributed to the combined effects of antioxidant and detoxification mechanisms in rice. Exposure to 1.0 - 50.0 μg·L−1 MC-LR resulted in significant depletion of GSH and MDA contents in rice leaves at later exposure times. The changes of nitric oxide synthase (NOS) in rice leaves under MC-LR exposure were firstly investigated in the current study. Low MC-LR concentrations promoted NOS activity, whereas high concentrations inhibited NOS activity during the later exposure times, implying that NO may play a role in MC-LR toxicity in rice. Reduced sucrose synthase (SS) activities in rice exposed to MC-LR can reduce the plant's ability to accumulate carbon and thus may be directly related to the reduction in vegetative growth. These findings suggest that even at low concentrations of MC-LR, terrestrial plants' normal physiological status is disrupted, which, when combined with previous findings, helps reveal the mechanism of MC-LR-induced phytotoxicity.