Overwintering, cold tolerance and supercooling capacity comparison between Liriomyza sativae and L. trifolii, two invasive leafminers in China

Abstract

Liriomyza sativae Blanchard and Liriomyza trifolii (Burgess) are two highly polyphagous pests that successively invaded China in the 1990s and 2000s, respectively, threatening vegetable and horticultural plants. Competitive displacement of L. sativae by L. trifolii occurred during the expansion process of the latter in southern China. However, whether L. trifolii can expand their range to northern China and, if so, how they compete with L. sativae in northern China remains unclear. Overwintering and cold tolerance capacity largely determine the species distribution range and can affect species displacement through overwintering and phenology. In this study, we compared the overwintering potential, cold tolerance and supercooling point (SCP) between these two leafminer species. Our results showed that L. trifolii can overwinter at higher altitudes than L. sativae. In addition, we found that they can both successfully overwinter in greenhouses in northern China, and the overwintering capacity of L. trifolii was higher than that of L. sativae. Moreover, the extreme low-temperature survival of L. trifolii was signi cantly higher than that of L. sativae, and the SCP of the former was lower than that of the latter. We thus conclude that the overwintering and cold tolerance capacity of L. trifolii is much better than that of L. sativae. Our ndings indicate that L. trifolii has the potential to displace L. sativae and expand its range to northern China. Moreover, our results have important implications for predicting overwinter ranges and developing management strategies for invasive leafminers in China.

Differential Response of Leafminer Flies Liriomyza trifolii (Burgess) and Liriomyza sativae (Blanchard) to Rapid Cold Hardening

“…Survival of the two species decreased significantly when exposed to a gradient of cold temperatures, and L. trifolii pupae were more cold tolerant than L. sativae pupae. Interestingly, adults of both species exhibited similar levels of cold tolerance; in this respect our results are similar to prior studies where thermal resistance of L. trifolii was stronger than L. sativae [14,43].…”

“…In the present study, the SCP of L. trifolii was significantly lower than L. sativae. Previous studies also confirmed that the SCP of L. trifolii pupae is much lower than L. sativae, indicating a huge difference in SCPs of the two species [14,26,28]. As described by Bale (1996) [61], there are five classes of insect cold hardness, and based on our survival data and SCP data, L. trifolii is chill susceptible and L. sativae is freeze avoiding.…”

“…For instance, in December 2020, the lowest temperature in Beijing, a typical northern city in China, was −12 • C. The lowest winter temperature was −20 • C in January 2021, and there were eight days in January when the mean temperatures were lower than −8 • C (China meteorological data service center) [67]. It is important to mention that L. trifolii may lose its competitive edge with respect to cold tolerance if global warming triggers warmer winter weather [14]. Furthermore, with the increasing abnormal temperature fluctuations accompanied by global warming, the greater RCH capacity of L. sativae may increase the survival of L. sativae overwinter.…”

“…We investigated the SCP and RCH of L. sativae and L. trifolii to better understand interspecies competition. Here, we address a hypothesis that RCH will affect the interspecific competition between L. sativae and L. trifolii and eventually the replacement of L. sativae by L. trifolii in northern regions of China will take longer than predicted by previous studies [14,19]. This research also provides a baseline for further metabolomic, proteomic, and transcriptomic studies of RCH, which will help elucidate the mechanistic basis of the phenomenon response and its role in interspecific competition.…”

“…L. trifolli has proven to be a more damaging pest of crops in the regions of China that it has invaded [12,13]. Due to its increased cold tolerance and lower supercooling point (SCP), L. trifolii has the potential to displace L. sativae and expand its range to northern China [14]. Climatic stress, overwintering, and cold tolerance are temperature-related factors that determine the geographical distribution of leafminers [5,15].…”