模拟增温和丛枝菌根对门源草原毛虫幼虫生长发育的影响

采用开顶式生长室(Open top chamber, OTC)模拟增温和苯菌灵抑制丛枝菌根研究上述两种因素综合作用下门源草原毛虫幼虫的生长速率、蛹化时间和蛹重。结果表明,增温和丛枝菌根抑制及其交互作用均对门源草原毛虫幼虫生长速率产生了显著影响。相比对照组而言,增温使该指标升高了34%。丛枝菌根抑制未对上述指标产生显著影响。增温和丛枝菌根抑制的交互作用使门源草原毛虫幼虫生长速率较对照组升高了16%,而较增温组降低了13%。增温处理下雌、雄幼虫的蛹化时间分别为204、218 d,而不增温处理下分别为212、223 d。增温使得雌、雄幼虫的蛹化时间较不增温处理分别提前了2%和4%。增温和不增温处理下的雌、雄虫蛹化时间差分别为15、12 d。增温将上述时间差扩大了25%。此外,增温及其与丛枝菌根抑制的交互作用对门源草原毛虫雌虫蛹重的影响显著,而对于雄虫的蛹重来说,仅增温处理的影响显著。增温和增温丛枝菌根抑制处理,使得雌蛹重较对照组增大了22%和8%。增温使雄蛹重增大了18%。首次研究了增温和丛枝菌根对植食性昆虫的综合影响。

Effect of simulated warming and arbuscular mycorrhiza fungi on the growth and development of Gynaephora menyuanensis larvae

It is known that global warming, an extremely threatening problem for human, changes the ecological processes and ecosystem in an unprecedented way. There is no doubt that climate warming can significantly affect insects that are more sensitive to the changes in environment and are regarded as the bio-indicator of ecosystem to disturbances. Herbivores attract more attention than other insects owing to their advantages in terms of quantity and function. Although the general effects of warming on herbivores are positive, recent studies suggest that they are highly variable across species and depend on the optimum temperature. In addition, there are many abiotic and biotic factors, such as soil fertilization, precipitation, wind, below ground herbivores, arbuscular mycorrhiza fungi, and enemies of herbivores affecting the interspecific interactions of predation. They can probably alter the responses of herbivores to warming. This hypothesis had been validated by some field studies. Arbuscular mycorrhiza fungi (AMF), one of the most widely distributed soil organisms, develop root symbiotic associations with nearly 85% of terrestrial plants. They can help roots uptake mineral elements, such as nitrogen (N) and phosphorus (P), in exchange for photosynthetic products from host plant. By this pathway, AMF can interact with their host plants, and the outcome of these interactions in plants can cascade up to insect herbivores. Despite little consensuses on the effects of AMF on predation, several studies have suggested that they cannot be ignored. Surprisingly, there is no study on the role of AMF in regulating the responses of herbivores to warming. To close this gap, we conducted an in situ experiment in Tibetan Plateau (TP), the highest and largest plateau on earth, where temperatures increase more rapidly than the global average. We used an open top chamber (OTC), benomyl simulating warming, and AMF control to investigate their influences on the growth rate (RG) and pupation time (PT) of Gynaephora menyuanensis larvae, an endemic generalist species in northeastern TP. The larvae acted an ideal object of study to solve the above problem. The results showed that the colonization rate of AMF with fungicide treatment was 29% lower than that in no fungicide treatment group, indicating that fungicide significantly suppressed mycorrhiza symbiosis. The mean GRs under no warming without fungicide (NWNF), no warming with fungicide (NWF), warming without fungicide (WNF), and warming with fungicide (WF) treatments were 1.63, 2.17, 1.57, and 1.88 mg/d. The effects of warming, fungicide, and their interaction on the GR of caterpillars were significant. The GRs under WNF and WF treatments increased by 34% and 16% compared with that under NWNF treatment. The GR under WF treatment decreased by 13% compared with that under WNF treatment. Besides, warming significantly affected the PT of both female and male. The advancement of pupation time of female (2%) and male (4%) under warming (W) treatment was higher than that under no warming (NW) treatment. The difference between the pupation of female and male caterpillars under W treatment increased by 25% compared with that under NW treatment. The effects of warming, fungicide, and their interaction on the pupal weight (PW) of female caterpillars were significant, but PW of males were only altered by warming. The PWs of females under WNF and WF treatments increased by 22% and 8% compared with that under NWNF treatment. And the PWs of males under W treatment was increased by 18% compared with that under NWNF treatment. This is the first report on the effects of warming and arbuscular mycorrhiza fungi on herbivores.