Climate Change Promotes the Large-Scale Population Growth of <i>Grapholita molesta</i> (Busck) (Lepidoptera: Tortricidae) within Peach Orchards in China

Cosmopolitan agricultural herbivorous pests are provided with a wide range of potential hosts. Therefore, they have high carrying capacity, and can cause extremely severe damage in agroecosystems. Understanding the ecological mechanisms of their population dynamics, especially as they relate to large-scale meteorological variations and geographical landscape influences, can help us to reveal how they became such important pests. The oriental fruit moth, Grapholita molesta, is a typical example of a significant pest distributed on a large scale, which is capable of damaging fruit trees of economic value such as peach, apple, pear, etc. This pest not only occurs in China, but exists on all continents except Antarctica. In order to prevent major pests and diseases, a system of plant protection has been established gradually in peach orchards within the Modern Agro-industry Technology Research System in China (CARS) since 2009. In the system, we collected the monitoring data of G. molesta by using pheromone traps at 17 experimental stations, and then used the corresponding climate data (temperature and precipitation) to explore the link between climate factors using mixed models. The results show that both monthly mean temperature and precipitation had a significant positive correlation with the occurrence of G. molesta. Therefore, global warming with higher levels of precipitation may favor G. molesta, allowing it to outperform other potential pests at the population level in peach orchards, on a large scale

Multipedal DNA Walker Biosensors Based on Catalyzed Hairpin Assembly and Isothermal Strand-Displacement Polymerase Reaction for the Chemiluminescent Detection of Proteins

In this study, two kinds of sensitive biosensors based on a multipedal DNA walker along a three-dimensional DNA functional magnet particles track for the chemiluminescent detection of streptavidin (SA) are constructed and compared. In the presence of SA, a multipedal DNA walker was constructed by a biotin-modified catalyst as a result of the terminal protection to avoid being digested by exonuclease I. Then, through a toehold-mediated strand exchange, a “leg” of a multipedal DNA walker interacted with a toehold of a catalyzed hairpin assembly (CHA)-H1 coupled with magnetic microparticles (MMPs) and opened its hairpin structure. The newly open stem in CHA-H1 was hybridized with a toehold of biotin-labeled H2. Via the strand displacement process, H2 displaced one “leg” of a multipedal DNA walker, and the other “leg” continued to interact with the neighboring H1 to initiate the next cycle. In order to solve the high background caused by the hybridization between CHA-H1 and H2 without a CHA-catalyst, the other model was designed. The principle of the other model (isothermal strand-displacement polymerase reaction (ISDPR)-DNA walker) was similar to that of the above one. After the terminal protection of SA, a “leg” of a multipedal DNA walker was triggered to open the hairpin of the ISDPR-H1 conjugated with MMPs. Then, the biotin-modified primer hybridized with the newly exposed DNA segment, triggering the polymerization reaction with the assistance of dNTPs/polymerase. As for the extension of the primer, the “leg” of a multipedal DNA walker was displaced so that the other “leg” could trigger the proximal H1 to go onto the next cycle. Due to its lower background and stronger signal, a multipedal DNA walker based on an ISDPR had a lower limit of detection for SA. The limit of detection for SA was 6.5 pM, and for expanding the application of the method, the detections of the folate receptor and thrombin were explored. In addition, these DNA walker methods were applied in complex samples successfully