Abstract: China is one of the countries in the world that is severely damaged by crop diseases, pests, and weeds.  There are more than 1 700 species of agricultural pests occurring annually, 53 of which are on the list of the 100 worst pests in the world (Chen and Wang 2014; Wu 2018).  Currently, China is still greatly challenged by a growing problem of agricultural pests that threaten the economy and health and pose ecological risks under the conditions of global climate change, economic integration, crop structure adjustment and so on.  Plant protection against crop diseases, insect pests and noxious weeds is necessary to ensure high-quality crop production and food safety.  However, traditional strategies of plant protection have mainly involved chemical pesticides, which bring a series of other problems, such as pesticide residues, pest resistance and resurgence.  During the past decades, Chinese scientists have been committed to
research on developing new plant protection methods through integrated pest management (IPM) in a safe, cost-effective and sustainable manner.  In this field, we organized this special issue to provide the most updated theories and technologies of plant protection.

There are 21 manuscripts accepted for publication in this special issue, including 13 reviews and eight research articles.  The 13 reviews involved a variety of relevant disciplines, such as insect ecology and molecular biology, phytopathology, biological invasions and pest management science.  Three papers documented the progress in insect ecology and molecular biology.  Bao and Zhang (2019) reported the recent molecular research in Nilaparvata
lugens on its endosymbionts, virus transmission, insecticide resistance, and host interaction.  Li et al. (2019) gave an overview of the discovery, biogenesis and functions of four kinds of ncRNAs, including miRNA, piRNA, circRNA and lncRNA in insects, and Xue et al. (2019) investigated thermal adaptation of Drosophila from three aspects of behavior, plastic responses and micro-evolution under global climate change.  Two papers investigated the threats from pathogenic microbes, Chinese wheat mosaic virus and fire blight disease, to wheat and pear production, respectively, in China, and provided cost-effective countermeasures to control these diseases in the future (Guo et al. 2019; Zhao Y Q et al. 2019).  Four other papers mainly focused on the introduction routes, expansion process (adaptation and interactions), ecological effects and control of invasive insects, including Bemisia tabaci, Phenacoccus solenopsis, Bactrocera dorsalis and Solenopsis invicta (Chu et al. 2019; Liu H et al. 2019; Tong et al. 2019; Wang et al. 2019a).  Additionally, there were three papers that provided sound prospects for improving the strategies currently employed in agricultural control, biological control and chemical control (Lu et al. 2019; Pan et al. 2019; Wang et al. 2019b).  Finally, Liu (2019) evaluated the current status and challenges of rodent biology and management in China.  

The eight research articles mainly involved the three aspects of reproductive biology and chemical ecology of pests, safety assessments of genetically modifed crop and weed control (He et al. 2019; Huang et al. 2019; Liu  Y M et al. 2019; Lü et al. 2019; Muhammad et al. 2019; Xiu et al. 2019; Zhao C C et al. 2019; Zheng et al. 2019).  Among those, there were two papers that explored the tradeoffs between reproduction and energy reserves (Huang et al. 2019; Zhao C C et al. 2019).  Liu Y M et al. (2019) proved that Bt maize expressing cry1Ab/2Aj or cry1Ac genes posed a negligible risk to adult Chrysoperla sinica.  In addition, Muhammad et al. (2019) and He et al. (2019) evaluated the effects of weed control under wheat stubble management and different culture patterns, respectively.

I believe these articles in this special issue should be of broad interest to a diverse audience at multiple levels in the areas of plant protection, and they are well-suited for the readers of Journal of Integrative Agriculture.  I sincerely appreciate all the authors who gave their high-quality contributions and efforts to this special issue.