Initial detections and spread of invasive Spodoptera frugiperda in China and comparisons with other noctuid larvae in cornfields using molecular techniques

The fall armyworm,Spodoptera frugiperda,is a species native to the Americas and has spread to many countries in Africa and Asia in recent years.Proactive actions for potential invasion of S.frugiperda to China coordinated by government agencies and agricultural extension systems resulted in timely detection in January 2019 in Yunnan province neighboring onto Myanmar.The extensive monitoring in southern provinces of China since February 2019 resulted in dynamic tracking of S.frugiperda spreading to 13 provincial regions in China within 4 months by May 10,2019,which is crucial for timely management actions in the fields.The first detections of S.frugiperda(corn strain)in China were confirmed using cytochrome oxidase subunit 1(COl)and triosephosphate isomerase(Tpi)genes molecular marker method.In addition to S.frugiperda,larvae of three other noctuid species with similar morphological appearance(S.litura,S.exigna and Mythimna separata)can occur simultaneously and cause similar damage in cornfields in southern China.Thus,we can use both morphological and molecular marker methods to compare larval stages of four noctuid species.Further,we discuss the risk of potential spread of invasive S.frugiperda to other regions and impact on corn production in China.

Impact of insect-resistant transgenic rice on target insect pests and non-target arthropods in China

Progress on the research and development of insect-resistant transgenic rice, especially expressing insecticidal proteins from Bacillus thuringiensis （Bt）, in China has been rapid in recent years. A number of insect-resistant transgenic rice lines/varieties have passed restricted and enlarged field testing, and several have been approved for productive testing since 2002 in China, although none was approved for commercial use until 2006. Extensive laboratory and field trials have been conducted for evaluation of the efficiency of transgenic rice on target lepidoteran pests and potential ecological risks on non-target arthropods. The efficacy of a number of transgenic rice lines currently tested in China was excellent for control of the major target insect pests, the rice stem borers （Chilo suppressalis, Scirpophaga incertulas, Sesamia inferens） and leaffolder （ Cnaphalocrocis medinalis）, and was better than most insecticides extensively used by millions of farmers at present in China. No significantly negative or unintended effects of transgenic rice on non-target arthropods were found compared with non-transgenic rice. In contrast, most of the current insecticides used for the control of rice stem borers and leaffolders proved harmful to natural enemies, and some insecticides may directly induce resurgence of rice planthoppers. Studies for developing a proactive insect resistance management of transgenic rice in the future are discussed to ensure the sustainable use of transgenic rice.