Identifying Potentially Climatic Suitability Areas for Arma custos (Hemiptera: Pentatomidae) in China under Climate Change.

Spodoptera frugiperda is a notorious pest that feeds on more than 80 crops, and has spread over 100 countries. Many biological agents have been employed to regulate it, such as Arma custos. A. custos is a polyphagous predatory heteropteran, which can effectively suppress several agricultural and forest pests. Thus, in order to understand where A. custos can survive and where can be released, MaxEnt was used to predict the potentially suitable areas for A. custos in China under climate change conditions. The results show that the annual mean temperature (bio1) and annual precipitation (bio12) are the major factors influencing the distribution of A. custos. The optimal range of the two are 7.5 to 15 °C, 750 to 1200 mm, respectively. The current climate is highly suitable for A. custos in Hebei, Henan, Shandong, Anhui, Hubei, Jiangsu, and Zhejiang Provinces. Considering the currently suitable distribution area of S. frugiperda, artificially reared A. custos is suitable for release in Fujian, Zhejiang, Jiangxi, Hunan, and southeastern Sichuan Provinces. Under the future climatic scenarios, the suitable area will decrease and shift towards the north. Overall, this result can provide a reference framework for future application of A. custos for biological control.

Synonymize Arma chinensis as Arma custos based on morphological, molecular and geographical data.

Arma custos and A. chinensis have a very conspicuous difference in the shape of the pronotal humeral angle, but the genitalic morphological characters are ambiguous and difficult to recognize. The aim of this study was to analyze the taxonomic status of A. chinensis and A. custos based on morphological, molecular, and geographical evidence, and to determine whether DNA barcoding could be a useful additional tool for differentiating similar species. The results clearly demonstrate that A. custos and A. chinensis have not diverged into separate species. So, the following new synonym is proposed: Arma chinensis Fallou, 1881 = Arma custos (Fabricius, 1794) syn. nov.. The results also showed that DNA barcoding using the marker COI can resolve insect taxonomic problems.