The damage characteristics and spatial distribution pattern of the new maize pest Paralipsa gularis (Zeller) in southwestern China

Author of the article:CHEN Shuang, ZHAO Sheng-Yuan, LIU Da-Zhong, YANG Xian-Ming, LI Na, WU Kong-Ming

Author's Workplace：State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing 100193, China

Key Words：Paralipsa gularis (Zeller); maize; damage characteristics; spatial distribution pattern; theoretical sampling

Abstract：[Objectives]  To clarify the damage characteristics and spatial distribution of larvae of Paralipsa gularis (Zeller), an emerging pest of maize in southwestern China, in order to provide theoretical support for the prediction and control of this species. [Methods]  A five-point random sampling method was used to survey the occurrence and damage caused by P. gularis larvae in summer maize fields in Jiangcheng county, Yunnan province. The spatial distribution patterns of larvae in maize fields were analyzed using the aggregation index method and regression analysis. [Results]  Field investigations found that larvae began to damage maize during the milk stage, and bored into maize ears, cores and stalks, causing grain defects and ear rot. Damaged areas had obvious borer holes, tunnels and white excrement, and mature larvae pupated on maize bracts and ears. Average larval densities ranged from 0.02 to 3.62 individuals per plant, and the rate of maize-damaged plants was 2% to 58%. The rate of damage to maize ears was positively correlated with average larval density. Larvae had an aggregated distribution in maize ears, indicating that individuals attracted each other. The basic component of the distribution was the individual group. The aggregation average l indicated that larvae aggregated in response to environmental factors. Based on these results, we derived the theoretical sampling formula: , for larvae of P. gularis and the larval density control index sampling formula: . [Conclusion]  The damage characteristics, spatial distribution habits of P. gularis larvae in maize fields were determined and a sampling method for field populations proposed. The results provide a scientific basis for population density surveys and the control of this pest in maize fields.