Evaluation of the biocontrol potential of Episyrphus balteatus (Diptera: Syrphidae) on wheat aphids in northern China.

Abstract

Marmalada hoverfly, Episyrphus balteatus De Geer (Diptera: Syrphidae), is a cosmopolitan fly species providing pest control and pollination services. As wheat aphids cause significant losses to global wheat production, a systematic evaluation of the predatory potential and biocontrol service functions of E. balteatus in wheat ecosystems was undertaken. The daily maximum prey consumption of third instar E. balteatus on the adult of Rhopalosiphum padi Linnaeus, Schizaphis graminum Rondani, and Sitobion miscanthi Takahashi (Hemiptera: Aphididae) were 250, 500, and 100 individuals/third instar larvae, respectively. The S. graminum population decline rates in cages after release of the third instars at ratios of 1:100 and 1:200 were 100% and 94.17%, respectively, 72-h after exposure. Feeding assays involving R. padi, S. graminum, and S. miscanthi showed a DNA detectability half-life of 4.17, 6.44, and 4.83 h, respectively, in third instar larvae of E. balteatus. Using multiplex polymerase chain reaction-based gut content analysis to detect prey DNA remains, we confirmed that E. balteatus larvae preyed upon R. padi, S. graminum, S. miscanthi, and Metopolophium dirhodum Walker (Hemiptera: Aphididae) in the field experiments during 2022 to 2024. A significant positive correlation was also found between corrected prey detection rate and aphid population dynamics. These results provide an entry point for understanding the ecological service function of E. balteatus and developing the biological control strategy of the wheat aphid management.