Presence and abundance ofDiaphorina citriinMurraya paniculatain urban areas free of huanglongbing in Brazil

Asian citrus psyllid (ACP),Diaphorina citriKuwayama (Hemiptera: Liviidae), is the vector of the bacteriumCandidatusLiberibacter sp., a quarantine pathogen in citrus production areas such as Australia, Europe, and northeast Brazil, associated with huanglongbing (HLB). The psyllids' preferred host isMurraya paniculata(L.) Jacq. (Rutaceae), an ornamental plant native to Asia and Oceania, and commonly found in urban areas next to citrus groves around the world. As there are insecticide application restrictions for urban areas, monitoring and use of biological control to suppress ACP are essential for an area-wide HLB management strategy, especially for production areas predominantly composed of small citrus farms. For this, it is necessary to understand the occurrence cycles of ACP and vegetative flush of the ornamental host. This study characterized the occurrence cycles ofM. paniculataflush shoot and accumulated rainfall, and the association with ACP presence (proportion of monitored trees) and abundance (per tree) in a Brazilian urban area free of HLB. A 3-year time series was constructed using spectral and co-spectral analysis. Spectral analysis showed the occurrence of at least seven flush shoot cycles ofM. paniculata, nearly 10 ACP presence and abundance cycles, and monthly cycles of accumulated rainfall. Cycles of ACP presence were associated with ACP abundance, with ACP presence cycles occurring around 7 days before ACP abundance cycles and the correlation and co-spectral analyses indicated an almost simultaneous occurrence of the main cycles ofM. paniculataflush shoots and ACP occurrence. These findings will facilitate the development of an ACP biological control program based on parasitoid releases in urban areas in HLB-free citrus groves.