Association Between Citrus Flushing Cycles and Asian Citrus Psyllid Demography in Huanglongbing-Free Area in Brazil

Diaphorina citri Kuwayama (Hemiptera: Liviidae), named as Asian citrus psyllid (ACP), is the vector of the bacterium associated with huanglongbing (HLB), the most destructive citrus disease. The use of citrus flushing and ACP monitoring tools is essential for the knowledge of the occurrence pattern of cycles of both and for the improvement of the ACP management. During 3 years, 20 branches from 20 trees were evaluated for vegetative flushing, ACP abundance, and occupation in tree and branches in a Brazilian citrus area free for HLB. The obtained data was investigated through spectral and co-spectral analyses. Four to 12 flush shoot cycles occurred per year, which were similar to abundance and occupation cycles of ACP, with an apparent synchronization between these variables. In general, there was a difference from 14 to 19 days between flushing and ACP peaks, with an occurrence of the flushing peaks before the ACP peaks. Results will provide useful information to citrus growers and agricultural defense agencies to apply a suitable and targeted ACP management, which will avoid or delay the disease entrance into still free HLB areas. In addition, the modeling of occupation and abundance cycles of vectors as applied in this study may be useful for other pathosystems which insect vectors are associated or even in the intrusion monitoring programs.