Asian citrus psyllid, Diaphorina citri (Hemiptera: Liviidae) responses to plant-associated volatile organic compounds: A mini-review

Authors: SANTOS SILVA, MARIANA - Federal University Of Bahia Reconcavo; Patt, Joseph - Joe; DE JESUS BARBOSA, CRISTIANE - Embrapa; FANCELLI, MARILENE - Embrapa; RIBEIRO MESQUITA, PAULO - Faculty Maria Milza; DEMEDEIROS RODRIGUES, FREDERICO - Faculty Maria Milza; SELBACH SCHNADELBACH, ALESSANDRA - Federal University Of Bahia Reconcavo

Submitted to: Crop Protection
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/27/2023
Publication Date: 4/1/2023
Citation: Santos Silva, M., Patt, J.M., De Jesus Barbosa, C., Fancelli, M., Ribeiro Mesquita, P.R., Demedeiros Rodrigues, F., Selbach Schnadelbach, A. 2023. Asian citrus psyllid, Diaphorina citri (Hemiptera: Liviidae) responses to plant-associated volatile organic compounds: A mini-review. Crop Protection. https://doi.org/10.1016/j.cropro.2023.106242.
DOI: https://doi.org/10.1016/j.cropro.2023.106242

Interpretive Summary: A tiny insect called the Asian citrus psyllid (pronounced ‘si-luhd’) transmits a disease called Citrus Greening or Huanglongbing. It is the most serious disease of citrus trees in the world. It is caused by bacteria that live inside the tree’s vascular system. The disease causes the vascular system to become clogged and unable to transport nutrients. When this happens, the tree starts to starve and eventually dies. There is no therapeutic treatment for the disease, which has caused the death of millions of citrus trees. Citrus growers rely on spraying chemical insecticides to control the pest. However, insecticides are expensive and have not stopped the spread of the disease. There are also many human health, environmental, and regulatory concerns about insecticides. For these reasons, growers are looking for additional ways to control this important pest. One way may be to use the aromas of different plants to influence psyllid movement in the grove. This is because psyllids can detect and respond to many kinds of plant aromas. It may be possible to use plant aromas to attract or repel psyllids in citrus groves. Attractive aromas could be used to improve the capture of psyllids on traps that monitor their presence and population size. Alternatively, repellent aromas could stop psyllids from entering groves and settling on trees. To date, only a few aromas that have a significant effect on psyllid behavior have been identified. Many of the original studies of psyllid response to plant aromas and were conducted in the labs on citrus and other plants. Current studies have grown in scope and use molecular tools to provide a more complete understanding of psyllid detection and response to plant aromas. However, more field studies are needed to verify the practicality of this approach. Here we provide an overview of the plant aromas that have been shown to be modify the psyllid's behavior and suggest areas that need more attention to make this approach a practical solution for citrus growers.

Technical Abstract: The Asian citrus psyllid (ACP), Diaphorina citri Kuwayama, vectors Candidatus Liberibacter asiaticus and C. L. americanus, the causal agents of Huanglongbing (HLB), the world’s most serious citrus disease. There are no therapeutic treatments for HLB and chemical insecticides are the primary means of controlling ACP. Although insecticide applications reduce local ACP populations, HLB spread has continued unabated. Because of insecticides’ inefficiency, cost, and associated regulatory issues, growers are looking for additional tools for ACP control. There has been a strong interest in identifying plant species and their associated volatile organic compounds (VOCs) that repel or attract ACP. Identification of effective behavioral modifiers is a necessary first step to developing highly efficient management tools for monitoring, repelling, and controlling ACP. While initial studies used olfactometry and analytical instruments, current investigations have grown in scope to include tools such genetic modification, RNAi, and olfactory binding proteins to provide a more comprehensive understanding of ACP olfactory perception and behavioral response. Here we provide an overview of the plant species and their associated VOCs that have been implicated as ACP behavioral modifiers.