Survival and feeding behavior of Diaphorina citri (Hemiptera: Liviidae) adults on common cover crops in citrus

Authors: George, Justin; KANISSERY, RAMDAS - Southwest Florida Research And Education Center; BASHYAL, MAHESH - Southwest Florida Research And Education Center; TAMAYO, BLESSY - University Of Florida; STELINSKI, LUKASZ - University Of Florida

Submitted to: Agriculture
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/9/2022
Publication Date: 12/19/2022
Citation: George, J., Kanissery, R., Bashyal, M., Tamayo, B., Stelinski, L.L. 2022. Survival and feeding behavior of Diaphorina citri (Hemiptera: Liviidae) adults on common cover crops in citrus. Agriculture. 12:2175. https://doi.org/10.3390/agriculture12122175.
DOI: https://doi.org/10.3390/agriculture12122175

Interpretive Summary: Citrus greening, aka Huanglongbing (HLB), is the most destructive citrus disease in the world. Asian citrus psyllid transmits the bacterial pathogen responsible for citrus greening disease. Although they primarily feed on the phloem of citrus and related plants, citrus psyllid may be able to use weed species and/or citrus cover crops as alternate sources of food and water for survival when host conditions are unfavorable. Application of cover crops to improve soil health is gaining traction as a management strategy in citrus. To test the possibility that cover crops in citrus groves may serve as refuges for this pathogen vector, psyllid feeding was investigated on several cover crop species using electrical penetration graph (EPG) recordings. Feeding behavior of psyllid adults was quantified on six common cover crops grown in Florida citrus groves (buckwheat, dicon radish, clover, cowpea, hairy vetch, peanut and Citrus macrophylla as control). EPG recordings revealed that the proportion of time spent by citrus psyllid feeding on xylem was similar or higher on all tested cover crops (17%–32%) compared to the positive control (12%), the preferred host, C. macrophylla. Very little to no phloem feeding was observed on cover crops by the adults. In the choice assays, more citrus psyllid adults settled on buckwheat (Fagopyrum esculentum) and cowpea (Vigna unguiculata) than on the host, C. macrophylla, 24 h after release. No choice behavioral assays showed that the citrus cover crop species evaluated extend the survival of citrus psyllids up to 8 d, because of xylem feeding. Our results indicate that some cover crop species may be less suitable refuge sites for citrus psyllids than others, but none served as breeding sites or supported more than 8 d of survival.

Technical Abstract: Asian citrus psyllid, Diaphorina citri, transmits Candidatus Liberibacter asiaticus (CLas), the bacterial pathogen responsible for citrus greening disease. To explore the possibility that cover crops in citrus groves may serve as refuges for this pathogen vector during unfavorable host conditions, psyllid feeding was investigated on six common cover crop species and citrus using electrical penetration graph (EPG) recordings and bioassays. EPG recordings revealed that the proportion of time spent by D. citri feeding on xylem was similar or higher on all tested cover crops (17%–32%) compared to the positive control (12%), the preferred host, C. macrophylla. Very little to no phloem feeding was observed on cover crops by the adults. In the choice assays, more D. citri adults settled on buckwheat (Fagopyrum esculentum) and cowpea (Vigna unguiculata) than on the host, C. macrophylla, 24 h after release. No choice behavioral assays showed that the citrus cover crop species evaluated extend the survival of D. citri up to 8 d, because of xylem feeding. Our results indicate that some cover crop species may be less suitable refuge sites for D. citri than others, but none served as breeding sites or supported more than 8 d of survival.