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

Asian citrus psyllid, Diaphorina citri, transmits Candidatus Liberibacter asiaticus (CLas), the putative causal agent of citrus greening aka Huanglongbing disease. Although they primarily feed on the phloem of citrus and related plants, when grove or host conditions are unfavorable D. citri may be able to use weed species and citrus cover crops as alternate food sources for survival. To explore this possibility of using cover crops in citrus groves and to understand psyllid feeding on these cover crops, electrical penetration graph (EPG) recordings were performed using psyllid adults on six common cover crops  grown in Florida citrus groves (buckwheat, dicon radish, clover, cowpea, hairy wetch, peanut and Citrus macrophylla as control). 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, Citrus macrophylla. Very little to no phloem feeding was observed on cover crops by the adults. In the choice assays, D. citri adults preferred buckwheat and cowpea as preferred host plants after 24 h, compared to Citrus macrophylla. No choice behavioral assays showed that adults can obtain some nutrition by feeding on these citrus cover crops (xylem feeding) and they may be able to survive on them for short intervals, when host conditions are unfavorable.