Huanglongbing (HLB) disease causes worldwide losses in citrus industry worth billions of dollars every year. The causative bacteria of HLB, Candidatus Liberbacter is transmitted by the Asian Psyllid. The current treatments for HLB are not effective and involve mostly preventive measures. Recently, Asian beetles have been used to control psyllid infestation. Our studies investigated the effects of Harmonia axyridis beetle hemolymph on the cause (psyllids) and the causative agent (C. Liberbacter) of HLB in an attempt to find novel treatments for the disease. We hypothesized that the beetle hemolymph will act as a pesticide against psyllids and as an antibiotic against Liberbacter. Hemolymph was extracted from dried and live beetles, and by soaking beetles in different solvents. The extracts were tested for pesticidal activity against ants and aphids, and as an antibiotic against E. coli and Liberibacter. Beetle extracts showed potent pesticidal activity. The extract either killed or drastically slowed pests activity. Hemolymph collected from live beetles, in methanol, or in water was more effective as pesticide than that collected in saline or from dried beetles. Results of antibiotic efficacy assessment of the hemolymph on E. coli suggested that extracts possess strong antibiotic properties. Hemolymph extracted in methanol was the most effective in inhibiting the growth of E. coli followed by water extract, and the saline extracts. The least effective was the extract from live beetles. Testing on L. crescens indicated that wild extract was the most effective. Saline and Methanol extracts, however, showed minimal antibiotic properties. Taken together, our data strongly suggest that beetles hemolymph could further be explored as a possible and a novel treatment for HLB.
Third Award of $1,000