Affordable Essential Oils for Management of the Asian Citrus Psyllid

Plant essential oils are commonly used to manage insects; they are widely available and some are inexpensive.  In this research we have selected five botanical oils costing less than $100 US per kilogram, to evaluate for repellency to Asian Citrus Psyllid (ACP), the insect vector of the causal pathogens of huanglongbing.  In olfactometer assays, fir oil was repellent; clove and camphor oils were attractive; and litsea and citronella oils elicited no response from ACP females.  In no-choice settling experiments, neither the low nor high fir oil treatment deterred ACP from settling.  Subsequently, ACP were presented with a choice test between control plants and fir oil plants with a single dose of fir oil contained in a polyethylene vial.  In this case, ACP disproportionately settled on control plants, avoiding fir oil baited trees completely.  Finally, we conducted a field trial using yellow sticky traps baited with a high or low dose of clove or camphor oil deployed from seven mL polyethylene vials.  We expected that the botanical oil baited yellow traps would catch more ACP than unbaited controls.  There was no significant increase in trap capture over the course of our experiment in male, female, or total ACP capture.  We hypothesize that this result may have been caused by sub-optimal release rates or the overriding visual cue elicited by yellow sticky traps. Our ongoing experiments are designed to improve the behavioral activity of release devices for these essential oils, which may have practical utility for ACP management

Repellent Activity of Botanical Oils against Asian Citrus Psyllid, Diaphorina citri (Hemiptera: Liviidae)

The Asian citrus psyllid, Diaphorina citri Kuwayama, is the insect vector of the pathogen causing huanglongbing. We selected three botanical oils to evaluate behavioral activity against D. citri. In laboratory olfactometer assays, fir oil was repellent to D. citri females, while litsea and citronella oils elicited no response from D. citri females. In choice settling experiments, D. citri settled almost completely on control plants rather than on plants treated with fir oil at a 9.5 mg/day release rate. Therefore, we conducted field trials to determine if fir oil reduced D. citri densities in citrus groves. We found no repellency of D. citri from sweet orange resets that were treated with fir oil dispensers releasing 10.4 g/day/tree as compared with control plots. However, we found a two-week decrease in populations of D. citri as compared with controls when the deployment rate of these dispensers was doubled. Our results suggest that treatment of citrus with fir oil may have limited activity as a stand-alone management tool for D. citri and would require integration with other management practices

Decreased nest mortality for the Carolina diamondback terrapin (Malaclemys terrapin centrata) following removal of Raccoons (Procyon lotor) from a nesting beach in Northeastern Florida

Raccoons (Procyon lotor) can account for \u3e 90% of nest failures of the Diamondback Terrapin (Malaclemys terrapin) in some areas. Previous studies have demonstrated that predator removal can decrease predation of turtle nests, thus increasing nest survivorship. We removed Raccoons from an island beach used by Diamondback Terrapins for nesting in northeastern Florida. Prior to predator removal, Raccoons depredated 53.5% of monitored nests and 80% of all nests found in 1997 and 50.9% of monitored nests and 76.0% of all nests found in 2000 on this island beach. We removed 29 Raccoons between February and September 2005 and monitored Diamondback Terrapin nesting from 25 April to 31 October 2005. Nest predation by Raccoons dropped to 12.0% and the overall predation rate fell to 17.2%. We again monitored the nesting beach in 2006 without predator removal. Nest predation by Raccoons was once again very high, claiming 86.7% of monitored nests and over 70.0% of all the nests found. © 2012. Eric C. Munscher. All Rights Reserved