Predicting When, Why, and Where Asian citrus psyllids move to increase effectiveness of insecticide sprays.

Predicting When, Why, and Where Asian citrus psyllids move to increase effectiveness of insecticide sprays.

Report Date: 10/15/2015
Project: 15-024   Year: 2015
Category: ACP Vector
Author: Lukasz Stelinski
Sponsor: Citrus Research and Development Foundation

The goals of this project are to: 1: Determine the fight initiation thresholds of ACP depending on temperature and humidity. 2: Determine the effect of wind speed on flight and the direction of psyllid flight with respect to wind. 3: Determine the effects of barometric pressure changes on psyllid dispersal. 4: Measure how psyllid dispersal is affected by abiotic factors in the field. 5: Establish a model to predict the risk of ACP dispersal/invasion based on prevailing abiotic conditions. Deliver this model as an online tool for growers. We initiated an experiment to investigate the effect of ambient temperature and relative humidity on the dispersal behavior of the Asian citrus psyllid (ACP). The experiment is set up in a climate controlled chamber where temperature and relative humidity are controlled precisely. Humidity and temperature are varied in a range that is in accordance with the conditions observed in Florida during spring and summer. The temperature treatments tested so far in the chambers were 15, 21, 25, 30, 35 �C and the humidity treatments 35%, and 75% RH. Fifty adult ACP of mixed sex from our HLB-free colony are caged within mesh bags on non-flushing seedling citrus plants and these plants are placed in a larger cage in the environmental chamber set to default conditions of 20 �C and 70% RH. After an acclimation period of 3 d, temperature and humidity are set at the treatment levels for 1 h. Thereafter, the mesh bag are removed, as well as, ACP that did not settle on the plant. Four newly flushing citrus seedlings are introduced into the cage 10 cm away from the infested plant so that the psyllids can freely move between the plants. At 1, 2, and 3 d after introduction of the new plants, the adult psyllids are removed and counted on the inserted plants to measure movement. So far we obtained the highest percentage of dispersal individual (67.8% after 3 days) at 30�C whereas at the range tested humidity did not affect the dispersal behavior of ACP. We did not observe any movement at 15�C whereas 23% of ACP dispersed at 21�C, indicating that the minimal temperature for psyllid movement is between 15 and 21�C. Further experiments will be conducted to determine precisely the minimum temperature threshold needed for psyllid movement. We have also initiated collaboration with IBM for modeling ACP movement based on our data. Finally, we are in the initial stages of designing a system that will automate counting ACP movement on several flight mills simultaneously removing the need for human labor in collection of these data.


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