Management Tactics Based on Psyllid Movement and Distribution in Florida Citrus

Management Tactics Based on Psyllid Movement and Distribution in Florida Citrus

Report Date: 07/14/2014
Project: 600   Year: 2014
Category: ACP Vector
Author: Phil Stansly
Sponsor: Citrus Research and Development Foundation

Issue date for this grant was 13 July 2012. Objectives are: 1. Assess effects of abiotic factors (light quality, photoperiod, air flow, temperature fluctuations) on psyllid movement, 2. Evaluate physiological limits and biotic factors effecting of movement including feeding, egg load, infection status, and population density, 3. Evaluate techniques for tracking psyllid movement in the field for mark recapture studies, 4. Characterize seasonal patterns of ACP distribution and movement at different scales in the field, 5. Develop strategies to protect young trees from colonization by ACP utilizing UV reflection for repellency and insecticide treated trap crops (such as Bergera koenigii) to attract and kill. Objective 1. Bioasssays using a wind tunnel to determine ACP response to different stimuli have shown that ACP movement stops when temperature dips below 67 F, and when there is no light. Wind speeds above 4.25 mph reduce movement greatly, as does humidity over 70%. ACP tend to move with the wind when lighting is even and increased light intensity does not increase ACP movement. Objective 2. Experiments were conducted with a laboratory flight mill in the Stelinski laboratory to determine the effect of applying Fenoxycarb, a juvenile hormone (JH) analogue, on flight behavior of ACP. No significant differences were observed between the controls and the psyllids treated with Fenoxycarb, suggesting that JH may not impact flight capability. Following their recent finding that Clas infection increased flight propensity of ACP, they are now testing the hypothesis that Clas infection may impact other movement patterns, such as male attraction toward female odor(s). In a laboratory olfactometer assay, non-infected ACP males were attracted by non-infected ACP female odors. However, if nymphal development was completed on HLB-infected plants, only infected ACP females were attractive to males. These data will be used to develop a predictive model for spread of the CLas pathogen causing HLB. Objective 3. Mark release trials were not successful and discontinued, but environmental effects on ACP movement was studied by hourly monitoring from sunrise to sunset of sticky cards placed between 3 year old orange trees with a final observation next day at sunrise. Captures increased in the morning with two peaks seen at mid-day followed by a gradual increase until dusk. Thus far we have not captured any ACP during the overnight period which was expected due to the results of the no light variable in the wind tunnel. This study is a good companion to Objective 1 allowing us to confirm the wind tunnel results in the the field. Objective 4. More ACP were captured on sticky cards in the upper canopy compared to the lower canopy of mature trees in a 2 year study at two locations, Bob Paul (‘Pineapple’ orange) and Tanner Road (‘Valencia’ orange). Sticky cards on the east side of the trees captures more ACP than the west side at both locations. At both locations and also the English grove (‘Valencia’), ACP captures are greatest adjacent to a hammock or wind break on the east and west sides. No differences were seen in trap captures facing insecticide sprayed or unsprayed blocks at Bob Paul. Two-sided clear and yellow sticky cards have been placed in several groves to compare directional responses in an attempt to determine whether ACP adults flying in one direction may turn back and be captured on the opposite side of the yellow card. Objective 5. A paper reporting positive results using UV reflective mulch to repel ACP the first 2 years after planting has been published in the refereed journal Pest Management Science. Subsequent results indicated diminished repellency from the 5 ft strip of metalized mulch after trees exceeded 6 ft in height. In another trial, repellency was demonstrated by the result that fewer ACP were captured on sticky traps set at 1 m in reflective mulch compared to 2 m, where as the opposite was true over white mulch or no mulch (grass) where more ACP were captured more at 1m than 2m.


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