The objective of this study is to provide a model for determining the population level (spray threshold) of Asian citrus psyllid (ACP) that would require insecticide treatment. Such a threshold could optimize the cost of ACP management in groves under conditions of high huanglongbing (HLB) incidence. We are trying to further optimize the economic threshold based on different insecticide mode of action rotation strategies such that use of this threshold can be integrated with resistance management. Ultimately, we will determine how various levels of pest control input using different insecticide rotation strategies affect both ACP densities and citrus yield in replicated field plots. First, the action thresholds of 0.2, 0.5 and 1.0 ACP adults per tap sample were assigned to field plots of Hamilin citrus. The plots were approximately 4 acres in size. Furthermore, the plots were split into two groups and each group was assigned to one of two insecticide rotation schemes. The rotations were: 1) dimethoate, cyantraniliprole, fenpropathrin, thiamethoxam, spinetoram, dimethoate, fenpropathrin, abamectin, and imidacloprid for rotation A; and 2) fenpropathrin, dimethoate, cyantraniliprole, diflubenzuron, thiamethoxam, abamectin, dimethoate, spinetoram and imidacloprid for rotation B. We collected samples chosen at random from the central rows of each plot sampling ACP adults. When the tapping number reached the 0.2, 0.5 or 1 ACP adult per tap threshold, an insecticide spray occurred. For the 0.2 adult threshold treatment, the following applications were made: The first treatment was dimethoate followed by cyantraniliprole, fenpropathrin, thiamethoxam, spinetoram and diflubenzuron for rotation A and fenpropathrin, dimethoate, cyantraniliprole, diflubenuron, thiamethoxam and spinetoram for rotation B. For the 0.5 adult per tap threshold treatment, the first treatment was dimethoate followed by cyantraniliprole, fenpropathrin and thiamethoxam for rotation A. For the second rotational scheme, we applied fenpropathrin, dimethoate, cyantraniliprole and diflubenuron for rotation B when the 0.5 ACP/tap thressholds were triggered. For the 1 adult threshold treatment, the first spray was dimethoate followed by cyantraniliprole for rotational A and fenpropathrin and dimethoate for rotational B. There were 6 applications for the 0.2 adult per tap threshold treatment, 4 applications for the 0.5 adult per tap threshold treatment, and 2 application for the 1 adult per tap threshold treatment. Second, we monitored ACP adults, eggs and nymphs to determine insecticide efficacy. Experimental treatments were evaluated by weekly counts before and after insecticide applications. For eggs and nymphs, 10 randomly selected flush samples were collected from each plot weekly and eggs and nymphs were quantified by a ranking method. The rankings for eggs were 0 = 0; 1= 1-20; 2 = 21-40; 3 > 41 and nymphs were 0 = 0; 1= 1-5; 2 = 6-10; 3 > 11. Adults were monitored by the tapping method by tapping 20 trees per plot. Densities of ACP adults were monitored every week from March 23, 2020 and eggs and nymphs were monitored weekly starting May 22, 2020. The results indicated that there were significant differences in numbers of ACP adults counted between rotation A and rotation B (df = 1; F = 6.35; p = 0.01). Furthermore, there were significantly differences in numbers of adults between each threshold treatment for 0.2, 0.5 and 1 adult per tap (df = 5; F = 27.51; p < 0.001). The average ACP count was higher in plots where the 1 adult/tap threshold was implemented than in plots where the 0.2 or 0.5 ACP/tap thresholds were implemented for both rotation A (0.42 ± 0.85) and rotation B (0.47 ± 0.95). There were no significant differences in numbers of ACP eggs between rotation A and rotation B (df = 1; F = 0.05; p = 0.81); However, there were significant differences between each threshold treatment for the numbers of eggs counted per flush (df = 4. F= 9.03; p < 0.001). More ACP eggs occurred in plots where the 1 adult/tap was used for rotation A (0.48 ± 0.86) and rotation B (0.50 ± 0.81) than in plots where the 0.2 and 0.5 ACP adults/tap thresholds were implemented. There were no significant differences in ACP nymph numbers between rotation A and rotation B (df = 1; F = 1.11; p = 0.29). However, there were significant differences between each threshold treatment (0.2, 0.5 and 1 ACP adults/tap) in the numbers of nymphs counted per flush (df = 4; F = 20.99; p < 0.001). Significantly more nymphs were counted in plots where the 1 ACP adult/tap threshold was implemented in both plots treated with rotation A (0.92 ± 1.17) and rotation B (0.80 ± 1.01) than in plots where the 0.2 or 0.5 ACP adults/tap thresholds were implemented3. Third, we use an insecticide bioassay to monitor changes in toxicity to thiamethoxam to field ACP after each application. This allowed us to determine if our field insecticide schedules are having an effect on resistance development of field ACP. Also, the incidence of the Candidatus Liberibacter asiaticus pathogen was determined before insecticide applications. For each bioassay, a total 5-8 concentrations were selected for testing. In plots that were managed with the 0.2 ACP adults/tap threshold, the resistance ratios ranged between 2.75-5.25 for rotation A and 1.63-5.12 for rotation B. For the 0.5 ACP adults/tap threshold, the resistance ratios varied from 1.6-6.75 for rotation A and 1.75-5.25 for rotation B. For the 1 ACP adult/tap threshold, the resistance ratios ranged between 3.13-4 for rotation A and 2.25-3.25 for rotation B. Overall, these results indicated that there were no great differences in susceptibility of ACP between the two rotations and various treatment thresholds and that all of our management schemes were effectively keeping resistance levels in check. To determine the level of CLas pathogen in treatment plots, three trees were sampled per plot for a total of 24 trees for each rotation. The presence of Candidatus Liberibacter asiaticus was determined by qPCR. We found that 100 % of the trees on this study were HLB positive. In the future, we will continue monitoring ACP populations and the HLB infection rate. An economic analysis will be used to calculate cost per acre and total cost per field for each insecticide application, as well as total insecticide costs for the growing season. The yield will be determined from each plot. Juice quality will be also be measured. Economic viability of each threshold treatment will be analyzed using yield data from all harvests.