Submitted to: Journal of Economic Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: December 5, 2009
Publication Date: January 15, 2010
Citation: Hall, D.G., Hentz, M.G. 2010. Sticky trap and stem-tap sampling protocols for the Asian citrus psyllid (Hemiptera: Psyllidae). Journal of Economic Entomology. 103(2):541-549. Interpretive Summary: Asian citrus psyllid is an important citrus pest because it transmits the bacterium responsible for citrus greening disease, sometimes referred to as huanglongbing. This is the most devastating disease of citrus worldwide and is currently jeopardizing citrus production in North America. Growers and researchers alike need methods of monitoring psyllids in citrus and estimating psyllid infestation levels. In terms of food safety, formal sampling procedures would facilitate the use of control thresholds for the psyllid should these be identified – the decision to spray a block of citrus trees would be based on sampling, which could reduce the use of insecticides. We developed a sampling protocol for two different sampling methods for estimating relative infestation levels of adult psyllids: sticky trap sampling and stem-tap sampling. The protocols identify optimum number of samples and how these should be allocated in order to achieve a desired level of precision in mean estimates.
Technical Abstract: Sampling statistics were obtained to develop a sampling protocol for estimating numbers of adult Diaphorina citri in citrus using two different sampling methods: yellow sticky traps and stem–tap samples. A 4.0 ha block of mature orange trees was stratified into ten 0.4 ha strata and sampled using each method seven times over a seven-month period. One sticky trap was deployed per tree on each of 16 trees randomly selected in each stratum, and numbers of adults on the traps were counted one week later. One stem–tap sample in which the number of adults falling into a pan after three rapid taps to a branch was taken per tree on each of 16 trees randomly selected in each stratum. A sampling protocol of one yellow sticky trap on each of 20 trees, or of one stem–tap sample on each of 30 trees, distributed uniformly across an area up to 4.0 ha in size (excluding block edges) was projected to provide an average sampling precision rate of less than 25 percent (SEM/mean*100) at means of one or more adults per trap or stem–tap sample. Validation sampling indicated 20 sticky trap samples consistently provided the desired precision level at means of around two or more adults per trap but not at means of 1.0 to 1.5 per trap. A sample size of 30 stem–tap samples consistently provided the desired average precision level, but the precision of some individual estimates was greater than 25 percent at means of around one adult per tap sample.