Evidence of distribution limitations of the Asian citrus psyllid Diaphorina citri Kuwayama (Hemiptera: Psyllidae) based on physiographic regions and Holdridge life zones

The Asian citrus psyllid, Diaphorina citri Kuwayama (Hemiptera: Psillidae) is the primary vector of citrus greening disease, which severely increases mortality of citrus plants and, therefore is considered the most destructive pest in citrus agriculture. Diaphorina citri is widespread throughout the Caribbean including Puerto Rico.  The diverse physiographic regions and Holdridge life zones, make the island an excellent model for the study of the occurrence of D. citri in relation to physical and ecological barriers.  Previous studies have demonstrated that the pest is distributed throughout the island with a negative correlation between elevation where at >600 meters, reduced or no populations are found. The objective of this study is to evaluate the distribution of D. citri in Puerto Rico in relation to physiographic regions and life zones using GIS. Samples were collected from farms, nurseries, roadsides and urban settings, and classified by physiographic region and life zones.  Physiographically, D. citri was found to occur significantly less in the mountainous regions.  The psyllid was also significantly less common in samples from the wet subtropical life zone. These results suggest that cultivation of citrus should be restricted or limited to mountainous/wet subtropical regions to decrease the spread of D. citri and citrus greening.