Lichen-host plant specificity on citrus plant species in coastal agroecosystems at No. 63 Benab, Berbice, Guyana

Abstract

This was a preliminary study into host-plant lichen specificity at two coastal agroecosystems sites at No. 63 Benab, Berbice, Guyana. For each of the two sites, sampling plots of 2000 meter square (2000 m2) were demarcated and at 50 m × 40 m study plots were established. Healthy mature trees were identified in each plot to assess the lichen communities host-plant specificity. Twine was used to mark the trunks of 40 healthy individual trees in the North, South, East, and West quadrants (each measuring 50 by 100 cm). A total of 52,311 lichens were recorded and these were placed into fifteen (15) families, twenty-three (23) genera, and thirty (30) species. Crustose lichens were the most abundant in the study. Cocos nucifera had the highest average number of lichens recorded and accounted for forty-five percent (45 %) of the overall host trees that were sampled. Four (4) species of lichens (Flavoparmelia soredians, Dirinaria applanate, Lecanora muralis and Lecanora conizaeoide) showed specificity towards all host trees in the study. Twenty-six (26) species did not show specificity to all twelve (12) of the host tree species sampled. Twelve (12) species of lichens (Parmelia sulcata, Flavoparmelia soredians, Flavoparmelia caperta, Dirinaria applanate, Chrysothrix candelaris, Lecanora muralis, Lecanora conizaeoide, Arthonia cinnabarina, Arthonia purinata, Candelaria concolor, Lepraria lobificans and Graphis elegans) showed host tree specificity for four (4) species of citrus trees sampled. 13.3 % species were found on all tree hosts: Flavoparmelia soredians, Dirinaria applanate, Lecanora muralis and Lecanora conizaeoide. Mangifera indica hosted 76.7 % (23 of 30 species) of all recorded species. Tamarindus indica hosted the least number of lichen species, 26.7 % of lichens (8 of 30 species). Given that a lot of development is considerably taking place in the coastal areas of Guyana which may increase the instances of pollution, studies of this type can be beneficial since prior research has established the importance of lichens as good indicators of air pollution.