Morphometric characterisation of Scutellonema bradys populations from the Guinea Savanna and Transitional Rain Forest ecological zones of Ghana

Yam (Dioscorea spp.) forms a large portion of Ghanaian diets and is cultivated in most regions. However, yam is highly susceptible to parasitism by the yam nematode, Scutellonema bradys. Ten major yam communities from 10 districts (Yendi, Karaga, East Gonja, Kumbungu, Savelugu/Nanton, Kintampo North, Techiman, Wenchi, Atebubu/Amanten and Ejura/Sekyeredumase) were selected for soil and yam tuber sampling. Body lengths ranged from 624.6 to 858.5 µm, and 609.5 to 854.1 µm for female and male S. bradys populations, respectively. Tail lengths ranged from 5.3 to 9.6 µm, and 5.2 to 8.6 µm for female and male S. bradys populations, respectively. Principal component analysis did not reveal distinct groups among the female and male populations. This was further confirmed through agglomerative hierarchical clustering with subgroupings showing less than 20% dissimilarity for both female and male populations, and nematodes from different locations clustered together. Significant morphological variation therefore exists both within and among female and male S. bradys populations as reflected in the formation of subgroups.