Morphological and Molecular Identification of Natural Fungi Associated with the Bean Fly, Aphis fabae (Scopoli) (Hemiptera: Aphididae), in Morogoro, Tanzania

Abstract

Common beans (Phaseolus vulgaris) play an essential role in the livelihoods of smallholder farmers in Tanzania, serving as a food security crop and a source of income. Despite their importance, production has been hindered by various factors, including insect pests such as Aphis fabae. Globally, different management practices have been employed to control the aphids, including the use of naturally occurring fungi species. However, in the least developed countries, such methods face challenges due to import restrictions and unsuitability for the local climate; therefore, there is a need to identify locally available fungi, which is the objective of this study. One hundred and twenty samples of bean aphid cadavers were collected monthly from December 2024 to March 2025 in Morogoro region in Tanzania. The samples were transported to the laboratory and cultured on potato dextrose agar (PDA). After 7 days, they were subcultured to obtain pure cultures. The pure cultures were morphologically and molecularly identified. The results from morphological identification revealed fungi belonging to the genera Fusarium, Cladosporium, Alternaria, and Paecilomyces, with various strains within these genera. However, molecular results identified 9 fungal strains of the Fusarium genus, 6 isolates of the Cladosporium genus, and 1 isolate each from the Alternaria and Paecilomyces genera. The results indicate that Fusarium spp. and Cladosporium spp. are dominant under natural conditions compared to Paecilomyces and Alternaria spp. This suggests that Fusarium and Cladosporium spp. can offer promising control measures against Aphis fabae; however, further research is necessary to confirm their effectiveness against bean aphids.