Evaluation of the biological activity of extracts obtained from bacteria against Atta cephalotes
Adriana Ortiz-Reyes, Miguel Uribe-Londoño , Magally Romero-Tabarez
Facultad de Ciencias, Universidad Nacional de Colombia, Colombia; Posgrado Entomología, Universidad Nacional de Colombia ; Facultad de Ciencias, Universidad Nacional de Colombia
Leaf-cutting ants (Atta cephalotes) are one of the main Neotropical pests; In Colombia, they affect more than 50 crops. This species, besides Acromyrmex sp., exhibit a unique trait among ants – fungi cultivation as a food source (Leucoagaricus gongylophorus). Commonly the methods of population control are based on synthetic insecticides that in turn has a high negative impact on the environment and human health, being necessary the applicability of integrated pest control. However, these integrated mechanisms require insecticidal and fungicidal activity. The aim of the present study was to assess the action of several bacterial extracts for their insecticidal and fungicidal properties on adult major workers of Atta cephalotes and L. gongylophorus. The bacterial strains were obtained from the “Gene Bank and culture collection of the biotechnology institute, National University of Colombia (IBUN)”. From each bacterium, extracts were prepared to test both insecticidal and repellent activity on worker ants, also to evaluate growth inhibition assays on L. gongylophorus. A total of 115 bacterial extracts, prepared from the same number of strains were evaluated, including Serratia sp., Xenorhabdus nematophila, Photorhabdus sp. and Bacillus thuringiensis. A total of 24 bacterial extracts showed biological activity against leaf cutting ants, from them, 12 extracts killed ants in less than 48 hours and seven showed antifungal activity. These results demonstrate the importance of bacteria as a valuable source of active secondary metabolites, and expands options on leaf cutting ants control.