Beauveria bassiana for the control of leafcutter ants: strain and host differences

ABSTRACT

Leafcutter ants are a serious pest for forestry plantations and crops in Latin America. They have been traditionally controlled using chemical synthetic pesticides, which are known to have many negative effects to non-target organisms and the environment. Therefore, there is an urgent need for the development of alternative strategies of control, among which the biological control using fungal pathogens is a promising one. We evaluated in laboratory 3 strains of Beauveria bassiana (B5, B6, B7) against workers from 4 to 7 field colonies from 5 species of Acromyrmex leafcutter ant species which are considered pests in the region. Our results showed that all strains were pathogenic, although there are some ant species that turned out to be more susceptible either due to their intrinsic immunity or the natural load of pathogens they carried. The three strains were similarly effective for 3 of the 5 species, A. ambiguus, A. crassispinus, and A. lundii, being responsible for more than 80% of their mortality overriding the effect of their natural pathogens. Only strain B6 was able to kill a similar percentage of ants of A. heyeri, and strain B7 half of them. B5 in A. heyeri, as well as all three strains in A. lobicornis, were responsible for up to 30% of the mortality, but with the additive effect of the pathogens naturally brought by these ants accounted for a 70% of their mortality. We recommend using B6 to test the control of Acromyrmex leaf-cutting ants in the field.

KEYWORDS:

• Acromyrmex
• biological control
• entomopathogens
• fungus

Acknowledgements

We thank Enrique R. Zeni Co. for allowing us to collect ants from their forestry plots; to the corresponding authorities of Corrientes and Río Negro Provinces from Argentina for issuing us permits to collect leafcutter ants; and to Biocontrol Science &Technology for granting us permission to use data of A. lundii for comparative purposes. We also thank Alejandra Kenigsten, Alejandra Fernández, and Noelia Gómez for their help in the field.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

This work was supported by the National Agency for Science and Technology Promotion (ANPCyT) [grant number PICT 1145/16], [grant number FITR 009/15]; Quilmes National University [grant number 1009/11].