Use of push pull strategies for management of leaf cutting ants in Salicacea plantations of the Delta del Paraná wetland

PERRI, DAIANA; GOROSITO, NORMA; CASAUBÓN, EDGARDO; SCHILMAN, PABLO; FERNANDEZ, PATRICIA

Buenos Aires

Simposio; Seventh International Poplar Symposium; 2018

International Union of Forest Research Organizations (IUFRO)- Ministerio de Agroindustria- INTA

Leaf cutting ants are insects of importance in natural ecosystems. However, due to simplification of agroecosystems, leaf cutting ants have become serious pests, especially in young forestry plantations. In the case of willow plantations, currently, the main control method is the use of broad spectrum insecticides, which is not always efficient and has a negative effect on non-target organisms and the environment. The objective of this work was to evaluate a Push-Pull strategy for management of the leaf cutting ant Acromyrmex ambiguus (Emery 1988). The assay consisted in four plots separated from each other by ̴100 m. Each plot was assigned one different treatment. Twelve young willow cuttings of Salix babylonica var. sacramenta were planted in two rows separated by 1.5 m within each plot. Treatments were as follows: 1) Push-Pull: Willow cuttings were protected by a repellent stimulus (farnesol + mechanical barrier), surrounding natural vegetation was kept in the plot to use as an attractant stimulus and as food alternative to willow plants. 2) Push: Willow cuts were protected by a repellent stimulus (same as above) but natural vegetation was mechanically removed. 3) Pull: Natural vegetation was kept but willow cuts were not protected. 4) Control: Natural vegetation was removed and willow cuts were not protected. Assays were replicated in two different field sites with different irrigation conditions. In site A, land was modified by levees and polders, so water was scarce and the number of A. ambiguus nests was high. In site B land was not modified, water could enter and leave as a natural flooding movement in a wetland ecosystem, thus the number of ant nests was minimum. Foliation percentage was visually estimated once a month during November and December 2017, January and March 2018. Results showed that foliation percentage remained above 70% in the push-pull treatment in both field sites suggesting the efficacy of the strategy. The difference between control and push-pull treatments at the end of the observations was higher in site A reflecting the higher foraging pressure in the modified field site. The protective effect of the surrounding vegetation per se (Pull treatment) was higher in site B, probably due to the presence of higher palatable plants. These results encourage further work with this strategy in a field setting and suggest that repellents can integrated with the use of surrounding palatable vegetation to manage the foraging behavior of leaf cutting ants.