Plant‐based compounds with potential as push‐pull stimuli to manage behavior of leaf‐cutting ants

Abstract

Leaf‐cutting ants are a serious pest of young forestry plantations. Currently, the main control method is the use of broad‐spectrum insecticides, which have a negative effect on non‐target organisms and the environment. In this work, plant‐based compounds were evaluated in laboratory assays with Acromyrmex ambiguus Emery (Hymenoptera: Formicidae) for their potential use as repellent and attractant stimuli to be used in a push‐pull strategy. Farnesol, a sesquiterpene present in many essential oils, was tested as a repellent at doses of 10, 50, and 100 mg. Its distance of action was studied by comparing the repellent effect of farnesol in a situation in which ants had to touch the farnesol in order to reach the food source in comparison to when ants could reach the food source without getting into direct contact with it. Different parts of the orange fruit (pulp and peel) were evaluated and compared as attractants, given that citrus‐based baits are among the most popular attractants used. Results from laboratory bioassays indicated that farnesol is repellent at doses of 50 mg and acts upon contact or at a very short distance. Furthermore, orange pulp was more attractive than the peel, and volatile compounds were highly responsible for the attraction. When both stimuli were tested simultaneously in a laboratory experiment, repellency of farnesol was enhanced in the presence of orange pulp odor. When tested in a field push‐pull experiment, the results also showed a good repellent effect of farnesol as well as an attractant effect of the orange pulp. These results encourage long‐term studies with these substances in a field setting and suggest that repellents can be enhanced by the use of attractants to manage leaf‐cutting ants behavior.

Survival and initial growth in the field of eucalyptus seedlings produced in different substrates

“…Before seedling plantation in the field, mechanical mowing was conducted in the total area of the experiment, followed by the control of leaf-cutting ants with a natural bait made with orange peel (Perri et al, 2017). The planting lines were marked with a subsoiler at a 50-cm depth, with a spacing of 3.0 m between the lines and 1.5 m in the line.…”

Push‐pull to manage leaf‐cutting ants: an effective strategy in forestry plantations

“…As a push ( i.e ., repellent) stimulus, a commercial mechanical barrier, commonly used by producers, 37 was placed around the twig in order to protect plant material. Additionally, farnesol (SIGMA Aldrich), a LCA repellent sesquiterpene, was applied (100 mg in 100 mg lanoline) below the mechanical barrier forming a 2 cm band around the twig 38 . As a pull stimulus, spontaneous farmland vegetation was allowed to grow in between young willow trees.…”

“…Additionally, farnesol (SIGMA Aldrich), a LCA repellent sesquiterpene, was applied (100 mg in 100 mg lanoline) below the mechanical barrier forming a 2 cm band around the twig. 38 As a pull stimulus, spontaneous farmland vegetation was allowed to grow in between young willow trees. The assay consisted of four experimental plots in a split plot design in each field site.…”

Act locally, think globally: Ant studies in Argentina in the context of ecological theory

“…Different plant-based compounds, plant species, and even waste generated by the ants themselves have been demonstrated to modulate ant foraging behavior (Farji-Brener and Sasal 2003;Ballari and Farji-Brener 2006;Medina et al 2012;Perri et al 2017;Alma et al 2019;Buteler et al 2021). Among those with repellent action, tea tree oil (a complex mixture of terpene hydrocarbons and tertiary alcohols distilled mainly from plantation stands of the Australian native plant Melaleuca alternifolia) and farnesol (present in many essential oils, such as Pluchea dioscoridis and Pittosporum undulatum) repel leaf-cutting ants at short distance in both laboratory and field assays (Perri et al 2017;Buteler et al 2021). Their low toxicity and persistence make them environmentally safer than other pesticides, but their high volatility might reduce their repellent power.…”

“…Even though its repellent effect is short-lived, further research identifying the compounds that cause the effect could lead to a novel ant repellent. In addition, heptyl butyrate, a volatile compound found in fresh apples and plums, and orange pulp can be used as attractant stimuli (Perri et al 2017;Alma et al 2019). Attractants and repellents could be combined in an IPM strategy termed push-pull, which involves the manipulation of ant foraging behavior by integrating stimuli that turns crops unsuitable or unattractive to the insect pest (push) and simultaneously attracts them towards another resource (pull) from where the pest is subsequently removed (Cook et al 2007).…”