Alginate-kaolinite beads incorporated with agrochemicals: new baits for leaf-cutting ants control

Abstract

Insect pests such as leaf-cutting ants (genera Atta spp. and Acromyrmex spp.) are a major problem in tropical countries because they can cause significant damage to crops, resulting in substantial production losses. These insects have been controlled chemically using granular baits. Although these granules are cheap, they can pose some problems due to their low resistance to humidity. Therefore, developing new formulations that present environmental resistance, sustained release of the active chemical, and good ant-killing efficacy can expand the management options. This work aimed to produce new baits in bead form to control leaf-cutting ants (Atta sexdens). The beads are derived from the interaction between organic and inorganic materials, synthesized from mixtures of alginate polymer, kaolinite clay, sodium tetraborate, Beauveria bassiana spores, and chlorpyrifos. X-ray Diffraction, Fourier Transform Infrared Spectroscopy, Thermogravimetric Analysis Coupled with Differential Scanning Calorimetry and Mass Spectrometry, and Scanning Electron Microscopy provided important information about the structure and composition of the produced baits. For all baits, the data of the "in vitro" release study of boron were adjusted according to Higuchi's kinetic model. The results of boron leaching in soil columns experiments showed that for some baits, 100% of B leached after 15 days. According to the laboratory and field bioassays results, the beads showed good attractiveness and efficiency in controlling leaf-cutting ants. The synthesis of new beads of alginate-kaolinite containing agrochemicals proved to be a suitable bait with ant-killing potential and efficient for the chemical control of A. sexdens.