Abstract
The last volcanic eruption of the Puyehue-Cordon-Caulle Volcanic Complex in the Andes cordillera of western South America, occurring on 4 June 2011, ejected pyroclastic materials that were accumulated in a wide region of the northern Patagonia (Argentina), affecting the environment and health of residents within the area. The aim of this work was to evaluate the practicability of using this waste material as a lowcost carrier for mycopesticide formulations. Beauveria bassiana is a recognized fungal agent for arthropod biologic control. Lengthy storage is critical for the development of mycoinsecticide formulations. Accordingly, the search for adequate materials to improve the shelf life of biocontrol products becomes desirable. First, several analytical techniques were employed to characterize the pyroclast physicochemically; then the viability of the fungal conidia was evaluated after an 18-month storage in the volcanic material. Finally, the pathogenicity of the conidia after that prolonged maintenance in the vehicle was assessed on the beetle Alphitobius diaperinus, an insect pest in poultry houses that causes major economic losses. The results from those bioassays proved auspicious for the eventual utilization of the pyroclast as a bioinsecticide carrier especially since the formulation had proven to be stable for at least 18 months under a wide range of environmental conditions. The constant moisture in a closed environment within a 5°C - 40°C temperature range insures a viable state during storage. The results indicate that what would otherwise be volcanic waste may be utilized as an efficient, abundant, inexpensive, and environmentally innocuous carrier of entomopathogenic fungi.
Highlights
The Andes cordillera in western South America is one of the most active tectonic and volcanic regions worldwide
Several analytical techniques—e.g., inductively coupled plasma atomic-emission spectroscopy (ICP-AES), differential thermal gravimetry, X-ray diffraction, scanning electron microscopy (SEM), Braunauer-Emmet-Teller (BET) adsorption, Raman spectroscopy, and particle-size-distribution measurement—were employed for physicochemical characterization of the pyroclast; the viability of the fungal conidia was evaluated after storage for 18 months in the volcanic material; and the pathogenicity of the conidia after that prolonged maintenance in the vehicle was assessed on the beetle Alphitobius diaperinus (Coleoptera: Tenebrionidae), an insect pest in poultry houses that causes major economic losses [12,13]
Likewise, polarizing-microscope studies indicated thepredominance (~80% - 90%) of vitreous fragments; where crystalline phases such as quartz, orthoclase, plagioclase, titanite, iron oxides, and pyrite were observed in minor proportions
Summary
The Andes cordillera in western South America is one of the most active tectonic and volcanic regions worldwide. S. Schalamuk et al / Journal of Agricultural Chemistry and Environment 3 (2014) 14-21 consideration of that pyroclast’s high abundance and low cost of extraction, several investigations have been directed at analyzing the potential use of the ash as raw material for the development of different technological processes (e.g., in adsorbents and binders and as substrates). Different geomaterials (mainly stable mineral species) as well as organic and inorganic compounds are employed as vehicles for agrochemicals and biopesticides, with silicates being the most commonly used because of their properties, stability, abundance, and low cost [3]. The development of fungal biocontrol formulations with clay minerals as carriers has highlighted the low environmental impact relative to other types of vehicles [6]. To the best of our knowledge, no information is as yet available on the utilization of pyroclastic material (ashes and pumices) for that purpose
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