Cumulative effects of volcanic ash on the food preferences of 2 Orthopteran species

Abstract

Los polvos inertes son una forma temprana de insecticida que todavía está en uso. Uno de los polvos inertes más comunes es la ceniza volcánica. Con el fin de estudiar la reacción de saltamontes de pastizales, Dichroplus vittigerum (Acrididae) y un katydid, Burgilis mendosensis (Phaneropteridae), a la presencia de cenizas volcánicas en sus fuentes de alimento y cómo cambió esta reacción en función del tiempo, Pruebas entre hojas limpias de su planta huésped preferida y hojas expuestas a cenizas volcánicas de diferentes tamaños de grano. La respuesta de comportamiento se midió como la calificación en la escala de preferencias de Thurstonian de hojas con ceniza en relación con las hojas limpias. Los resultados mostraron que la evitación de cenizas volcánicas aumentó en función del tiempo en ambas especies.

Inert dusts are an early form of insecticide which is still in use. One of the most common inert dusts is volcanic ash. In order to study the reaction of rangeland grasshoppers, Dichroplus vittigerum (Acrididae) and a katydid, Burgilis mendosensis (Phaneropteridae), to the presence of volcanic ash in their food sources and how this reaction changed as a function of time, we conducted paired preference tests between clean leaves of their preferred host plant and leaves exposed to volcanic ash of different grain size. The behavioral response was measured as the rating on the Thurstonian preference scale of leaves with ash in relation to clean leaves. The results showed that the avoidance of volcanic ash increased as a function of time in both species. Both species studied are occasionally exposed to volcanic activity, and come from an area in which a volcanic eruption had recently occurred. As their populations did not decrease after the ash fall, we propose that some behavioral responses such as avoidance of places with ash, works as tolerance mechanism to inert dusts exposure.