Respirometry recordings from: Diatomaceous earth as insecticide: physiological and morphological evidence of its underlying mechanism

Open-flow RespirometryRespirometric measurements were performed in two groups of insects. One that we called <i>“DE”</i> that was previously treated with diatomaceous earth, and the other called <i>“Control”</i>, which was not exposed to diatomaceous earth. For the DE group we used a concentration of half gram of Diatomaceus earths per kg of wheat grain (0.5 g kg^-1). After the two days treatment, 14 replicates of DE and 13 of Control group of 30 individuals each were placed inside the respirometric chamber for measurement. Insect's water and carbon dioxide emission rate were measured at real time using a high-resolution TR-2 Stable System International's open flux respirometry setup (SSI, Las Vegas, NV, USA). Insects are placed inside a respirometric chamber (RC-M; internal volume ≈13ml; SSI), which is connected to an open circuit of air flow, generated and controlled by a flow controller (SS4 sub-sampler, SSI). The setup has a set of analyzers and modules that enables us to measure carbon dioxide and water emission of the insects inside the chamber, as well as ambient temperature, chamber temperature and insect's activity (movement), in high resolution and real time. The analog outputs from the analyzers were connected to an A/D converter (UI-2; SSI) and stored in a computer by ExpeData data acquisition software (SSI) at a frequency of 1 Hz.