Effect of volcanic ash over Orthoptera survival in Patagonia

Abstract

The aim of this work was to evaluate the ash toxicity from the Puyehue-Cordón Caulle volcanic complex on the survival of two Orthopteran species: the grasshoper Dichroplus vittigerum and the green locust Brugilis sp. Two grain size were used to evaluate the effect of volcanic eruption on these insects. Chemical analyses from this eruption proved that the ashes were very abrasive and predominantly composed of silica shards (SiO 2 ) and aluminia (Al 2 O 3 ), two substances with insecticidal properties. In northern Patagonia, both orthopteran species are polyphagous chewers on grasses and dicots. The laboratory data showed that sustained exposure to volcanic ash induced mortality in adult grasshoppers. Survival of D. vittigerum significantly decreased once exposed to the two ash granulometries. In turn, Brugilis sp. survival was significantly reduced when exposed to fine grain ashes. These results suggest that the onset of the volcanic eruption with the consequent suspension of the pyroclastic material in the air might negatively impacted these orthopteran due to the mortality of adults. The ash from the Puyehue-Cordón Caulle volcanic complex could be compared to the application of non-persistent and broad spectrum insecticide, causing a temporary reduction in orthopteran populations.

Functional Response of Three Species of Chrysoperla1 Preying on Melanaphis sacchari2

“…1a). This is common in invertebrate predators (Holling 1959a, Hassell et al 1977) and has also been reported for the same Chrysoperla species in this study, but feeding on other prey species (Holling 1959a, Atlihan et al 2004, Fernandez-Arhex and Corley 2004, Mushtaq and Khan 2010, Hassanpour 2011, Palomares-Pérez et al 2019). In all cases, the curves diverged at prey density greater than 32, and C. carnea had greatest consumption ability than the other two species studied, even at 256 M. sacchari nymphs.…”

Bifurcation Analysis in a Coffee Berry-Borer-and-Ants Prey–Predator Model

“…In particular, the Holling Type II functional response assumes that the predation rate is proportional to the encounter rate between prey and predators but also takes into account predator satiation as prey density increases. In other words, the Holling Type II functional response in a prey-predator model captures the following observed behavior in nature: predators cannot consume prey indefinitely at constant rates, but their efficiency decreases as prey density increases [22]. One mathematical expression of the Holling Type II functional response is as follows:…”

Effect of egg production dynamics on the functional response of parasitoids

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