Diatomaceous earth (DE) products, composed of microscopic fossils of diatoms, can be an alternative to chemical methods in controlling stored products infestations. Insecticidal activity depends on the DE capacity to damage insects’ cuticle and cause water loss from their bodies, so that they die of desiccation. The efficacy of DE products depends on several parameters, such as insect morphology, type of grains, DE physical parameters, temperature and relative humidity. The insecticidal activity of Protector® was tested against the eggs and the larval instars of Rhyzopertha dominica (L.) (Coleoptera Bostrychidae) (the lesser grain borer) and Tribolium castaneum (Hebst) (Coleoptera Tenebrionidae) (the red flour beetle). Preliminary tests were carried out to assess the development time from egg to adult for both insects at 23 °C and 34 °C. The experiments with DE were performed at 23 ± 0.2 °C and 34 ± 0.2 °C within one-liter glass jars using, as feeding substrate, soft wheat for R. dominica and corn for T. castaneum where they had previously laid their eggs. Samples were treated with a Protector® dosage of 0.25 g/Kg. The most sensitive larval instars of T. castaneum were identified at both temperatures. The results showed that Protector® can prevent infestations of both insects, especially T. castaneum. The efficacy of the product depended on the biological and morphological characteristics of the insects and on the temperature. The temperaturer hid the efficacy of the treatment at 23 °C against R. dominica because dead insects were collected in controls, but were not found in untreated samples at 34 °C; the mortality rate in treated jars at 23 °C was 74% and in untreated jars 8%. At 23 °C for T. castaneum no offsprings was observed, while at 34 °C we counted some adults. However, the number of the latter was considerably lower than that obtained in untreated samples. The sensitivity of the larval instars to Protector® showed that it was efficacious against T. castaneum larvae at both temperatures. We also noticed that the product was lethal for first instar larvae but not for older larval stages. The persistence of product efficacy was observed against R. dominica but not for T. castaneum.

Analysis of the sensitivity of different stages of Rhyzopertha dominica and Tribolium castaneum to diatomaceous earth

BALDASSARI, NADIA;MARTINI, ANTONIO;BARONIO, PIERO
2004

Abstract

Diatomaceous earth (DE) products, composed of microscopic fossils of diatoms, can be an alternative to chemical methods in controlling stored products infestations. Insecticidal activity depends on the DE capacity to damage insects’ cuticle and cause water loss from their bodies, so that they die of desiccation. The efficacy of DE products depends on several parameters, such as insect morphology, type of grains, DE physical parameters, temperature and relative humidity. The insecticidal activity of Protector® was tested against the eggs and the larval instars of Rhyzopertha dominica (L.) (Coleoptera Bostrychidae) (the lesser grain borer) and Tribolium castaneum (Hebst) (Coleoptera Tenebrionidae) (the red flour beetle). Preliminary tests were carried out to assess the development time from egg to adult for both insects at 23 °C and 34 °C. The experiments with DE were performed at 23 ± 0.2 °C and 34 ± 0.2 °C within one-liter glass jars using, as feeding substrate, soft wheat for R. dominica and corn for T. castaneum where they had previously laid their eggs. Samples were treated with a Protector® dosage of 0.25 g/Kg. The most sensitive larval instars of T. castaneum were identified at both temperatures. The results showed that Protector® can prevent infestations of both insects, especially T. castaneum. The efficacy of the product depended on the biological and morphological characteristics of the insects and on the temperature. The temperaturer hid the efficacy of the treatment at 23 °C against R. dominica because dead insects were collected in controls, but were not found in untreated samples at 34 °C; the mortality rate in treated jars at 23 °C was 74% and in untreated jars 8%. At 23 °C for T. castaneum no offsprings was observed, while at 34 °C we counted some adults. However, the number of the latter was considerably lower than that obtained in untreated samples. The sensitivity of the larval instars to Protector® showed that it was efficacious against T. castaneum larvae at both temperatures. We also noticed that the product was lethal for first instar larvae but not for older larval stages. The persistence of product efficacy was observed against R. dominica but not for T. castaneum.
BALDASSARI N.; BERLUTI A.; MARTINI A.; BARONIO P.
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11585/832
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