Influence of temperature and application rate on efficacy of a diatomaceous earth formulation against Tribolium castaneum adults

Abstract

Unsanitary storage bins can harbor grain-infesting insects, including the red flour beetle, Tribolium castaneum (Herbst). In a previous study involving heat treatment of empty bins, temperatures in the range of 50-55C for 2-4 h were effective in completely killing storedproduct insects. Previous research in flour mills showed improved efficacy in killing storedproduct insects by using diatomaceous earth (DE) dusts at temperatures below 50°C. In the current study, the efficacy of a diatomaceous earth formulation (DiaFil® 610) applied to concrete arenas, to simulate floor of empty bins, was examined at three application rates (0, 2.5 and 5.0 g/m 2) to control T. castaneum adults at five constant temperatures (28, 36, 42, 44, and 46°C). Ten adults of T. castaneum were placed on individual untreated and DE-treated concrete arenas for 4, 8, 12, and 24 h at each of the five temperatures. The efficacy of DE against T. castaneum adults increased with an increase in temperature and exposure time. Generally more adults died at 5.0 g/m 2 when compared with 2.5 g/m 2. In 2.5 and 5.0 g/m 2 DE treatments, exposure for 12 h at a temperature of 42°C resulted in 73-77% mortality of adults with 100% mortality observed after 24 h. At 44 and 46C, 100% mortality of adults was observed after 24 h of exposure at both DE rates. At these two temperatures, the high mortality in untreated arenas (controls) at 8, 12, and 24 h exposures ranged from 27-100% confounding the true effects of DE. Our results suggest that combined use of DE and temperatures below 50C can be used as an integrated approach for controlling insects in empty bins prior to storage of newly-harvested grain.

Control of Maize Weevil With Application of Diatomaceous Earth in Corn Grains Stored in Diverse Temperatures

“…When evaluating the effect of three corn grain storage temperatures (15, 25 and 30°C) submitted to three doses of DE (500, 750 and 1000 g t -1 ), Ceruti et al (2008) observed that the higher the dose and the temperature, higher the mortality, corroborating with the results obtained in the present study. Likewise, Frederick and Subramanyam (2016) found higher mortality rate of Tribolium castaneum, Herbst, 1797 (Coleoptera: Tenebrionidae) adults when the grains treated with DE were stored at higher temperatures.…”

“…In recent years several studies evaluating the effect of DE on the control of insect pests of stored grains have been published, highlighting its potential as a protective agent for stored grains (FREDERICK;SUBRAMANYAM, 2016;JAIROCE et al, 2016;WAKIL and SCHMITT, 2015;KAVALLIERATOS et al, 2015;ZIAEE et al, 2014;EISSA et al, 2014;ATHANASSIOU et al, 2014;NWAUBANI et al, 2014;DOUMBIA et al, 2014). However, the studies are largely dedicated to the evaluation of doses and sources, with few studies evaluating the efficacy of DE at different storage temperatures and its residual effect (long-term storage), especially for the protection of stored corn grains against S. zeamais, associating its influence on the quantitative parameters of the grains.…”

Disinfestation techniques for major cereals: A status report

“…Moreover, the increase in the moisture content of the treated commodities has a notable positive effect on the disinfestation using dielectric heating methods of radiofrequency, infrared, and microwave treatments (Jiang et al., 2019; Pan et al., 2008; Vadivambal et al., 2008). The investigations on the pesticidal efficacy of spinosad (Athanassiou et al., 2008) and diatomaceous earth (Frederick & Subramanyam, 2016) have reported that the changes in factors such as temperature and relative humidity affect the insect mortality and the impact varies depending on the insect species. Mcneil (1991) reviewed that factors such as temperature, relative humidity, day length, light intensity, wind speed, and atmospheric conditions affect the emission and reception of pheromones.…”

Potential of diatomaceous earth as a management tool against Acanthoscelides obtectus infestations

“…Moreover, higher temperatures usually increase insect movement inside the grains, causing increased contact with the diatomaceous earth and, consequently, greater cuticular damage. Furthermore, it is important to feature that unlike synthetic insecticides, DE is inert and does not degrade with the increase of temperature, which allow farmers to use DE products combined with elevated temperatures (Dowdy, 1999;Fields and Korunic, 2000;Athanassiou et al, 2005;Athanassiou et al, 2011;Bohinc et al, 2013;Frederick and Subramanyam 2016). Values in the same row followed by different lowercase letter are significantly different when exposed to different temperatures; Similar capital letters on the same column indicate no significant differences between treatments (Duncan's multiple range (P < 0.05; df (4,14) ) was 19.36 for columns and rows).…”