Differential Effects of Abiotic Factors on the Insecticidal Efficacy of Diatomaceous Earth against Three Major Stored Product Beetle Species
Laboratory of Entomology and Agricultural Zoology, Department of Agriculture, Crop Production and Rural Environment, University of Thessaly, Phytokou Street, 38446 Nea Ionia, Greece
*
Author to whom correspondence should be addressed.
Agronomy 2022, 12(1), 156; https://doi.org/10.3390/agronomy12010156
Submission received: 29 November 2021
/
Revised: 21 December 2021
/
Accepted: 27 December 2021
/
Published: 9 January 2022
Abstract
:This study evaluated the influence of temperature and relative humidity (RH) on the insecticidal effect of diatomaceous earth (DE) at two concentrations, 500 and 1000 ppm, on wheat, for the control of Cryptolestes ferrugineus (Stephens) (Coleoptera: Cucujidae), Oryzaephilus surinamensis (L.) (Coleoptera: Silvanidae), and Tribolium confusum Jacquelin du Val (Coleoptera: Tenebrionidae). These bioassays were carried out in all combinations of four temperature levels (15, 20, 25, and 30 °C), and two relative humidity levels (55 and 75%). Cryptolestes ferrugineus and O. surinamensis were found to be much more susceptible to the DE-treated wheat than T. confusum, but the increase of the DE dose increased the mortality level for all three species. Although the increase of temperature and the decrease of RH increased insect mortality in some of the combinations tested, the reverse was observed in some treatments, suggesting that there are considerable differential effects of these factors in DE efficacy. The increase of insect exposure from 1 to 21 days notably increased insect mortality, suggesting that exposure is a critical factor that may alleviate possible differential effects of certain abiotic conditions. The results of the present work provide data that illustrate the viability of the utilization of DE in stored product protection, as alternatives to chemical control methods.
1. Introduction
Diatomaceous earths (DEs) are promising alternatives over the use of traditional insecticides that are currently in use in stored product protection. In this context, over the last three decades there has been a renewed interest on research towards the use of DEs as insecticides, which has yielded in numerous commercially available formulations [1,2,3,4]. This research has shown that the application of DE can be effective on a wide range of conditions, either as a grain protectant, i.e., through admixture with the grains, or as a surface treatment, i.e., through applications in different types of surfaces in food storage and processing facilities. Between these two ways of application, the use of DEs through direct application with the grains has been by far the most thoroughly studied scenario [4,5,6].
Grain storage in bulks in different types of facilities is usually carried out for long intervals, and thus, the efficacy of the grain protectants that have been applied on the commodity is subjected to the seasonal changes of the abiotic conditions within the grain mass, such as temperature and relative humidity (RH). Athanassiou and Buchelos [7] demonstrated that there are considerable fluctuations of the grain temperature and moisture content of wheat through an eight-month storage period in vertical silos, from a period that started from summer (June) and lasted until winter (January). Interestingly, the authors reported that although there was an apparent effect of the fluctuation of grain temperature and moisture content in the population densities of different stored product beetle species, there was no significant correlation between these abiotic conditions and insect numbers [7]. Conversely, it is postulated that these fluctuations are likely to be important in the case of a wide range protectants, in terms of a gradual reduction in their efficacy [8,9,10,11,12]. For instance, Arthur [13] found that the insecticidal effect of the pyrethroid deltamethrin, which is one of the most widely used grain protectants globally, is negatively affected by the increase of temperature, a parameter that should be seriously taken into account in real-world applications with these insecticides.
In contrast with the traditional grain protectants, it is generally regarded that the efficacy of DEs is not much reduced with time, given that DEs are inert materials and, as such, they have little interaction with the environment. This aspect has been examined under laboratory conditions by Athanassiou et al. [14], who tested different commercially available DE formulations on wheat and barley and found that the efficacy against the rice weevil, Sitophilus oryzae (L.) (Coleoptera: Curculionidae) was high for at least 270 days of storage. Similar results have been reported by Wakil et al. [15] for the lesser grain borer, Rhyzopertha dominica (F.) (Coleoptera: Bostrichidae). Nevertheless, these data are based on laboratory experiments where temperature and RH levels were stable, and, although some conclusions can be drawn, the results of these studies are not representative of the dynamic changes of these conditions during real-scale storage.
The effect of temperature and RH on DE efficacy has been examined in various studies and under a wide range of conditions and application scenarios, with various and often contradictory data [16,17]. For instance, Aldryhim [18] observed that the confused flour beetle, T. confusum was more susceptible to DEs at 20 than at 30 °C, while the reverse was true in the case of the granary weevil, Sitophilus granarius (L.) (Coleoptera: Curculionidae). In contrast, Athanassiou et al. [3] found that the increase of temperature increased adult mortality of both S. oryzae and T. confusum after exposure to a commercial DE formulation applied on wheat. Regarding the effect of RH or moisture content of the grains on the efficacy of DEs, Vayias and Athanassiou [19] found that even an increase from 55 to 65% RH reduced the efficacy of DE against T. confusum. Moreover, Athanassiou et al. [20] tested three DE formulations in stored maize for the control of the larger grain borer, Prostephanus truncatus (Horn) (Coleoptera: Bostrichidae) and found that temperature and RH did not affect the efficacy of one of these formulations. In a thorough screening of different stored product insect species, Fields and Korunić [21] found differential interactions between those abiotic conditions and insect mortality. For example, the authors reported that the red flour beetle, Tribolium castaneum (Herbst) (Coleoptera: Tenebrionidae) was generally more susceptible at 20 than at 30 °C [21].
In an attempt to carry out a comparable study that can clarify the influence of temperature and RH on the efficacy of DE against stored product beetle species, and to add more data towards this direction, we carried out a series of laboratory bioassays with a commercial DE formulation, against three major species—the rusty grain beetle, C. ferrugineus, the sawtoothed grain beetle, O. surinamensis, and T. confusum. For this purpose, we used a realistic value range of these abiotic conditions, which are suitable for insect development in bulked grains [7], while DE efficacy was tested on a wide range of exposure intervals, which ranged between 1 and 21 days.
2. Materials and Methods
2.1. Insect Species, Commodity and Formulation
Mixed-sex adults, 7–21-day-old C. ferrugineus, O. surinamensis, and T. confusum were used in the bioassays. All insects were taken from laboratory cultures maintained at the Laboratory of Entomology and Agricultural Zoology (LEAZ), Department of Agriculture, Crop Production and Rural Environment, University of Thessaly, Nea Ionia, Magnesia, Greece, at 25 ± 1 °C and 56 ± 5% RH, in continuous darkness. Oryzaephilus surinamensis and C. ferrugineus were reared in oat flakes, while T. confusum in whole wheat flour, according to the laboratory’s rearing protocols. For the experiments, uninfested organic soft wheat, taken from a local flour mill was ground using a stainless-steel mill (Thermomix TM31-1, Vorwerk Elektrowerke GmbH & Co. KG., Wuppertal, Germany) and sieved with a 2-mm opening sieve, in order to obtain the cracked kernels. Afterwards, 10% cracked kernels and 90% intact kernels were mixed together and used as the commodity in all tests. Prior to the initiation of the experiments, the moisture content of the grains was determined by a Multitest moisture meter (Multitest, Gode SAS, Le Catelet, France) and was 11% ± 0.3%. The commercial DE formulation Silicid (Detia Garda GmbH, Laudenbach, Germany) with CAS number 61790-53-2 was used for the experiments in the form of dust.
2.2. Bioassays
Separate bioassays were made in all combinations of four temperature levels, 15, 20, 25, and 30 °C, as well as two levels of RH, 55 and 75%. Maintenance of the desired temperature levels was carried out in incubator chambers, while the required RH levels were achieved with saturated salt solutions, as suggested by Vayias and Athanassiou [19]. For the bioassays, 500 g of the commodity were placed in glass jars of 1 L capacity (15 cm diameter, 35 cm high, Bormioli Rocco, Italy), and treated with either 500 or 1000 ppm, corresponding to 500 and 1000 mg of DE per kg of grain, with different series of jars per DE dose. The jars were then tightly sealed with lids and thoroughly shaken by hand for 1 min to achieve a uniform distribution of the DE in the entire grain mass [2]. A separate series of jars containing untreated commodity were used in the same way as controls. Subsequently, from each jar, three samples of 10 g of the treated grain were placed in three cylindrical plastic vials (3 cm in diameter, 8 cm high, Rotilabo Sample tins Snap on lid, Carl Roth, Germany). Then, ten adults of each species were introduced into each vial, with different series of vials per species. The whole process was repeated two times for each combination of species—DE dose—temperature—RH (i.e., 6 vials per combination). The vials were placed in separate chambers with the desired temperature-RH combinations. Insect mortality was evaluated after 1, 7, 14, and 21 days of exposure to the treated commodity.
2.3. Statistical Analysis
To examine variations in mortality of the tested species among the exposure periods, the effects of the treatments on adult mortality were analyzed separately for each species using the MANOVA fit repeated-measures procedure with Wilk’s lambda test by using JMP software [22] with insect mortality at each exposure interval as the response variable and dose rate, temperature, and RH as the main effects. A one-way ANOVA was performed, with mortality as the response variable and dose as the main effect, within each combination of temperature, RH, and exposure period (1, 7, 14, and 21 days), separately for every species. In addition, a one-way ANOVA was performed with mortality as the response variable and exposure period as the main effect, within each combination of temperature, RH, and dose, separately for each species. Means were separated by the Tukey–Kramer HSD test at 0.05 [23].
3. Results
3.1. Cryptolestes Ferrugineus
All main effects and their associated interactions were significant, with the exception of time × dose × RH (Table 1). After 1 d of exposure at 55% RH, adult mortality was negligible, but there was an increase with the increase of temperature (Table 2). Nevertheless, at this exposure period, mortality did not exceed 20%. At the 7-d exposure interval, adult mortality at 1000 ppm ranged between 91 and 98%, but was not complete (100%) for any of the treatments tested. At longer intervals, i.e., 14 and 21 d, on wheat treated with 500 and 1000 ppm, all adults were dead in some of the temperatures tested. In general, mortality of C. ferrugineus adults at 55% RH was comparable for all temperatures, and mostly depended on the DE dose (Table 2).
At 75% RH, as above, adult mortality of this species varied at the 1-d exposure interval, and increased with the increase of temperature, at 1000 ppm (Table 3). At the 7-d exposure, on wheat treated with 500 ppm, mortality was significantly higher at 15 °C than at the other temperatures, but for this exposure interval, mortality among temperatures was comparable at 1000 ppm. At the 14- and 21-d exposure, and at 500 ppm, adult mortality was higher at 15 °C, as compared with 30 °C. Moreover, at these intervals, and at 1000 ppm, adult mortality reached 100% only in the case of 15 °C (Table 3).
3.2. Oryzaephilus Surinamensis
Most main effects and their interactions were significant (Table 1). At 55% RH, and after 1-d exposure interval, the increase of dose and temperature increased adult mortality (Table 4). After 7 d of exposure, and at 500 ppm, adult mortality was comparable among the different temperatures, and ranged between 26 and 45%. However, at this exposure, and at 1000 ppm, adult mortality was 100% or close, regardless of the temperature tested. After 14 d of exposure, the increase of DE dose increased mortality, and, in three out of the four temperatures tested, all adults were dead. Finally, after 21 d of exposure all adults were dead at 100%, for all temperatures at 1000 ppm, but reached this percentage at 500 ppm only at 25 °C (Table 4).
At 75% RH, and after 1 d of exposure, the increase of temperature generally increased adult mortality at 1000 ppm (Table 5). At the 7-d exposure interval, adult mortality fluctuated between 23 and 58% on wheat treated with 500 ppm of DE, but there were no specific trends among the four temperatures tested. At this exposure, the increase of the DE dose to 1000 ppm further increased adult mortality, which ranged between 95 and 100%. At the 14-d exposure, on wheat treated with 500 ppm, adult mortality was generally lower at 15 and 25 °C, as compared with 20 and 30 °C. At this exposure, all adults were dead at 1000 ppm, regardless of the temperature. Similar trends were noted in the case of the 21-d exposure interval, while at 500 ppm, and at 15 and 25 °C adult mortality was only slightly increased (Table 5).
3.3. Tribolium Confusum
Most main effects and interactions were significant (Table 1). At 55% RH, and after 1 d of exposure, all adults were found to be alive, regardless of the temperature and DE dose (Table 6). At the 7-d exposure, adult mortality of T. confusum was negligible at 500 ppm, but further increased at 1000 ppm. Hence, at this dose, the increase of temperature notably increased adult mortality. After 14 d of exposure, and despite the fact that at 500 ppm adult mortality did not exceed 22%, all adults were dead at 1000 ppm at the two higher temperatures tested. Similar results were noted in the case of the 21-d exposure, where all adults were dead on wheat treated with 1000 ppm, with the exception at 20 °C (Table 6).
At 75% RH, and after 1 d of exposure, there was no adult mortality for any of the temperatures and doses tested (Table 7). At the 7-d exposure, on wheat treated with 500 ppm all adults were recorded as alive. At this interval, and at 1000 ppm, adult mortality was generally higher at 15 and 20 °C, as compared with the other two temperatures. Similarly, at the 14-d exposure, mortality was extremely low at 500 ppm, while at 1000 ppm, mortality was higher at 15 than at 30 °C. Finally, at the 21-d exposure, on wheat treated with 1000 ppm, the increase of temperature decreased mortality.
4. Discussion
The results of the present study illustrate the differential effects of temperature in DE efficacy, according to the target species, but also to RH, exposure interval, and dose. Hence, for some of the combinations tested, the increase of temperature increased the efficacy of DE, while in other combinations the reverse was reported. For instance, in the case of T. confusum, at 55% RH, DE efficacy was higher at elevated temperatures, when adults had been exposed for 7 d, on wheat treated with 1000 ppm. In contrast, for the same species, at 75% RH, for the same DE dose, and after 14 d of exposure, the increase of temperature decreased adult mortality. Considering the differential results for the temperature range tested, we estimate that there are considerable interactions of temperature with other factors, including RH. Nevertheless, Athanassiou et al. [3] found that, for adults of the same species, the increase of temperature caused an almost linear increase in the insecticidal effect of the commercially available DE SilicoSec, which seemed to contradict the results of the present study. Still, different insect strains and experimental conditions may be responsible for these variations.
The most widely adopted theory for the effect of temperature on DE efficacy is based on the fact that desiccation occurs much more rapidly at elevated temperatures, and that water stress is more likely to be lethal when prevailing temperatures are high [2,3,4,21]. At the same time, insects are considered more mobile at higher temperatures and, hence, the possibilities of contact with the DE particles is increased, which, in turn, causes a more rapid desiccation [2,21]. However, we found that, in some of the combinations tested, DE efficacy was higher at 15 °C than at higher temperatures, which may not be related with water stress of mobility factors, but with the effect of low temperatures, which stand close to the lower developmental thresholds for the development of most stored product beetle species [12]. Thus, we consider that insects were stressed at 15 °C, and the addition of DE on the treated substrate might have increased this stress. Although stored product insect mortality may not be considerable at this temperature, as it was indicated by the survival reported in the control vials in our study, insect development and progeny production capacity are more likely to be controlled at 15 °C, and this is why aeration models in bulked grains are based on temperature levels that are usually <20 °C [24].
Considering the mode of action of DEs, it is generally expected that the increase of RH in a given storage and processing facility or moisture content of the grain will decrease DE efficacy through water absorption from the surrounding environment [1,2,21]. However, we found that RH had a certain effect for some of the combinations tested, but not in others. For instance, we found no substantial differences between the two RH levels tested in the case of C. ferrugineus, for most of the combinations tested, which suggest that, at least in the case of the specific factors examined, RH had no effect. Conversely, for T. confusum adults, the increase of RH did cause a negative effect on DE efficacy, suggesting that the effect of this factor is rather species-mediated. Fields and Korunić [21] also reported dissimilar effects of both temperature and moisture content for a wide range of species and strains of stored product insects, also suggesting that there is no “golden rule” for the influence of these abiotic factors in DE efficacy as grain protectants. The data reported here underline the need to design DE-based control protocols according to the target species, and the conditions prevailing in the target facility.
We found that the dose of 1000 ppm was much more effective than 500 ppm. This dose, which corresponds to 1 kg of DE per ton of grain, is related to the label rate of most of the commercially available DE formulations, incl. the one tested here [2,5,12,19]. DEs are generally slow-acting, and while in lower concentrations adult mortality can still occur, reproduction and the concomitant progeny production may not be totally avoided. There are studies that show that there are certain formulations that can be effective at lower concentrations, when applied either alone, or in combination with other methods [12,15]. The utilization of DEs that can be effective at lower doses is a critical issue that has to be evaluated further, as increased DE concentration can cause adverse effects in some key grain properties, such as the test weight [25,26].
In summary, the data reported here show that the DE tested can be effective at 1000 ppm, but this efficacy is notably moderated by temperature and RH, in a dissimilar way that depends on the treatment scenario. Although temperature and RH played a key role here, it seems that the exposure is an additional critical parameter, as longer exposures seem to “normalize” the influence of abiotic conditions. Our study contributes further in strengthening the use of DEs at the post-harvest stages of durable agricultural commodities, as an important component of non-chemical strategies in stored product protection.
Author Contributions
Conceptualization and methodology, C.G.A.; investigation and formal analysis, G.V.B. and E.L.; writing—original draft, G.V.B., E.L. and C.G.A.; writing—review and editing, supervision, C.G.A.; funding acquisition, C.G.A. All authors have read and agreed to the published version of the manuscript.
Funding
This research was co-financed by the European Regional Development Fund of the European Union and Greek national funds through the Operational Program Competitiveness, Entrepreneurship and Innovation, under the call RESEARCH–CREATE-INNOVATE (Τ2ΕΔΚ-03532).
Data Availability Statement
Not applicable.
Conflicts of Interest
The authors declare no conflict of interest.
References
- Korunić, Z. Diatomaceous earths, a group of natural insecticides. J. Stored Prod. Res. 1998, 34, 87–97. [Google Scholar] [CrossRef]
- Subramanyam, B.; Roesli, R. Inert dusts. In Alternatives to Pesticides in Stored-Product IPM; Subramanyam, B., Hagstrum, D.W., Eds.; Kluwer Academic Publishers: Dordrecht, The Netherlands, 2000; pp. 321–380. [Google Scholar]
- Athanassiou, C.G.; Vayias, B.J.; Dimizas, C.B.; Kavallieratos, N.G.; Papagregoriou, A.S.; Buchelos, C.T. Insecticidal efficacy of diatomaceous earth against Sitophilus oryzae (L.) (Coleoptera: Curculionidae) and Tribolium confusum Du Val (Coleoptera: Tenebrionidae) on stored wheat: Influence of dose rate, temperature and exposure interval. J. Stored Prod. Res. 2005, 41, 47–55. [Google Scholar] [CrossRef]
- Losić, D.; Korunić, Z. Diatomaceous earth, a natural insecticide for stored grain protection: Recent progress and perspectives. In Diatom Nanotechnology: Progress and Emerging Applications; Losić, D., Ed.; Royal Society of Chemistry: Croydon, UK, 2018; pp. 219–247. [Google Scholar]
- Baliota, G.V.; Athanassiou, C.G. Evaluation of a Greek diatomaceous earth for stored product insect control and techniques that maximize its insecticidal efficacy. Appl. Sci. 2020, 10, 6441. [Google Scholar] [CrossRef]
- Ziaee, M.; Ebadollahi, A.; Wakil, W. Integrating inert dusts with other technologies in stored products protection. Toxin Rev. 2021, 40, 404–419. [Google Scholar] [CrossRef]
- Athanassiou, C.G.; Buchelos, C.T. Grain properties and insect distribution trends in silos of wheat. J. Stored Prod. Res. 2020, 88, 101632. [Google Scholar] [CrossRef]
- Subramanyam, B.; Cutkomp, L.K. Influence of posttreatment temperature on toxicity of pyrethroids to five species of stored-product insects. J. Econ. Entomol. 1987, 80, 9–13. [Google Scholar] [CrossRef]
- Fleurat-Lessard, F.; Vidal, M.; Budzinski, H. Modelling biological efficacy decrease and rate of degradation of chlorpyrifos-methyl on wheat stored under controlled conditions. J. Stored Prod. Res. 1998, 34, 341–354. [Google Scholar] [CrossRef]
- Nayak, M.K.; Collins, P.J. Influence of concentration, temperature and humidity on the toxicity of phosphine to the strongly phosphine-resistant psocids Liposcelis bostrychophila Badonnel (Psocoptera: Liposcelididae). Pest Manag. Sci. 2008, 64, 971–976. [Google Scholar] [CrossRef]
- Athanassiou, C.G.; Kavallieratos, N.G. Evaluation of spinetoram and spinosad for control of Prostephanus truncatus, Rhyzopertha dominica, Sitophilus oryzae, and Tribolium confusum on stored grains under laboratory tests. J. Pest Sci. 2014, 87, 469–483. [Google Scholar] [CrossRef]
- Athanassiou, C.G.; Arthur, F.H. Bacterial insecticides and inert materials. In Recent Advances in Stored Product Protection; Athanassiou, C.G., Arthur, F.H., Eds.; Springer: Berlin, Germany, 2018; pp. 83–98. [Google Scholar]
- Arthur, F.H. Residual efficacy of deltamethrin as assessed by rapidity of knockdown of Tribolium castaneum on a treated surface: Temperature and seasonal effects in field and laboratory settings. J. Stored Prod. Res. 2018, 76, 151–160. [Google Scholar] [CrossRef]
- Athanassiou, C.G.; Kavallieratos, N.G.; Economou, L.P.; Dimizas, C.B.; Vayias, B.J.; Tomanović, Z.; Milutinović, M. Persistence and efficacy of three diatomaceous earth formulations against Sitophilus oryzae (Coleoptera: Curculionidae) on wheat and barley. J. Econ. Entomol. 2005, 98, 1404–1412. [Google Scholar] [CrossRef] [PubMed]
- Wakil, W.; Riasat, T.; Ashfaq, M. Residual efficacy of thiamethoxam, Beauveria bassiana (Balsamo) Vuillemin, and diatomaceous earth formulation against Rhyzopertha dominica F. (Coleoptera: Bostrychidae). J. Pest Sci. 2012, 85, 341–350. [Google Scholar] [CrossRef]
- Wakil, W.; Riasat, T.; Ghazanfar, M.U.; Kwon, Y.J.; Shaheen, F.A. Aptness of Beauveria bassiana and enhanced diatomaceous earth (DEBBM) for control of Rhyzopertha dominica F. Entomol. Res. 2011, 41, 233–241. [Google Scholar] [CrossRef]
- Riasat, T.; Wakil, W.; Yasin, M.; Kwon, Y.J. Mixing of Isaria fumosorosea with enhanced diatomaceous earth and bitterbarkomycin for control of Rhyzopertha dominica. Entomol. Res. 2013, 43, 215–223. [Google Scholar] [CrossRef]
- Aldryhim, Y.N. Efficacy of the amorphous silica dust, Dryacide, against Tribolium confusum Duv.; Sitophilus granarius (L.) (Coleoptera: Tenebrionidae and Curculionidae). J. Stored Prod. Res. 1990, 26, 207–210. [Google Scholar] [CrossRef]
- Vayias, B.J.; Athanassiou, C.G. Factors affecting efficacy of the diatomaceous earth formulation SilicoSec against adults and larvae of the confused beetle Tribolium confusum Du Val (Coleoptera: Tenebrionidae). Crop Prot. 2004, 23, 565–573. [Google Scholar] [CrossRef]
- Athanassiou, C.G.; Kavallieratos, N.G.; Peteinatos, G.G.; Petrou, S.E.; Boukouvala, M.C.; Tomanović, Z. Influence of temperature and humidity on insecticidal effect of three diatomaceous earth formulations against larger grain borer (Coleoptera: Bostrychidae). J. Econ. Entomol. 2007, 100, 599–603. [Google Scholar] [CrossRef] [PubMed]
- Fields, P.; Korunić, Z. The effect of grain moisture content and temperature on the efficacy of diatomaceous earths from different geographical locations against stored-product beetles. J. Stored Prod. Res. 2000, 36, 1–13. [Google Scholar] [CrossRef]
- SAS Institute Inc. Using JMP® Software, version 7.0; SAS Institute Inc.: Cary, NC, USA, 2007.
- Sokal, R.R.; Rohlf, F.J. Biometry, 3rd ed.; Freedman & Company: New York, NY, USA, 1995. [Google Scholar]
- Morrison, W.R., III; Arthur, F.H.; Wilson, L.T.; Yang, Y.; Wang, J.; Athanassiou, C.G. Aeration to manage insects in wheat stored in the Balkan Peninsula: Computer simulations using historical weather data. Agronomy 2020, 10, 1927. [Google Scholar] [CrossRef]
- Korunić, Z.; Fields, P.G.; Kovacs, M.I.P.; Noll, J.S.; Lukow, O.M.; Demianyk, C.J.; Shibley, K.J. The effect of diatomaceous earth on grain quality. Postharvest Biol. Technol. 1996, 9, 373–387. [Google Scholar] [CrossRef]
- Korunić, Z.; Cenkowski, S.; Fields, P.G. Grain bulk density as affected by diatomaceous earths and application method. Postharvest Biol. Technol. 1998, 13, 81–89. [Google Scholar] [CrossRef]
Table 1.
Repeated measures MANOVA parameters for mortality levels of C. ferrugineus, O. surinamensis, and T. confusum adults between exposure intervals (error df = 108).
Table 1.
Repeated measures MANOVA parameters for mortality levels of C. ferrugineus, O. surinamensis, and T. confusum adults between exposure intervals (error df = 108).
| C. ferrugineus | O. surinamensis | T. confusum | ||||||
|---|---|---|---|---|---|---|---|---|
| Source | df | F | p | F | p | F | p | |
| Intercept | 1 | 3134.5 | <0.01 | 1924.8 | <0.01 | 1429.2 | <0.01 | |
| Between variables | Dose | 2 | 679.9 | <0.01 | <0.01 | <0.01 | <0.01 | <0.01 |
| Temperature | 3 | 5.1 | <0.01 | <0.01 | <0.01 | 2.5 | 0.06 | |
| Dose × temperature | 6 | 2.8 | <0.01 | 1.2 | 0.33 | 1.3 | 0.25 | |
| RH | 1 | 4.2 | 0.04 | 0.1 | 0.78 | 44.9 | <0.01 | |
| Dose × RH | 2 | 5.6 | <0.01 | 0.1 | 0.88 | 11.5 | <0.01 | |
| Temperature × RH | 3 | 6.0 | <0.01 | 2.2 | 0.10 | 16.6 | <0.01 | |
| Dose×temperature × RH | 6 | 4.6 | <0.01 | 2.2 | 0.05 | 5.4 | <0.01 | |
| Within variables | Time | 3 | 664.1 | <0.01 | 593.6 | <0.01 | 483.7 | <0.01 |
| Time × dose | 6 | 92.8 | <0.01 | 113.5 | <0.01 | 148.1 | <0.01 | |
| Time × temperature | 9 | 6.5 | <0.01 | 4.4 | <0.01 | 2.7 | <0.01 | |
| Time × dose × temperature | 18 | 6.7 | <0.01 | 4.4 | <0.01 | 3.4 | <0.01 | |
| Time × RH | 3 | 6.4 | <0.01 | 4.7 | <0.01 | 27.3 | <0.01 | |
| Time × dose × RH | 6 | 2.0 | 0.07 | 1.1 | 0.36 | 21.8 | <0.01 | |
| Time × temperature × RH | 9 | 3.6 | <0.01 | 3.1 | <0.01 | 10.7 | <0.01 | |
| Time × dose × temperature × RH | 18 | 2.6 | <0.01 | 2.2 | <0.01 | 9.3 | <0.01 | |
Table 2.
Mean mortality (% ± SE) of C. ferrugineus adults exposed for 1, 7, 14, and 21 days to wheat treated with three different doses of diatomaceous earth (0, 500, and 1000 ppm) and four different temperatures (15, 20, 25, and 30 °C), at 55% RH.
Table 2.
Mean mortality (% ± SE) of C. ferrugineus adults exposed for 1, 7, 14, and 21 days to wheat treated with three different doses of diatomaceous earth (0, 500, and 1000 ppm) and four different temperatures (15, 20, 25, and 30 °C), at 55% RH.
| Exposure Time (Days) | |||||
|---|---|---|---|---|---|
| Temperature (°C) | Dose (ppm) | Day 1 | Day 7 | Day 14 | Day 21 |
| 15 | 0 | 0.0 ± 0.0 | 0.0 ± 0.0c | 0.0 ± 0.0c | 0.0 ± 0.0c |
| 500 | 0.0 ± 0.0B | 63.3 ± 11.7bA | 70.0 ± 10.6bA | 75.0 ± 10.5bA | |
| 1000 | 0.0 ± 0.0B | 98.3 ± 1.6aA | 100.0 ± 0.0aA | 100.0 ± 0.0aA | |
| F | - | 53.0 | 69.7 | 72.8 | |
| p | - | <0.01 | <0.01 | <0.01 | |
| 20 | 0 | 0.0 ± 0.0B | 0.0 ± 0.0cB | 0.0 ± 0.0bB | 6.6 ± 3.3bA |
| 500 | 1.6 ± 1.6B | 66.6 ± 8.4bA | 90.0 ± 6.8aA | 90.0 ± 6.8aA | |
| 1000 | 0.0 ± 0.0B | 91.6 ± 5.4aA | 95.0 ± 3.4aA | 100.0 ± 0.0aA | |
| F | 1.0 | 67.0 | 147.0 | 136.3 | |
| p | 0.39 | <0.01 | <0.01 | <0.01 | |
| 25 | 0 | 0.0 ± 0.0B | 0.0 ± 0.0bB | 0.0 ± 0.0bB | 20.0 ± 8.5bA |
| 500 | 3.3 ± 2.1C | 76.6 ± 6.6aB | 95.0 ± 3.4aA | 100.0 ± 0.0aA | |
| 1000 | 20.0 ± 9.6B | 93.3 ± 4.9aA | 96.6 ± 3.3aA | 96.6 ± 3.3aA | |
| F | 3.5 | 107.9 | 403.3 | 72.8 | |
| p | 0.05 | <0.01 | <0.01 | <0.01 | |
| 30 | 0 | 1.6 ± 1.6bB | 1.6 ± 1.6cB | 1.6 ± 1.6bB | 50.0 ± 5.1bA |
| 500 | 0.0 ± 0.0bC | 70.0 ± 8.5bB | 95.0 ± 3.4aA | 100.0 ± 0.0aA | |
| 1000 | 20.0 ± 5.1aB | 93.3 ± 6.6aA | 100.0 ± 0.0aA | 100.0 ± 0.0aA | |
| F | 12.5 | 56.5 | 637.1 | 93.8 | |
| p | <0.01 | <0.01 | <0.01 | <0.01 | |
For each exposure time and temperature, mortality means followed by the same lowercase letter do not differ significantly according to the Tukey–Kramer HSD test at p < 0.05, in all cases df = 2,17. For each dose and temperature, mortality means followed by the same uppercase letter do not differ significantly across treatments according to the Tukey–Kramer HSD test at p < 0.05. Where no letters exist, no significant differences were noted. ANOVA parameters for dead adults were: at 15 °C and 500 ppm, F = 13.5, p < 0.01, at 15 °C and 1000 ppm, F = 3561.0, p < 0.01, at 20 °C and 0 ppm, F = 4.0, p = 0.02, at 20 °C and 500 ppm, F = 41.7, p < 0.01, at 20 °C and 1000 ppm, F = 223.2, p < 0.01, at 25 °C and 0 ppm, F = 5.5, p = 0.07, at 25 °C and 500 ppm, F = 132.3, p < 0.01, at 25 °C and 1000 ppm, F = 40.8, p < 0.01, at 30 °C and 0 ppm, F = 66.7, p < 0.01, at 30 °C and 500 ppm, F = 99.9, p < 0.01, at 30 °C and 1000 ppm, F = 85.6, p < 0.01, whereas for 15 °C and 0 ppm, ANOVA parameters were not defined, in all cases df = 3,23.
Table 3.
Mean mortality (% ± SE) of C. ferrugineus adults exposed for 1, 7, 14, and 21 days to wheat treated with three different doses of diatomaceous earth (0, 500, and 1000 ppm) and four different temperatures (15, 20, 25, and 30 °C), at 75% RH.
Table 3.
Mean mortality (% ± SE) of C. ferrugineus adults exposed for 1, 7, 14, and 21 days to wheat treated with three different doses of diatomaceous earth (0, 500, and 1000 ppm) and four different temperatures (15, 20, 25, and 30 °C), at 75% RH.
| Exposure Time (Days) | |||||
|---|---|---|---|---|---|
| Temperature (°C) | Dose (ppm) | Day 1 | Day 7 | Day 14 | Day 21 |
| 15 | 0 | 0.0 ± 0.0 | 0.0 ± 0.0b | 0.0 ± 0.0b | 1.6 ± 1.6b |
| 500 | 0.0 ± 0.0B | 88.3 ± 6.0aA | 98.3 ± 1.6aA | 100.0 ± 0.0aA | |
| 1000 | 6.6 ± 6.6B | 96.6 ± 3.3aA | 100.0 ± 0.0aA | 100.0 ± 0.0aA | |
| F | 1.0 | 182.3 | 3541.0 | 3481.0 | |
| p | 0.39 | <0.01 | <0.01 | <0.01 | |
| 20 | 0 | 1.6 ± 1.6 | 1.6 ± 1.6c | 1.6 ± 1.6c | 5.0 ± 3.4c |
| 500 | 0.0 ± 0.0B | 41.6 ± 14.70bAB | 53.3 ± 16.8bA | 60.0 ± 14.3bA | |
| 1000 | 6.6 ± 3.3B | 80.0 ± 6.3aA | 93.3 ± 6.6aA | 93.3 ± 6.6aA | |
| F | 2.6 | 17.8 | 19.1 | 22.7 | |
| p | 0.10 | <0.01 | <0.01 | <0.01 | |
| 25 | 0 | 1.6 ± 1.6bB | 1.6 ± 1.6cB | 1.6 ± 1.6cB | 18.3 ± 5.4bA |
| 500 | 1.6 ± 1.6bC | 46.6 ± 8.0bB | 85.0 ± 5.6bA | 95.0 ± 5.0aA | |
| 1000 | 38.3 ± 7.0aB | 98.3 ± 1.6aA | 98.3 ± 1.6aA | 98.3 ± 1.6aA | |
| F | 24.4 | 100.3 | 221.2 | 107.4 | |
| p | <0.01 | <0.01 | <0.01 | <0.01 | |
| 30 | 0 | 1.6 ± 1.6bB | 1.6 ± 1.6cB | 1.6 ± 1.6cB | 26.6 ± 8.4cA |
| 500 | 0.0 ± 0.0bB | 45.0 ± 10.2bA | 50.0 ± 10.6bA | 56.6 ± 9.5bA | |
| 1000 | 41.6 ± 4.7aB | 93.3 ± 3.3aA | 93.3 ± 3.3aA | 95.0 ± 3.4aA | |
| F | 65.3 | 53.1 | 49.6 | 20.2 | |
| p | <0.01 | <0.01 | <0.01 | <0.01 | |
For each exposure time and temperature, mortality means followed by the same lowercase letter do not differ significantly according to the Tukey–Kramer HSD test at p < 0.05, in all cases df = 2,17. For each dose and temperature, mortality means followed by the same uppercase letter do not differ significantly across treatments according to the Tukey–Kramer HSD test at p < 0.05. Where no letters exist, no significant differences were noted. ANOVA parameters for dead adults were: at 15 °C and 0 ppm, F = 1.00, p = 0.413, at 15 °C and 500 ppm, F = 237.52, p < 0.01, at 15 °C and 1000 ppm, F = 153.26, p < 0.01, at 20 °C and 0 ppm, F = 0.55, p = 0.650, at 20 °C and 500 ppm, F = 4.09, p = 0.020, at 20 °C and 1000 ppm, F = 49.41, p < 0.01, at 25 °C and 0 ppm, F = 7.35, p < 0.01, at 25 °C and 500 ppm, F = 58.07, p < 0.01, at 25 °C and 1000 ppm, F = 62.30, p < 0.01, at 30 °C and 0 ppm, F = 7.86, p < 0.01, at 30 °C and 500 ppm, F = 8.55, p < 0.01, at 30 °C and 1000 ppm, F = 48.17, p < 0.01, in all cases df = 3,23.
Table 4.
Mean mortality (% ± SE) of O. surinamensis adults exposed for 1, 7, 14, and 21 days to wheat treated with three different doses of diatomaceous earth (0, 500, and 1000 ppm) and four different temperatures (15, 20, 25, and 30 °C), at 55% RH.
Table 4.
Mean mortality (% ± SE) of O. surinamensis adults exposed for 1, 7, 14, and 21 days to wheat treated with three different doses of diatomaceous earth (0, 500, and 1000 ppm) and four different temperatures (15, 20, 25, and 30 °C), at 55% RH.
| Exposure Time (Days) | |||||
|---|---|---|---|---|---|
| Temperature (°C) | Dose (ppm) | Day 1 | Day 7 | Day 14 | Day 21 |
| 15 | 0 | 1.6 ± 1.6 | 1.6 ± 1.6b | 1.6 ± 1.6c | 1.6 ± 1.6c |
| 500 | 0.0 ± 0.0B | 28.3 ± 12.2bAB | 50.0 ± 17.1bAB | 56.6 ± 18.0bA | |
| 1000 | 0.0 ± 0.0B | 95.0 ± 5.0aA | 100.0 ± 0.0aA | 100.0 ± 0.0aA | |
| F | 1.0 | 39.1 | 24.5 | 22.3 | |
| p | 0.3 | <0.01 | <0.01 | <0.01 | |
| 20 | 0 | 1.6 ± 1.6 | 1.6 ± 1.6c | 5.0 ± 3.4c | 13.3 ± 4.2b |
| 500 | 0.0 ± 0.0C | 41.6 ± 16.2bBC | 66.6 ± 14.1bAB | 86.6 ± 6.1aA | |
| 1000 | 13.3 ± 7.6B | 100.0 ± 0.00aA | 100.0 ± 0.0aA | 100.0 ± 0.0aA | |
| F | 2.6 | 27.6 | 33.3 | 117.6 | |
| p | 0.10 | <0.01 | <0.01 | <0.01 | |
| 25 | 0 | 0.0 ± 0.0B | 0.0 ± 0.0cB | 0.0 ± 0.0bB | 8.3 ± 3.1bA |
| 500 | 1.6 ± 1.6C | 45.0 ± 16.6bB | 80.0 ± 10. 0aAB | 100.0 ± 0.0aA | |
| 1000 | 13.3 ± 6.1B | 98.3 ± 1.6aA | 98.3 ± 1.6aA | 100.0 ± 0.0aA | |
| F | 3.9 | 25.9 | 79.8 | 889.7 | |
| p | 0.04 | <0.01 | <0.01 | <0.01 | |
| 30 | 0 | 0.0 ± 0.0B | 0.0 ± 0.0cB | 0.0 ± 0.0cB | 45.0 ± 7.6bA |
| 500 | 1.6 ± 1.6C | 26.6 ± 6.1bB | 73.3 ± 7.6bA | 93.3 ± 4.9aA | |
| 1000 | 13.3 ± 6.1B | 100.0 ± 0.0aA | 100.0 ± 0.0aA | 100.0 ± 0.0aA | |
| F | 3.9 | 212.9 | 139.2 | 32.7 | |
| p | 0.04 | <0.01 | <0.01 | <0.01 | |
For each exposure time and temperature, mortality means followed by the same lowercase letter do not differ significantly according to the Tukey–Kramer HSD test at p < 0.05, in all cases df = 2,17. For each dose and temperature, mortality means followed by the same uppercase letter do not differ significantly across treatments according to the Tukey–Kramer HSD test at p < 0.05. Where no letters exist, no significant differences were noted. ANOVA parameters for dead adults were: at 15 °C and 0 ppm, F = 0.0, p = 1.00, at 15 °C and 500 ppm, F = 3.4, p = 0.04, at 15 °C and 1000 ppm, F = 387.6, p < 0.01, at 20 °C and 0 ppm, F = 3.4, p = 0.04, at 20 °C and 500 ppm, F = 11.2, p < 0.01, at 20 °C and 1000 ppm, F = 130.0, p < 0.01, at 25 °C and 0 ppm, F = 7.4, p < 0.01, at 25 °C and 500 ppm, F = 19.5, p < 0.01, at 25 °C and 1000 ppm, F = 168.9, p < 0.01, at 30 °C and 0 ppm, F = 34.7, p < 0.01, at 30 °C and 500 ppm, F = 57.5, p < 0.01, at 30 °C and 1000 ppm, F = 198.8, p < 0.01, in all cases df = 3,23.
Table 5.
Mean mortality (% ± SE) of O. surinamensis adults exposed for 1, 7, 14, and 21 days to wheat treated with three different doses of diatomaceous earth (0, 500 and 1000 ppm) and four different temperatures (15, 20, 25, and 30 °C), at 75% RH.
Table 5.
Mean mortality (% ± SE) of O. surinamensis adults exposed for 1, 7, 14, and 21 days to wheat treated with three different doses of diatomaceous earth (0, 500 and 1000 ppm) and four different temperatures (15, 20, 25, and 30 °C), at 75% RH.
| Exposure Time (Days) | |||||
|---|---|---|---|---|---|
| Temperature (°C) | Dose (ppm) | Day 1 | Day 7 | Day 14 | Day 21 |
| 15 | 0 | 0.0 ± 0.0B | 0.0 ± 0.0cB | 1.6 ± 1.6cB | 10.0 ± 2.6cA |
| 500 | 0.0 ± 0.0B | 40.0 ± 15.9bAB | 61.6 ± 15.8bA | 65.0 ± 15.8bA | |
| 1000 | 13.3 ± 8.0B | 95.0 ± 5.0aA | 100.0 ± 0.0aA | 100.0 ± 0.0aA | |
| F | 2.7 | 24.5 | 29.2 | 23.9 | |
| p | 0.09 | <0.01 | <0.01 | <0.01 | |
| 20 | 0 | 0.0 ± 0.0 | 0.0 ± 0.0c | 6.6 ± 3.3b | 6.6 ± 3.3b |
| 500 | 0.0 ± 0.0C | 58.3 ± 9.4bB | 86.6 ± 6.6aA | 96.6 ± 2.1aA | |
| 1000 | 3.3 ± 2.1B | 98.3 ± 1.6aA | 100.0 ± 0.0aA | 100.0 ± 0.0aA | |
| F | 2.5 | 79.5 | 137.6 | 540.7 | |
| p | 0.11 | <0.01 | <0.01 | <0.01 | |
| 25 | 0 | 1.6 ± 1.6 | 1.6 ± 1.6b | 1.6 ± 1.6c | 8.3 ± 4.8c |
| 500 | 1.6 ± 1.6B | 23.3 ± 11.7bAB | 43.3 ± 18.7bAB | 63.3 ± 12.8bA | |
| 1000 | 3.3 ± 2.1B | 100.0 ± 0.0aA | 100.0 ± 0.0aA | 100.0 ± 0.0aA | |
| F | 0.3 | 57.0 | 20.7 | 34.1 | |
| p | 0.76 | <0.01 | <0.01 | <0.01 | |
| 30 | 0 | 0.0 ± 0.0bB | 0.0 ± 0.0cB | 11.6 ± 3.1bA | 18.3 ± 4.7bA |
| 500 | 3.3 ± 2.1bC | 40.0 ± 3.7bB | 93.3 ± 3.3aA | 98.3 ± 1.6aA | |
| 1000 | 36.6 ± 6.6 aB | 98.3 ± 1.6aA | 100.0 ± 0.0aA | 100.0 ± 0.0aA | |
| F | 25.3 | 455.3 | 353.1 | 255.8 | |
| p | <0.01 | <0.01 | <0.01 | <0.01 | |
For each exposure time and temperature, mortality means followed by the same lowercase letter do not differ significantly according to the Tukey–Kramer HSD test at p < 0.05, in all cases df = 2,17. For each dose and temperature, mortality means followed by the same uppercase letter do not differ significantly across treatments according to the Tukey–Kramer HSD test at p < 0.05. Where no letters exist, no significant differences were noted. ANOVA parameters for dead adults were: at 15 °C and 0 ppm, F = 9.7, p < 0.01, at 15 °C and 500 ppm, F = 4.7, p = 0.01, at 15 °C and 1000 ppm, F = 81.0, p < 0.01, at 20 °C and 0 ppm, F = 2.6, p = 0.08, at 20 °C and 500 ppm, F = 54.5, p < 0.01, at 20 °C and 1000 ppm, F = 1279.4, p < 0.01, at 25 °C and 0 ppm, F = 1.4, p = 0.26, at 25 °C and 500 ppm, F = 4.3, p = 0.02, at 25 °C and 1000 ppm, F = 2102.5, p < 0.01, at 30 °C and 0 ppm, F = 10.2, p < 0.01, at 30 °C and 500 ppm, F = 260.4, p < 0.01, at 30 °C and 1000 ppm, F = 83.5, p < 0.01, in all cases df = 3,23.
Table 6.
Mean mortality (% ± SE) of T. confusum adults exposed for 1, 7, 14, and 21 days to wheat treated with three different doses of diatomaceous earth (0, 500, and 1000 ppm) and four different temperatures (15, 20, 25, and 30 °C), at 55% RH.
Table 6.
Mean mortality (% ± SE) of T. confusum adults exposed for 1, 7, 14, and 21 days to wheat treated with three different doses of diatomaceous earth (0, 500, and 1000 ppm) and four different temperatures (15, 20, 25, and 30 °C), at 55% RH.
| Exposure Time (Days) | |||||
|---|---|---|---|---|---|
| Temperature (°C) | Dose (ppm) | Day 1 | Day 7 | Day 14 | Day 21 |
| 15 | 0 | 0.0 ± 0.0 | 0.0 ± 0.0b | 0.0 ± 0.0b | 0.0 ± 0.0c |
| 500 | 0.0 ± 0.0B | 0.0 ± 0.0bB | 3.3 ± 2.1bB | 10.0 ± 2.5bA | |
| 1000 | 0.0 ± 0.0D | 15.0 ± 2.2aC | 80.0 ± 5.1aB | 100.0 ± 0.0aA | |
| F | - | 45.0 | 197.5 | 1365.0 | |
| p | - | <0.01 | <0.01 | <0.01 | |
| 20 | 0 | 0.0 ± 0.0 | 0.0 ± 0.0b | 0.0 ± 0.0b | 0.0 ± 0.0c |
| 500 | 0.0 ± 0.0B | 0.0 ± 0.0bB | 3.3 ± 2.1bAB | 10.0 ± 3.6bA | |
| 1000 | 0.0 ± 0.0C | 46.6 ± 9.8aB | 88.3 ± 5.4aA | 98.3 ± 1.6aA | |
| F | - | 22.3 | 221.9 | 545.3 | |
| p | - | <0.01 | <0.01 | <0.01 | |
| 25 | 0 | 0.0 ± 0.0 | 0.0 ± 0.0b | 0.0 ± 0.0b | 0.0 ± 0.0c |
| 500 | 0.0 ± 0.0 | 1.6 ± 1.6b | 21.6± 12.4b | 43.3 ± 19.4b | |
| 1000 | 0.0 ± 0.0C | 76.6 ± 5.6aB | 100.0 ± 0.0aA | 100.0 ±0.0aA | |
| F | - | 169.8 | 53.2 | 20.0 | |
| p | - | <0.01 | <0.01 | <0.01 | |
| 30 | 0 | 0.0 ± 0.0 | 0.0 ± 0.0b | 3.3 ± 2.1b | 3.3 ± 2.1c |
| 500 | 0.0 ± 0.0B | 0.0 ± 0.0bB | 21.6 ± 12.4bAB | 46.6 ± 15.2bA | |
| 1000 | 0.0 ± 0.0C | 83.3 ± 3.3aB | 100.0 ± 0.00aA | 100.0 ± 0.0aA | |
| F | - | 625.0 | 49.3 | 29.9 | |
| p | - | <0.01 | <0.01 | <0.01 | |
For each exposure time and temperature, mortality means followed by the same lowercase letter do not differ significantly according to the Tukey–Kramer HSD test at p < 0.05, in all cases df = 2,17. For each dose and temperature, mortality means followed by the same uppercase letter do not differ significantly across treatments according to the Tukey–Kramer HSD test at p < 0.05. Where no letters exist, no significant differences were noted. ANOVA parameters for dead adults were: at 15 °C and 500 ppm, F = 8.0, p < 0.01, at 15 °C and 1000 ppm, F = 299.7, p < 0.01, at 20 °C and 500 ppm, F = 5.0, p < 0.01, at 20 °C and 1000 ppm, F = 61.9, p < 0.01, at 25 °C and 500 ppm, F = 3.1, p = 0.05, at 25 °C and 1000 ppm, F = 288.9, p < 0.01, at 30 °C and 0 ppm, F = 1.7, p = 0.21, at 30 °C and 500 ppm, F = 5.1, p < 0.01, at 30 °C and 1000 ppm, F = 825.0, p < 0.01, whereas for 15, 20 and 25 °C and 0 ppm, ANOVA parameters were not defined, in all cases df = 3,23.
Table 7.
Mean mortality (% ± SE) of T. confusum adults exposed for 1, 7, 14, and 21 days to wheat treated with three different doses of diatomaceous earth (0, 500, and 1000 ppm) and four different temperatures (15, 20, 25, and 30 °C), at 75% RH.
Table 7.
Mean mortality (% ± SE) of T. confusum adults exposed for 1, 7, 14, and 21 days to wheat treated with three different doses of diatomaceous earth (0, 500, and 1000 ppm) and four different temperatures (15, 20, 25, and 30 °C), at 75% RH.
| Exposure Time (Days) | |||||
|---|---|---|---|---|---|
| Temperature (°C) | Dose (ppm) | Day 1 | Day 7 | Day 14 | Day 21 |
| 15 | 0 | 0.0 ± 0.0 | 0.0 ± 0.0b | 0.0 ± 0.0b | 0.0 ± 0.0c |
| 500 | 0.0 ± 0.0 | 0.0 ± 0.0b | 3.3 ± 2.1b | 11.6 ± 6.0b | |
| 1000 | 0.0 ± 0.0C | 36.6 ± 4.9aB | 91.6 ± 4.7aA | 100.0 ± 0.0aA | |
| F | - | 55.0 | 297.9 | 248.3 | |
| p | - | <0.01 | <0.01 | <0.01 | |
| 20 | 0 | 0.0 ± 0.0 | 0.0 ± 0.0b | 0.0 ± 0.0b | 0.0 ± 0.0b |
| 500 | 0.0 ± 0.0 | 0.0 ± 0.0b | 0.0 ± 0.0b | 0.0 ± 0.0b | |
| 1000 | 0.0 ± 0.0C | 38.3 ± 4.7aB | 78.3 ± 7.9aA | 96.6 ± 2.1aA | |
| F | - | 64.5 | 97.7 | 2102.5 | |
| p | - | <0.01 | <0.01 | <0.01 | |
| 25 | 0 | 0.0 ± 0.0 | 0.0 ± 0.0b | 0.0 ± 0.0b | 0.0 ± 0.0b |
| 500 | 0.0 ± 0.0B | 0.0 ± 0.0bB | 0.0 ± 0.0bB | 8.3 ± 4.0bA | |
| 1000 | 0.0 ± 0.0C | 11.6 ± 1.6aC | 73.3 ± 6.1aB | 90.0 ± 2.5aA | |
| F | - | 49.0 | 142.4 | 325.7 | |
| p | - | <0.01 | <0.01 | <0.01 | |
| 30 | 0 | 0.0 ± 0.0 | 0.0 ± 0.0b | 0.0 ± 0.0b | 0.0 ± 0.0b |
| 500 | 0.0 ± 0.0 | 0.0 ± 0.0b | 1.6 ± 1.6b | 3.3 ± 2.1b | |
| 1000 | 0.0 ± 0.0B | 11.6 ± 4.7aB | 68.3 ± 7.9aA | 83.3 ± 7.6aA | |
| F | - | 6.0 | 69.5 | 107.3 | |
| p | - | 0.01 | <0.01 | <0.01 | |
For each exposure time and temperature, mortality means followed by the same lowercase letter do not differ significantly according to the Tukey–Kramer HSD test at p < 0.05, in all cases df = 2,17. For each dose and temperature, mortality means followed by the same uppercase letter do not differ significantly across treatments according to the Tukey–Kramer HSD test at p < 0.05. Where no letters exist, no significant differences were noted. ANOVA parameters for dead adults were: at 15 °C and 500 ppm, F = 3.0, p = 0.06, at 15 °C and 1000 ppm, F = 189.5, p < 0.01, at 20 °C and 1000 ppm, F = 82.6, p < 0.01, at 25 °C and 500 ppm, F = 4.3, p = 0.02, at 25 °C and 1000 ppm, F = 168.2, p < 0.01, at 30 °C and 500 ppm, F = 1.4, p = 0.27, at 30 °C and 1000 ppm, F = 47.3, p < 0.01, whereas for 15, 20, 25 and 30 °C and 0 ppm and for 20 °C and 500 ppm, ANOVA parameters were not defined, in all cases df = 3,23.
Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations. |
© 2022 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https://creativecommons.org/licenses/by/4.0/).
Share and Cite
MDPI and ACS Style
Baliota, G.V.; Lampiri, E.; Athanassiou, C.G. Differential Effects of Abiotic Factors on the Insecticidal Efficacy of Diatomaceous Earth against Three Major Stored Product Beetle Species. Agronomy 2022, 12, 156. https://doi.org/10.3390/agronomy12010156
AMA Style
Baliota GV, Lampiri E, Athanassiou CG. Differential Effects of Abiotic Factors on the Insecticidal Efficacy of Diatomaceous Earth against Three Major Stored Product Beetle Species. Agronomy. 2022; 12(1):156. https://doi.org/10.3390/agronomy12010156
Chicago/Turabian StyleBaliota, Georgia V., Evagelia Lampiri, and Christos G. Athanassiou. 2022. "Differential Effects of Abiotic Factors on the Insecticidal Efficacy of Diatomaceous Earth against Three Major Stored Product Beetle Species" Agronomy 12, no. 1: 156. https://doi.org/10.3390/agronomy12010156
Note that from the first issue of 2016, this journal uses article numbers instead of page numbers. See further details here.
