Commercial Diatomaceous Earth Research Articles

Evaluation of a Greek Diatomaceous Earth for Stored Product Insect Control and Techniques That Maximize Its Insecticidal Efficacy

Laboratory bioassays were conducted to evaluate the insecticidal efficacy of a diatomaceous earth deposit from Greece, for a wide range of stored product insects. In this context, populations of five different insect species, Tribolium confusum Jacquelin DuVal, the confused flour beetle; Sitophilus oryzae (L.), the rice weevil; Rhyzopertha dominica (F.), the lesser grain borer; Oryzaephilus surinamensis (L.), the sawtoothed grain beetle; Cryptolestes ferrugineus (Stephens), the rusty grain beetle, which cover a major spectrum of insects species of stored products worldwide, were used in the bioassays. The different treatment of diatomaceous earth (DE) rocks (grinding, diatomaceous enrichment, powder granulometry) led to the creation of five types of formulations (namely DE1, DE2, DE3, DE5 and DE6) that exhibited significant fluctuations in their insecticidal efficacy when applied on wheat. In general, some of the modified formulations were found to be very effective against species such as R. dominica and T. confusum that may be difficult to control at the current labeled doses of commercial DE formulations. Overall, our data clearly indicate that this specific Greek deposit has considerable insecticidal properties, which can be further utilized in designing commercial formulations for insect control at the postharvest stages of durable agricultural commodities, provided that the deposit will be modified at specific enrichment and granulometry levels.

Bio-efficacy of the indigenous entomopathogenic fungus, Beauveria bassiana in conjunction with desiccant dust to control of coleopteran stored product pests

The insecticidal activity and effects of sublethal combinations of the fungus, Beauveria bassiana-IRAN441C and commercial diatomaceous earth (DE) were assessed on adult coleopterans, Callosobruchus maculatus (F.) (Chrysomelidae), and Oryzaephilus surinamensis (L.) (Silvanidae). Dry conidia and DE were applied singly or in combination. The agents produced acceptable mortality, however, results were not affected by species of host plant seeds fed to the beetles. F1 progeny reduction was notably increased in both beetle species when mixtures of the fungus and DE were each at the LC50 level. In addition to avoidance behavior, different combinations of fungus/DE dosages induced winged morphs (non-reproductive phase) in the C. maculatus population after 50 d exposure. Our results demonstrated that a combination of B. bassiana and DE resulted in high mortality of both beetle species and co-application of B. bassiana and DE is feasible in a stored product pest management program.

Purification, characterization and application of cherty rocks as sorbent for separation and preconcentration of rare earths

Cherty rocks, most abundant byproduct of mining industry, were used as adsorbent for the extraction of rare earth elements. Purified chert was characterized by various analytical methods (XRD, FX-ED, MEB, FTIR, laser granulometry). XRD patterns showed diffraction peaks of quartz, tridymite, cristobalite and clinoptilolite-Ca phases. SEM micrographs showed granular morphology of studied chert and particle size distribution was lower than 100μm and unimodal. Adsorption behaviors of La(III) and Ce(III) ions on chert were investigated with various chemical methods and ICP-AES. Various experimental parameters were optimized such as contact time, initial rare earth concentration, temperature, agitation rate, and calcination of chert. Stable adsorption of Ce(III) and La(III) on chert were observed at stirring speed 400 and 200rpm respectively. However the process of calcination does not affect the adsorption capacity of the two rare earths. The adsorption kinetics, the effect of various parameters influencing the adsorption capacity and adsorption isotherms were determined. Results showed instantaneous adsorption, fast kinetics and maximum percentages of adsorption ranged between 80 and ∼100%. Highest correlation coefficients were obtained for the pseudo-second order kinetic that are described satisfactorily by the Langmuir model. Thermodynamic parameters obtained indicate an endothermic and spontaneous adsorption process for lanthanum and exothermic and nonspontaneous adsorption process for cerium. Adsorption of rare earths on chert showed similar adsorption capacities to commercial diatomaceous earth and low matrix effect was observed when chert is used as an adsorbent of REE from a phosphogypsum leachate.

Laboratory evaluation of Turkish diatomaceous earths as potential stored grain protectants

In this study, efficacy of local diatomaceous earths (DE) collected from different regions of Turkey against stored grain insects, Sitophilus oryzae (L.), Tribolium confusum du Val. and Rhyzopertha dominica (F.), was investigated. For this purpose, biological tests were carried out at concentrations of 500 and 1000 ppm (mg DE / kg wheat) of 9 local diatomaceous earths and one commercial diatomaceous earth, namely Silicosec® as positive control at 25 ± 1 ° C temperature and 65 ± 5% relative humidity in wheat. In addition, the studies on some of the chemical and physical analysis of the tested diatomaceous earths (silicon dioxide (SiO2) ratio, particle size and adhesion rate on commodity) were also conducted. In biological tests conducted at 500 ppm concentration for 14 days of exposure in wheat the highest mortality rates (97 to 98%) of S. oryzae adults were recorded in CB2N-1, AGN-1 and BGN-1 diatomaceous earths, while the highest mortality rates of T. confusum adults were obtained from only AGN-1 and BGN-1 diatomaceous earths. In the case of R. dominica, the highest mortality rate (64.4%) was recorded only in CB2N-1 diatomaceous earth. At concentration of 1000 ppm for 14 days of exposure in wheat, 100% mortality of S. oryzae adults was observed in all tested local diatomaceous earths except FB2N-1 and Silicosec® while mortality rates of T. confusum adults ranging from % 95 to %100 were obtained in all tested local diatomaceous earths except FB2N-1, FBN-1 and Silicosec®. In the case of R. dominica adults, mortality rates ranging from 80% to 93% were recorded in CB2N-1, CCN-1 and AG2N-1 diatomaceous earths. In conclusion, laboratory bioassays indicated that CB2N-1 and BGN-1 local diatomaceous earths had high efficacy against S. oryzae, T. confusum and R. dominica adults and thus could be potential to be successfully used for controlling stored grain insect pests as a grain protectant.

Evaluation of the potential value of the F 1 H and F 2 H Diatomaceous earth formulations as grain protectants against Rhyzopertha dominica (Fabricius) (Coleoptera: Bostrichidae):

An insecticidal efficacy of two newly developed grain protectant formulations were assessed against lesser grain borer Rhyzopertha dominica (Fabricius) (Coleoptera: Bostrichidae) on wheat and corn after 6 months period of. Tested formulations, marked as F1H and F2H, based on inert dust, laurel leaves, lavender essential oil, corn oil, silica gel (both F1H and F2H) and pyrethrin (only F2H) were tested at six doses (from 100 ppm to 600 ppm) depending on formulation and type of grain. The appropriate weights of each formulation, were added seperately to plastic containers containing 10 kg of wheat or corn. An initial population of 200 adults of R. dominica were added into each container and left under natural environmental conditions for up to 6 months. A commercial diatomaceous earth (DE) insecticide, Celatom® Mn 51, was used for the comparison of the results, in addition to the untreated control. After six months, both formulations showed higher insecticidal effect than DE Mn 51 in corn and in wheat. Furthermore, the initial population of R. dominica, introduced in wheat was suppressed almost completely, with only 0.7%-5.3% live adults found, depending on formulations and dose. The order of efficacy was F1H>F2H>DE Mn 51. Similar suppression of the initial population was recorded in corn, where F2H was slightly more effective than F1H with 2.0%-10.6% and 4.1%-9.5% live adults found, respectively. At the same time, in the treatments with DE Mn 51 there were 4.7%-74.7% and 33.4%-56.1% live adults in wheat and corn, respectively.

Insecticidal effect of Central Anatolian Region diatomaceous earths against confused flour beetle ( Tribolium confusum Du Val.) on stored paddy

In this study, insecticidal efficacy of different local diatomaceous earth (DE) deposits obtained Central Anatolian Region in Turkey and commercial DE deposit (German origin), Silicosec® were evaluated against substantial pest on stored grain as Tribolium confusum du Val (Coleoptera: Tenebrionidae) at five different concentrations of 100, 300, 500, 900 and 1500 ppm on stored paddy. Mortality of the exposed adults was assessed after 7, 14 and 21 days of exposure. Also progeny productions were assessed after 65 days The tests were carried out at 25±1 oC temperature, 55±5% R.H. under dark conditions. The most effective DE in a short time were assessed AG2N-1 which caused 97% mortality of T. confusum adults at 1500 ppm concentration after 7 days of exposure in paddy. Complete mortality of T. confusum adults was recorded on AG2N-1 at 900 ppm for 14 days and treatments of AG2N-1, BGN-1, CBN-1 for 21 days at 500, 900 and 1500 ppm respectively whereas 87% mortality rate was determined for 21 days exposure of Silicosec® at the highest concentrations on paddy. In conclusion, this study indicated that Turkish DE deposits, AG2N-1, BGN-1 and CBN-1 had high insecticidal efficacy in comparison with the commercial Silicosec® and would have potential to be used against insects in the pest management of stored paddy.

Evaluation of insecticidal efficacy and persistence of Nigerian raw diatomaceous earth against Callosobruchus maculatus (F.) on stored cowpea

The insecticidal efficacy and persistence of Nigerian raw diatomaceous earth (DE) were evaluated in the laboratory on cowpea against Callosobruchus maculatus (F.) (Coleoptera: Chrysomelidae). The raw DE was applied to 1.5 kg lots of cowpea seeds at 0 (untreated control), 250, 500, 750, 1000 and 1500 mg/kg, and a commercial DE formulation (Protect-It®) applied at 1000 mg/kg was included in the test as positive (treated) control. The treated cowpea seeds were kept under ambient laboratory conditions (26 - 34°C and 24 - 93% RH. Bioassays were conducted on samples taken from each treatment at the day of storage and every 30 d for 6 consecutive months. Adult C. maculatus were exposed for 3 and 5 d to the samples and adult mortality was assessed over this exposure interval and progeny production and seed damage were assessed after additional 30 d. On freshly treated cowpea, both the raw DE and Protect-It® were highly effective against C. maculatus causing 100% adult mortality following 5 d of exposure. In general, the raw DE was less persistent on cowpea providing complete adult mortality only for two months. Protect-It® on the other hand was stable over the 6- month period of storage causing 95.8 to 100% adult mortality. None of the treatments completely inhibited progeny production after 2-3-moths storage period. The results of this study indicated that Protect-It® may provide suitable protection for 6 months against C. maculatus, but the raw DE in its present state is not suitable for long-term protection against this insect pest.

Testing the Insecticidal Activity of Nanostructured Alumina on Sitophilus oryzae (L.) (Coleoptera: Curculionidae) Under Laboratory Conditions Using Galvanized Steel Containers

Most stored-grain pest insects increase their population within a relatively short time, causing serious damage to stored products. Sitophilus oryzae (L.) is one of the world’s major stored-grain pest insects and was chosen as the model insect for our studies. This study compared the efficacy of three different dusts under laboratory conditions: aluminum dust (nanostructured alumina), DiatomiD®, and Protect-It® (commercial diatomaceous earth). Parental survival, grain damage, and progeny production were measured at 250 and 500 ppm in treated wheat. The tests were conducted in 400 mL galvanized steel jars, an experimental model used for the first time to measure the effectiveness of nanostructured alumina, since most studies have been typically performed in small petri dishes. Parental survival obtained was highest in the untreated controls, followed in decreasing order by DiatomiD®, Protect-It®, and nanostructured alumina (NSA). NSA caused the greatest mortality. All treatments significantly reduced grain weight loss and frass production in wheat infested by S. oryzae. The degree of progeny (F1) suppression was directly related to the product and treatment rate, progeny being significantly suppressed by NSA in wheat followed by Protect-It® and DiatomiD®. Therefore, NSA had a greater impact on insect population dynamics.

Diatomaceous earth used against insect pests, applied alone or in combination with Metarhizium anisopliae and Beauveria bassiana

Abstract Laboratory bioassays were conducted to assess the insecticidal efficacy of the formulation SilicoSec® used alone or in combination with isolates of entomopathogenic fungi, Metarhizium anisopliae (Metschinkoff) Sorokin and Beauveria bassiana (Balsamo) Vuillemin. SilicoSec® is a commercial diatomaceous earth (DE) formulation. Wheat was treated with 200 mg/kg of DE, 400 mg/kg of each isolates alone or a combination of them, against Tribolium castaneum Herbst, Rhyzopertha dominica (F.), and Oryzaephilus surinamensis L. The experiments were carried out at 27±1°C and 65±5% relative humidity (RH) in continuous darkness. The pathogenicity of all isolates was significantly low even after 7 days of exposure, with the exception of R. dominica. The isolates were virulent to the beetles, but the efficacy of the isolates was enhanced in combination with the DE. Tribolium castaneum was the most resistant species, followed by R. dominica. The findings indicated that the addition of the DE to the isolates increased the pathogenicity especially at the highest exposure interval. The addition of DE may provide satisfactory control of the insect-pests of stored products.

Efecto de la tierra de diatomeas en las propiedades químicas del suelo en el cultivo de maíz (Zea mays, L.)

<p>Este trabajo se desarrolló a partir de la necesidad de brindar productos y servicios dirigidos al campo, que cubran las necesidades nutrimentales de las plantas, sin que esto implique un daño ambiental por utilización excesiva de fertilizantes y plaguicidas químicos. Se evaluó el efecto fertilizante de dos tierras de diatomeas y un fertilizante líquido, para corroborar la evidencia empírica de varios productores, que utilizaron un producto comercial con base en los materiales de estudio y obtuvieron mejores niveles de rendimiento en diferentes cultivos. Se realizó un muestreo del área experimental antes de establecer el cultivo y al término del mismo. Se evaluaron dos tierras comerciales de diatomeas identificadas como 289 y 400 P comercializadas por Celite Internacional, a dos concentraciones 20 kg ha-1 y 40 kg ha-1 y 18 kg ha-1 y 36 kg ha-1 respectivamente, además de un fertilizante orgánico líquido (FOL) a dosis de 2 L ha-1 y 4 L ha-1, como testigo se consideró la muestra de suelo tomada antes de la aplicación de tratamientos. El diseño experimental utilizado en campo para la aplicación de los tratamientos fue en bloques completos al azar (DBA) con 5 repeticiones. La planta indicadora fue maíz híbrido HC8. Las variables evaluadas en suelo mediante análisis de laboratorio fueron: propiedades físicas de textura y densidad aparente (DA); y químicas de pH, carbono orgánico (CO), materia orgánica (MO), conductividad eléctrica (CE), capacidad de intercambio catiónico (CIC), nitrógeno (N), fósforo (P), potasio (K), calcio (Ca), magnesio (Mg) y sodio (Na). Los resultados se analizaron bajo un ANOVA y prueba de Tukey para la comparación de medias por tratamiento, utilizando el paquete estadístico JMP. Los resultados de laboratorio indican que hubo cambios en las características químicas del suelo entre el testigo y los tratamientos en la mayoría de las características químicas analizadas (pH, CO, MO, N, P, K, Ca, Mg y Na). Sin embargo estadísticamente y bajo un nivel de significancia del 5%, solo mostraron diferencias las propieda­des de CO, MO, CE, N, K y Na.</p>

EFFICACY OF DIFFERENT NATURAL AND SYNTHETIC SILICAS AGAINST TWO STORED GRAIN PESTS: SITOPHILUS GRANARIUS (L.) AND SITOPHILUS ORYZAE (L.)

The development of non-chemical pesticides, e.g., physically active substances such as diatomaceous earth (DE) is promising. The purpose of the present study was to compare the efficacy of different silica products against two stored insect pests, the granary weevil, Sitophilus granarius (L.), and the rice weevil, Sitophilus oryzae (L.), under different environmental conditions. Different AL-06-formulations (developed at Humboldt University) were compared with commercial DE products Fossil Shield ® (FS100, FS90.0s and FS80p) and three synthetic amorphous silica formulations (SAK). The experiments were conducted in Petri dishes with and without food under different climate conditions. Mortality and mass of the beetles were recorded over time. The mortality rate was determined after 1, 2, 4, 7, 14, and 28 d. The highest S. granarius mortality, with 92% after 48h, was achieved with a commercially available SAK. This study indicates that SAK can effectively control S. granarius. The hydrophilic DE FS100 and another SAK failed to control the beetles effectively. Beetle mortality rate increased with dosages of all materials. Feeding material increased survival time significantly, most likely because beetles were able to metabolize water from the food. Four of the DE products decreased the beetle population within 14 d to less than 50% and within 28 d to 15%, respectively. The poor performance of some formulations was due to the loss of insecticidal efficacy as a consequence of water saturation of these hydrophilic substances when held in higher humidity. The application products consisting of smaller particles resulted in generally higher mortality rates than the use of DEs with larger particles. Further studies are planned to identify water saturation effects.

Direct and admixture toxicity of diatomaceous earth and monoterpenoids against the storage pests Callosobruchus maculatus (F.) and Sitophilus oryzae (L.)

We investigated the effects of two commercial diatomaceous earth based insecticides (DE), Protect-It® and SilicoSec®, the nano-structured silica product AL06, developed by the section for Urban Plant Ecophysiology at Humboldt University Berlin, and the monoterpenoids, eugenol, and cinnamaldehyde on two stored product pests, Callosobruchus maculatus and Sitophilus oryzae. Protect-It® was more effective than SilicoSec® against C. maculatus while the reverse was true for S. oryzae. Generally C. maculatus was more sensitive towards DE and silica treatment than S. oryzae. Mortality rate of both pest species increased when DE’s were applied to food commodities previously treated with a monoterpenoid. In admixture experiments, the toxicity of SilicoSec® + cinnamaldehyde (LD50 = 42.73 ppm), SilicoSec® + eugenol (LD50 = 24.30 ppm), and Protect-It® + eugenol (LD50 = 2.60 ppm) was increased over DE alone against S. oryzae. Both substances showed a synergistic effect considering their co-toxicity coefficient relative to the LD50-value. In contrast, we could not find any synergistic effects in experiments with C. maculatus. Here only Protect-It® + cinnamaldehyde (LD50 = 20.84 ppm) showed an additive effect while all other combinations of monoterpenoid and DE indicated antagonistic effects. In addition to contact insecticidal effects both monoterpenoids showed a strong fumigant action. The presented results indicate that the natural product DE has great potential to replace synthetic pesticides commonly used in stored product pest management. Efficacy of DE can be improved by adding certain monoterpenoids against certain insect pests.

Formation of a Vitreous Phase at the Surface of Some Commercial Diatomaceous Earth Prevents the Onset of Oxidative Stress Effects

To understand the effect of the commercial processing of diatomaceous earths (DEs) on their ultimate surface structure and potential toxicity, we investigated the influence of the industrial processing and the nature of the deposit. Two flux calcined specimens from different deposits, DE/1-FC and DE/2-FC, and the simply calcined sample DE/1-C, from the same deposit as DE/1-FC, were compared in both their bulk and their surface properties. X-ray diffraction (XRD) analysis in a heating chamber revealed the presence of cristobalite in all samples, more abundant on the flux calcined ones. The crystal lattice is probably imperfect, as the alpha-beta transition, visible by XRD in DE/1-FC and DE/2-FC, is not detected by differential scanning calorimetry. Progressive etching with HF solutions suggests that most of the crystalline phase is at the core and not at the outer region of the samples. The combined use of spectroscopic (UV-vis and IR) and calorimetric techniques (heat of adsorption of water as a measure of hydrophilicity) reveals that DE/1-FC and DE/2-FC particles have an external layer of glass, absent in DE/1-C, where iron impurities act as network-forming and sodium ions as modifier species, with few patches of a hydrophobic phase, the latter relatable to a heated pure silica phase. When tested on a macrophage cell line (MH-S) in comparison with appropriate positive and negative controls (an active and an inactive quartz dust, respectively), only DE/1-C exhibited a cell damage and activation similar to that of active quartz (measured by lactate dehydrogenase release, peroxidation of membrane lipids and synthesis of NO). It is likely that the presence of a vitreous phase mitigates or even eliminates the cellular responses of silica in DE.

Control of Rhyzopertha dominica in stored rough rice through a combination of diatomaceous earth and varietal resistance

AbstractAdults of Rhyzopertha dominica (F.), the lesser grain borer, were exposed on four varieties of rough rice with Dobie indices of susceptibility of 1.1 to 1.1 (low), and four varieties with Dobie indices of susceptibility of 3.4 to 3.8 (high). The varieties with low and high Dobie indices were classified as resistant and susceptible, respectively, to R. dominica. The purpose of the study was to evaluate control of R. dominica through the use of diatomaceous earth (DE) in combination with rice varieties that were either susceptible or resistant to R. dominica. The rice was treated with varying rates of the commercial DE Insecto®, up to a maximum of 1 000 mg DE/kg of rice. Adult mortality at each application rate of DE was generally greater on three of four resistant varieties compared to three of four susceptible varieties. Progeny production from the parental generation exposed on the rice was also greater in 3 of the 4 resistant varieties compared to 3 of the 4 susceptible varieties at DE rates of 500 mg/kg or more. Progeny production in rice treated with a maximum rate of 1 000 mg/kg DE ranged from 7‐44 adults on the resistant varieties compared to 75‐155 adults on the susceptible varieties. At DE rates of 500, 750, and 1 000 mg/kg, the percentage of insect‐damaged kernels (IDK) was also greater in 3/4 resistant varieties than in the susceptible varieties. Results show combining the use of DE with varietal resistance of rough rice to R. dominica could be used to limit populations of this insect in stored rice and help prevent economic damage.

Evaluation of methoprene alone and in combination with diatomaceous earth to control Rhyzopertha dominica (Coleoptera: Bostrichidae) on stored wheat

A series of experiments were conducted in which different formulations of the insect growth regulator methoprene were evaluated for control of Rhyzopertha dominica (F.), the lesser grain borer, a major internal insect pest of stored wheat. In the first test, application rates of 10-ppm R, S-methoprene (a racemic mixture of the R and S isomers of methoprene) and 1 and 5-ppm S-methoprene ( S-isomer only) gave 100% suppression of F 1 adult progeny of R. dominica for 24 weeks. In the second test, adult R. dominica were exposed at 27°C and 32°C, 57% and 75% relative humidity (r.h.) on untreated wheat and wheat treated with 1- to 10-ppm S-methoprene dust. Survival after a 3-week exposure decreased with increasing concentration of dust, and ranged from 69% to 99%, but no F 1 adult progeny were produced in treated wheat. In the final test, concentrations of 0, 0.25, 0.50, 0.75, and 1.0 ppm S-methoprene EC were combined with concentrations of 0, 75, 150, 225, and 300 ppm of the commercial diatomaceous earth (DE) Protect-It ®. Within each methoprene concentration, survival generally decreased with increasing concentration of DE, and was generally greater at 75% than at 57% r.h. Only the wheat treated with 0-ppm methoprene contained an appreciable number of F 1 adults. In summary, both the dust and EC formulations of S-methoprene gave 100% suppression of F 1 adult progeny R. dominica at application rates of 1 ppm, and combination treatments involving reduced rates of methoprene and DE gave effective control of R. dominica.

Ground kenaf core as a filtration aid

The objective of this study was to examine the filtration characteristics of ground kenaf core, a waste material generated during the production of kenaf bast fibers for paper. The constant-pressure precoat filtration characteristics of ground kenaf core were compared to commercial diatomaceous earth (DE). Three challenge solutions were studied: a yeast solution, a bacterial solution, and a standard silica-particle solution. The kenaf and DE both satisfactorily permitted removal of all silica particles from solution without noticable flux degradation over the course of the filtration. The kenaf and DE also removed yeast particles. In this case, the flux loss with time was lower with the DE precoated filter than in the kenaf precoated filter. The DE precoat excluded less than 10% of the bacterial particles from solution, whereas the kenaf removed about 40% of these small particles.

An ultrastructural study of acute and long-term lung response to commercial diatomaceous earth

The acute pulmonary effects of intratracheally instilled particles of calcined diatomaceous earth were found to include a pronounced neutrophil invasion of the bronchioles by 4 h after exposure which remained well developed through 1 day post-exposure. The number of macrophages and neutrophils in the alveoli continued to increase through 1 day post-exposure and remained above control values through 7 days post-exposure. The number of macrophages, many of which contained diatomaceous earth, remained elevated for the duration of the experiment. Most phagocytosis of the particles was carried out by macrophages, with minor participation by neutrophils. Many of the reactive macrophages in the groups with post-exposure periods longer than 2 h showed various types of pathological alterations. A few particles were found in type I epithelial cells. Oedematous changes were observed in some type I epithelial cells and proliferation of type II epithelial cells was evident in some alveoli, particularly those near the respiratory bronchioles. Mild diffuse fibrosis was first observed at 6 months and was still present at 15 months but remained confined to the areas containing the diatomaceous earth.

The Catalytic Effect of the Support on Terpene Compounds in Gas-Liquid Chromatography

Abstract The catalytic action of several solid supports, that is, glass, rock crystal, quartzite, sea sand, unglazed porcelain and commercial supports, have been examined. Glass shows practically no catalytic action in the examined terpene compounds, except for linalyl acetate and α-santalol, which were decomposed and/or isomerized slightly, but this support does show an adsorption of oxygen-containing compounds. The catalytic action of rock crystal is slightly greater than that of glass, but the adsorptivity of rock crystal is extremely small. Commercial diatomaceous earth supports show a remarkable catalytic action.