Effect of oilseed type on the efficacy of five diatomaceous earth formulations against Tribolium castaneum Herbst (Coleoptera: Tenebrionidae)

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1 Payam Nour University From the SelectedWorks of Adel Khashaveh 27 Effect of oilseed type on the efficacy of five diatomaceous earth formulations against Tribolium castaneum Herbst (Coleoptera: Tenebrionidae) Adel Khashaveh Available at:

2 27 Vol. (4): DOI 1.7/s y ORIGINAL PAPER EVect of oilseed type on the eycacy of Wve diatomaceous earth formulations against Tribolium castaneum Herbst (Coleoptera: Tenebrionidae) Masumeh Ziaee Amin Nikpay Adel Khashaveh Received: 12 December 26 / Revised: 6 March 27 / Accepted: 19 March 27 Springer-Verlag 27 Abstract The insecticidal eycacy of Wve diatomaceous earth (DE) formulations,, SilicoSec, Insecto, Perma-Guard D-1 and Dryacide was evaluated against adult Tribolium castaneum Herbst, the red Xour beetle, on three oilseeds: sazower, sunxower and sesame. The s were applied at three rates:.5, 1 and 1.5 g/kg. The experiment was carried out at 26 C and 55 ( 5)% RH in the dark. The mortality of T. castaneum adults was measured after 3, 7, 14 and 21 days exposure. After the 21-day mortality count, all surviving insects were removed and the samples retained under the same conditions for a further 45 days to assess progeny production (F1). SigniWcant diverences were recorded among the three oilseed types as well as between the s tested. After 21 days exposure, even at the lowest treatment rate, adult mortality was high (>9%) in sazower for all s. In contrast adult mortality was signiwcantly lower in the case of sesame. Increased application rates improved the eycacy of DEs in sunxower and sesame. Even at the lowest rate the complete suppression in progeny production was achieved on treated sazower. The greatest number of progeny was recorded for treated sunxower seeds. and Dryacide were the most eycient s against T. castaneum. Keywords Diatomaceous earth SaZower Sesame SunXower Tribolium castaneum M. Ziaee (&) Department of Zoology, Branch of Urmia, Young Researcher Club of Islamic Azad University, P.O. Box 969, Urmia, Iran masumeh_ziaee@yahoo.com A. Nikpay A. Khashaveh Department of Entomology, Agricultural Faculty, Urmia University, Urmia, Iran 199 Introduction Diatomaceous earth (DE) has long been known as a potentially useful grain protectant. It is composed almost entirely of amorphous silicon dioxide, formed from fossilized diatoms (single-celled algae). Amorphous silicon dioxide is a low-toxicity substance to mammals (Anonymous 1986) and is registered in many countries as a food additive (Anonymous 1981, 1991). DE particles adhere to the body of the insect and damage the protective waxy layer of the insect cuticle by sorption, and to a lesser degree, by abrasion. Death is caused by loss of water from the insect s body (Nikpay 26). DE is also known to repel insects (White et al. 1966). One of the most important factors determining the eycacy of DEs against stored-product insect species is the type of grain. Aldryhim (1993) Wrst reported diverent eycacies of DE Dryacide against Rhyzopertha dominica (F.) on diverent classes of wheat; durum, hard and soft wheat. McGaughey (1972) found a diverence in the eycacy of DE Perma-Guard against Sitophilus oryzae (L.) and Tribolium confusum (Du Val.) on rough rice when compared with brown and milled rice. Commodities diver in their physical and chemical properties. Pomeranz et al. (1988) found that kernel hardness was one of the most obvious diverences between wheat classes and varieties. This property may have an inxuence on the level of infestation by insects and also on the adherence of DE to the kernels. Tribolium castaneum Herbst, the red Xour beetle (RFB), is one of the most common and probably the least susceptible stored-product insects to DE protectants, so a which is able to control Xour beetles should be able to control most insects occurring in stored grain and seeds (Korunic 1998; Fields and Korunic 2; Arnaud et al. 25).

3 The object of our study was to evaluate the eycacy of Wve commercially available s against adults and reproductive capacity of T. castaneum on three diverent oilseeds. Materials and methods Insects Adults of T. castaneum were reared on 95% wheat Xour plus 5% brewers yeast at 28 C and 65 ) 5)% RH in the dark. All adults used in the experiments were 7 14 days old of mixed sex. Insects were obtained from cultures maintained in the laboratory for at least 3 years, with no history of exposure to insecticides. s The Wve s used in the tests were: 1. is a mixture of freshwater DE (Hedley Technologies Inc., 21 Mateson Bldvde. Suite 5, Mississauga, ON, L4W 5A8, Canada) with 1% silica aerogel to enhance insecticidal activity. It contains approximately 83.7% amorphous silicon dioxide, 5.6% Al 2 O 3, 2.3% Fe 2 O 3,.9% CaO,.3% MgO, and 1.9% other oxide (e.g. TiO 3, P 2 O 3 ), and 3 5% moisture content (m.c.). The median particle size is 5 μm (Korunic and Fields 1995). 2. Insecto is a marine DE (Natural Insects products, Inc., North EckhoV Street, Orange, CA, 92668, USA) with 1% food-grade bait. It has 87% amorphous silicon dioxide, with 2 4% m.c., and with chemical composition of about 3% Al 2 O 3, 1% Fe 2 O 3, less than 1% CaO, MgO, TiO 3, and P 2 O 3. The median particle size is about 8.2 μm (Subramanyam et al., 1994). 3. The freshwater DE Perma-Guard D-1 (Perma- Guard Inc., PO Box 25282, Albuquerque, NM, 87125, USA) contains 93% SiO 2, 3% Al 2 O 3, 1.3% Fe 2 O 3, 1.1% CaO,.6% Na 2,.3% K 2 O and.2% TiO 3 and maximum 4.5% m.c. The median particle size is about 1.7 μm (Arnaud et al. 25). 4. The marine DE Dryacide (Dryacide USA LLC, 3536 Emerson Street, San Diego, CA 9216, USA) is a white dust that contains 91 92% amorphous silicon dioxide, 3 5% clay minerals, less than.1% Silica aerogel and 3 5% m.c. with a mean particle size of μm (A. McLaughlin, personal communication). 5. SilicoSec is a freshwater formulation of diatomaceous earth obtained from Biofa GmbH, Münsingen, Germany and is composed of 92% SiO 2, 3% Al 2 O 3, 1% Fe 2 O 3 and 1% Na 2 O. The median particle size is between 8 and 12 μm (Athanassiou et al. 25). Oilseeds SunXower, Helianthus annus L. (var Armaveriski); spring sazower, Carthamus tinctorius L. (var IL-III) and sesame, Sesamum indicum L. (the white variety) obtained from Oil Research Development Company of West Azarbaijan, Iran, were used for experimentation. The moisture content of the three commodities as determined by a Dickey John moisture meter (Dickey John Multigrain CAC II, Dickey-John Co, USA) ranged between 6.4 and 6.9%. The lipid content of sunxower, sazower and sesame recorded by the Oil Research Development Company was 42.37, and 58., respectively. The commodities were in a very good condition, clean and with a very low proportion of broken kernels. For all commodities tested, 1% cracked seeds were included in the sample both to represent actual practice and to ensure food was accessible for the red Xour beetle. Bioassays Each was applied in three rates:.5, 1 and 1.5 g/kg and each rate was replicated four times. There were 45 rate-commodity combinations. Fifty grams of each commodity (whole + 1% cracked) were taken and placed in a small glass vial. The samples were treated individually with the respective quantities of DEs; subsequently the vials were shaken for 1 min to obtain an even distribution of the DE on the seed sample. Thirty adults of T. castaneum were introduced into each glass vial which was covered with muslin cloth to provide suycient aeration. The untreated commodities served as the control treatment with four replicates for each commodity (12 vials). The vials were then placed in incubators set at 26 C and 55 ( 5)% RH. Mortality was measured after exposure for 3, 7, 14 and 21 days. After the 21-day mortality count, all dead and surviving insects were removed and the seed samples retained under the same conditions for a further 45 days to assess progeny production. Data analysis The mortality counts were corrected by using Abbott s (1925) formula. Percentage of reduction in progeny production was determined by the [(No. progeny in control No. progeny in treatment)/no. progeny in control ] formula (Aldryhim 199). To equalize variances, mortality percentage of adults and percentage of reduction in progeny production were transformed using the square root of the arcsin. The data were analyzed using Analysis of Variance (SAS 2). Means were separated by using the Tukey Multiple Range Test at P =.5. The dose required to kill 5% of the insects (LC 5 ) was estimated using probit analysis (SPSS 1999). 2

4 Table 1 The lethal dose for 5% (LC 5 ) of T. castaneum adults in oilseeds treated with Wve s Results LC 5 (g/kg) Insect mortality ConWdence limits (95%) Probit/log regression line All main evects and associated interactions of T. castaneum mortality after 7 days interval were signiwcant ( F 4,179 =37.9, P <.1; rate F 2,179 = 152.8, P <.1; commodity F 2,179 =46.6, P <.1; rate F 8,179 = 8.36, P <.1; commodity F 8,179 =14.8, P <.1; rate commodity P Chisquare SaZower Y = 2.7x SunXower Y = 2.88x Sesame Y =.9x F 4,179 =2.2, P <.1; rate commodity F 16,179 = 3.2, P <.1). Insecticidal eycacy of DEs, based on LC 5 s is presented in Table 1. The 7-day LC 5 of T. castaneum adults was.59 g/kg for sazower; however; g/kg of DEs was needed to achieve 5% mortality of adults in sesame seeds. Mortality was very low, 3 days after the introduction of the insects with the exception of and Dryacide treated-sazower with the highest rates resulting in more than % mortality of the exposed T. castaneum adults (Fig. 1). After 7 days exposure, mortality levels were considerably higher with % mortality being recorded at the 1.5 g/kg treatment rate for and SilicoSec on sazower seeds (Fig. 2). After 14 days exposure, mortalities ranged between 3.63% (Perma-Guard at.5 g/kg on sunxower) and % ( at.5 g/kg and Dryacide at 1 g/kg on sazower), and all the DE products at 1.5 g/kg on sazower with the exception of Perma-Guard (Fig. 3). (%) mortality Fig. 1 Mean ( SE) of T. castaneum adults exposed to oilseeds treated with Wve s at the rates of.5, 1, 1.5 g/kg after 3 days of exposure 21 Fig. 2 Mean ( SE) of T. castaneum adults exposed to oilseeds treated with Wve s at the rates of.5, 1, 1.5 g/kg after 7 days of exposure

5 2 mortlity(%) 2 SilicoSec Insecto PermaGuardt Dryacide 2 mortality(%) 2 SilicoSec Insecto PermaGuardt Dryacide (%) mortality 2 Fig. 3 Mean ( SE) of T. castaneum adults exposed to oilseeds treated with Wve s at the rates of.5, 1, 1.5 g/kg after 14 days of exposure mortality(%) 2 SilicoSec Insecto PermaGuardt Dryacide Fig. 4 Mean (%) mortality ( SE) of T. castaneum adults exposed in oilseeds treated with Wve s at the rates of.5, 1, 1.5 g/kg after 21 days of exposure Finally, after 21 days exposure, % mortality was recorded in sazower at 1 and 1.5 g/kg rates for all the products except Perma-Guard. Of the three commodities, sesame recorded signiwcantly lower mortalities with only 9.9% being achieved with SilicoSec at.5 g/kg and the highest mortality of only 72.27% with at 1.5 g/kg (Fig. 4). F1 Progeny All main evects and associated interactions were signiwcant ( F 4,179 =33.6, P <.1; rate F 2,179 = , P <.1; commodity F 2,179 =75.7, P <.1; rate F 8,179 =2.68, P <.1; commodity F 8,179 = 9.94, P <.1; rate commodity F 4,179 = 33.46, P <.1; DE formulation rate commodity F 16,179 = 2.52, P <.1). The degree of progeny suppression was directly related to treatment rate with progeny being signiwcantly suppressed in sazower at the.5 g/kg rate. This rate was insuycient to control progeny in the other two commodities although progeny production was signiwcantly reduced at the higher rate levels, (Table 2), % of the progeny Table 2 Mean percentage of reduction ( SE) in progeny production (f 1 ) of T. castaneum in oilseeds: sazower, sunxower, sesame treated with Wve s Treatments (g/kg) Means followed by the same letter are not signiwcantly diverent; Tukey Multiple Range Test at P =.5 was controlled when commodities were treated with 1.5 g/ kg of and Dryacide. In contrast just 5.25% reduction in progeny production was recorded when Perma-Guard applied at the rate of.5 g/kg (Table 3). Discussion SaZower SunXower Sesame a b b a a a 1.5 a a a The results conwrm that the type of oilseed plays an even bigger role than the DE product employed in determining the level of control of the infesting live adults, although this 22

6 Table 3 Mean percentage of reduction ( SE) in progeny production (f 1 ) of T. castaneum in oilseeds treated with Wve s: Protect- It, SilicoSec, Insecto, Perma-Guard and Dryacide Treatments (g/kg) SilicoSec Insecto Perma-Guard TM Dryacide bcd cd bcd d cd a abc ab bcd a 1.5 a a a abc a Means followed by the same letter are not signiwcantly diverent; Tukey Multiple Range Test at P =.5 factor was less signiwcant in determining the number of F1 progeny. As the moisture contents of the three oilseeds tested were more or less the same, this can be discounted as a source for the widely varying results recorded. The percentage of cracked seeds was also controlled at the same 1% level so this is unlikely to be a source of the variance. Reports by other researchers throw some light on the source of this variance. Aldryhim (1993) reported two contributing factors being the degree of adhesion of DE particles to diverent commodities and the rate that DE particles are picked up by beetles. La Hue (1972) also reported diverent dust retention rates to explain discrepant results obtained for insect mortalities on wheat, sorghum grain and corn. McGaughey (1972) found that a 21-day exposure to rough rice treated with 1.75 and 3.5 g/kg of Perma-Guard produced % mortality of S. oryzae and T. confusum, respectively. However, dosages of 3.5 and 5.25 g/kg were required to cause % rice weevil mortality on milled and brown rice, respectively. More than 56 days were required to cause % mortality in T. confusum in brown rice treated with 7. g/kg. McGaughey found lower mortality in pretreated brown rice (exposed 21 days after treatment) than with fresh treatments and explained it with the possible saturation of DE by oils from the surface of rice kernels. Subramanyam (1995) explained the diverent mortality results observed between wheat and corn as being (1) greater retention of dusts on wheat than on corn as well as (2) loss of activity of dusts due to adsorption of lipids from corn surfaces. Corn has a much higher lipid content than wheat. This latter factor is logical as the eycacy of all DE products is a function of their sorptive capacity for cuticular waxes, and the adsorption of seed lipids should detract from its ability to adsorb insect wax. According to our results the survival of the exposed T. castaneum adults in sesame was higher than that on sazower and sunxower from the seventh day of exposure and so on. Therefore sesame seems to be the seed that DEs are less evective in comparison with the other two commodities tested. High lipid content and less skin hardness of sesame seeds seem to contribute for this diverence. It is also evident from the results that the eycacy of DE products can diver signiwcantly. In the test conditions employed here, and for eycacy in controlling the adult 23 insects and the suppression of F1 progeny, and Dryacide were signiwcantly more evective than the other products. Perma-Guard was the least evective product and no signiwcant diverence was observed between Silico- Sec and Insecto. The ability of s divers on diverent commodities. Fields et al. (22) indicated that wheat is one of the most challenging commodities for evective control of T. castaneum adults by DEs; Dryacide, Perma-Guard, and Insecto. The authors stated that less than 7 ppm (.7 g/kg) of DEs was suycient to achieve 5% mortality of adults after 7 days of exposure. The results of this trial demonstrate that the same rate of DEs tested would provide protection of sazower exposed to red Xour beetle infestations. In contrast high concentrations of DEs are required to protect sunxower and sesame seeds from T. castaneum infestations. The tests further conwrmed the results reported by other researchers, (Aldryhim 199; McLaughlin 1994; Ziaee et al. 26) that the control of T. castaneum on oilseed commodities by DE products requires extended exposure periods and elevated treatment rates. The 1.5 g/kg rate was insuycient to eradicate the adult insects and totally suppress progeny in sunxower and sesame seeds. This result supports the conclusion drawn by A. McLaughlin (1997, personal communication) that a rate of 2 g/kg of an evective DE product is required for the control of the red Xour beetle in sunxower seeds. In summary, the main conclusions can be drawn from the tests are: longer exposure intervals and higher rates are needed to achieve satisfactory control of T. castaneum in oilseeds, the physical and compositional characteristics of a speciwc commodity avect the eycacy of s, s have diverent eycacies on the same commodity and the same has diverent eycacies on diverent commodities. Acknowle1mdgments The authors wish to thank the Oil Research Development Company for providing oilseeds. Our gratitude is extended to Dr. Alan McLaughlin and Dr. Zlatko Korunic for helpful comments and for reviewing the manuscript prior to journal submission.

7 References Abbott WS (1925) A method of computing the evectiveness of an insecticide. J Econ Entomol 18: Aldryhim YN (199) EYcacy of the amorphous silica dust, Dryacide against Tribolium confusum DuV. and Sitophilus granarius (L) (Coleoptera: Tenebrionidae and Curculionidae). J Stored Prod Res. 26:27 21 Aldryhim YN (1993) Combination of classes of wheat and environmental factors avecting the eycacy of amorphous silica dust, Dryacide, against Rhyzopertha dominica (F.). J Stored Prod Res 29: Anonymous (1981) Federal Register (Nov 1) 46(217), , USA Anonymous (1986) Silica and some silicates. IARC Monograph Series: 42, WHO, Lyons, p 289 Anonymous (1991) EPA R.E.D. FACTS: Silicon dioxide and Silica Gel;. 21T 121, 1 4 Arnaud L, Lan HTT, Brostaux Y, Haubruge E (25) EYcacy of diatomaceous earth formulations admixed with grain against populations of Tribolium castaneum. J Stored Prod Res 41: Athanassiou CG, Vayias BJ, Dimizas GB, Kavalieratos NG, Papagregoriou AS, Buchelos CTh (25) Insecticidal eycacy of diatomaceous earth against Sitophilus oryzae (L.) (Coleoptera: Curculionidae) and Tribolium confusum Du Val (Coleoptera: Tenebrionidae) on stored wheat: inxuence of dose rates, temperature and exposure interval. J Stored Prod Res 41:47 55 Fields PG, Korunic Z (2) The evect of grain moisture content and temperature on the eycacy of diatomaceous earths from diverent geographical locations against stored-product beetles. J Stored Prod Res 36:1 13 Fields PG, Allen S, Korunic Z, McLaughlin A, Stathers T (22) Standardized testing for diatomaceous earth. In: Proceedings of the 8th International Work. Conf. Stored-Prod. Prot. York, England, pp Korunic Z (1998) Diatomaceous earths, a group of natural insecticides. J Stored Prod Res 34:87 97 Korunic Z and Fields PG (1995) Diatomaceous earths, insecticidal composition. USA Patent 5, La Hue DW (1972) The retention of diatomaceous earths and silica aerogels on shelled corn, hard winter wheat, and sorghum grain. ARS 51 44, US Department of Agriculture, p 8 McGaughey WmH (1972) Diatomaceous earth for confused Xour beetle and rice weevil control in rough, brown, and milled rice. J Econ Entomol 65: McLaughlin A (1994) Laboratory trials on desiccant dust insecticides. In: Highley E, Wright, EJ, Banks HJ, Champ BR (eds) Proceedings of the 6th international work. conf. stored-prod. prot., Canberra, Australia, 65, pp University Press, Cambridge Nikpay A (26) Diatomaceous earths as alternatives to chemical insecticides in stored grain. Insect Sci 13: Pomeranz Y, Czuchajowska Z, Shoreu MD et al (1988) Hardness and functional (bread and cookie making) properties of US wheats. Cereal Food World 33: SAS (2) The SAS System version 7 for Windows. SAS Institute, Cary SPSS (1999) SPSS for Windows User s Guide Release 1. SPSS Inc, Chicago Subramanyam Bh (1995) Comparative eycacy of diatomaceous earth dusts on stored-product insects. Poster presented at the Annual Entomological Society of America, December , Las Vegas, Nevada Subramanyam Bh, Swanson CL, Madamanchi N, Norwood S (1994) EVectiveness of Insecto, a new diatomaceous earth formulation, in suppressing several stored-grain insect species. In: Highley E, Wright, EJ, Banks HJ, Champ BR (eds) Proceedings of the 6th international work. conf. stored-prod. prot., Canberra, Australia, 65, pp University Press, Cambridge White GD, Berndt WL, Schesser JH, Wilson JL (1966) Evaluation of four inert dusts for the protection of stored wheat in Kansas from insect attack. USDA/ARS Report No. 51 8, pp 22 Ziaee M, Shayesteh N, Safaralizadeh MH, Uromchi S (26) Action of SilicoSec formulation of diatomaceous earth against Tribolium castaneum Herbst (Col.: Tenebrionidae). In: Proceedings of the 8th European Cong. Entomol., Supplementary Book 2, pp 1, September , Izmir, Turkey 24