Response of Insect Pests of Stored Grain to Silicon Dioxide Treatment

Article 3 of Russian Federal Law 280-FZ “On orga­nic produce” of August 3, 2018 requires that organic (i.e., ecologically clean) food should be produced with­out “application of agrochemicals, pesticides, antibiot­ics, growth and fattening factors, and hormonal prepara­tions, with the exception of those approved by the cur­rent national and international standards in the sphere of organic produce.”

In view of this, proper delivery of organic grain to the final consumer depends not only on meeting the stat­utory farming requirements but also on observing these requirements during grain storage, transport, and pro­cessing.

At present, only synthetic pesticides (organophos­phates, pyrethroids, and metal phosphides) included in the Federal catalogue of approved pesticides and agro­chemicals are used for stored grain protection in Russia. After treatment with these pesticides, grain and grain products are automatically excluded from the “organic” category, basically wasting the efforts of clean grain farmers. Therefore, of great importance is development of means of grain protection meeting the demands of Federal Law 280-FZ.

Russian State Standard R 56508-2015 “Organic pro­duce: rules for manufacture, storage, and transportation” permits the use of silicon dioxide in organic farming and food production.

Our previous research demonstrated the efficiency of silicon dioxide against the grain weevil Sitophilus gra- narius L. in stored grain (Fernas and Zakladnoy, 2010, 2011; Zakladnoy and Fernas, 2012, 2014).
This paper is devoted to the possibility of using sili­con dioxide preparation against the principal insect pests in stored grain.
 

The test species were the rice weevil Sitophilus oryzae L., grain weevil Sitophilus granarius L., lesser grain borer Rhyzopertha dominica F., sawtoothed grain beetle Oryzaephilus surinamensis L., and rusty grain beetle Laemophloeus ferrugineus Steph., which pose the greatest hazard to stored grain in Russia. Adult beetles were obtained from long-term laboratory cul­tures which had no previous contact with insecticides, without sorting them by sex or age.

Mortality of major stored grain pests in grain treated with AgroStrazh silicon dioxide preparation, in relation to the dosage (humidity 13.5%, temperature 25°C)

Pest species	Time required for complete extermination of beetles (days) at different dosages of silicon dioxide preparation (kg/t)
	0.125	0.25	0.5	1	2	3
Laemophloeus ferrugineus Steph.	3	1	4	1	1	1
Sitophilus oryzae L.	*	31	31	4	4	3
Sitophilus granarius L.	*	31	31	7	5	4
Oryzaephilus surinamensis L.	*	*	*	2	2	2
Rhyzopertha dominica F.	*	*	*	7	2	2

* Some beetles survived for 31 days.

The tested preparation was AgroStrazh produced by Voronezhpenosteklo LLC. This formula is a fine, high- porous light gray powder of hyalite cristobalite rock containing 800 g/kg of silicon dioxide.

Experiments were carried out in plastic containers measuring 10 x 7 x 5 cm with perforated covers; 50 g of soft wheat grains (humidity 13.5%) was placed in each container. AgroStrazh was added at dosages of 0, 0.125, 0.25, 0.5, 1, 2, and 3 kg/t and carefully mixed with the grain by repeatedly turning over the containers. The containers were stored in desiccators partly filled with the same wheat grain in order to maintain the relative air humidity corresponding to the equilibrium moisture content of the grain. Ten beetles of the pest species listed above were placed in each container. The desiccators were kept at 25°C in temperature controlled chambers. The experiments were carried out in three replications. The state of the tested insects was assessed daily, and the dead beetles were removed after counting. Observations stopped when no dead beetles were recorded in three consecutive checks.

RESULTS AND DISCUSSION

The timing of pest mortality in relation to the dosage of silicon dioxide preparation is given in the table.

Rusty grain beetles showed high sensitivity to silicon dioxide: they perished in 1-4 days at small dosages of 0.125-0.5 kg/t and perished completely within 24 h at dosages of 1-3 kg/t.

Rice weevils perished completely starting with a dos­age of 0.25 kg/t; at 0.25 and 0.5 kg/t the period of com­plete pest extermination lasted for almost a month, while at 1, 2, and 3 kg/t the beetles died in 3-4 days.
Grain weevils were largely similar to rice weevils in their response to the preparation dosage and timing of mortality. Similar to the preceding species, the beetles were completely exterminated in 31 days at small dos­ages of 0.25 and 0.5 kg/t, whereas at 1, 2, and 3 kg/t they died in 7, 5, and 4 days, respectively.

Sawtoothed grain beetles did not completely perish at dosages up to 0.5 kg/t, but at 1 kg/t the timing of extermination was reduced to only 2 days and remained at this level at 2 and 3 kg/t of the preparation.
Lesser grain borers were the most resistant to the preparation. They did not die within a month at dosages up to 0.5 kg/t; yet at 1, 2, and 3 kg/t they perished in much shorter time: 7, 2, and 2 days, respectively.
On the whole, mortality of all the studied species was faster at higher dosages and increased with the duration of contact with the treated grain. Therefore, the scheme of grain treatment with silicon dioxide should be devel­oped taking into account the optimal proportion of these two factors.

REFERENCES

1.  Fernas, A.V., and Zakladnoy, G.A., “The Possibility of Stored Grain Protection from Pests with a Silicon Di­oxide Preparation,” in Innovative Scientific Technologies (as the Basis of Food Supply Security in the Russian Federation: Proceedings of the 4th Conference of Young Researchers at the Storage and Processing Branch of the Russian Agricultural Academy, December 9, 2010 (Moscow, 2010), pp. 213-214.)
2.  Fernas, A.V., and Zakladnoy, G.A., “Response of Grain Weevils to Treatment of Grain of Different Moisture Content with a Silicon Dioxide Preparation,” in Modern Methods of Modifying Physicochemical and Technologi­cal Properties of Agricultural Raw Materials for Healthy Food Production: Proceedings of the 5th Conference of Young Researchers at the Storage and Processing Branch of the Russian Agricultural Academy, October 12, 2011 (Moscow, 2011), pp. 284-286.
3.  Zakladnoy, G. and Fernas, A., “SiO₂ Dust against Stor­age Pests,” in Proceedings of the 9th International Con­ference on Controlled Atmosphere and Fumigation in Stored Products, Antalya, Turkey. 15-19 October 2012, Ed. by Navarro, S., Banks, H.J., Jayas, D.S., Bell, C.H., Ferizli, A.G., Emekei, M., Isikber, A.A., and Alagusun- daram, K. (AR-BER Professional Congress Services, Turkey, 2012), p. 329.
4.  Zakladnoy, G.A. and Fernas, A.V., “Silicon Dioxide against Grain Weevils,” in Innovative Scientific Aspects of Grain Storage and Processing: a Monograph Dedi­cated to the 85 th Anniversary of All-Russian Scientific and Research Institute for Grain and Products of its Pro­cessing (Moscow, 2014), pp. 319-323 [in Russian].

G. A. Zakladnoy
All-Russian Scientific and Research Institute for Grain and Products of its Processing -
Branch of VM. Gorbatov Federal Research Center for Food Systems, Moscow, 127434 Russia

ISSN 0013-8738, Entomological Review, 2019, Vol. 99, No. 8, pp. 1125–1127. © Pleiades Publishing, Inc., 2019.
Russian Text © The Author(s), 2019, published in Entomologicheskoe Obozrenie, 2019, Vol. 98, No. 4, pp. 741–744.
DOI: 10.1134/S0013873819080062