Acta agriculturae Slovenica, 117/2, 1–8, Ljubljana 2021 doi:10.14720/aas.2021.117.2.1961 Original research article / izvirni znanstveni članek Synthesis of a synthetic analogue for the Sitophilus weevil aggregation pheromone and study on its hygienic and toxicological indexes Gulnara SHAKIRZYANOV A 1 , Liliya ROMANOV A 2 , Bahrom BABAEV 1 , Vladimir АBDUKACHAROV 1 , Tulkun ISKANDAROV 2 , Sabina GAYIBOV A 1* Received November 12, 2020; accepted March 16, 2021. Delo je prispelo 12. novembra 2020, sprejeto 16. marca 2021. Synthesis of a synthetic analogue for the Sitophilus weevil ag- gregation pheromone and study on its hygienic and toxico- logical indexes Abstract: The work was initiated to study hygienic and toxicological indices of a synthetic analogue for the Sitophilus weevil aggregation pheromone. The toxicity testing of 5-hy- droxy-4-methyl-3-heptanone demonstrated its extremely low toxicity for the warm-blood animals, as compared to the one of the typical pesticides. The average lethal dose of the product per orally administered to the white mice was established to be 4375.0 mg kg -1 LD16 and LD84 being 2225.0 mg kg -1 and 6550.0 mg kg -1 , respectively. The average lethal dose for rabbits was 5900.0 mg kg -1 5-hydroxy-4-methyl-3-heptanone proved to have a mild skin and conjunctival irritant action, and equally mild functional cumulation. As to chronic toxicity, the accept- able daily dose of 4.3 mg/person/d was calculated and scien- tifically substantiated. The odor threshold was determined at the dose ranging from 0.35 to 0.7 mg l -1 with the practical limit ranging from 0.35 to 1.5 mg l -1 , taste sensation threshold was found at the dose ranging from 1.0 to 3.0 mg l -1 with the practi- cal limit ranging from 3.0 to 7.0 mg l -1 . Key words: L-proline; aggregation pheromone; sitophil- ure; aldol condensation; pest insect, toxicological indexes 1 Institute of Bioorganic Chemistry Uzbek Academy of Sciences, Mirzo Ulugbek Str., 83, Tashkent, Uzbekistan 2 Ministry of Health care Institute of Sanitation hygiene and occupational diseases, Oltin Tepa str., 325, Tashkent, Uzbekistan * Corresponding author: gayibova.sabina@gmail.com Sinteza sintetičnega analoga agregacijskega feromona in pre- učevanje higienskih in toksikoloških indeksov pri zatiranju žitnih žužkov (Sitophilus spp.) Izvleček: Članek predstavlja raziskavo higienskih in to- ksikoloških indeksov pri sintezi agregacijskega feromona žitnih žužkov (Sitophilus spp.). Kot rezultat poskusov je bila izraču- nana dovoljena dnevna doza na osebo, in sicer 4,3 mg/osebo/ dan; najmanjša izračunana doza za zaznavanje vonja je bila 0,42 mg l -1 , najmanjši vrednosti za okušanje in praktično uporabo sta bili določeni na ravni 1,44 in 3,3 mg l -1 . Največja dovoljena in priporočena doza agregacijskih feromonov za žitne žužke v vodnih zbiralnikih je bila 0,4 mg l -1 ; pri čemer je bil vonj izbran kot omejujoč dejavnik za škodljivost; največja dovoljena kon- centracija v zraku je bila določena kot 0,3 mg m -3 in največja dovoljena koncentracija v zraku v delovnem prostoru je bila do- ločena kot 3,5 mg m -3 . Rezultati raziskave so pokazali, da je imel 5-hidroksi-4-metil-3-heptanon blag dražilni učinek na koži in na sluznicah ter šibke akumulacijske vplive na splošno počutje. Ključne besede: optične izomere; L-prolin; agregacijski feromon; žitni žužki; aldolna kondenzacija; toksikološki inde- ksi Acta agriculturae Slovenica, 117/2 – 2021 2 G. SHAKIRZYANOV A et al. 1 INTRODUCTION Production and reduction to practice of novel chemical, physical and biological products for pest man- agement in agriculture are underway worldwide (Bohinc et al., 2020a). Search for novel highly efficient methods for pest control is driven by development of pesticide re- sistance in pest organisms caused by constant use of the products resulting in the uprise of the pesticide-resistant pest insect populations (Petrunya, 2011). To prevent both quantitative and qualitative losses of agricultural products, the integrated pest management consisting of economically and environmentally feasi- ble measures is needed. The system is based on the bal- anced combination of quarantine, preventive, physical- mechanical and biological measures, as well as of direct control to keep the proliferation of pest insects to rea- sonably safe level. The diversity of chemical products for crop protection suggests the increase of their toxic effects on living organisms making the search for environmen- tal friendly protection products an urgent task. Preventive and economic operations calling for high-level culture of storage and treatment of grain prod- ucts at the granaries and grain mills comprise the back- bone of the integrated test management. The fumigation or any other chemical treatment is supposed feasible in terms of grain infestation extent. As natural bioregulators, the insect pheromones are thought to be promising in controlling the grain in- festation extent at the granaries, maintaining the grain quality and avoiding the environmental pollution. The insect pheromones are known to exercise control over the pest insects resistant to existing insecticides or those requiring their multiple use (Trdan et al., 2019). This is especially true for covert living pests acquiring the pesti- cide resistance. The pheromone traps help bring to light the locations of pests with the lowest numbers when the visual inspection turns out inefficient. The synthetic ana- logues of the insect sex pheromones showed good results as tools for detection and monitoring of pest populations. The synthetic chemicals, such as methyl bromide and aluminum phosphate were used in the largescale fumigations of granaries to control pests (Sousa et al., 2009). Furthermore, since larval and pupal instars devel- op within the rice and maize grains, any sustainable con- trol strategy demands the timely and accurate monitor- ing of the prevalence of adult weevils (Ukeh et al., 2012). Sitophilus is a genus of weevils in the tribe Litosomini. Notable and the most menacing pest species include the rice weevil (S. oryzae, (Linnaeus, 1763), wheat weevil (S. granaries, Linnaeus, 1758), and maize weevil (S. zeamais, Motschulsky, 1858) (Ukeh et al., 2008), as well as the large mealworm, the cereal moth and other pests (Oe- hlschlager, 2016). The weevils of Sitophilus genus are the impactful pests of stored grains in tropical and sub-trop- ical regions, but they are common in Europe too (Bohinc et al., 2020b; Athanassiou & Buchelos, 2001). They attack various stored products including maize, wheat, oats, barley, rye, and dried cassava roots, as well as processed food such as macaroni, noodles, biscuits, and cakes. The post-harvest losses due to storage pests, such as weevils Sitophilus pose major problems to food security in the world (Orlov, 2006). The losses of stock products due to the insect pests like this have long been a serious farmer problem around the world. Any human efforts and fi- nances committed in the crop production are wasted. Sit- ophilus infest ripening standing crops immediately prior to harvest and in storage, causing damage by boring into the grains and eating the inner part, which reduces maize mass and quality in terms of consumption and germina- tion (Zakladnoi et al., 2003). The synthetic pheromones were successfully used to control the curculionid beetles by mass trapping, as the pheromones attract both males and females (Adda et al., 2002). The pheromone-based monitoring helps determine the time and necessity of chemical treatment, avoid use of pesticides and save the stored products ecologically pure. The study on toxicological and hygienic character- istics is indispensable. Our work was initiated to study the toxicity of a synthetic analogue for the Sitophilus wee- vil aggregation pheromone. 2 MATERIAL AND METHODS All chemicals and solvents were purified by stand- ard techniques. For thin-layer chromatography (TLC), Silufol silica gel plates (Sigma-Aldrich, Germany) and ethyl ether/hexane (1:1) system of eluents was used; the compound was visualized by irradiation with iodine va- por. Flash chromatography was performed using TLC Silica gel 60 F254 (Merck KGaA, Darmstadt, Germany) and ethyl ether/hexane (1:1) system of eluents. HPLC was performed using the Agilent 1100 Series HPLC Sys- tem (USA) with a Daicel CHIRALPAK AS HPLC Ana- lytical Column, 10 μm, ID 4.6 mm x L 250 mm - 20025, and Amylose tris [(S)--methylbenzylcarbamate] as a stationary phase coated on a 10μm silica support (Daicel Chemical Industries, Ltd. Japan); the mobile phase was acetonitrile (solvent A) and i-PrOH (solvent B) in the gradient mode: 0—10 min, 2—10 % B and 10—15 min 10 % B. High-resolution mass spectra were recovered on 6420 Triple Quad LC/MS (Agilent Technologies, USA) with acetonitrile as an eluent in isocratic regime; the flow rate was 0.25 ml min -1 . The mass spectra were registered Acta agriculturae Slovenica, 117/2 – 2021 3 Synthesis of a synthetic analogue for the Sitophilus weevil aggregation pheromone and study on its hygienic and toxicological indexes To assess the cumulative properties of the com- pound, two groups of white 150-180g rats of both sexes were selected for the experiment. The first group of rats received the product at the dose of 1/10 LD 50 , the second one served as the control. 2.6 CHRONIC TOXICITY Chronic toxicity was expressed as effective and non- effective doses. 2.7 ASSESSMENT OF IMPACT IN THE ENVIRON- MENTAL SAMPLES To assess the impact of the compound in the envi- ronmental samples, its concentrations ranging from 0.17 to 8.0 g l -1 were used. 3 RESULTS AND DISCUSSION The aggregation pheromone of Sitophilus granarius and Sitophilus oryzae is produced by the insects in the period good to the development of a population, that is, where there is enough food and possibilities for repro- duction, as well as appropriate environmental humidity and temperature. The food attractants and sexual stimu- lants cannot supersede the aggregation pheromone pro- duced by both females and males. The rise and corn wee- vils were found to produce the aggregation pheromone in the form of (4S, 5R) - hydroxy-methyl-3-heptanon- eenantiomer (Fig.1) (Faustini et al., 1984). Diastereoisomers of 5-hydroxy-4-methyl-3-hep- tanone were identified as an aggregation pheromone pro- duced by the male rice weevils (Sitophilus oryzae), and the maize weevils (S. zeamais). The compound has previ- ously been reported as an aggregation pheromone pro- duced by Rhinostomus barbirostris (Fabricius, 1775) (Co- leoptera: Curculionidae, Fabricius, 1775) males. All three Sitophilus species belong to the subfamily Dryophthori- nae, as R. barbirostris (Phillips et al., 1985; Ambrogi et with negative ionization. Conditions were as follows: the scanning range was 50-2200 m/z, dehydrating gas con- sumption – 3 min -1 , gas temperature 300 °С, gas pres- sure on needle sprayer 20 psi, evaporator temperature – 300 °С, tension on the capillary - 4000В. 2.1 GENERATION OF ALDOL PRODUCT To generate the aldol product, propionaldehyde (3 mmol) was added to a heterogeneous mixture of anhy- drous chloroform (10 ml), 3-pentanone (0.06 mol) and L-proline (25 %). The resulting mixture was stirred at the room temperature for 32 h. The reaction mixture was treated with the saturated NH 4 Cl solution; the layers were separated, and the aqueous layers were extracted several times with ethyl acetate, dried with anhydrous Na 2 SO 4 and evaporated. The pure aldol product was obtained by flash column chromatography with the yield of 74 %. HPLC was performed using ChiralPak AS - amylose tris [(S)-α-methylbenzylcarbamate] with 98 % MeCN and 2 % i-PrOH. Conditions were as follows: tR (major) = 7.998 VP , tR(minor) = 7.072 VV; S : R - 57.0722 : 28.0855, tR(major) = 8.007 VP, tR(minor) = 7.025 VV; S* : R*- 43.4765 : 30.0490. MS [C8H16O2], 143 [M – H+]-, 87 [M – C3H5O]-. 2.2 ACUTE TOXICITY Acute toxicity assessment was performed on the laboratory white mice. The animals’ behavior, general health condition, terms for manifestation of intoxication sign and eventually death were the key criteria for the product’s acute toxicity following its single administra- tion to the animals. 2.3 SKIN IRRITANT ACTION To assess the skin irritant action of the compound, its native sample was applied on the skin of laboratory white rats and animals were carefully monitored for any skin irritation signs. 2.4. CONJUNCTIV AL IRRITATION T o assess the conjunctival irritant action of the com- pound, 2 drops of the product were put in the conjunc- tival sac of one rat’s eye, while the second one served as the control. The effects were registered in 1-4 hours and in 1, 3 and 5 days. 2.5 CUMULATIVE PROPERTIES Figure 1: (4 S, 5 R) - hydroxy-methyl-3-hetanone Acta agriculturae Slovenica, 117/2 – 2021 4 G. SHAKIRZYANOV A et al. al., 2008; Ambrogi et al., 2009). This compound is known to cause a behavioral response in the adult weevils. Ac- cording to Ismuxambetov (2015), and the findings from our trials, there is the weevils’ response to various com- binations of enantiomers. According to that formula, the compound can exist in the form of 4 steric enantiomers (Fig. 2). Unelius et al. resolved the four stereoisomers of 4-methyl-5-hydroxy-heptan-3-one by chiral gas chro- matographic–mass spectrometric (GC-MS) analysis employing a CycloSil-B capillary column with the fol- lowing elution order: (4R, 5S)-, (4S, 5R)-, (4R, 5R)-, (4S, 5S)-isomers (Unelius et al.,2012). Thus, to determine the absolute configuration of the Rhinostomus barbirostris pheromone, the mixture of all stereoisomers of synthetic sitophilure was also resolved in a CycloSil-B capillary column. The major component had the same retention time as the (4S, 5R)-isomer, and that of the minor phero- mone component matched that of the (4S, 5S)-isomer (Unelius et al., 2012). The mixture of four stereoisomers of sitophilure has been synthesized previously by three different synthetic approaches. The first synthesis was re- ported even before the identification of this compound as a pheromone by coupling the lithium anion from 3-pen- tanone and propanal in 89 % yield (Smith & Levenberg, 1981). Fauve et al. reported on the multigram synthesis as a more traditional approach with sodium hydroxide to generate the anion from 3-pentanone and subsequently to couple with propanal, giving hydroxyl-ketone in 46 % over-all yield (Fauve et al., 1984). The third method Figure 2: 4 steric enantiomers of (4, 5) - hydroxy- methyl-3-heptanone Figure 3: The synthesis of 5-hydroxy-4-methyl-3-heptanone started by the alkylation of 3, 5-heptanedione following by the reduction of one carbonyl group in 76% yield for two steps (Kalaitzakis et al., 2006). Unelius et al. identified the minor component of Sitona discoideus Gyllenhal 1834 (Coleoptera : Cur- culionidae, Gyllenhal, 1834) pheromone, as (4S, 5S)- 5-hydroxy-4-methyl-3-heptanone by enantioselective GC analyses of the natural compounds on a modified β-cyclodextrine stationary phase in comparison with synthetic mixture of all four stereoisomers and deriva- tives obtained by enantiselective transesterification of the (4R, 5R)- and (4S, 5R)-isomers catalyzed by lipase from Candida antarctica (Goto, Sugiy. & Iizuka) Kurtz- man, M.J. Smiley, C.J. Johnson & M.J. Hoffman (Un- elius et al.,2012). We have synthetized diastereomers of 5-hydroxy-4-methyl-3-heptanone by means of different methods. The corresponding ketol has been obtained by aldol condensation between diethylketone and propy- laldehyde; the asymmetric catalytic aldol reaction was carried out according to interaction of 3-pentanon and propylaldehyde by L-proline initiation, as well (Shakirzy- anova et al., 2018). In the present work, in the conditions of aldol condensation between 3-pentanon and propyl aldehyde, we have obtained the corresponding ketol – Acta agriculturae Slovenica, 117/2 – 2021 5 Synthesis of a synthetic analogue for the Sitophilus weevil aggregation pheromone and study on its hygienic and toxicological indexes Figure 4: Synthesis of the L-proline-catalyzed aldol product 5-hydroxy-4-methyl-3-heptanone, an aggregation pher- omone of granary and rice weevils (Fig. 3). The ratio of R*S * and R*R* diastereomers was about 1:1. For aldol condensation we used 1.33 M 3-pentanon, 0.33 M propylaldehyde and 7 % KOH solution in metha- nol with reaction temperature 15°C and yield being 50 %. The findings from the preliminary studies taken into account, we performed the synthesis of the weevil ag- gregation pheromone adding aldol in the presence of L- proline as a catalyst. Organocatalysis is a promising sphere in both or- ganic and bioorganic chemistry. It is the way to get or- ganic compounds from achiral predecessors in the pres- ence of a small number of asymmetric metal-free organic molecules acting as the chiral inductors, but not getting involved into the process (Demyanovich et al., 2001). Most enzymatic transformations have a synthetic counterpart. Often though, the mechanisms by which natural and synthetic catalysts operate differ markedly. The catalytic asymmetric aldol reaction as a fundamental C-C bond forming reaction in chemistry and biology is an interesting case in this respect. Chemically, this reac- tion is dominated by approaches that utilize preformed enolate equivalents in combination with a chiral catalyst (Denmark et al., 1998). Some of them, according to their activity and enantioselectivity, do not act as metal-com- plex catalysts. The aldol reaction is widely regarded to be one of the most important carbon-carbon bond-form- ing utilized in organic synthesis (List et al., 2010). The catalytic enantioselective carbon-carbon bond-forming is a significant problem in the synthesis of biologically active substances. The chiral amino acid catalysts have wide usage for most powerful enantioselective reactions (Hayashi, 2005). In nature, that reaction goes through the action of aldolases (types I and II). In the laboratory con- ditions, their effect could be simulated by natural amino acids, some chiral amines and small peptides. Amino acids use a fundamentally different strategy and catalyze the direct aldolization of two unmodified carbonyl com- pounds (Ramachandran et al., 1996). Many enantioselec- tive aldol-krotonic reactions catalyzed by L-proline; and the reaction is performed via an enamine intermediate complex. The L-proline-catalyzed aldolyzation can be initiated with different aldehydes. The low price and wide spread availability in two en- antiometric forms are among the advantages of L-proline as a catalyst. Proline, as a small molecular compound, can be used for direct intramolecular aldol condensation (List et al., 2010), and many reactions with proline can be performed in industrial production. It is also important that the reaction be conducted in the room conditions without inert medium, requiring no transformations of the carbonyl substrate; that is, with neither deprotona- tion nor stimulation during reaction. Moreover, the cata- lyst is water soluble and can be easily extracted. Here, we describe structure-activity relationships of proline catalysts of direct assymmetric aldol addition re- actions, as well as the findings from study on the reaction mechanism. As the result of interaction of 3-pentanone, as a donor and propion aldehyde, as an acceptor into the presence of L-proline, the direct asymmetric aldolization has been performed. The L-proline-catalyzed asymmet- ric aldolization requires anhydrous solvents. The reaction was performed via an enamine intramolecular complex. As it is, the intramolecular complex of direct asymmet- ric aldol reaction is the enamine formation involving L- proline and appropriate 3-pentanone, a donor-substrate. Thereafter, the acceptor’s carbonyl-group from propion- aldehyde attacks the enamine intramolecular complex; Acta agriculturae Slovenica, 117/2 – 2021 6 G. SHAKIRZYANOV A et al. Figure 5: Proposed enamine mechanism of the proline-catalyzed asymmetric aldol reaction the process is completed by formation of an aldol prod- uct (Fig. 4). After separation, the reaction product was ana- lyzed by HPLC (ChiralPak® AS – Amylose tris [(S)-α- methylbenzylcarbamate] with 98 % MeCN and 2 % i- PrOH. In addition, we have analyzed the component con- sisting of (4S, 5S)-4-methyl-5-hydroxy-heptan-3-one by the electrospray ionization mass spectrometry (ESI-MS) with the registration of the mass spectra with negative ionization. Thus, we have synthesized isomers of (5S, 4S)–-5- methyl-4-hydroxy-3-heptanone, an aggregation phero- mone of rice, granary and maize weevils. The interac- tion of 3-pentanone and propionaldehyde in the aldol condensation reaction was realized in the presence of L-proline. Chloroform was more suitable solvent for the cross-coupling. The aldolization was performed via the enamine intramolecular complex. Changing terms of re- action couldn’t influence the product’s of enantio selec- tivity (Fig. 5). Acute toxicity assessment revealed that animals’ snorting and cheeping were among the typical clinical symptoms. They started rushing around the cages; the excitement was followed by the motor activity reduction; the breath was shallow. The animals died within the first experimental day. The average lethal dose of the product per orally administered to the white mice was established to be 4000.0 mg kg -1 ; LD 16 and LD 84 being 2600.0 and 5300.0 mg kg -1 , respectively. The dose range from 1000.0 to 7000.0 mg kg -1 was used to be per orally administered to the white rats. Statistical processing of the data al- lowed establishing the average lethal dose to be 4375.0 mg kg -1 ; LD 16 and LD 84 being 2225.0 mg kg -1 and 6550.0 mg kg -1 , respectively. According to Deichmann (1943), the average lethal dose for rabbits was 5900.0 mg kg -1 . In accordance with the Uzbekistan Sanitary Regulations and Standards for Classification of Pesticides by Toxicity and Hazard (Iskandarov et al., 2015), as a low-toxic com- pound 5-hydroxy-4-methyl-3-heptanone can be ranged in the IV class of hazard. Following the 4-hour exposure, as well as in 1 and 16 hours after single exposure the dermal response was registered. At application the strong odor of the product made the animals sneeze and snort. The application re- moved and washed out, insignificant hyperemia of the chosen areas was observed to preserve after 1 hour and to be less marked one. In 24 hours after the experiment started, the residual hyperemic effect persisted; neither skin cracks nor peeling was registered. No signs of skin irritant action were found on the 2nd day of experiment. The findings could be the evidence for weak skin irritant action of the compound under study. Conjunctival irritation results showed that follow- ing the administration, the rats cheeped and snorted try- ing to scratch the eye. In an hour, insignificant conjunc- tival hyperemia could be registered; the palpebral fissure was narrowed. In 3 hours, the signs of irritation subsided, while mild hyperemia and the palpebral fissure’s narrow- ness persisted. In 24 hours, the palpebral fissure’s size Acta agriculturae Slovenica, 117/2 – 2021 7 Synthesis of a synthetic analogue for the Sitophilus weevil aggregation pheromone and study on its hygienic and toxicological indexes was within normal limits; hyperemia was unregistered. During the whole period of assessment (up to 5 days), no signs of irritation could be seen to confirm the mild conjunctival irritation. Evaluation of the cumulative properties showed that during the experiment no animals died; any calcula- tions of the cumulation factor failed. But manifestation of some intoxication signs suggested the mild functional cumulation. Minimum effective and non-effective doses of the compound under study were established to be 18.0 and 3.6 mg kg -1 , respectively. The acceptable daily dose of 4.3 mg/person/d was calculated and scientifically sub- stantiated. According to environmental impact assessment data the sample was found to give a specific indescribable smell and bitter taste tang to water. The odor threshold (1 point) was determined at the dose ranging from 0.35 to 0.7 mg l -1 with the practical limit ranging from 0.35 to 1.5 mg l -1 , taste sensation threshold was found at the dose ranging from 1.0 to 3.0 mg l -1 with the practical limit ranging from 3.0 to 7.0 mg l -1 . 4 CONCLUSION As it can be seen, negligible effective doses and the environmental safety are typical of pheromones used to assess the phytosanitary conditions, localization and eradication of pest centers and to reduce the numbers of quarantine pest insects. In contrast to pesticides (Abasov et al., 2015), the pheromones’ effects are not toxic and en- vironmentally safe. We have synthesized isomers of (5S, 4S)–-5-methyl-4-hydroxy-3-heptanone, an aggregation pheromone of rice, granary and maize weevils. Our tox- icity testing of 5-hydroxy-4-methyl-3-heptanone dem- onstrated its extremely low toxicity for the warm-blood animals, as compared to the one of the typical pesticides. The average lethal dose of the product per orally ad- ministered to the white mice was established to be 4375.0 mg kg -1 ; LD 16 and LD 84 being 2225.0 mg kg -1 and 6550.0 mg kg -1 , respectively. According to D. LeBlanc, the aver- age lethal dose for rabbits was 5900.0 mg kg -1 . 5-hydroxy- 4-methyl-3-heptanone proved to have a mild skin and conjunctival irritant action, and equally mild functional cumulation. As to chronic toxicity, the acceptable daily dose of 4.3 mg/person/d was calculated and scientifically substantiated. The odor threshold was determined at the dose ranging from 0.35 to 0.7 mg l -1 with the practi- cal limit ranging from 0.35 to 1.5 mg l -1 , taste sensation threshold was found at the dose ranging from 1.0 to 3.0 mg l -1 with the practical limit ranging from 3.0 to 7.0 mg l -1 . As a part of the integrated pest management, the pheromone-based monitoring is successfully used to control the most menacing Sitophilus and Rhinostomus barbirostris species in Uzbekistan. ACKNOWLEDGMENTS The work was supported by Uzbekistan Ministry of Innovation (grant ITD-9) 5 REFERENCES Abasov, M., Atanov, M., Kuzina, N., Kuzina, A., & Ponomarev, V . (2015). Program for the identification of quarantine pests in the Russian Federation using pheromone and color traps in areas of greatest pest risk for 2016-2018 (In Russian). https:// vniikr.ru/files/contact/pr_16_18.pdf Adda, C., Borgemeister, C., Biliwa, A., Meikle, W., Markham, R., & Poehling, H. (2002). Integrated pest management in post-harvest maize: A case study from the Republic of Togo (West Africa). Agriculture, Ecosystems & Environ- ment, 93(1-3), 305-321. https://doi.org/10.1016/s0167- 8809(01)00344-9 Ambrogi, B. G., & Zarbin, P. H. (2008). Aggregation phero- mone in Sternechus subsignatus (Coleoptera: Curculioni- dae): olfactory behaviour and temporal pattern of emis- sion. Journal of Applied Entomology, 132(1), 54-58. https:// doi.org/10.1111/j.1439-0418.2007.01240.x Ambrogi, B. G., Vidal, D. M., Zarbin, P. H., & Rosado-Ne- to,  G.  H. (2009). Aggregation pheromone in Curculio- nidae (Insecta: Coleoptera) and their taxonomic impli- cation.  Quimica Nova, 32(8), 2151-2158. http://dx.doi. org/10.1590/S0100-40422009000800029 Athanassiou, C.G. & Bucheloc, G.Th. (2001). The presence of Sitophilus zeamais Motschulsky (Coleoptera: Curculioni- dae) in Greece: distribution and food preferences. Annales of Benaki Phytopathological Institute, 19, 140–144. Bohinc, T., Horvat, A., Ocvirk, M., Košir, I. J., Rutnik, K., & Trdan, S. (2020a). The first evidence of the Insecticidal po- tential of plant powders from invasive alien plants against rice weevil under laboratory conditions. Applied Sciences, 10(21), 7828. https://doi.org/10.3390/app10217828 Bohinc, T., Horvat, A., Andrić, G., Golić, M. P., Kljajić, P., & Trdan, S. (2020b). Natural versus synthetic zeolites for con- trolling the maize weevil (Sitophilus zeamais)–like Messi versus Ronaldo? Journal of Stored Products Research, 88, 101639. https://doi.org/10.1016/j.jspr.2020.101639 Deichmann, W .B., LeBlanc, T .J. (1943) Determination of the ap- proximate lethal dose with approximately six animals. The Journal of Industrial Hygiene and Toxicology, 25, 415–417. Demyanovich, V ., Shishkina, I., & Zefirov, N. (2001). Catalyzed asymmetric dialkylzinc addition to benzaldehyde in the presence of new chiral ligands δ-(1-phenethyl) aminoal- cohols. Chirality, 13(8), 507-509. https://doi.org/10.1002/ chir.1068 Denmark, S. E., Stavenger, R. A., & Wong, K. T. (1998). A no- table exception is Denmark’s chiral Lewis base-catalyzed Acta agriculturae Slovenica, 117/2 – 2021 8 G. SHAKIRZYANOV A et al. Mukayama-type aldol reaction. Journal of Organic Chemis- try, 63(4), 918-919. https://doi.org/10.1021/jo972168h Faustini, D. L., Giese, W . L., Phillips, J. K., & Burkholder, W . E. (1984). Aggregation pheromone of the male granary wee- vil, Sitophilus granarius (L.). Journal of Chemical Ecology, 8(4), 679-687. https://doi.org/10.1007/bf00988309 Fauve, A., & Veschambre, H. (1984). Use of biological systems for the preparation of chiral molecules IV: A two-step che- moenzymatic synthesis of a natural pheromone (4r, 5s)- (−)-4-methyl 5-hydroxy heptan 3-one, sitophilure. Tetra- hedron Letters, 28(42), 5037-5040. https://doi.org/10.1016/ s0040-4039(00)96689-9 Hayashi,  Y. (2005). Recent progress in the asymmetric or- ganocatalysis. ChemInform, 36(41), 464-477. https://doi. org/10.1002/chin.200541296 Iskandarov, T., Iskandarova, G., & Romanova, L. (2015, Sep- tember 22). Sanitary and preventive instruction of the Republic of Uzbekistan № 0321-15. Hygienic classification of pesticides by toxicity and hazard. Ministry of Health of the Republic of Uzbekistan. https://www.minzdrav.uz/pdf/ read.php?f=48050 Ismuxambetov,  J.  D. (2015). Stock pest control in Kazakh- stan. Bulletin of Science of the Kazakh Agrotechnical Univer- sity named after S. Seifullin (interdisciplinary), 2(85), 4-12. List, B., Lerner, R. A., & Barbas III, C. F. (2010). Proline-cat- alyzed direct asymmetric aldol reactions. Journal of the American Chemical Society, 31(22), 2395-2396. https://doi. org/10.1002/chin.200022046 Oehlschlager, A. C. (2016). Palm weevil pheromones – discov- ery and use. Journal of Chemical Ecology, 42(7), 617-630. https://doi.org/10.1007/s10886-016-0720-0 Orlov V. N. (2006). Insect-pests of grain-crops. Moscow: Print- ing City, 102 p. Petrunja, E. V . (2011). Grain stock pest control measures: clas- sic and new (in Russian). Pest Management, 2(78), 20-23. Phillips, J. K., W algenbach, C. A., Klein, J. A., Burkholder, W . E., Schmuff, N. R., & Fales, H. M. (1985). (R*, S*)-5-hydroxy- 4-methyl-3-heptanone male-produced aggregation phero- mone of Sitophilus oryzae (L.) and S. zeamais Motsch. Journal of Chemical Ecology, 11(9), 1263-1274. https://doi. org/10.1007/bf01024114 Ramachandran, P ., Xu, W ., & Brown, H. C. (1996). Contrasting steric effects of the ketones and aldehydes in the reactions of the diisopinocampheyl enolborinates of methyl ketones with aldehydes. Tetrahedron Letters, 37(28), 4911-4914. https://doi.org/10.1016/0040-4039(96)00969-0 Shakirzyanova, G. S., Babaev, B. N., Elmuradov, B. G., Mama- drahimov, A., & Abdukacharov, V. S. (2018). Synthesis of optical active isomer – sitophilure – aggregetion phero- mone of rice (Sitophilus oryzae L.), grainary (S. grana- rius L.) and maize. Bulletin of Science and Education, Mos- cow, 9(33), 15-21. Smith, III,  A.  B., & Levenberg,  P.  A. (1981). Oxidation of β-hydroxyketones and esters: A convenient synthesis of 1, 3-Diketones and β-ketoesters. Synthesis, (07, 567- 570. https://doi.org/10.1055/s-1981-29532 Sousa, A., Faroni, L., Pimentel, M., & Guedes, R. (2009). Devel- opmental and population growth rates of phosphine-resis- tant and -susceptible populations of stored-product insect pests. Journal of Stored Products Research, 45(4), 241-246. https://doi.org/10.1016/j.jspr.2009.04.003 Trdan, S., Čuk, J., Poženel, A., Bavcon Kralj, M., Rot, M., Car- levaris, B., Žežlina, I., Vidrih, M., Laznik, Ž., & Bohinc, T. (2018). Field testing of different synthetic attractants for mass trapping of common European cockchafer (Melolon- tha melolontha [L.], Coleoptera, Scarabaeidae) adults. Acta Agriculturae Scandinavica, Section B — Soil & Plant Science, 69(2), 174-180. https://doi.org/10.1080/09064710.2018.152 4020 Ukeh, D. A., & Udo, I. A. (2008). Analysis of insect populations in stored crops in Cross River state, Nigeria. Global Jour- nal of Pure and Applied Sciences, 14(1), 31-36. https://doi. org/10.4314/gjpas.v14i1.16769 Ukeh, D. A., Umoetok, S. B., Bowman, A. S., Jennifer Mordue (Luntz), A., Pickett, J. A., & Birkett, M. A. (2012). Alliga- tor pepper, Aframomum melegueta, and ginger, Zingiber officinale, reduce stored maize infestation by the maize weevil, Sitophilus zeamais in traditional African grana- ries. Crop Protection, 32, 99-103. https://doi.org/10.1016/j. cropro.2011.10.013 Unelius, C. R., Park, K., McNeill, M., Wee, S. L., Bohman, B., & Suckling, D. M. (2012). Identification and electrophysi- ological studies of (4s, 5s)-5-hydroxy-4-methyl-3-hepta- none and 4-methyl-3, 5-heptanedione in male Lucerne weevils. Naturwissenschaften, 100(2), 135-143. https://doi. org/10.1007/s00114-012-1003-4 Zakladnoi, G. A., Sokolov, E. A., Kogteva, E. F ., & Chirkov, A. M. (2003). A guide to pests of grain stocks and “Expanse” as a means of combating them. Moscow: Publishing House of Moscow State Educational Institution, 107 р.