In recent years, the use of plant derivatives including essential oils and plant extracts has been taken into consideration as an alternative to chemical pesticides for pest control. In this study, antifeedant activity of purple nutsedge, Cyperus rotundus L. essential oil was investigated against sawtoothed grain beetle, Oryzaephilus surinamensis L. and khapra beetle, Trogoderma granarium Everts by using flour disc method, under laboratory conditions (27±2°C, 65±5% RH and continuous darkness). Results showed that feeding indices were affected by essential oil and the relative growth rate, relative consumption rate and efficacy of conversion of ingested food decreased for both insects with increasing concentration. The efficacy of conversion of ingested food decreased from 7.80% and 6.18% at control to 3.05% and 3.68% at highest concentration for O. surinamensis and T. granarium, respectively. The feeding deterrence index for both insects increased from 32.57% and 39.02% at the lowest concentration to 46.85% and 49.33% at highest concentration, respectively. According to these results, the essential oil affected test insects in two ways; feeding deterrence and post ingestive toxicity. The results demonstrated that C. rotundus essential oil could be used as a probable substitution to chemical pesticides for stored products protection against storage pests.

The khapra beetle, Trogoderma granarium (Everts) is one of the most important insect pests of stored products, especially wheat grains, in Iran and some other countries of the world. In this research, effect of various wheat genotypes including Heidari, Aftab, Gaskojen, Kouhdasht, Tirgan, N-91-9, and N-92-19 was studied on biology and two-sex life table parameters of T. granarium under 33 ± 1°C, relative humidity of 65 ± 5%, and a photoperiod of 14:10 (L:D) h. Our results showed that the immature period of T. granarium was the longest on N-91-9, Heidari, and Aftab. The net reproductive rate (R0) ranged from 9.03 offspring on N-92-19 to 34.13 offspring on Gaskojen. The lowest intrinsic rate of increase (r) was for T. granarium reared on Heidari, Aftab, N-91-9 and N-92-19. The results of this study indicated that Heidari, Aftab, N-92-19 and N-91-9 were unfavorable genotypes for T. granarium development and population increase. These genotypes could be used as one of the sources of resistance in management programs of T. granarium.

Entomopathogenic fungi produce a variety of degrading enzymes, including proteases, chitinases and lipases, to facilitate their entry through the massive barriers of insect cuticle. Isolates of the entomopathogenic fungi vary considerably in their proteolytic activity and virulence. The proteolytic activity of different isolates has been hypothesized to reflect their virulence toward the host. In this study, we evaluated the virulence and proteolytic activity of 17 Beauveria bassiana sensu lato isolates collected from different geographical regions in Iran. The selective medium D0C2 was used for isolating B. bassiana from soil samples. Casein substrate was used for protease assay. Total mortalities caused by different B. bassiana isolates through the dipping method, were between 25 and 60% with the highest and lowest rates for isolates BA and MITE, respectively. Our results revealed a wide variation in both proteolytic activity and virulence among the studied isolates. Additionally, we found a strong positive correlation between the proteolytic activity on Casein substrate and virulence of the isolates against the Khapra beetle, Trogoderma granarium. This finding will facilitate the screening and selection process of virulent fungal isolates as efficient agents for use in biological control programs of insect pests.

Khapra beetle Trogodermagranarium (Evert.) (Coleoptera: Dermestidae), has been considered as one of the most invasive pest for stored products in the world. The insect has become tolerant to conventional pesticides including fumigant such as phosphine and methyl bromide. Application of plant essential oils can be a suitable alternative for fumigation. In this study, fumigant and persistence toxicity of the essential oils from leaves of Mentha pulegium L., Eucalyptus microtheca F. Muell and walnut hulls Juglans regia L. evaluated against T. granarium under laboratory conditions of 30±2ºC, 65±5% R.H and darkness. Adult stage have high sensitivity to essential oils. In a period of 48 h exposure, LC50 value against adult stage of T. granarium were 6028.66, 6383.48 and 5498.20 ppm for eucalyptus, walnut and pennyroyal essential oils, respectively. LC50 values indicated that essential oil of pennyroyal (confidence limit: 4646.17-6482.07) had the most insecticidal activity against T. granarium. There was significant differences among LC50 values at p<0.5. The persistence assay against adult stage of insect showed the LT50 value was 8.69, 9.71 and 8.54 d for eucalyptus, pennyroyal and walnut, respectively. Therefore, the persistence of pennyroyal (8.44-11.10) essential oil was the most among the tested plants.

The khapra beetle, Trogoderma granarium (Everts), 1898 is one of the damaging pests of different stored cereal grains in Iran. In this research, effect of four cereal grain species including wheat (varieties N-91-9 and Aftab), barley (varieties Dasht and Oxin), maize (varieties AR and 704), and rice (varieties Hashemi and Fajr) was studied on nutritional indices and digestive proteolytic and amylolytic activities of T. granarium fifth instar at 33±1˚C, relative humidity of 65±5% and a photoperiod of 14: 10 (L: D) h. The results showed that the highest food consumption by larvae was observed on wheat N-91-9 and the lowest value was seen on maize 704 and rice Fajr. The relative growth rate was the highest on wheat N-91-9 and barley Dasht. The highest proteolytic activity was in larvae fed on wheat Aftab, barley Dasht and rice Hashemi, and the lowest activity was in those fed on rice Fajr. The amylolytic activity of larvae fed on varieties Dasht, N-91-9, Hashemi and AR was significantly higher than those fed with other tested cereals. The results of this study indicated that barley Dasht and both wheat varieties tested were relatively more favorable than other examined cereals for feeding of T. granarium larvae.

Bioprotection agents, including living biocontrol agents and naturally occurring non-living substances such as diatomaceous earth, play a crucial role in controlling stored commodity pests to maintain food health. The problem with using diatomaceous earth in storage is that their recommended dose increases grains' bulk density and decreases flowability. Therefore, the present study aimed to determine the biocompatibility between two commercial formulations of Iranian diatomaceous earth, Sayan, and foreign Celite 610 with the indigenous entomopathogenic fungus isolate, Beauveria bassiana DE (Hypocreales), and to solve the problem of reducing grains' flowability using a low-lethal dose of diatomaceous earth in the mixture. For this purpose, 14-day bioassays were first performed by impregnating wheat seeds separately with the fungus and two diatomaceous earths against adults of Khapra beetle, Trogoderma granarium Everts. Then, to determine the interaction effects, five different doses of B. bassiana were mixed with LD25 of each diatomaceous earth. Based on the results, LD50 values for fungus, Sayan®, and Celite 610® were calculated at 295.3, 4439.5, and 992.3 ppm, respectively. According to the lethal dose ratio test, the insecticidal activity of Celite 610® was estimated to be 4.47 times more than Sayan®. Moreover, the interaction was synergistic in all mixtures of B. bassiana with the low-lethal dose of each diatomaceous earth except for the highest dose of the fungus, which was estimated additive. In addition, all mixtures effectively reduced progeny production during the eight-week storage period, indicating the compatibility of these two agents for co-application in the integrated T. granarium management programs.

Rice (Oryza sativa L.) is one of the most important cereal grains and serves as a staple food for nearly half of the world’s population. Trogoderma granarium Everts (Coleoptera: Dermestidae), commonly known as the Khapra beetle, is a significant pest that infests stored grains and other stored products in various countries worldwide, including Iran. The pest's polyphagous nature and high ability to survive for extended periods without food necessitate using chemical fumigants to control T. granarium in storage facilities. However, the serious adverse effects of these insecticides on humans and the environment render it imperative to explore alternative pest control approaches. One of the best safe options is using resistant cultivars in integrated pest management programs. Insect-plant interactions and the resistance of various cultivars to herbivorous insects can be studied by insects’ life history and population parameters.

The resistance and susceptibility of six commercial rice cultivars (Tisa, Khazar, Shafagh, Sadri, Nemat, and Hashemi) to T. granarium were determined by analyzing the life history and population growth parameters of the pest. The seeds of tested rice cultivars, which have a large cultivation area in Iran, were obtained from the Agricultural and Natural Resources Research Center (Gilan province, Iran). The initial colony of T. granarium was obtained from the laboratory of Department of Plant Protection, University of Mohaghegh Ardabili (Ardabil, Iran), and was reared in groups on wheat seeds (as the main host). The adult insects obtained from the primary colony were transferred to the seeds of tested rice cultivars (20 pairs on each cultivar), and were reared as a group for two generations. Then, the eggs (1-day-old) laid on each rice cultivar were used for the experiments. The beetle rearing and all experiments were carried out in a growth chamber set at 33 ± 1°C, 65 ± 5% RH, and 24 h darkness. Subsequently, the raw data obtained from the life history of T. granarium on various rice cultivars were analyzed with TWOSEX-MSChart software using an age-stage, two-sex life table model.

The study results indicated that immature survival rate on cultivar Sadri was higher than on the other tested cultivars. The incubation period was longer on cultivar Shafagh than on cultivars Sadri and Tisa. The shortest larval, pupal and the entire immature periods were observed on cultivars Sadri and Tisa, and longest on cultivar Khazar. The beetles raised on cultivar Khazar took approximately eight days longer to complete their development than those on cultivar Sadri. The fecundity of T. granarium (number of eggs laid by each female) on cultivars Sadri and Tisa was significantly higher than on cultivar Khazar. The longest oviposition period was observed on cultivars Sadri and Tisa, and the shortest on cultivar Khazar. The longevity of female and male adults was longest on cultivars Sadri and Tisa, and shortest on cultivar Khazar. The intrinsic rate of increase (r) was highest on cultivar Sadri and lowest on cultivars Hashemi, Shafagh, and Khazar. Additionally, the finite rate of increase (λ) was higher on cultivars Sadri and Tisa than on the other tested cultivars. The longest mean time generation was observed on cultivar Khazar and the shortest on cultivars Sadri and Tisa.

One of the reasons for the rapid development and high survival of T. granarium on cultivar Sadri may be the high protein content of its seeds, which has provided sufficient energy for the immature stages' rapid growth. However, the amount of protein and starch in cultivar Khazar is lower than in other cultivars, which may be a factor in this cultivar's resistance to T. granarium. Our results indicate that Sadri and Tisa are the most susceptible cultivars to potential population increase of the pest because the highest values of r and λ are on these two cultivars. However, owing to the highest values of r and λ on cultivars Hashemi, Shafagh, and Khazar, they are the most resistant cultivars to T. granarium. Consequently, resistant cultivars can be used in the genetic engineering of plants to minimize the damage caused by this key pest.

Trogoderma granarium (Everts) is an economic insect pest of stored grains in Iran and many tropical and subtropical regions. If stored products contaminated with this insect are consumed by humans, it would cause serious digestive diseases. To control T. granarium in storage, chemical insecticides and fumigants are often used, but due to their extreme toxicity to humans and other dangerous side-effects, their application has been limited. Therefore, in order to develop alternative control methods with minimal harmful effects to humans and other non-target organisms, there is a need to understand feeding performances of the pest on different cultivars. The use of insect-resistant plants is one of the effective methods in integrated pest management programs. Study of nutritional indices of stored product insects is one of the important methods of measuring the resistance in plant cultivars.

Nutritional indices of T. granarium larvae were investigated using the gravimetric method provided by Wadbauer (1968). The grains of wheat genotypes including N-91-9, Heidari, Aftab, Tirgan, N-92-19, Gaskojen and Kouhdasht were crushed using a grinder. Then, first instar larvae were reared on the grains of these genotypes under 33 ± 1°C, 65 ± 5% R.H., and 14:10 (L:D) h. After emergence of fifth instar, the weight of larvae, before and after feeding, and the amount of grain eaten by the larvae were measured. The data were analyzed using one-way ANOVA using SPSS ver.16. Then, Tukey's HSD test, with a probability level of 5%, was used to investigate the statistical differences among the means.

There were significant differences in the nutritional indices of T. granarium fifth instar larvae on grain of different wheat genotypes. The larvae raised on line N-91-9 had the lowest weight of food consumption (24.33 ± 3.38 mg/10 larvae) compared to other genotypes tested. Larvae fed with line N-91-9 (5.33 ± 0.33 mg/10 larvae) and cultivars Aftab (3.00 ± 0.57 mg/10 larvae) and Heidari (3.00 ± 0.57 mg/10 larvae) showed lower weight gain than those fed with other genotypes. The highest efficiency of conversion of ingested food (ECI) was on cultivars Gascojen (36.56 ± 1.46 %) and Tirgan (33.42 ± 0.60 %), and the lowest was observed on cultivars Aftab (7.32 ± 1.51 %) and Heidari (7.86 ± 1.38 %). The highest relative consumption rate (RCR) was found on cultivar Gascojen (1.08 ± 0.05 mg/mg/day) and line N-92-19 (0.95 ± 0.02 mg/mg/day), and the lowest was seen on line N-91-9 (0.16 ± 0.03 mg/mg/day), and cultivars Heidari (0.19 ± 0.02 mg/mg/day) and Aftab (0.24 ± 0.02 mg/mg/day). As compared with the other examined genotypes, the relative growth rate (RGR) was the highest on cultivar Gascojen (0.394 ± 0.022 mg/mg/day). Larvae feeding from cultivar Gascojen (5.61 ± 0.17 mg/day) had the highest growth rate (GR), and larvae feeding from line N-91-9 (0.76 ± 0.04 mg/day) and cultivars Heidari (0.42 ± 0.08 mg/day) and Aftab (0.42 ± 0.08 mg/day) had the lowest GR value. The change in the nutritional indices of T. granarium larvae can be due to the differences in physical and chemical characteristics of the grains of tested wheat genotypes. The ECI index represents the ability of an insect to use eaten food to increase its body size and weight. In other words, the increase in ECI value on cultivars Gaskojen and Tirgan indicates the high ability of fifth instar larvae to convert the eaten grain into body biomass. This finding may be due to the high protein content and low grain hardness of these cultivars. The low weight of food eaten and body weight in larvae fed with cultivar Heidari and line N-91-9 may be due to the high grain hardness of these genotypes.

Our results showed that line N-91-9 and cultivars Heidari and Aftab had lower nutritional value than the other tested genotypes for T. granarium larvae, because the amount of food eaten, larval weight gain and nutritional indices of larvae fed with these genotypes were lower than other genotypes tested. So, these two genotypes can be used in genetic engineering programs to minimize the damage of T. granarium. The presence of defensive chemical compounds, grain hardness or the lack of essential nutrients for the development of the pest may be the reason why some of the tested cultivars are unsuitable for T. granarium feeding.

Essential oils of some plant species have shown suitable insecticidal properties against stored-product pests, which are one of the main factorsaffectingpost-harvestfoodlosses. In this study mortality, repellent effects and durability of fumigant toxicity of the formulated essential oils of golpar (Heracleum persicum), thyme (Thymus vulgaris), eucalyptus (Eucalyptus globules), peppermint (Mentha piperita) and rosageranium (Pelargonium roseum) as 2.5 gr sticks (10%), were studied on two important pests of stored products, Oryzaephilus surinamensis and Trogoderma granarium in laboratory at 28 ± 1 °C, 70 ± 5 % RH and dark condition. The results showed that sticks of rosageranium and golpar had the lowest toxicity and sticks of peppermint and thyme had the highest toxicity effects especially on O. surinamensis. The highest repellency effect was observed in peppermint and eucalyptus on O. surinamensis (94 and 91/6 % respectively) while repellency of rosageranium sticks was observed below 20% on both pests. Sticks durability in comparison with pure essential oils of plants was significantly different so that from the fourth day by the end of the eighth week the mortality rate was approximately constant while the durability of pure essential oils decreased after 2-3 weeks represents the slow-releasing of essential oils in stick formulation.

The incidence of pests’ resistance to pesticides, adverse effects of pesticides on non-target species, and environmental hazards have increased the tendency of applying various pests control techniques. Nanopesticide formulations are thus considered as one of the recent techniques in controlling pests. Using this technology increases the effectiveness of pesticides under various environmental conditions, including light and hot situations. Indeed, it decreases the amount of pesticide use and ultimately decreases the chance of pests’ resistance to insecticides.

In the current study, the silica nanoparticles were prepared using the sol-gel method and loaded with deltamethrin, pyriproxyfen, and chlorpyrifos. The mosaic and galvanized steel surfaces were treated with either deltamethrin (0.0025 and 0.005 g(a.i.)/m2), pyriproxyfen (0.001, 0.01 and 0.1 g(a.i.)/m2) and chlorpyrifos (0.01 and 0.2 g(a.i.)/m2) alone or loaded in nanosilica. The experiments were carried out at 3 replicates, and 3 sub replicates. In each replicate, 10 small or large larvae of Trogoderma granarium Everts (Coleoptera: Dermestidae) were introduced, and 2 g wheat Chamran variety was utilized as food source. All experiments were conducted at 30±1 °C, 65±5 % RH, and darkness. The initial mortality of small and large larvae of T. granarium was counted 1, 3, and 7 days after exposure, and delayed mortality was assessed 7 days thereafter. For each larval group, the variance analysis of initial and delayed mortality was subjected to the factorial test (concentration and time as main effects). Means were separated by Tukey Kramer HSD test at p < /em> =0.05 using SPSS software version 16.

Results indicated that initial and delayed mortality increased by raising concentration levels and exposing time to each concentration in all experiments. In all cases, the small larvae of T. granarium were more sensitive than large larvae.  Deltamethrin, followed by chlorpyrifos, was the most toxic to the larvae of T. granarium. Due to our findings, the mortality was dramatically higher in galvanized steel than the mosaic one. It could be attributed to the steel's flat surface, reducing insecticide residues' absorbance within the surface. Moreover, the insecticidal efficacy of nanosilica loaded with insecticides was significantly greater than the application of insecticides without nanosilica. Utilizing nanoparticles, we found an increase in the ratio of surface area to volume of insecticides, resulting in more insect contact to insecticide particles and eventually improved the mortality rate of insecticide.

It is therefore concluded that the application of loaded insecticides in silica nanoparticles significantly increased T. granarium larvae's mortality rate. Furthermore, silica nanoparticles can be introduced as the carrier of insecticides to control T. granarium in the stored wheat efficiently. Besides, deltamethrin loaded SNPs is potentially recommended as one capable component that can be effectively conducted during pest management programs in terms of stored products pest control.