Plodia interpunctella and Trogoderma variabile larval penetration and invasion of untreated and methoprene-treated foil packaging

Packaged food products inside retail stores and food warehouses are susceptible to infestation by stored-product insects. The insect growth regulator methoprene can be impregnated onto packaging materials to help limit stored-product insect population development and prevent infestations. The objectives of this study were to determine the effect of methoprene-treated foil packaging on egg hatchability and the penetration and invasion ability of the warehouse beetle, Trogoderma variabile Ballion, and the Indian meal moth Plodia interpunctella (Hübner). Twenty-five eggs of each species were added to Petri dishes containing untreated packaging or packaging containing 0.1, 0.25, and 0.5% of the active ingredient methoprene. Petri dishes were held for 7 d in an environmental chamber at 27 °C and 60% r.h. to determine percent hatchability of eggs. Additionally, 6 cm by 8 cm food packages were created from untreated and methoprene-treated packaging and placed into 0.18-L vials. First or third instars of each species were introduced into vials containing diet or no diet, to determine penetration ability after 21 and 42 d. In a separate experiment, packages were pierced with pinholes, and first instar T. variable or P. interpunctella were introduced and observed after 21 and 42 d for package invasion. The foil packaging had no significant effect on egg hatchability of either species. T. variabile were unable to penetrate or invade any foil packages. P. interpunctella invaded all packages containing pinholes. The methoprene-treated packaging reduced adult emergence of P. interpunctella and caused pupal and adult deformations in T. variabile. Methoprene-treated packaging presents a valuable option for food manufacturers to prevent insect infestations and maintain integrity of packaged food products.     

Effect of methoprene treated polymer packaging on fecundity,egg hatchability,and egg-to-adult emergence of Tribolium castaneum and Trogoderma variabile

The fecundity, egg hatchability, and egg-to-adult emergence of the red flour beetle, Tribolium castaneum (Herbst) and warehouse beetle, Trogoderma variabile Ballion, were evaluated on untreated and methoprene-treated polyethylene-to-polyethylene (PE-PE) and polyethylene terephthalate-to-polyethylene (PET-PE) packaging at 27 and 32 °C and 60% r.h. Inside and outside surfaces of the packaging were fit into ∼62 cm² Petri dishes, and 500 mg of flour (T. castaneum) or vanilla shake mix diet (T. variabile) were added to arenas as food for developing larvae. On methoprene-treated PE-PE packaging, hatchability of added T. castaneum eggs was consistently lower than on untreated packaging. On PET-PE packaging, hatchability of T. castaneum eggs on inside surfaces at both temperatures was significantly lower than on untreated packaging. No consistent trends were observed in T. variabilile hatchability between the packaging types, temperatures, and on inside and outside surfaces of untreated and methoprene-treated packaging. The fecundity of T. variabile was not significantly different between the packaging types. None of the T.castaneum eggs on inside and outside surfaces of the PE-PE methoprene-treated packaging emerged as adults. Methoprene-treated PET-PE packaging reduced fecundity of T. castaneum. Generally, hatchability of eggs laid by both species was not significantly different among the treatment combinations. Only the inside surface of PET-PE packaging gave 100% suppression of egg-to-adult adult emergence of T. castaneum. Development of T. variabile larvae was arrested at the pupal stage at both temperatures on the outside surface of methoprene-treated PE-PE packaging, whereas on the inside surface larvae completed development to adulthood. A 87–97% reduction in egg-to-adult emergence of T. variabile was observed on the inside surface of the PET-PE packaging relative to emergence in corrresponding control treatments at both temperatures. The packaging types evaluated in this study can potentially protect food products stored in these packages from infestations of T. castaneum and T. variable.     

Susceptibility of Trogoderma granarium Everts and Trogoderma inclusum LeConte (Coleoptera: Dermestidae) to residual contact insecticides

Commercial formulations of the pyrethroid insecticides β-cyfluthrin and deltamethrin were evaluated for delayed mortality of Trogoderma granarium (Everts), the khapra beetle, and T. inclusum (LeConte), the larger cabinet beetle. Ten 3-4 week-old larvae of either species were exposed on treated concrete arenas for 1, 2, 3, and 7 d then transferred into 175 ml diet cups containing 5 g of untreated rearing media for 30 d to evaluate delayed mortality. In a subsequent study, residual efficacy of β-cyfluthrin, deltamethrin, and chlorfenapyr was evaluated at 0–12 wks post-treatment against adults and larvae of a laboratory and a field strain of T. granarium. Ten adults or larvae of either strain were exposed on treated arenas at selected wks post-treatment and mortality was assessed after 4 and 30 d of exposure for adults and larvae, respectively. In the first study, delayed morality of T. granarium and T. inclusum larvae was <26% when exposed on arenas treated with the two pyrethroids, and T. inclusum larvae were less susceptible than T. granarium. Adult mortality was 90–100% for both strains of T. granarium across post-treatment assays regardless of insecticide treatment and there was no difference between strains. All three insecticides produced 100% mortality for the laboratory strain of T. granarium larvae in initial post-treatment assays, but then efficacy declined. Field strain larvae were more tolerant to the insecticides than laboratory strain larvae, and larvae of both T. granarium strains were more tolerant than adults. Longer exposure times were required to produce complete mortality of larvae compared to adults. All three insecticides provided residual efficacy of adults for up to three months.     

Survey of Trogoderma spp. in Spanish mills and warehouses

The distribution of Trogoderma granarium Everts has expanded steadily in recent years. This is a very destructive coleopteran species with many economic implications for the trade of grains in countries where it is present. Therefore, it is important to gather data that can confirm or reject the pest’s establishment in a particular country. Spain has been cited as a location where the species is established; however, the present study demonstrates that no actual data support its stablishment in Spain. We surveyed fifteen storage premises (mills and warehouses for animal feed, wheat, and rice) distributed along the Iberian Peninsula over two years. We used traps baited with Trogoderma spp. sex pheromone to conduct the survey. Collected samples were morphologically and molecularly identified, since the morphological identification of this species is difficult. Although we found populations of T. inclusum in most of the sampled premises, and even T. variabile in one of them, no T. granarium was found in any of them. Abundant samples of other coleopterans were captured in the traps, including Oryzaephilus surinamensis, Tribolium spp., Sitophilus spp., Cryptolestes ferrugineus, Lasioderma serricorne and Rhyzopertha dominica. In conclusion, no T. granarium was found in our samplings in Spain.     

Efficacy of phosphine fumigation for different life stages of Trogoderma inclusum and Dermestes maculatus (Coleoptera: Dermestidae)

Despite the importance of dermestid beetles as targets for stored product protection, including the protection of museum artifacts and animal-based products, there are only a few published reports regarding their susceptibility to phosphine fumigation, in contrast with other major stored product insect species. In the current study, we evaluated phosphine against all life stages of Trogoderma inclusum LeConte, the larger cabinet beetle, and Dermestes maculatus (DeGeer), the hide beetle. There were two series of laboratory bioassays; in the first series the concentrations were 0 (control), 50, 100, 200 and 600 ppm, and in the second series the concentrations were 0 (control), 50, 150, 300, 400, 500 and 600 ppm. Both series were carried out on a 5-day insect exposure protocol. The results for both species clearly indicated that eggs were by far the least susceptible life stage, followed by pupae, while most adults and larvae were killed at the 50-ppm concentration. Concentrations between 300 and 400 ppm could be utilized to provide 100% mortality for both species and all life stages. To our knowledge, our results are the first that have provided data regarding efficacy of phosphine for the control of T. inclusum and D. maculatus. Resource managers can utilize our results to more efficiently target these dermestids with specific concentrations of phosphine, depending on the target life stage.     

Evaluations of the new deltamethrin-treated all-in-one hermetic bag for the control of the Khapra beetle,Trogoderma granarium (Everts)

The khapra beetle, Trogoderma granarium (Everts), is a highly destructive stored product insect that presents a significant threat to stored bagged grain. Hermetic packaging is designed to maintain the quality and safety of stored grain, while continually protecting the grain from insect infestations during storage. The objective of this research was to evaluate a prototype deltamethrin, all-in-one treated hermetic bag on contact efficacy, larval mobility, and the control of T. granarium in artificially infested wheat. The insecticidal activity of the deltamethrin-treated packaging was tested against larvae and adults of T. granarium through contact bioassays. There was a significant reduction in responsive adults after 5 day and >86% of larvae were unresponsive after 9 d of exposure on the treated bag. Trogoderma granarium movement toward a food bait was <10% after a 24 h exposure on the treated bag compared to ~45% of larvae on untreated bag. Lots of 15 kg of wheat were artificially infested with 100 T. granarium larvae and placed inside treated and untreated storage bags, sealed, and stored in a semi-field warehouse, and observed after 2, 6, and 8-weeks for T. granarium survival and grain quality attributes. The weight and number of insect damaged kernels was lower across all storage intervals for grain held in the treated bags, as compared with control bags. Live adult T. granarium were observed at 2-weeks in treated and untreated bags, but there were no live adults observed after 8-weeks of storage in both bags. The new prototype hermetic bags maintained positive grain qualities, however more information on the hermetic parameters are needed to understand how some individuals survived.     

Efficacy of d-tetramethrin and acetamiprid for control of Trogoderma granarium Everts (Coleoptera: Dermestidae) adults and larvae on concrete

The khapra beetle, Trogoderma granarium Everts (Coleoptera: Dermestidae) is a dangerous insect of stored products that has currently expanded in Africa, Asia and Europe. Control of this species encounters difficulties when synthetic insecticides are applied either as surface treatments or as grain protectants. Therefore, new insecticidal formulations should be assessed as additional tools towards an effective management of T. granarium. In the current study, we tested the new insecticidal formulation Dobol, that contains the pyrethroid insecticide d-tetramethrin and the neonicotinoid insecticide acetamiprid, as treatments on concrete. Their direct and delayed mortality against adults and larvae of T. granarium were estimated under two label doses (min and max) and two temperature levels (30 and 35 °C) after 1, 2, 3, 4 and 7 d of exposure interval. Results revealed that Dobol caused direct mortality to T. granarium adults that ranged between 87.8 and 96.7%. Concerning larvae, direct mortality was generally much lower, being at most 84.4% at the max dose after 7 d of exposure. Temperature had significant impact on the direct mortality of T. granarium adults and larvae within the vast majority of the tested exposure intervals at both doses. However, when the surviving adults and larvae were transferred on untreated concrete surfaces, despite higher mortality at 35 than 30 °C, there was no significant impact of temperature on their mortalities within any exposure interval and dose. Our study revealed that Dobol is a promising insecticidal formulation that can be effectively used against adults and larvae of T. granarium on concrete surfaces.     

Susceptibility of Tribolium castaneum and Trogoderma variabile larvae and adults exposed to methoprene-treated woven packaging material

Methoprene is an insect growth regulator (IGR) registered in the United States for direct application to stored raw grains, as an aerosol or residual contact insecticide, and for use as a coating for protection of packaged products. A series of tests was conducted to determine the adverse effects of short term exposure, sub-lethal exposure, and continual exposure of the red flour beetle, Tribolium castaneum (Herbst) and warehouse beetle, Trogoderma variabile Ballion, on methoprene-treated woven packaging material at 27 and 32 °C and 60% r.h. In the first test, larvae of both species were added to individual arenas and exposed for different time intervals, removed and resulting adult emergence was assessed. In the second test, eggs of both species were exposed on the packaging surfaces to determine percent egg hatchability. In the third test, adults of T. castaneum and T. variabile were added to arenas and held for 7 and 3 d, respectively, to determine number of eggs laid per female and subsequent egg hatchability. The eggs were held in arenas to determine the effect of continual exposure on egg-to-adult emergence. Results showed normal adult emergence decreased with increasing exposure time and temperature. Exposure to methoprene-treated packaging did not adversely affect fecundity of T. variabile adults, but did affect fecundity of T. castaneum. Continual exposure gave 100% suppression of T. castaneum adult emergence and a reduction of T. variabile emergence. This study indicated that methoprene-treated packaging could be a valuable addition to an existing integrated pest management program to increase protection of packaged products.     

Influence of frozen storage and packaging on oxidative stability and texture of bread produced by different processes

The influence of packaging barrier properties and frozen storage on phenolic and phytosterol content, oxidative stability and crumb texture of frozen dough, part-baked and fully baked frozen bread was investigated in comparison to conventionally produced bread. Samples were stored either in blue coloured high density polyethylene (PE-HD) or transparent polyester-polyethylene-ethylene-vinyl alcohol copolymer (PET-PE/EVAL/PE) pouches for 22 days at −18 °C. Packaging materials were different in oxygen permeability: 3.67 cm³m⁻²day⁻¹ bar⁻¹ for PET-PE/EVAL/PE and 2080 cm³m⁻²day⁻¹ bar⁻¹ for PE-HD material, which did not significantly change during storage. Total phenolic content and oxidative stability of bread samples decreased during storage depending on the process. Frozen dough bread had the lowest phenolics decrease and the highest oxidative stability. Total phenolic content and oxidative stability of frozen breads during 8 days were similar to conventional bread. The phenolics reduction was higher for samples stored in PET-PE/EVAL/PE laminate than in PE-HD packaging. Total sterol content did not significantly change during bread storage in investigated packaging and did not contribute to the oxidation. Bread firmness was affected only by the process and not by the storage time and packaging material.     

Comparative performance of the Khapra beetle,Trogoderma granarium Everts (Coleoptera: Dermestidae) on various wheat cultivars

The Khapra beetle, Trogoderma granarium Everts (Coleoptera: Dermestidae), is known as a serious pest of stored grains and stored products. Host plant is an effective ecological factor on performance of an insect pest. In this study, effects of ten wheat cultivars were evaluated on life table parameters and nutritional indices of T. granarium under laboratory conditions, 33 ± 1 °C, 60 ± 5% RH and a photoperiod of 14: 10 (L: D) h. Our research showed that various wheat cultivars have significant effects on life history, demographical parameters and nutritional indices of T. granarium. The highest immature survival rate was observed on cultivar Gaskojen. Significant differences on developmental time, adult fecundity and longevity of T. granarium were found across tested wheat cultivars. In addition, there were significant differences among the wheat cultivars for population growth parameters of T. granarium. The highest (r_m) values were observed on Gaskojen (0.078 eggs/female/day) and its lower values were resulted from rearing of T. granarium on Kouhdasht and Bezostaya. The larvae fed on Gaskojen showed the higher value of food consumption as compared with others. In addition, the higher value of relative growth rate (RGR) was found on cultivar Gaskojen, while the relative lower value was observed on cultivar Kouhdasht. The results indicated that Gaskojen cultivar was a relatively susceptible wheat cultivar and Kouhdasht cultivar was relatively unsuitable host for feeding of T. granarium which could prove useful in the development of IPM programs for this pest.     

Maize hybrids affected nutritional physiology of the khapra beetle,Trogoderma granarium Everts (Coleoptera: Dermestidae)

The Khapra beetle, Trogoderma granarium Everts (Coleoptera: Dermestidae), is an important insect pest of stored cereals, grains and other stored products in Iran and some countries of the world. Nutritional indices and digestive enzymatic activity of fifth instar T. granarium were investigated on nine maize hybrids (704, AR 89, AS 71, AS 77, BC 678, KSC 703, PL 472, SC 704, and Simax) at 33 ± 1 °C, relative humidity of 65 ± 5%, and a photoperiod of 14: 10 (L: D) h. The highest and lowest food consumption by larvae was on AR 89 and BC 678, respectively. Fifth instar larvae fed on 704 had the highest efficiency of conversion of ingested food, and those fed on BC 678 showed the lowest relative growth rate. The larval growth index, standardized insect-growth index and fitness index were the highest when larvae were reared on PL 472, and the lowest when they were reared on BC 678. The highest proteolytic and amylolytic activity was on KSC 703, and the lowest activity was on BC 678. The results of this study indicated that BC 678 was an unsuitable hybrid for feeding of fifth instar T. granarium. Studying the nutritional physiology of T. granarium on different maize hybrids can be useful in identifying the anti digestive compounds of host grains, which can be expressed in genetically engineered crops to confer resistance to this key pest.     

Residual efficacy of deltamethrin and β-cyfluthrin against Trogoderma variabile and Trogoderma inclusum (Coleoptera: Dermestidae)

Trogroderma variabile Ballion, warehouse beetle, and Trogoderma inclusum LeConte, larger cabinet beetle, are dermestid pests of stored products. A series of laboratory bioassays were conducted to evaluate residual toxicity of the pyrethroids deltamethrin and β-cyfluthrin, applied on a concrete surface substrate for control of adults and larvae of both species, to provide initial baseline susceptibility data for dermestids. Commercial formulations were applied at calculated deposition rates of 8, 16, and 24 mg active ingredient [AI] per m² for deltamethrin and 10 and 20 mg active ingredient [AI] per m² for β-cyfluthrin. Ten adults or larvae of either species were introduced to individual untreated and treated arenas at 0, 0.5, 1, 2, and 3 mo post-treatment. Adult mortality was evaluated after 4 d of exposure with no food provided, and larval mortality was assessed 30 d after exposure with provision of food. Adult mortality of both species exposed to both insecticides ranged from 72.4 ± 6.9 to 100% depending on exposure interval. Larval mortality ranged from 18.3 ± 5.4 to 96.7 ± 2.1% on arenas treated with deltamethrin, and was significantly lower than adult mortality (P < 0.001) at bioassays conducted at 2 and 3 mo post-treatment for both species at all three rates. Larval mortality on arenas treated with β-cyfluthrin ranged from 20.0 ± 4.5 to 71.7 ± 4.8%, and was always lower (P < 0.001) at all exposure times at both rates for both species. There were only 4 out of a possible 20 comparisons with a significant difference (P < 0.05) between the three rates of deltamethrin and no occasions where there is a significant difference in mortality between the two rates of β-cyfluthrin. There were three occasions where mortality of T. inclusum adults or larvae was greater than T. variabile, and one occasion with the reverse, for exposures with deltamethrin. Results show larvae of both species were more tolerant than adults of both species, and larvae could be used as an indicator stage for future studies insecticidal susceptibility of Dermestids.     

Life history of Trogoderma granarium Everts (Coleoptera: Dermestidae) on peeled barley,peeled oats and triticale

The life history of the khapra beetle, Trogoderma granarium Everts (Coleoptera: Dermestidae), was investigated on cracked peeled barley, cracked peeled oats and cracked triticale. The results suggest that the biological and demographic parameters of T. granarium are affected by the tested commodities. The developmental time of total immature period of T. granarium was significantly lower on barley (35.06 days) than on oats (42.87 days) and triticale (43.58 days). Mean longevities of adult females were 7.00, 7.89 and 8.24 days, and for adult males were 5.79, 6.05 and 5.49 days when T. granarium fed on barley, oats and triticale, respectively. The highest fecundity recorded when T. granarium fed on barley (39.0 eggs/female) or triticale (35.2 eggs/female), but it was significantly lower when this species fed on oats (25.4 eggs/female). While the net reproductive rate did not differ significantly when T. granarium fed on barley (14.6 females/female), oats 10.2 (females/female) and triticale (11.0 females/female), the mean generation time was significantly lower when fed on barley (40.5 days) than on oats (48.7 days) and triticale (46.1 days). The intrinsic rate of increase of T. granarium did not differ significantly when fed on barley and triticale (0.066 and 0.052 females/female/day, respectively), but it was significantly lower when fed on oats (0.047 females/female/day). The biological and demographic parameters of T. granarium may be incorporated in population models that evaluate the population dynamics aiming to the optimization of management strategies against this noxious species.     

Different diets affecting biology and digestive physiology of the Khapra beetle,Trogoderma granarium Everts (Coleoptera: Dermestidae)

The Khapra beetle, Trogoderma granarium Everts (Coleoptera: Dermestidae), is a serious pest of grain and other stored products through the world. In this research, effect of five host diets including barley, rice, rye, wheat and walnut was studied on some of biological traits, nutritional indices and digestive enzymatic activity of T. granarium at 33 ± 1 °C, 65 ± 5% RH and a photoperiod of 14:10 (L:D) h. The Khapra beetle larvae reared on walnut had the highest number of larval instar and longest duration of larval and pupal stages (91.30 ± 0.4 days). The heaviest pupal weight of T. granarium was on rye (4.22 ± 0.01 mg) and the lightest weight was on rice (3.99 ± 0.01 mg) and walnut (4.00 ± 0.01 mg). The highest realized fecundity and fertility were recorded for the females reared on rye (45.88 ± 1.08 eggs/female and 69.39 ± 0.68%, respectively) and wheat (49.02 ± 1.55 eggs/female and 67.54 ± 0.69%, respectively), and the lowest ones were observed for the females came from larvae fed walnut (15.45 ± 0.71 eggs/female and 34.55 ± 0.82%, respectively). Also, the results showed that T. granarium larvae reared on walnut had the lowest values of the efficiency of conversion of ingested food (7.67 ± 0.04%) and relative growth rate (0.044 ± 0.0002 mg/mg/day). The lowest midgut amylolytic (0.044 ± 0.0005 and 0.047 ± 0.0005 mU/individual, respectively) and proteolytic (0.015 ± 0.0004 and 0.016 ± 0.0001 mU/individual, respectively) activity of the sixth instar was detected on walnut and rice. The highest inhibition of amylase (53.37 ± 0.75%) and protease activity (48.54 ± 0.96%) was estimated by incubating midgut extracts from the last instars with wheat and barley proteinaceous extracts, respectively. The results indicated that walnut was the most unsuitable diet for feeding and development of T. granarium.     

Efficacy of the furanosesquiterpene isofuranodiene against the stored-product insects Prostephanus truncatus (Coleoptera: Bostrychidae) and Trogoderma granarium (Coleoptera: Dermestidae)

In plant and animal kingdoms, isofuranodiene is a widespread, lipophilic and volatile furanosesquiterpene endowed with insecticidal properties. In the current study, we evaluated its toxicity against the larger grain borer, Prostephanus truncatus (Horn) (Coleoptera: Bostrychidae) adults and the khapra beetle, Trogoderma granarium Everts (Coleoptera: Dermestidae) adults and larvae at 500 and 1000 ppm. Results showed that the overall mortality of P. truncatus adults exposed to 500 ppm was low, while at the higher dose tested it increased to 56.7% after 7 days of exposure. Notably, isofuranodiene killed 95.6 and 96.7% of the exposed T. granarium adults 5 and 7 days post-exposure at 1000 ppm. On the other side, T. granarium larval mortality did not exceed 24.4 and 37.8% at 500 and 1000 ppm respectively, after 7 days of exposure. Isofuranodiene could be considered further to develop novel green tools against T. granarium adults, since there is a lack of effective grain protectants against this noxious species.     

Influence of different non-grain commodities on the population growth of Trogoderma granarium Everts (Coleoptera: Dermestidae)

We investigated the population growth of the khapra beetle, Trogoderma granarium Everts (Coleoptera: Dermestidae) on seven groups of commercially available non-grain commodities. Six powdered spices were used in the first group of experiments: black pepper, clove, nutmeg, allspice, cinnamon and turmeric. The second group of the tested commodities included seven animal products: powdered cow milk, powdered pork zelatin, sheeps’ wool, goat’s skin, ducks’ feathers, dry dog food and dry cat food. The third group of commodities was consisted of six herbs: oregano, spearmint, basil, coriander, laurel and marjoram. The fourth group of commodities contained ten pulses: chickpeas, lentil, split peas, black-eyed peas, beans, soybean flour and whole kernels, lima beans, mung bean, and broad beans. The fifth group comprised six dried fruits: Corinthian currants, sultanas, banana chips, melons, apricots and figs. The sixth group was consisted of five non-grain commodities: cottonseed cake, tobacco, black tea, Turk kahvesi and potato flour. The seventh group included seven nuts: sunflower seeds, pumpkin seeds, pistachios, roasted chickpeas (yellow), almonds, hazelnuts and walnuts. Finally, six cracked containment categories (0% cracked kernels, 5% cracked kernels and 95% intact kernels, 10% cracked kernels and 90% intact kernels, 25% cracked kernels and 75% intact kernels, 50% cracked kernels and 50% intact kernels and 100% cracked kernels) from five pulses were tested: chickpeas, black-eyed peas, mung bean, soybean and split peas. The highest progeny production (3.01 individuals per vial) was recorded on powdered cow milk. On pistachios, split peas, sunflower seeds, soybean flour, pumpkin seeds, walnuts, almonds and coriander, T. granarium built high population densities rapidly, while on roasted chickpeas, cottonseed cake, hazelnuts, chickpeas, dog food and lentils, its population growth was much less. Broad beans, melons, figs, lima beans, beans, Corinthian currants, pork zelatin and potato flour were less suitable diets for the development of this species. On black pepper, clove, nutmeg, allspice, cinnamon, turmeric, sheeps’ wool, goat’s skin, ducks’ feathers, cat food, sultanas, banana chips, apricots, tobacco, black tea, Turk kahvesi, oregano, spearmint, basil, laurel and marjoram, no progeny production was recorded. The proportion of 100% cracked black-eyed peas or mung beans was more suitable for the population growth of T. granarium. Also, the percentages of 50% cracked chickpeas or 10% cracked soybeans enhanced the development of the species, in comparison with the whole kernels of each pulse. Our study indicated that several non-grain commodities are beneficial for the population growth of T. granarium, a fact that should be seriously taken into account in international trade, as this pest may utilize them as “vehicles” of expansion.     

Effect of three entomopathogenic nematode species to Trogoderma granarium Everts (Coleoptera: Dermestidae) larvae on stored-wheat

Grain commodities are subjected to multiple insect infestations during processing and storage. The kharpa beetle, Trogoderma granarium Everts (Coleoptera: Dermestidae) is categorized as a destructive stored-product pest due to its elevated survival potential, preference for dry conditions and resistance to many insecticides. While public concern about pesticide related risks increases, the development of alternative, environmentally more benign disinfestation methods of stored commodities is pursued. The current study evaluated the effectiveness of three entomopathogenic nematodes, Heterorhabditis bacteriophora Poinar (Rhabditita: Heterorhabditidae), Steinernema carpocapsae (Weiser) (Rhabditita: Steinernematidae) and Steinernema feltiae (Filipjev) (Rhabditita: Steinernematidae) against small and large larvae of T. granarium. Suspensions of nematodes were applied at six doses: 100, 500, 1000, 5000, 10000 and 50000 infective juveniles (IJs)/ml of water on wheat at 30 °C. Mortality of larvae was estimated 4 and 8 days post-exposure to nematodes. All three entomopathogenic nematodes were able to cause mortality on the insect. High mortality rates were accomplished by the two Steinernema species. The most efficient entomopathogenic nematode against small larvae was S. feltiae which attained 98.9% mortality followed by S. carpocapsae which caused 91.1% mortality after 8 days of exposure. Similarly, S. feltiae and S. carpocapsae killed 87.8 and 63.3% of the exposed large larvae on wheat treated with 50000 IJs/ml after 8 days of exposure. In contrast, at the highest dose, H. bacteriophora was less effective than S. carpocapsae and S. feltiae since it caused 76.7 and 60.0% mortalities to exposed small and large larvae after 8 days of exposure. The effectiveness of all three entomopathogenic nematodes was increased at higher doses and longer exposures. The findings of the current study indicate that entomopathogenic nematodes are efficient biological control organisms of T. granarium larvae infesting stored-wheat.     

Different diets affecting biology,physiology and cold tolerance of Trogoderma granarium Everts (Coleoptera: Dermestidae)

Biology, some physiological processes and cold hardiness of Trogoderma granarium Everts (Coleoptera: Dermestidae) on ten diets (barley, corn, millet, rice, rye, sorghum, triticale, wheat groundnut, and walnut) were studied under laboratory conditions (33 ± 1 °C with 65 ± 5% RH, 14L: 10D). According to the results, the insects reared on triticale had shortest development time, and the highest fecundity and fertility. By contrast, the longest development time, and the lowest fecundity and fertility were on groundnut. The survival rates ranged from 40 to 87% with the lowest values observed on groundnut. T. granarium larvae fed on triticale and millet had the highest amylolytic activity. In contrast, groundnut-fed larvae possessed the lowest amylolytic activity. The highest and lowest proteolytic activity was on rice and millet, respectively. Different diets had a significant effect on larval energy reserves (total body sugars, glycogen, lipid, and protein), which were at the highest levels on triticale and rye, and lowest levels on sorghum. The highest level of trehalose was on triticale, groundnut and rye, and the lowest level was on barley and sorghum. The supercooling point (SCP) of larvae reared on triticale was −20.6, which was significantly lower than on the other diets. Exposures to −5 and −10 °C/24 h were somewhat endured by larvae fed on triticale, rye, walnut, and groundnut whilst exposure to −20 °C/24 h caused 100% mortality in these food groups. These results suggest that larval food quality can affect biological and physiological characteristics and influence the supercooling point and cold hardiness of T. granarium.     

Effects of type of packaging material on shelf-life of fresh broccoli by means of changes in weight,colour and texture

Five polymeric films were studied to determine their ability to retain the colour, weight and texture of broccoli (Brassica oleracea L. var. Italica Monterey). The materials were oriented polypropylene (OPP), polyvinyl chloride (PVC) and two different low-density polyethylenes (LDPE), one of which contained a sachet reported to absorb ethylene. The broccoli was packaged and stored at 4 and 10 °C for 4 weeks. The weight, colour, chlorophyll content and texture were monitored during storage as well as O₂ and CO₂ concentrations inside the packages. Packaging prolonged the broccoli shelf-life by up to 14 days. The shelf-life varied depending on the packaging material and quality parameter considered. The atmosphere was modified inside the packages; however, no package provided the recommended atmosphere (O₂ 1–2% and CO₂ 5–10%) for broccoli. Packaging in OPP resulted in the highest CO₂ concentration, 6%, while the lowest O₂ concentration, 9%, was created in the LDPE package without a sachet for ethylene absorption. Storage in LDPE without ethylene absorber resulted in the overall longest shelf-life. Broccoli stored in PVC deteriorated faster than broccoli packaged in the other materials. The influence of packaging material was greater at the higher temperature.     

Feeding efficiency and digestive physiology of Trogoderma granarium Everts (Coleoptera: Dermestidae) on different rice cultivars

The Khapra beetle, Trogoderma granarium Everts (Coleoptera: Dermestidae), is one of the economic pests infesting many stored cereals in the world. The effects of six commercial rice, Oryza sativa L. cultivars including Hashemi, Shiroodi, Gilane, Khazar, Ali Kazemi and Domsiah were evaluated on nutritional indices and digestive enzymatic activity of fifth instar T. granarium at controlled conditions (33±1 °C, relative humidity of 65 ± 5%, and a photoperiod of 14:10 (L:D) h). Fifth instar larvae consumed more food when reared on Gilane, and less food when reared on Khazar and Ali Kazemi. The larvae fed with Khazar had the lowest weight gain, efficiency of conversion of ingested food and growth index. The relative growth rate was the highest when larvae were fed with Gilane and lowest when they were fed with Khazar. The highest midgut proteolytic and amylolytic activities of larvae were on Gilane. However, the lowest proteolytic activity was on Khazar and the lowest amylolytic activity was on Khazar and Ali Khazemi. According to the obtained results, Khazar is an unsuitable cultivar for feeding and growth of T. granarium.