Stored Product Pest Management Research Articles

Ruta chalepensis L. (Rutaceae) uçucu yağının beş coleopteran depo ürün zararlısına karşı fumigant ve kontak toksisitesi ile kolinesterazlar üzerine etkileri

The essential oil composition of aerial parts of Ruta chalepensis L. was analyzed with GC-MS. Seventy-nine compounds were detected representing 85.93 ± 1.08% (n = 3) of the essential oil. The major components of the essential oil were 2-undecanone 21.52 ± 0.21%, 2-nonanone 18.31 ± 0.27%, and 2-nonyl acetate 13.22%. The highest insecticidal contact toxicity of the oil was observed against Rhyzopertha dominica F. with 0.018 μl/insect LD50 and 0.039 μl/insect LD90 after 24h. Essential oil also produced considerably low 0.50 and 0.59 μl/insect LD50 values after 24h against Sitophilus oryzae L. and Sitophilus granarius L. respectively. The lowest contact toxicity was observed against Tribolium castaneum Herbst. and Tribolium confusum Jacquelin du Val. 0.138 and 0.078 μl/insect LD50 after 24h respectively. The highest fumigant toxicity was observed against S. granarius for the application concentration of 10 μl, 10% oil/acetone (v:v) in a 10 ml chamber which afforded 100.00 ± 0.00% mortality after 48h. The essential oil also produced high fumigant toxicity against S. oryzae, T. castaneum and R. dominica which were 95.47 ± 3.41%, 93.30 ± 5.54%, and 85.47 ± 3.41% mortality at 20 μl application concentration of the oil solution after 48h. The R. chalepensis essential oil produced low acetylcholinesterase enzyme 5.29 ± 1.20% (n=3) inhibition and mediocre butyrylcholinesterase enzyme inhibition 42.6 ± 0.71% (n=3). According to the insecticidal activity assays performed, the essential oil R. chalepensis seems to be a promising source that could yield natural compounds that could be employed in stored product pest management.

Importance of Sanitation for Stored-Product Pest Management.

Sanitation is essential for the cost-effective pest management of stored-product insects. The Food, Drug and Cosmetic Act of 1938 led to the Food and Drug Administration (FDA) tightening regulatory standards, and many local surveys, courses and conferences were organized to prepare the industry for these new regulations. Sanitation removes insects and residual food, which may also provide shelter for insects, with heat treatments and insecticide applications. The number of insects removed by cleaning may be reduced as the number of available hiding places increases. Decreased sanitation negatively affects the efficacy of most other pest management practices, with means of 1.3- to 17-fold decreases in efficacy. The majority of studies quantifying the efficacy of sanitation have been performed on the farm storage of grain, but some studies have been conducted for grain elevators, food processing, and the marketing system. Results ranged from no effect of sanitation alone to very effective alone or with other methods. Sanitation can also reduce insect infestation prior to harvest. Some cost-benefit analyses have been conducted for sanitation.

Individual and combined effects of α-Pinene and a native diatomaceous earth product on control of stored product beetle pests

The development of alternatives to chemical insecticides has been an attractive topic in stored product pest management due to the limited number of options. This study examined the individual and combined activities of two promising eco-friendly alternatives, the diatomaceous earth product Detech® and the plant-based essential oil α-pinene, against Sitophilus granarius (L.), S. zeamais Motschulsky, 1855 (Coleoptera: Curculionidae), Tribolium confusum Jaquelin Du Val, 1868 (Coleoptera: Tenebrionidae) and Rhyzopertha dominica (Fabricius, 1792) (Coleoptera: Bostrichidae) under laboratory conditions. Individual and combined insecticidal effects of Detech® and α-pinene were evaluated by their direct application to wheat or maize. Complete mortality against S. granarius, R. dominica, and T. confusum occurred at 2 days with 10 and 15 ppm of α-pinene, while 15 ppm of α-pinene produced 100% mortality after 3 days of exposure for S. zeamais. The highest mortality with Detech® was 38.6% at 21 days using 500 ppm for S. zeamais, while it was 51.7 % against S. granarius, and 72.7 % against R. dominica. Detech® did not show any significant activity against T. confusum at any application level. Combined applications of Detech®+α-pinene demonstrated the highest mortality on R. dominica (40.4% mortality), S. zeamais (27.9%), and S. granarius (18.5%), while no significant effect was found on T. confusum (1.1%). Overall, α-pinene was more effective than Detech® against all four tested beetles species. Combined applications led to reduced mortality.

The Type of Grain Counts: Effectiveness of Three Essential Oil-Based Nanoemulsions against Sitophilus oryzae

Essential oil (EO)-based nanoemulsions (NEs) are promising grain protectants in the management of stored-product pests. However, the potential impact of the stored-grain species on the green insecticide effectiveness has been poorly studied. In this study, two concentrations of EO-based NEs from Carlina acaulis L., Mentha longifolia (L.) Huds., and Hazomalania voyronii (Jum.) Capuron were evaluated as insecticides against the major stored-product pest Sitophilus oryzae (L.) on barley, oats, and maize kernels. The C. acaulis EO-based NE applied at 1000 ppm on barley achieved the highest mortality, killing 94.4% of S. oryzae adults after a 7-day exposure, followed by 1000 ppm of H. voyronii EO-based NE (83.3%). The lowest mortality (1.1%) was recorded with 500 ppm of M. longifolia EO-based NE on maize after the same interval. All tested NEs exhibited elevated efficacy when applied on barley, while mortalities were lower on oats and maize. Furthermore, C. acaulis EO-based NE was the most effective when applied on all commodities, followed by H. voyronii and M. longifolia EO-based NEs. Overall, our results highlighted the significant impact of the stored cereal on the insecticidal effectiveness of EO-based NE used for stored-product pest control. Sitophilus oryzae adults on barley can be adequately controlled through the application of C. acaulis and H. voyronii EO-based NEs.

A comprehensive review of effective essential oil components in stored-product pest management

A comprehensive review of effective essential oil components in stored-product pest management

EFFICACY OF SOME INDIGENOUS PLANT SMOKE AGAINST RED FLOUR BEETLE, TRIBOLIUM CASTANEUM (L)


 Red flour beetle, Tribolium castaneum Herbst (Coleoptera: Tenebrionidae) is one of the major insect pests of stored grains. Due to export legislation and zero-tolerance for live insects in trade commodities, extensive use of synthetic insecticides is in practice to eliminate pest infestations from the lots. Currently, the only acceptable chemical to be used in stored grain is phosphine but due to its excessive usage, the stored grain pests are becoming resistant to it. Hence, the discovery of alternative compounds is much needed. In this study, we have compared the repellency of different plants smoke from five commonly found plants of Pakistan, viz. neem Azadirachta indica (Meliaceae), costus Saussurea lappa (Asteraceae), turmeric Curcuma longa (Zingiberaceae), sweet flag Acorus calamus (Acoraceae) and valerian Valeriana officinalis (Caprifoliaceae) against T. castaneum. After two hours of smoke, Azadirachta indica showed a maximum 75.89±2.14% repellency followed by Saussurea lappa (44.15±1.87%), Curcuma longa (43.22±2.51%), Acorus calamus (23.15±1.75%;) and Valeriana officinalis (18.40±1.40%). This is a baseline study for the management of T. castaneum, further research on this aspect is required to be investigated. The results of this study support the use of botanicals alternative to synthetic insecticides for stored product pest management.

Promising Insecticidal Efficiency of Essential Oils Isolated from Four Cultivated Eucalyptus Species in Iran against the Lesser Grain Borer, Rhyzopertha dominica (F.).

Simple SummaryEucalyptus essential oils have shown promising insecticidal effects on several insect pests. The lesser grain borer, Rhyzopertha dominica (F.), causes economically significant damage to stored grains as an internal primary insect pest. In this study, the chemical compositions of essential oils isolated from four Eucalyptus species. E. microtheca, E. procera, E. spatulata, and E. torquata were detected and identified using a gas chromatography-mass spectrometer, and their lethal and sublethal insecticidal effects were evaluated against the adults of R. dominica. Although all essential oils have significant fumigant toxicity, due to the high relative potency, R. dominica was more susceptible to the E. procera essential oil than the others. The total protein, glycogen, and lipid contents and digestive amylase and protease enzyme activities of the treated insects were reduced. The nutritional indices consumption index, relative consumption rate, and relative growth rate were also reduced in the treated adults. The findings of this study reveal that E. microtheca, E. procera, E. spatulata, and E. torquata essential oils can be potentially used for the development of eco-friendly natural agents for the management of R. dominica. The lesser grain borer, Rhyzopertha dominica (F.), causes damage to stored grains resulting in both quantitative and qualitative losses. The use of synthetic fumigants in the management of stored-product pests resulted in undesirable side effects such as environmental contamination and threat to human and animal health. In this study, the lethal and sublethal effects of essential oils from four Eucalyptus species, E. microtheca, E. procera, E. spatulata, and E. torquata were studied against R. dominica adults. Gas chromatographic–mass spectral analysis of the essential oils was carried out, in which terpenes such as 1,8-cineole and globulol were abundant in essential oils. The pest was susceptible to the fumigation of the essential oils and, considering concentrations and exposure times (24, 48, and 72 h), had significant effects on the pest mortality. The total protein, glycogen, and lipid contents and digestive amylolytic and proteolytic activities of the adults treated with tested essential oils were reduced. The consumption index, relative consumption rate, and relative growth rate were also reduced in the treated adults. According to the insecticidal effects on the adults of R. dominica, the essential oils of E. microtheca, E. procera, E. spatulata, and E. torquata can be candidates for further investigations as grain protectant agents.

Effect of Pheromones, Plant Volatiles and Spinosad on Mating, Male Attraction and Burrowing of Cadra cautella (Walk.) (Lepidoptera: Pyralidae).

Simple SummarySex pheromones used at higher concentrations than their availability in insects have been successful in decreasing the insect population. Furthermore, botanical oils have also had negative impacts on the insect population level. In the first study, we investigated the combined effect of sex pheromones and plant oils on mating of almond moth. The second study sought the burrowing ability of almond moth larvae through different flour media. Mating declined on the presence of pheromones and botanical oils, whereas burrowing ability differed with flour type. Exposure to spinosad affected both mating success and larval penetration through flour media. The findings of this study reveal that various applications of sex pheromones, plant oils and spinosad ensure the better protection of cereal-based agricultural produce from insect infestation during storage.Mating disruption of Cadra cautella (Walk.) (Lepidoptera: Pyralidae) using its sex pheromone components, (Z, E)-9,12-tetradecadienyl acetate (ZETA) and (Z)-9-tetradecadien-1-yl acetate (ZTA), is successful in its population management. In addition, botanical oils have extensively been investigated in stored product pest management, but the effect of synthetic sex pheromones on the mating of C. cautella in the presence of plant volatiles is still unknown. Spinosad is used in food facilities as a contact insecticide but, if C. cautella larvae burrow into food, they may escape from spinosad. Importantly, the impact of spinosad on burrowing ability of C. cautella remains unknown. Therefore, the objectives of this study were to determine the effects of sex pheromone components ZETA and ZTA in the presence of botanical oils on the mating of C. cautella and the burrowing ability of C. cautella larvae in different types of flour treated with spinosad. In the first study, male and female moths were introduced into the cubicle having botanical oils and pheromone components. The mating status of female moths and male moth attraction to the trap was determined. The control experiments had only the botanical oils or pheromones. In the second study, burrowing ability of C. cautella larvae through different flour types was evaluated over 10 d. The flour was sprayed with spinosad (treatments) or water (controls). The mating success was higher with botanical oils alone but declined with exposure to pheromone either alone or combined with botanical oils. No differences in male attraction to traps were observed in botanical only, pheromone only or pheromone + botanical oil treatments. The burrowing of C. cautella larvae differed with flour type and spinosad altered burrowing ability. Thus, we conclude that the mating and burrowing of C. cautella is influenced by its pheromone and by exposure to botanicals and spinosad.

Fumigant effect of essential oils against pulse beetle (Callosobruchus chinensis L.) and rice weevil (Sitophilus oryzae L.) in stored products

Objectives: To develop a method to replace the usage of synthetic fumigants in stored product pest management. Methodology: For this purpose, we employed four plant based essential oils namely, Lantana camara (Lantana) oil, Citronella nardus (Citronella) oil, Cinnamomum zeylanicum (Cinnamon) oil and Trachyspermmum copicum (Ajwain) oil and evaluated against pulse beetle, Callosobruchus chinensis L., and rice weevil, Sitophilus oryzae L., for their fumigant toxicity and the weight loss caused by them. The oils of Lantana and Citronella were extracted from leaves, Cinnamon and Ajwain from barks and seeds respectively. Findings: Among the essential oils tested for fumigant toxicity, C. zeylanicum performed better with Lethal Concentration (LC50) of 23.16 and 21.91ml in minimal period of exposure i.e. at 12 h of treatment and found effective against adults of test insects viz., C. chinensis, and S. oryzae respectively. During the maximum period of exposure i.e. at 72 h. the fumigation efficacy of T. copicum was noticed to be the highest (3.43 ml) against adults of C. chinensis whereas C. zeylanicum was found better against S. oryzae (6.19ml). The minimum loss of pulse grains was observed in C. zeylanicum treated at 60 % of 24 h LC50 ; with 7.41 % weight loss. The minimum weight loss was noticed in C. zeylanicum about 60 % of 24 h LC50 with 9.68 per cent against S. oryzae. The fumigant toxicity bioassay revealed that as the exposure period increases, mortality of test insects also found increased i.e. exposure period directly proportional to mortality of insects. Keywords: Coleoptera; essential oils; fumigant toxicity; stored product pests; volatiles

Insect Pest Management in Stored Products

Insects are a common problem in stored produce. The author describes the extent of the problem and approaches to countering it. Stored products of agricultural and animal origin, whether edible or non-edible, are favourite food for insect pests. Durable agricultural produce comprising dry raw and processed commodities and perishables (fresh produce) are vulnerable to insect pests at various stages from production till end-use. Similarly, different animal products and museum objects are infested mainly by dermestids. Insect pests proliferate due to favourable storage conditions, temperature and humidity and availability of food in abundance. In addition to their presence in food commodities, insects occur in storages (warehouses, silos) and processing facilities (flour mills, feed mills). Insect infestation is also a serious issue in processed products and packed commodities. The extent of loss in stored products due to insects varies between countries depending on favourable climatic conditions, and pest control measures adopted. In stored food commodities, insect infestation causes loss in quantity, changes in nutritional quality, altered chemical composition, off-odours, changes in end-use products, dissemination of toxigenic microorganisms and associated health implications. The insects contribute to contaminants such as silk threads, body fragments, hastisetae, excreta and chemical secretions. Insect activity in stored products increases the moisture content favouring the growth of moulds that produce mycotoxins (e.g., aflatoxin in stored peanuts). Hide beetle, Dermestes maculatus infesting silkworm cocoons has been reported to act as a carrier of microsporidian parasite Nosema bombycis that causes pebrine disease in silkworms. In dried fish, insect infestation leads to higher bacterial count and uric acid levels. Insects cause damage in hides and skins affecting their subsequent use for making leather products. The trend in stored product insect pest management is skewing in favour of pest prevention, monitoring, housekeeping and finally control. Hermetic storage system can be supplemented with CO2 or phosphine application to achieve quicker results. Pest detection and monitoring has gained significance as an important tool in insect pest management. Pheromone traps originally intended for detection of infestations have been advanced as a mating disruption device ensuing pest suppression in storage premises and processing facilities; pheromones also have to undergo registration protocols similar to conventional insecticides in some countries. Control measures involve reduced chemical pesticide use and more non-chemical inputs such as heat, cold/freezing and desiccants. Furthermore, there is an expanding organic market where physical and biological agents play a key role. The management options for insect control depend on the necessity or severity of pest incidence. Generally, nonchemical treatments, except heat, require more treatment time or investment in expensive equipment or fail to achieve 100% insect mortality. Despite insect resistance, environmental issues and residue problems, chemical control is inevitable and continues to be the most effective and rapid control method. There are limited options with respect to alternative fumigants and the alternatives have constraints as regards environmental and health concerns, cost, and other logistics. For fumigation of fresh agricultural produce, new formulations of ethyl formate and phosphine are commercially applied replacing methyl bromide. Resistance management is now another component of stored product pest management. In recent times, fumigation techniques have improved taking into consideration possible insect resistance. Insect control deploying nanoparticles, alone or as carriers for other control agents, is an emerging area with promising results. As there is no single compound with all the desired qualities, a necessity has arisen to adopt multiple approaches. Cocktail applications or combination treatments (IGRs plus organophosphorus insecticides, diatomaceous earth plus contact insecticides, nanoparticles plus insecticides/pathogens/phytocompounds and conventional fumigants plus CO2; vacuum plus fumigant) have been proved to be more effective. The future of store product insect pest management is deployment of multiple approaches and/or combination treatments to achieve the goal quickly and effectively.

Bio-efficacy of the indigenous entomopathogenic fungus, Beauveria bassiana in conjunction with desiccant dust to control of coleopteran stored product pests

The insecticidal activity and effects of sublethal combinations of the fungus, Beauveria bassiana-IRAN441C and commercial diatomaceous earth (DE) were assessed on adult coleopterans, Callosobruchus maculatus (F.) (Chrysomelidae), and Oryzaephilus surinamensis (L.) (Silvanidae). Dry conidia and DE were applied singly or in combination. The agents produced acceptable mortality, however, results were not affected by species of host plant seeds fed to the beetles. F1 progeny reduction was notably increased in both beetle species when mixtures of the fungus and DE were each at the LC50 level. In addition to avoidance behavior, different combinations of fungus/DE dosages induced winged morphs (non-reproductive phase) in the C. maculatus population after 50 d exposure. Our results demonstrated that a combination of B. bassiana and DE resulted in high mortality of both beetle species and co-application of B. bassiana and DE is feasible in a stored product pest management program.

Evaluation of fast neutron irradiation as a new control method against the Indian meal moth, Plodia interpunctella (Hübner)

ABSTRACTIonizing radiation is considered a promising treatment for stored product pest management. The dose levels 0, 64, 128, 192, and 256 Gy of Fast Neutron Irradiation (FNI) were tested to deter...

Effect of passing Beauveria bassiana through alkane based media on the adult mortalities of Rhyzopertha dominica and Sitophilus oryzae : Poster

Entomopathogenic fungi have been investigated for management of stored product pests as alternatives to chemical control. Beauveria bassiana is commonly considered and thus increasing its efficacy has also been studied. The purpose of this study is to evaluate the effect of passing two B. bassiana cultures (wild and singlespore cultures) through n-hexadecane and n-octocasane based media on Rhyzopertha dominica and Sitophilus oryzae adult mortalities. For each Petri plate, 2 ml of 10% alkane was spread, let to evaporate and fungus was inoculated. After sporulation, spores for pathogenicity tests were produced by solid fermentation method on rice. Pathogenicity tests were conducted by application of 500 ppm (w/w) spores in wheat on 20 adults at 25±2oC, 65±5 r.h. in darkness with five replications. The efficacy of wild culture towards R. dominica adults was enhanced in both treatments. Mortality in 7 days increased from 35% to 55 and 69% when n-hexadecane and noctocasane were used, respectively. Similarly, these treatments increased 14-day mortalities from 65% to 77 and 87%, respectively. Treatment of single-spore culture, however, either showed no change or reduced mortality. Passing both cultures through both alkane based media did not statistically affect the activity against S. oryzae. This study illustrated that increasing the virulence of B. bassiana is possible for R. dominica and increase depends both on the starting fungus culture and alkane used. Starting with a wild fungus culture with a wider genetic diversity, and using n-octocasane can produce a better enhancement.

Comparative insecticidal activity of different plant materials from six common plant species against Tribolium castaneum (Herbst) (Coleoptera: Tenebrionidae).

Tribolium castaneum (Herbst) (Coleoptera: Tenebrionidae) is one of the major insect pests of stored grains. Due to export legislation and zero-tolerance for live insect in trade commodities, extensive use of synthetic insecticides is in practice in order to eliminate pest infestations from the lots. Currently, the one and only acceptable chemical to be used in stored grain is phosphine but due to its excessive usage the stored grain pests are becoming resistant against it. Hence discovery of alternative compounds is much needed. In this study we have compared insecticidal efficacy of different plant materials from six commonly grown plants of Pakistan, viz. Allium sativum (Alliaceae), Zingiber officinale (Zingiberaceae), Cymbopogon citratus (Poaceae), Eucalyptus globulus (Myrtaceae), Nicotiana tabacum (Solanaceae), and Azadirachta indica (Meliaceae) against T. castaneum infesting stored wheat, rice, corn and gram pulse. Various plant parts were dried, powdered, and used as admixtures to the stored commodities in the experiments. The results have suggested that A. sativum (garlic) and Z. officinale (ginger) were more effective resulting into 15 times higher adult mortality and 4 to 5 times reduction in grain weight losses when mixed with rice grains. Similarly, A. indica when admixture with wheat checked the population growth in the resources resulting into 3.5 times less adult production compared to controls. A subsequent experiment was conducted to study the dose response of neem seed powder against the beetle pest infesting milled products. Surprisingly, better control was observed either at lowest (1% w/w) or the highest doses (5% w/w). This finding is of great interest to understand the underlying phenomenon which we assume is the ability of T. castaneum to feed selectively in flour mediums, however, further research on this aspect is required to be investigated. The results of this study support the use of botanicals for stored product pest management.

The synergistic effects of Carum copticum essential oil on diatomaceous earth against Sitophilus granarius and Tribolium confusum

In this study, synergistic/antagonistic interaction between Carum copticum (L.) powder and essential oil with diatomaceous earths (DEs) was assessed against Tribolium confusum Jacquelin du Val. and Sitophilus granarius (L.) adults. The obtained synergistic interaction was interpreted by measurement of insects' locomotor activity when exposed to C. copticum essential oil. Essential oil had strong fumigant toxicity against adult insects; however, toxicity diminished in the presence of wheat commodity. Plant essential oil synergized the performance of DE samples such that they generally became more insecticidal than DE alone. However, plant powder effects were antagonistic; effects were not as severe as predicted in terms of the insect mortality. Insects' locomotor activity increased significantly when exposed to C. copticum essential oil. These results support the hypothesis that essential oil can enhance the efficacy of DE, at least by increasing locomotor activity and insect-contact toxicity of DE particles. Therefore, combination of essential oil with DE could have potential for use in integrated stored-product pest-management programs.

Spatial Pattern in Aerosol Insecticide Deposition Inside a Flour Mill

Aerosol insecticides are commonly used for management of stored-product pests inside food facilities, but the physical complexity of the interior of most food facilities may influence the dispersal and deposition of droplets and create spatial variation in dosage. The spatial pattern in aerosol deposition was evaluated inside a flour mill using a high density grid of bioassay insects. Three insecticides, Aerotech with NyGuard and Pyrocide 100 + Diacon II, both pyrethrin and insect growth regulator combinations, and Vap20, an organophosphate, were evaluated at normal (27 degrees C) and high (40 degrees C) target temperatures. Using a newly developed efficacy index, there was spatial pattern to aerosol deposition detected for the pyrethrin insecticides and the pattern differed between aerosols and temperatures. Walls and corners, especially behind the direction of application, were especially vulnerable to zones of lower efficacy, and open areas in center of the room tended to have the highest efficacy. The organophosphate insecticide provided complete efficacy at all bioassay dish locations, probably due in part to its vapor toxicity. Using boxes 1 m in depth and 5, 10, or 20 cm in height and open on only one end, it was shown that aerosol dispersal under horizontal surfaces could be impacted by gap height, aerosol, and temperature. These results show the potential for spatial variation in aerosol efficacy within a food facility and identify locations with the potential to receive a lower insecticide dosage. To increase overall efficacy, these locations may be targeted for additional interventions to provide more uniform pest population suppression.

Residual insecticides, inert dusts and botanicals for the protection of durable stored products against pest infestation in developing countries

Insect pests associated with durable grains and processed food cause considerable quantitative and qualitative losses throughout the world. Insect infestation can occur just prior to harvest, during storage in traditional storage structures, cribs, metal or concrete bins, and in warehouses, food handling facilities, retail grocery stores as well as in-transit. Many tools are available for managing insects associated with grains and processed food. Although pest management strategies are changing to meet consumer’s demand for food free of insecticide residues, address concerns about safety of insecticides to humans, delay insecticide resistance development in insects and comply with stricter insecticide regulations, the use of synthetic residual insecticides will continue to be a major component of stored-product pest management programmes. Selective use of residual insecticides requires a through understanding and evaluation of risks, costs and benefits. The use of plant and inert materials may be a safe, cost-effective and environmentally friendly method of grain preservation against pest infestation among low-resource poor farmers who store small amounts of grains. There is a dearth of information on the use of plant materials by rural farmers in Africa for stored-product protection. The most promising candidate plant materials for future utilization as grain protectants are Azadirachta, Acorus, Chenopodium, Eucalyptus, Mentha, Ocimum, Piper and Tetradenia together with vegetable oils from various sources. Neem is the only plant from which several commercial products have been developed worldwide. However, unlike synthetic insecticides these alternatives often do not provide effective or rapid suppression of pest populations and may not be effective against all species of pests. These alternatives are also more expensive than synthetic insecticides, and have not been tested extensively under field conditions in the tropics. This paper focuses on the current state of the utilization of residual insecticides, inert dusts and botanicals by resource-poor farmers for protection of durable stored produce against pest infestation in Africa. A major research priority is a well designed on-farm trials to validate the efficacy of botanicals and inert dusts for stored-product protection using standard procedures and formulations that can be transferred to other communities. Key words : Botanicals, Residual insecticides, Inert dusts, Grain storage, Storage pests, Stored products

Direct and admixture toxicity of diatomaceous earth and monoterpenoids against the storage pests Callosobruchus maculatus (F.) and Sitophilus oryzae (L.)

We investigated the effects of two commercial diatomaceous earth based insecticides (DE), Protect-It® and SilicoSec®, the nano-structured silica product AL06, developed by the section for Urban Plant Ecophysiology at Humboldt University Berlin, and the monoterpenoids, eugenol, and cinnamaldehyde on two stored product pests, Callosobruchus maculatus and Sitophilus oryzae. Protect-It® was more effective than SilicoSec® against C. maculatus while the reverse was true for S. oryzae. Generally C. maculatus was more sensitive towards DE and silica treatment than S. oryzae. Mortality rate of both pest species increased when DE’s were applied to food commodities previously treated with a monoterpenoid. In admixture experiments, the toxicity of SilicoSec® + cinnamaldehyde (LD50 = 42.73 ppm), SilicoSec® + eugenol (LD50 = 24.30 ppm), and Protect-It® + eugenol (LD50 = 2.60 ppm) was increased over DE alone against S. oryzae. Both substances showed a synergistic effect considering their co-toxicity coefficient relative to the LD50-value. In contrast, we could not find any synergistic effects in experiments with C. maculatus. Here only Protect-It® + cinnamaldehyde (LD50 = 20.84 ppm) showed an additive effect while all other combinations of monoterpenoid and DE indicated antagonistic effects. In addition to contact insecticidal effects both monoterpenoids showed a strong fumigant action. The presented results indicate that the natural product DE has great potential to replace synthetic pesticides commonly used in stored product pest management. Efficacy of DE can be improved by adding certain monoterpenoids against certain insect pests.

Semiochemicals of stored-product insects: Research and applications

Development of semiochemical-based pest management systems in stored-products is being necessitated by the loss of traditional residual and fumigant pesticides. This review article evaluates our current state of knowledge and practice with semiochemicals for storage pests, it summarizes methods used for isolation and identification of semiochemicals, and it elaborates possible future research trends and applications. Pheromones are known from over 35 species of stored-product insects. The most successful applications of these compounds are as attractants in traps for detecting and monitoring pests in storage facilities. Recent research has focused on improving trapping technology by the discovery of additional pheromones, incorporation of food odor synergists, developing better slow-release formulations, and improving trap design. Direct control of storage pests with pheromones can be approached with the attracticide and mating disruption methods. Both techniques utilize synthetic female sex pheromones to prevent males from reproducing. Recent research is investigating attractants for female moths. Semiochemicals to manipulate female behavior will provide new tools for many different pest management approaches. Semiochemicals may be available to manipulate the behavior of beneficial natural enemies of storage pests. Host-finding efficiency of natural enemies in biological control programs could be improved with the use of kairomones in mass-rearing or release protocols. The role of semiochemicals in stored-product pest management is increasing as more biorational methods are employed.