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1.
Biological control of bruchids infesting cowpea stores was achieved by introducing adults of an endemic parasitoid Dinarmus basalis (Rondani) (Hymenoptera: Pteromalidae) into farmers’ storage systems in the guinean zone in Togo and the sudano-sahelian zone in Burkina Faso. In the guinean zone, introduction of 20 or 40 pairs of D. basalis adults at the beginning of storage and again 15 days later reduced the development of the bruchid populations after 5 months of storage. Consequently, weight losses from 25 kg batches of treated cowpea seeds were lower than 10% as compared with around 30% in controls. In the sudano-sahelian zone, an introduction of 40 pairs of D. basalis adults at the beginning of storage and again 15 days later was effective, also maintaining seed weight losses from 25 kg batches at less than 10%. These results illustrate that biological control of bruchids by the introduction of D. basalis adults into farmers’ cowpea storage systems is possible in the two climatic zones of Western Africa, and produces better cowpea seed quality. However, the introduction must take place right at the beginning of storage, and the number to be introduced must take into account the initial rate of seed infestation by the bruchids.  相似文献   

2.
A study was conducted to investigate species diversity and relative abundance of Callosobruchus (Coleoptera: Chrysomelidae), a major insect pest infesting stored cowpea in the central region of Ghana. Cowpea stocks from Burkina Faso, Ejura, Ghana and Niger were obtained from the markets, and held to collect adults emerging from the cowpeas. Adult Callosobruchus spp. were identified based on the pattern of their hind femora and elytra. Five species, Callosobruchus maculatus, Callosobruchus rhodesianus, Callosobruchus chinensis Callosobruchus analis and Callosobruchus subinnotatus, were identified, with C. maculatus being the most abundant.  相似文献   

3.
Stored insect pests often create major problems for farmers worldwide. Comprehensive data of insect pests of stored sorghum in Burkina Faso are scarce. Understanding the population structure of insect fauna infesting stored sorghum is important for development of management strategy. Sorghum panicles were collected from January to September 2011 in farmers' granaries in the Northern-Sudanian ecological zone of Burkina Faso to determine the diversity of insect pests and their importance in post-harvest losses. A total of 14 species of insect pests were recorded, including twelve coleopteran and two lepidopteran species. Species diversity peaked between May and September. The highest insect diversity was recorded in sorghum stored in straw granaries and on red coloured grains when compared with that of sorghum stored in mud granaries and on white coloured grains. Rhyzopertha dominica (Fabricius) appears to be the primary insect pest followed by secondary pests including Oryzaephilus mercator (Fauvel), Cryptolestes ferrugineus (Stephens) and Sitophilus zeamais (Motschulsky). The distribution pattern of the pests in granaries corresponds to the Mandelbrot model in which colonization of species in an environment depends on the physical conditions of that environment and on the species currently present, which suggest a progressive colonization occurs in waves with stocks of grain.  相似文献   

4.
Almonds (Prunus dulcis) are one of the high-value nuts facing insect pest infestation predicaments during post-harvest operations and subsequent storage. The red flour beetle (Tribolium castaneum) (Coleoptera: Tenebrionidae) is an economically important and notorious insect pest that globally infest almonds thereby resulting in high storage losses. Currently, the fumigants (hydrogen phosphide and propylene oxide) commonly used during almond storage pose a health hazard to the applicator and consumer as well as the environment. Other disadvantages of chemical methods include chemical residue, high exposure time (2–4 days), pest resistance, the demise of beneficial insects and incomplete disinfestation of the egg stage of the target pest. Among other physical disinfestation methods, the use of microwave as a disinfestation technique offer advantages of less processing time, lower energy consumption, clean technology, and no residues. Therefore to test the efficacy of microwave in pest control of stored almonds, we exposed life stages of T. castaneum to microwave irradiation at different power levels (120–600 W) and durations (30–90 s). Hundred percent mortality of all selected life stages was achieved at 480 and 600 W when infested almonds exposed for 90 and 60 s respectively. The quality attributes of treated almonds such as color difference, water activity, hardness, peroxide value, free fatty acid, and iodine value were measured and found to be acceptable. The fatty acid composition and sensory analysis demonstrated no significant difference (p > 0.05) in control and microwave treated almonds. The storage studies revealed that microwave treated almonds were free from infestation and rancidity for up to 12 months, whereas untreated almonds were spoiled within 3 months.  相似文献   

5.
We assessed the performance of hermetic triple layer Purdue Improved Crop Storage (PICS) bags for protecting Hibiscus sabdariffa grain against storage insects. The major storage pest in the grain was a bruchid, Spermophagus sp.. When we stored infested H. sabdariffa grain for six months in the woven polypropylene bags typically used by farmers, the Spermophagus population increased 33-fold over that initially present. The mean number of emergence holes per 100 seeds increased from 3.3 holes to 35.4 holes during this time period, while grain held for the same length of time in PICS bags experienced no increase in the numbers of holes. Grain weight loss in the woven control bags was 8.6% while no weight loss was observed in the PICS bags. Seed germination rates of grain held in woven bags for six months dropped significantly while germination of grain held in PICS bags did not change from the initial value. PICS bags can be used to safely store Hibiscus grain after harvest to protect against a major insect pest.  相似文献   

6.
Trials of the Purdue Improved Crop Storage (PICS) bag technology for the storage of paddy rice, Oryza sativa L., were conducted in Burkina Faso, Ghana and Niger. Paddy rice naturally infested with insects, the most abundant species being Tribolium spp. and Rhizopertha dominica, was sealed in triple layer PICS bags, or in conventional woven polypropylene sacks. At the end of 7–18 months of storage in PICS bags the number of insects did not increase, the weight of 100 seeds did not change, and the proportion of damaged seeds was not different from that present when the paddy was first put into the bags. By contrast, paddy stored in the conventional way in woven polypropylene bags exhibited weight losses ranging from 3 to 8.7%. In Bolgatanga, Ghana, where paddy was stored for 18 months, germination of paddy kept in the PICS bags was comparable to that present at the beginning of the experiment. PICS bags can be used for the safe, low-cost, insecticide free storage of paddy rice.  相似文献   

7.
Callosobruchus maculatus, a pest that causes serious damage to chickpea Cicer arietinum, cannot develop in the seeds of Phaseolus or Vigna spp. which contain lectins. The insecticidal activity towards C. maculatus in these seeds is attributed both to lectins with specific affinity to N-acetylglucosamine, the major component of insect chitin, and to alpha-amylase inhibitors (lectin-like proteins). The insecticidal properties of bean meal or bean protein extracts from different sources towards different pest species are variable and need to be experimentally evaluated. The main objective of this study was to determine through a feeding trial on artificial chickpea seed the potential of bean seed meal from a wild bean Vigna caracalla, four varieties of Phaseolus vulgaris, and of a protein extract of P. vulgaris seed, to alter different life history traits of C. maculatus. The chickpea weevil was set up on artificial chickpea seeds containing different amounts of bean meal to observe the effects on female oviposition, percentage of development to adulthood and juvenile development time. These traits were combined in a composite index measuring the alteration of the multiplication rate of C. maculatus fed on artificial seed. The activity of lectin-like extracts was observed on chickpea artificial seed spiked with bean seed extract. Incorporation of bean flour at a rate of 10 and 20% in chickpea artificial seed significantly decreased C. maculatus female fecundity, percentage of adult emergence, and greatly increased the development time. Feeding trials with protein extracts of P. vulgaris reduced fecundity and survival of C. maculatus. Incorporation of 10% V. caracalla bean seed meal in chickpea artificial seed, reduced the multiplication potential of C. maculatus by over 90% showing that bean seed lectin extracts are worthy of further investigation for post-harvest infestation control.  相似文献   

8.
Sunflower seeds are regularly infested by Plodia interpunctella during storage. Although this pest prefers damaged seeds, in practice it can infest undamaged seeds as well. This research assessed the influence of the sunflower seed type (oil, protein for human consumption and bird-feed) and the initial seed damage during post-harvest processing (dehulled kernels, 10, 20, 30% of damaged seeds and undamaged seeds) on development of P. interpunctella (larval mortality, larval development, mean developmental duration, adult emergence and fecundity). Biochemical analysis of seeds, kernels and hulls detected the highest content of phenols in the seed and hull and tocopherols in the kernel of the oil type hybrid. The antioxidative activity was the highest in the seed, kernel and hull of the protein type for bird feed. The shortest development (39.5 days) and the highest fecundity (91.3) were on the oil type seeds, while the longest development (42.1 days) and the lowest fecundity (68.1) were on the seeds of the protein type for bird feed. The highest mortality of larvae was on the undamaged seeds of the protein type for bird feed and human consumption (21.3% and 14.0%, respectively). The type of sunflower and the level of initial damage affected larval mortality, developmental duration and fecundity. The mean developmental duration and the number of emerged adults were dependent only on the initial seed damage. Principal component analysis detected strong positive correlation between mortality and development with the tocopherol content on the undamaged seeds while fecundity was associated with the state of kernel and the amount of tannins, proteins and oil content in the seed. The undamaged seeds of the protein type for the bird feed were the least suitable for the development of this pest, while the oil type kernels were the most suitable.  相似文献   

9.
In West Africa, the most damaging lepidopteran pest of maize ears is the pyralid Mussidia nigrivenella. Although it is mostly described as a field pest, it can be found feeding on maize stored for up to 4 months. A survey was conducted in Benin in 2006 to assess M. nigrivenella infestations in different maize storage systems in the Southern (SGS) and Northern Guinea Savanna (NGS). In SGS and NGS the percentage of infested stores decreased from 86.7% to 26.7% and from 51.4% to 14.3%, respectively, during the first 28 weeks of storage. During the same time, mean numbers of M. nigrivenella per cob decreased from 0.36 to 0.04 across both zones. All larval stages, but mostly 3rd-5th instars, were frequently found even after more than 12 weeks, indicating that M. nigrivenella may have reproduced in storage, although reinfestation or delayed development could also explain this observation. The highest M. nigrivenella incidences of 16.8% and 14.4% were found in the “Ava” and crib stores, respectively. Infestations were highest in “Ava” and lowest in maize grain stored in polyethylene bags or in mud silos. In a laboratory experiment, the presence of post-harvest beetles negatively affected the bionomics of M. nigrivenella, indicating strong interspecific competition.  相似文献   

10.
Seeds of mung bean (Vigna radiata (L.) R. Wilczek) are subject to loss of viability due to aging and damage from pulse beetles (or bruchids; Callosobruchus spp.) infestation during storage. We investigated whether seed drying using desiccants and hermetic packaging would prevent or ameliorate these consequences of storage. Sun-dried mung bean seeds at a moisture content of 10% were subjected to further drying for 72 h using five different desiccants: Drying Beads® (a zeolite-based desiccant), silica gel, sodium aluminum silicate, activated alumina, and cow-dung ash (a traditional desiccant). Seeds were subsequently stored in hermetic plastic containers in the presence of these desiccants under ambient conditions along with sun-dried seeds stored in cloth bags or in hermetic containers. In addition, parallel samples of each treatment were inoculated with one pair of bruchid beetles (C. chinensis L.) and stored under the same conditions. The seed drying treatments did not affect initial seed quality (germination percentage and seedling vigor) significantly. After storage for 9 months at ambient temperatures, seeds dried using Drying Beads, silica gel, sodium aluminum silicate and activated alumina had higher germination percentages, seedling vigor indices and soil emergence, and lower electrical conductivity (leakage upon imbibition) and fungal infestation compared to other conditions. In addition, the mung bean seeds inoculated with bruchids and stored with these effective desiccants had less damage, oviposition, and insect respiratory activity in the hermetic containers and maintained higher seed germination and seedling vigor after six months of storage compared to other treatments and controls. The results demonstrate the superior ability of desiccants to quickly and safely dry seeds prior to and during storage and the benefits of such drying and hermetic storage conditions for preventing seed deterioration and insect damage during storage.  相似文献   

11.
The cowpea weevil, Callosobruchus maculatus (F.) (Col.: Bruchidae) is a cosmopolitan field-to-store pest ranked as the major post-harvest pest of cowpea in tropical regions. The cold tolerance of an insect species can vary as a result of abiotic features including food resources. In this study, C. maculatus larvae were fed with proline and trehalose (10, 20, and 40 mmol) treated cowpea seeds to determine the effects of these potential cryoprotectants on the supercooling (SCP) and cold hardiness of the upcoming adult beetles. The SCPs of the control, proline-fed and trehalose-fed adults non-significantly changed from −18.2 °C for the control to −17.2 °C for trehalose-fed adults. The cold hardiness (24 h at 0, -5.0, −7.5, −10.0, and −12.5 °C) of the adults was almost the same for control and treatments. Median lethal times (LT50; lethal time for 50% mortality) were 6.3, 6.0, and 5.4 h, respectively. Moreover, feeding the larvae with proline and trehalose-treated seeds did not affect the proline and trehalose contents of the adult beetles. Our results showed that C. maculatus could not tolerate subzero temperatures well above their SCP, indicating that this species might be a chill-susceptible insect.  相似文献   

12.
Cowpea cultivars Ife Brown, Maiduguri-A, Maiduguri-B and TVu 2027, were screened for resistance to Callosobruchus maculatus (F.) attack using different seed and insect densities. The number of eggs laid on the seeds and most other demographic variables increased with increase in insect density (number of females per 40 seeds). Although the same trend was observed with increase in seed density (seeds per 8 females), this was less predictable. However, the number of eggs per seed decreased significantly as seed density increased, but increased with increase in female density. Adult emergence increased significantly with increase in both insect and seed density while the growth index did not vary. Significantly more eggs were laid on the seeds of TVu 2027 (the resistant control) than on all the other cultivars when 20 or 40 seeds were available to 8 females, or at the lowest insect density (2 females per 40 seeds). However, percentage adult emergence and growth were higher on Ife Brown (susceptible control) than on TVu 2027 and the two Maiduguri cultivars. Measurements of percentage adult emergence and growth index indicated clear cultivar differences at all seed and insect densities. Also, although the loss in weight of seed increased with increase in insect density and decreased significantly with increase in seed density, meaningful differences in resistance among test cultivars were not always apparent at all densities. Based on these findings, we propose using 40 seeds and 2 pairs of adult beetles in screening cowpea for resistance. In addition, we conclude that % adult emergence, growth index and % weight loss are the most reliable indicators for resistance of cowpea to damage by this insect. The need to standardize experimental procedures used for host plant resistance work on storage pests of cowpea is emphasized.  相似文献   

13.
Prostephanus truncatus is a pest that causes serious losses in stored maize (Zea mays L.) especially in developing countries. This research was conducted to investigate the use of post-harvest insect resistance maize in combination with biological control of P. truncatus by the predator Teretrius nigrescens to reduce maize storage losses. We studied the population dynamics of P. truncatus with and without a predator in combination with susceptible maize and resistant maize to insects under laboratory conditions. This study confirms that P84c3 is a resistant variety against P. truncatus. Maize resistant kernels had a reduction of 30% losses in comparison with susceptible kernels. Significant and favorable interactions were observed between P84c3 maize and presence of T. nigrescens. A dramatic reduction of 80% in progeny number, 81% grain weight loss, and 75% frass production caused by P. truncatus was observed when the predator was used in combination with P84c3. Resistant maize reduced the prey development time and consequently the insect density allowing the predator to control more effectively the population. Prey/predator proportion on resistant maize was significantly higher in comparison with susceptible kernels; thus, giving a more effective pest population control by the predator. These results demonstrated that the combination of post-harvest insect resistance maize with the predator T. nigrescens reduces grain maize losses by P. truncatus.  相似文献   

14.
The effect of different initial adult population densities of Tribolium castaneum (Herbst) at several post infestation storage times on the final adult population density, the percentage of damaged beans, the percentage of weight loss, and the weight of insect feeding residues on cocoa beans was investigated in laboratory experiments. Both factors interactively had highly significant (P < 0.01) effects on variables assessed. The highest mean final adult population density of 129.7 ± 4.6 was recorded in samples infested with the highest initial adult population density and stored for 150 d, while the least mean adult population density of 10.8 ± 0.54 was recorded on samples infested with the lowest initial adult population density in samples stored for 30 d. The highest percentage damaged cocoa beans 51.0 ± 1.21% was recorded in samples infested with the highest initial adult population density, while the least mean percentage damaged beans of 16.9 ± 1.26% was also recorded on samples infested with the lowest initial adult population density. Similar trends of means were recorded for all the remaining variables. Correlation between factors was significant and positive. Multiple and simple linear regressions analyses were also significant (P < 0.01) and all equations fitted the regression models and perfectly described the relationship between the independent and the dependent variables. Our results show that T. castaneum can impact negatively on both the quantity and quality of stored cocoa within just 30 days of infestation, with the impact increasing with increasing population density and post infestation storage time.  相似文献   

15.
Laboratory and on-farm trials were carried out to determine the effectiveness of cowpeas triple-bagging with heavy-grade polyethylene to control the cowpea weevil, Callosobruchus maculatus (F.), the main storage pest of cowpea, Vigna unguiculata, Walp, in West Africa. In the laboratory bruchids numbers and seed damage were significantly reduced when storing cowpeas within 2 layers High Density Polyethylene (HDPE) bags of at least 80 μm wall thicknesses. This thickness considerably reduced oxygen concentration in the bag after 5 days of storage and inhibited insect development. However late instar larvae and pupae were less affected by low oxygen concentration. On-farm storage trials with 2 layers HDPE 50 kg capacity bags tightly sealed and placed in an additional woven nylon bag (triple bag) was effective in controlling the bruchids for 7 months. Moreover, seed damage (<7%) and grain germination were not significantly affected (>89%). These findings allow optimizing the triple-bagging technology with readily local manufactured and affordable bags for long duration cowpea storage.  相似文献   

16.
Groundnut seeds are prone to quality deterioration and damage due to improper storage. Hermetic storage of pods offers a novel, sustainable and ecologically safe alternative over traditional methods. In this paper, we demonstrate the efficacy of triple-layer “Purdue Improved Crop Storage (PICS)” bags, (that comprises of two inner high density polyethylene bags and one outer woven polypropylene bag), for protecting pods from quality deterioration, damage by bruchids (Caryedon serratus) and aflatoxin contamination (Aspergillus flavus). Custom made triple-layer bags were used and pods (of cv ICGV 91114) were placed @ 2 kg/bag. Over four months of storage under ambient conditions, triple-layer bags supported retention of seed weight, germinability and oil content significantly better than cloth bags. Further, under both natural and artificial infestations with A. flavus, seed aflatoxins levels were lower in PICS bags compared to cloth bags. Toxin accumulation in PICS bags deliberately infested with bruchids and A. flavus was less compared to cloth bags under similar conditions. Bruchid damage to pods was less in PICS bags versus cloth bags in all cases. Our results suggest the superiority of triple-layer PICS bags over cloth bags in protecting seed viability, seed weight and oil content while safeguarding the groundnuts from bruchids and retarding toxin accumulation.  相似文献   

17.
Maize production in Ghana has been increasing steadily but increases in yield are being undermined by post-harvest losses. This study is part of a larger project to characterize post-harvest losses in Ghana at different points in distribution channels. Here we determined factors contributing to losses during on-farm storage in the Northern Region of Ghana. This study was conducted in six communities: Adubiyili, Diari, Pong-Tamale, Savelugu, Toroyili and Zamnayili. Losses were determined for maize on cobs stored in thatched granary structures, shelled maize in polypropylene (PP) bags stored on the floor in farmers’ homes or small storehouses, and shelled maize in PP bags stored in warehouses. Maize moisture content, temperature, percent weight loss, percent insect damaged kernels on numerical basis (IDKnb), insect pest abundance, and mycotoxin (aflatoxin and fumonisin) levels were determined. Moisture content values of maize at pre-harvest and heaping stages in all six communities were below 15% wb. There were no insect pests on maize at the pre-harvest stage and only a few larvae were found in the heaping stage, but Sitophilus spp., Tribolium castaneum and Cryptolestes ferrugineus infested maize during storage, with significantly more found in granary structures than maize in PP bags in homes or storehouses. Warehouses had significantly fewer insects than granaries and homes or storehouses. Percent IDKnb values in all six communities were <2% per 250 g in the field. Aflatoxin levels were significantly lower at the pre-harvest stage, with average concentration below action limits established in Ghana, compared to the heaping stage, where average level exceeded the threshold. Fumonisin levels were low and similar for both stages. Data from the present study show that heaping maize on-farm prior to primary processing can increase aflatoxin beyond the acceptable level and should not be practiced.  相似文献   

18.
Tocopherol-enriched oil was extracted by supercritical fluid extraction of carbon dioxide (SFE-CO2) from Kalahari melon and roselle seeds. The SFE-CO2 process was optimised using response surface methodology (RSM) with central composite design (CCD). Three SFE-CO2 parameters namely extracting pressure, extracting temperature, and flow rate of carbon dioxide were examined. The optimal SFE-CO2 conditions were determined and the quadratic response surfaces were drawn from the mathematical models. The optimal SFE-CO2 conditions for the extraction tocopherol-enriched oil from Kalahari melon seeds were: extracting pressure 290 bar, extracting temperature 58 °C, and flow rate of carbon dioxide 20 ml/min. The optimum conditions for roselle seeds were extracting pressure 200 bar, extracting temperature 80 °C, and flow rate of carbon dioxide 20 ml/min. These optimum conditions yielded tocopherol concentration of 274.74 and 89.75 mg/100 g oil from Kalahari seed and roselle seed, respectively. No significant (P > 0.05) differences were obtained between the experimental and predicted values.  相似文献   

19.
The quality of maize offered for sale in West African public markets was evaluated by analysing 281 samples collected in 24 markets in Benin, Togo, Ghana and Burkina Faso from February to March 2014. Grain moisture content ranged from 8.5 to 14.4 percent (wt/wt), while extraneous matter content ranged between 0.0 and 2.0% and the proportion of mouldy grains between 0.0 and 0.6%. Insect pest infestations were noted in about one-fourth of the samples with Sitophilus sp., Cryptolestes ferrugineus Stephens, Tribolium sp. and Prostephanus truncatus Horn found at densities varying between 0 and 2.4 individuals per 500 g of grain. Aflatoxin levels exceeding the accepted USA standard of 20 ppb were recorded in only 4.6% of the samples across the four countries. In most locations, grain moisture was within the acceptable range for aflatoxin- and insect-safe storage of maize using hermetic technology such as PICS bags.  相似文献   

20.
Moth pests belonging to the Tineidae attack clothing and other animal products, during the processing or manufacturing stage as well as in storage. The insects cause considerable loss or damage to the commodity in terms of quantity, quality and market value. Insect control measures in these products differ depending on the conditions of storage or processing and the relevant cost factor. Fumigation products play an important role in insect pest elimination for the majority of stored animal products. The need of detailed studies on alternatives methods involving the exploitation of insect traps for pest management has been highlighted. In the past years test systems for the evaluation of attractant products have been developed and further refined in our laboratory. In this study, a standardized test system for the evaluation in vitro of commercial traps for Tineola bisselliella, the webbing clothes moth (WCM), was validated. Three sticky traps baited with female-produced sex pheromone were tested in the laboratory and in vivo at the “Mobilier National”, a repository of valuable artefacts. In both types of experiment the number of individuals captured was closely linked with the kinetic release of volatile organic compounds (VOCs) from the sticky traps. The test system allowed clear discrimination of the products according their efficiency in a reliable manner but none of the traps tested were effective enough to reduce the damage potential of the pest.In the light of these results, the characteristics needed for an effective trap in warehouse conditions is discussed.  相似文献   

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