Insect-damaged Kernels Research Articles

A study to clarify whether sunn pest (Eurygaster integriceps) increases amylase activity in wheat

There is uncertainty as to whether amylase is injected into wheat kernels by the sunn pest (SP). There are conflicting results in the literature as to whether the amylolytic activity (AA) of insect-damaged wheat is increased. Therefore, the research question of this study is whether amylase is injected into wheat kernels by SP. Two bread wheat cultivars with different levels of SP-damage were used (first year Golia 2.35 % SP damaged kernel ratio [SPDR], second year Golia 3.92 % SPDR and Sagittario 7.8 % SPDR). Sound and SP-damaged wheat (SPDW) kernels were manually separated. In addition, SPDW kernels were divided into four categories according to their infection rates. The AA of these different wheats was determined by using AACC methods 22-05.01 and 56–81.04. In cultivar Golia, the α-amylase activity of the most damaged wheat (C4/4 WGWF) was 9.5 times higher than that of the undamaged wheat. The SP-damaged samples had a lower Falling Number (FN), i.e. higher AA, than the undamaged samples in both cultivars. The FN values of the flour samples prepared from the 100 % SPDW were reduced by up to 40 % compared to the undamaged samples. In conclusion, we clearly found increased amylase activity in SPDW. As the proportion of insect-damaged kernels in the wheat mass increased, the AA of the wheat and its flour also increased, as did the proteolytic activity. Because the AA in some wheats is insufficient for bread-making, SPDW can be blended to sound wheat varieties within certain limits to reduce or reset the use of amylase base additives and reduce bread costs.

Preharvest insect pests of peanuts and associated aflatoxin contaminants in Georgia, USA.

On-farm losses of peanuts (Arachis hypogaea L.,Fabales: Fabaceae) pose a persistent threat to the sustainable production and value of peanuts in the United States. This study presents empirical data on the spatial distribution of subterranean insect pests and various quality aspects of peanuts. Surveys were conducted in 20 randomly selected peanut fields in 10 counties in Northeast, Southeast, and Southwest Georgia. The primary insect pests found in Georgia's peanut production counties were Pangaeus bilineatus (Say), Elasmopalpus lignosellus (Zeller), and Diabrotica undecimpunctata Howardi. In the northeast counties, a high prevalence of P. bilineatus led to a significant increase in insect-damaged pods (%IDP), insect-damaged kernels (%IDK), discolored kernels (%DK), pod weight loss (%PWL), and kernel weight loss (%KWL). Similarly, southeast counties had a high %DK, cracked pods (%CP), and E. lignosellus infestation. In southwest counties, predominantly high D. undecimpunctata infestations resulted in the highest %IDP. Moisture content (%MC) was excessively high in all the counties (22.19%-23.17%). Preharvest aflatoxin contamination in peanuts was prevalent across all studied locations, particularly in counties with a high incidence of P. bilineatus and may cause increased risk in aflatoxin levels along the supply chain. Nevertheless, the diverse regional abundance of insect pests and the widespread presence of aflatoxins in Georgia's peanut fields offer valuable insights for developing integrated pest management strategies targeting subterranean insect pests. This is especially crucial in addressing the impact of P. bilineatus, E. lignosellus, and D. undecimpunctata on aflatoxins content of peanuts and determining the pathway for mitigation of aflatoxin contaminations in peanuts at harvest.

Efficacy of two amorphous silica powders applied to soft red winter wheat against the lesser grain borer, Rhyzopertha dominica (F.) (Coleoptera: Bostrichidae)

The increased demand for residue-free grains and development of insect resistance to insecticides has led to a surge in the utilization of diatomaceous earths as grain protectants. Diatomaceous earth formulations, effective at lower application rates, are crucial for managing stored product insects without compromising grain quality. In this study, the efficacy of two different amorphous silica powders applied to soft red winter wheat was tested against the lesser grain borer, Rhyzopertha dominica (F.). Twenty adults of R. dominica were exposed to 100 g of organic soft red winter wheat admixed with varying application rates (0 for the untreated control, 0.05, 0.1, 0.15, and 0.20 g/kg) of silica powders 1 and 2. Mortality assessments were made after 14 d of exposure, and data on adult progeny production, insect-damaged kernels, and grain weight loss were determined at 42 d. Exposing R. dominica adults to wheat treated with 0.20 g/kg of silica powder 1 resulted in a mean ± SE of 94.5 ± 5.5% mortality and 1.3 ± 1.3 adult progeny production. Insect-damaged kernels and grain weight loss caused by R. dominica exposed to 0.20 g/kg of silica powder 1 were 0.19 ± 0.19 and 0.1 ± 0.1%, respectively. Exposure of R. dominica adults exposed to wheat mixed with 0.20 g/kg of silica powder 2 resulted in complete mortality, with no observed adult progeny production, insect-damaged kernels, or grain weight loss. Overall, silica powder 2 exhibited greater efficacy than silica powder 1, and this superior performance can be attributed to its higher oil adsorption capability and low pH (<8.5) value.

Insecticidal efficacy of two candidate diatomaceous earth powders against the lesser grain borer, Rhyzopertha dominica (F.) (Coleoptera: Bostrichidae)

The insecticidal efficacy of amorphous silica powders 1 and 2 with different physical and elemental compositions were evaluated against the lesser grain borer, Rhyzopertha dominica (F.) using concrete arenas. The particle diameter and shape characterization (circularity, elongation, aspect ratio, and convexity) of the two silica powders were performed using Morphology G3 instrument. The particle diameter and shape characteristics (circularity and elongation) of silica powder 1 were significantly higher compared to silica powder 2. However, these factors did not influence the efficacy of silica powders against R. dominica. Silica powder 2 showed higher mortality at lower application rates and shorter exposure times compared to silica powder 1. The efficacy of silica powder 2 was due to its higher oil adsorption capability, low pH, and high silicon dioxide content compared to silica powder 1. Adult progeny production was inversely related to the powder application rate. Silica powder 2 was more effective on R. dominica in inhibiting adult progeny production at 0.25 g/m2. Lower percentages of insect-damaged kernels and grain weight loss were observed at lower application rates (0.10–0.20 g/m2) following exposure to silica powder 2 compared to silica powder 1, which required higher application rates (2.0–3.5 g/m2). Overall, silica powder 2 demonstrated superior efficacy against R. dominica in terms of mortality, progeny production, insect-damaged kernels, and grain weight loss.

Competition of Rhyzopertha dominica and Sitophilus oryzae on six sorghum varieties

We tested the effect of simultaneous infestation by adults of the lesser grain borer, Rhyzopertha dominica (F.) and the rice weevil, Sitophilus oryzae (L.) on six sorghum varieties. For this purpose, vials containing sorghum and either each species alone or both species were placed at 30 °C and 65% relative humidity. After ten days, all parental adults were removed and the vials were returned to the same conditions. Five weeks later the vials were emptied, to record adult emergence, the percentage of insect damaged kernels (IDK), and frass weight. Our results indicated that progeny production capacity for both species was not affected by the simultaneous presence of R. dominica and S. oryzae, and that adult emergence was more of a variety- mediated parameter. Both species had previously shown similar preferences towards specific sorghum varieties. IDK and frass were higher in vials containing R. dominica alone rather than S. oryzae alone, but these indicators were not always related to progeny production. Specifically, the most and the least frass production was noted on Sumac and PE sorghum varieties for both species, respectively. When the two species were placed together in the same vial, the most frass production was noted in the Non-Waxy Burgundy and Sumac varieties. Our results suggest that varietal resistance in sorghum could be utilized to help reduce post-harvest infestations by S. oryzae and R. dominica.

Persistence and efficacy of diatomaceous earth against stored product insects in semi-field trials

The utilization of inert dusts, such as diatomaceous earths (DEs), has been successfully evaluated against a wide range of major stored-product pest species, as an environmentally friendly alternative to conventional insecticides, emphasizing further their prominent position in Integrated Pest Management (IPM) protocols. However, the majority of the published research about the DEs’ insecticidal efficacy has been conducted under laboratory conditions in small-scale samples (usually in small vials containing few grams of grains) and against specific insect species, while field and semi-field applications for the same purpose are disproportionally few. The objective of this work was to evaluate the insecticidal activity of a commercial DE formulation against stored product species that either artificially or naturally infested hard wheat, under “real-world” storage conditions. For this purpose, DE doses of 0 (control), 500 and 1000 ppm were applied in a series of lots of 20 kg of hard wheat stored in polypropylene woven bags and kept from August to December in a storage facility in Central Greece. According to our results, even the lower DE dose significantly suppressed the insect populations of Sitophilus oryzae (L.) (Coleoptera: Curculionidae), Rhyzopertha dominica (F.) (Coleoptera: Bostrychidae) and Trogoderma granarium Everts (Coleoptera: Dermestidae) that were artificially added in the wheat bags but also of five other insect pest species that were found in the commodity, based on weekly monitoring via probe traps or grain samples. Rhyzopertha dominica, T. granarium and S. zeamais were the most numerous species found, while T. granarium was the most frequently sampled species. In general, the probe traps were more sensitive to captures, as compared to the grain samples. The evaluation of the grain quality (bulk density, insect damaged kernels) throughout the trials indicated higher insect infestations in the untreated wheat as compared to the treated one. At the same time, grain bulk density was lower in the treated than in the untreated wheat. We conclude that DE applications can effectively suppress the populations of a wide range of stored insect species, offering a prolonged protection under a wide range of environmental conditions.

Efficacy of deltamethrin and pirimiphos-methyl in proportionally layer-treated maize against the larger grain borer and the maize weevil.

Two insecticides (deltamethrin and pirimiphos-methyl) were evaluated in laboratory assays as grain protectants when applied as a total percentage of a maize mass to control adult Prostephanus truncatus and Sitophilus zeamais. All experiments were conducted at the University of Thessaly in Greece at 30°C and 65% RH under continuous darkness. Either insecticide was applied to 20 g of maize placed in a vial or to the upper one half, one fourth, or one-eighth layer of the maize, then insects were either added to the vials before or after the maize in a completely randomized block design CRBD with n = 9 replicates. Mortality, progeny production, and insect damaged kernels (IDK) were then evaluated for each vial. Insect introduction method (before or after) did not have any impact on any of the variables. Mortality was nearly 100% for all treatments for both insecticides for P. truncatus. Subsequently, progeny production and the number of insect damaged kernels were very low or zero for P. truncatus. Mortality of S. zeamais remained low across layer treatments for deltamethrin. However, S. zeamais was easily controlled by pirimiphos-methyl. The results of this laboratory study show that while deltamethrin and pirimiphos-methyl have some effectiveness as a layer treatment on a column of maize, efficacy will be dependent on the target species, and the depth of the treated layer, as well as the location on which the insects are present.

Assessment of the Purdue Improved Crop Storage (PICS) bag for maize storage in Ghana

Despite the recent introduction of improved grain storage methods and technologies, many smallholder maize farmers in Ghana still use traditional storage practices and structures for storing their maize grains after harvest. This practice contributes to the high post-harvest losses in maize grain at the smallholder level largely due to insect pest infestation. Hermetic bag storage is a proven technology effective in reducing grain damage and losses from insect pests. In this study, the efficacy of the Purdue Improved Crop Storage (PICS) bag was compared with a polypropylene (PP) bag stored with maize treated with Betallic Super EC chemical and PP bag stored with maize without Betallic treatment (Control) during a 6-month storage period. Data on grain moisture content (MC), number of live insects, insect damaged kernels (IDK) and maize weight loss were collected monthly for analysis. Grain viability and nutrient analysis were also conducted before and after storage. The results showed initial grain moisture content of 11.4% was not significantly affected in the PICS bags but increased by 1-2% in the PP bags. Purdue Improved Crop Storage (PICS) bags and Betallic treatment significantly reduced insect damage grains with mean weight loss of &lt; 5% and 6.35 % respectively compared to the control (PP bag without Betallic) treatment with mean weight loss of 21 % over the 6-month storage period. Germination rate of sampled seeds after storage in the PICS bags (75 %) was not significantly different to the initial germination rate (78 %) compared to the control (PP bag without Betallic) treatment of 56 %. Overall, maize grains stored in the PICS bags showed no signs of deterioration as compared to grains in the PP bags. The PICS bags were superior to the PP bags in terms of other grain quality metrics assessed and the nutrient characterization such as protein and carbohydrate which had no significant difference (p&lt;0.05) between the initial and the three treatments. The results showed that PICS bags can be effective in protecting maize grains during storage. Smallholder farmers are therefore encouraged to consider this technology especially for controlling insect pests of stored maize. Key words: Insect pests, Polypropylene, Smallholder farmers, Purdue Improved Crop Storage bag

Population Growth Changes in Major Stored Product Insects on Rice Fortified with Spearmint and Basil

Rice is the most important durable food product for more than half of the world’s population, as it is very nutritious food in terms of carbohydrate containment and can meet a large part of human caloric needs on a daily basis. The sensitivity of a rice product fortified with spearmint or basil was evaluated for three stored product insect species: Sitophilus oryzae (L.) (Coleoptera: Curculionidae), Rhyzopertha dominica (F.) (Coleoptera: Bostrychidae) and Oryzaephilus surinamensis (L.) (Coleoptera: Silvanidae). Five different containments of fortified rice were used (0, 25, 50, 75 and 100% of the total rice quantity), and the population growth of the above species was examined after 65 days. We found that fortification generally reduced the infestation level of the species tested and reduced their population growth, as compared with the control rice. In some of the treatments, there were some differences between the application of spearmint and basil. There was higher frass production in the rice that had been fortified with basil than that with spearmint, indicating different infestation patterns. For S. oryzae, with the gradual increase in fortification, the number of insect-damaged kernels and weight of damaged kernels reduced, and significant differences were recorded between the fortification with spearmint and that with basil. The results of the present study are certainly encouraging for further utilization of the characteristics of fortified rice for stored product insect control.

Competition between Prostephanus truncatus and Sitophilus oryzae on maize: the species that gets there first matters

AbstractLaboratory tests were carried out in order to examine the population growth of Prostephanus truncatus (Horn) (Coleoptera: Bostrychidae) and Sitophilus oryzae (L.) (Coleoptera: Curculionidae) on maize. These two species were placed either simultaneously or one species was allowed to colonize the kernels 7 days earlier than the other, at two temperatures, 26 and 30 °C for 65 days. Apart from progeny production, grain quality parameters, such as insect-damaged kernels (IDK) and undamaged kernels (NDK), the weight of frass and kernel weight were measured. Our data confirms that temperature plays a key role in the competition of these two species; P. truncatus seems to perform better at the higher temperature (30 °C), regardless of the presence of an additional species. Moreover, the results of the present study demonstrates that P. truncatus outcompetes S. oryzae. Sitophilus oryzae produced fewer progeny than P. truncatus in all combinations. Given the outcome of a competition, we hypothesize that most of the kernel damage was due to feeding by P. truncatus. Based on these data, we surmise that P. truncatus has a competitive advantage as an invasive species in new areas with stored maize, even in the presence of S. oryzae.

Assessing efficacies of insect pest management methods to preserve nutritional composition of bagged maize in storehouses located in markets in Nigeria

Maize needs to be stored using effective and safe postharvest management measures to prevent physical insect damage as well as ensure stability of nutritional quality during storage. In this study, conducted in February–December 2016, insect pest management methods for bagged maize preservation in storehouses located in markets in Nigeria were evaluated for their ability to preserve nutritional quality. Study locations were in three grain markets, namely Eleekara market in Oyo town and Arisekola market in Ibadan, Oyo State, South West Nigeria, and Ago market in Ilorin, Kwara State, North Central Nigeria. Treatments comprised Piper guineense(Botanical), Bularafa diatomaceous earth (DE), permethrin powder(Rambo™) (Permethrin), PICSbags(hermetic)and ZeroFly® bags(non-hermetic). The study also had negative control(Control)comprising untreated maize in polypropylene bags. In general, as a result of insect infestation, protein content increased in all treatments except PICS which had the least infestation. After 11 months of storage, Permethrin and PICS treatments had the lowest insect infestation levels and the highest energy levels. Energy level in the Botanical treatment was also high and similar to levels in Permethrin and PICS treatments most likely due to fats and essential oils in P. guineense being adsorbed and/or absorbed by kernels. Fat content was lower in the Control and DE treatments likely due to the Control having the highest insect infestation and the DE adsorbing and/or absorbing fat from kernels. During storage carbohydrate content decreased in all treatments except the Control. However, even in the Control, there was a clear trend of decrease in carbohydrate content. Because the Control had the highest insect (Sitophilus zeamais) infestation and insect damaged kernels (IDK), this trend in decrease in carbohydrate content may be insect related. Ash content increased in the ZeroFly treatment, was unchanged in Botanical, Control, and PICS treatments, and decreased in DE and Permethrin treatments. Nutritional quality variables in this study were within or close to the known value ranges for maize. Therefore, use of maize that had been fumigated well and had a relatively low initial grain MC (9.1%), in addition to the effects of the treatments most likely slowed down population growth of the several insect species that were found and contributed to preserving nutritional quality. The relatively low insect populations in all treatments, including the Control, during the February–September period probably reduced the clarity of effects of infestation on nutritional composition reported in this study.

Efficacy of visual evaluation of insect-damaged kernels of malting barley by Sitophilus granarius from various observation perspectives

Although there is growing evidence that arthropod detection methods are not sensitive enough to meet current quality demands, few adequate validations are available for the detection of insect-damaged kernels (IDK- quality parameter). Therefore the aims of this work were to (i) describe categories of exit holes of Sitophilus granarius (L.) in terms of their location on the grain surface; (ii) analyse spatial distribution of exit holes on kernels of three varieties of malting barley; (iii) analyse the sensitivity of visual laboratory methods for IDK detection, and (iv) test if the turning effect of automatic shaking can increase damage visibility from the upper-view perspective of an inspector. Six topological categorises of exit holes were described and photo-documented. It was found that the relative distribution of exit holes on the kernel surface was in decreasing order from lateral, brush, ventral or dorsal (depending on variety), subapical, to germ area. The ventral and dorsal exit holes were significantly bigger than the apical exit holes. It was found that distribution patterns of exit holes on kernels affected their proportional visibility from various observation perspectives. Only 50% of lateral or dorsal exit holes was visible from top or crease views, respectively. The most effective was the side (brush end) view perspective, with visibility of up to 90% of exit holes. Although the shaking effect was statistically significant, it only increased the efficacy of upper view detection perspective from 54% to 58%. This is the first study showing that the inspector upper view of inspected grain samples (without grain rotation) poses a risk of underestimating actual insect-damaged kernels by 50%. Thus, advanced methods that are independent of observation perspectives (X-ray, NIRS, etc.) should be promoted for routine use in commercial laboratories, despite higher cost.

Susceptibility of Ethiopian wheat varieties to granary weevil and rice weevil infestation at optimal and sub-optimal temperatures

Integrating varietal resistance with temperature manipulation during storage may provide a better option for protection of stored grains and may decrease reliance on the use of synthetic chemicals. The current study was conducted to determine the susceptibility of different varieties of wheat seed to the infestation by the granary weevil, Sitophilus granarius (L.), and rice weevil, Sitophilus oryzae (L.), at optimal (30 °C) and sub-optimal (19 °C) temperatures. Kernels of six wheat varieties namely, Danda'a, Digalu, ET-13-A2, Kakaba, Millennium, and Pavon-76 were examined over a period of 90 d. Significant interactions were detected between wheat varieties and storage temperature for progeny emergence, percentage of insect damaged kernels, grain weight loss, and amount of powder produced per gram of wheat. Kernels of Danda'a, infested with S. oryzae at 30 °C exhibited significantly lower mean progeny counts (13.3 live insects), lower percentage of grain weight loss (4.2%) and insect-damaged kernels (6.4%), and powder production (1.5 mg/g). Kernel weight and hardness index were negatively associated with percentage of insect damaged kernels and grain weight loss. Kernel diameter was positively associated with both of percentage of insect damaged kernels and grain weight loss. Wheat varieties with high Zeleny sedimentation values had lower percentage of insect-damaged kernels and grain weight loss. These results indicated that kernel weight, hardness index, and protein content are predominant factors contributing to wheat resistance against S. granarius and S. oryzae. The varieties Millennium and Danda'a can be considered with other integrated pest management approaches to reduce stored grain losses of wheat in Ethiopia.

Impact of storage structures on moisture content, insect pests and mycotoxin levels of maize in Ghana

Insect pests and fungal pathogens can cause extensive product losses and pose health risks in sub-Saharan Africa. In this experiment, maize stored as de-husked cobs or shelled maize in a ventilated crib and a metal bin, and in bags in warehouses, was monitored monthly in Ghana from October of 2015 to December of 2015 (the major season) and from January to April of 2016 (the minor season). Temperature, moisture content, insect pests, and associated damage were assessed monthly, and samples were taken in October, December, January, and April for mycotoxin analyses. Moisture content, which ranged from 9 to 15% during the year was occasionally greater in the bin and warehouse compared to the crib, and greater in months associated with the major season compared to other months. Temperatures varied with season but were generally warmer in the bin compared to the warehouse and crib. The predominant insect collected was Sitophilus zeamais (Motschulsky), with the lowest populations in the crib, but in each structure the populations were about 10x greater in the major season compared to the minor season. Sitotroga cerealella (Olivier) was the second most-prevalent species, but populations of this species were greater in the crib compared to the bin or warehouse. Scattered populations of other stored product insects were collected from the maize samples and in pheromone traps. Percentage insect damaged kernels (IDK) and weight loss were also greater in samples from months where S. zeamais was present. Aflatoxin was above 10 ppb only in the warehouse in December, while fumonisin levels in all the storage structures were <0.5 ppm for all months. Results show that maize stored during the major season in Ghana is at risk from insect damage, and metal bins could be utilized more frequently for storage.

Contact Toxicity of Filter Cake and Triplex Powders From Ethiopia Against Adults of Sitophilus zeamais (Coleoptera: Curculionidae).

Filter cake and Triplex are powdered by-products of aluminum sulfate and soap factories in Ethiopia, respectively. This study was aimed at determining contact toxicity of filter cake and Triplex powders against maize weevil, Sitophilus zeamais Motschulsky. Lethal concentrations for 99% mortality (LC99) against S. zeamais were determined by exposing adults for 12 h to filter cake (0.5-8 g/m2) and Triplex (1-9 g/m2) in concrete arenas. Lethal times for 99% mortality (LT99) were determined by exposing adults over time (1-24 h) in concrete arenas to 3 g/m2 of filter cake and 9 g/m2 of Triplex. Exposed adults were transferred to containers with 30 g of organic wheat and held at 28°C and 65% RH for 14 d to determine mortality. LC99 values for S. zeamais adults were 7.54 and 23.46 g/m2 when exposed to filter cake and Triplex, respectively. The corresponding LT99 values were 21.92 and 39.62 h when exposed to filter cake and Triplex, respectively. Effective concentrations and times for the 99% reduction of progeny production were determined from percentage reduction in adult progeny relative to production in control treatments after 42 d. EC99 values for progeny reduction were 2.48 and 18.59 g/m2 for filter cake and Triplex treatments, respectively. The corresponding ET99 values for progeny reduction were 17.49 and 22.31 h for filter cake and Triplex, respectively. Sitophilus zeamais exposed to filter cake produced lower percentage insect-damaged kernels and weight loss than Triplex. Filter cake was more efficacious against S. zeamais than Triplex.

Moisture content, insect pest infestation and mycotoxin levels of maize in markets in the northern region of Ghana

Reliable quantitative data on maize post-harvest losses and factors that cause them in northern Ghana are limited. In this study we assessed maize at six markets in the Northern Region of Ghana, in and around Tamale, during the harvest and storage period of October 2015–June 2016. Across all the markets and sampling periods grain temperature was 32.6 ± 0.2 °C and equilibrium moisture content (EMC) was 9.5 ± 0.2%. EMC tended to decrease to a low in January and February and then increased again, while mean maize temperature was above 30 °C in all months. The primary stored product insects collected from the samples were Tribolium castaneum (Herbst), Sitophilus spp., Rhyzopertha dominica (Fauvel), and Cryptolestes ferrugineus (Stephens). Using all the market and sampling month data, there was a significant correlation between EMC and total number of insects recovered, but not between total number of insects and temperature. The average percentage of insect-damaged kernels (IDK) in the maize sampled across all the markets and sampling periods was 2.7 ± 0.2%, with a range between 0 and 21.4%. Using all the market and sampling month data, levels of insect damage tended to be positively correlated with maize moisture, but not temperature, and levels of insect damage increased with number of stored product insects recovered. The action threshold for aflatoxin in maize in Ghana is 15 ppb, but overall mean aflatoxin level was 19.8 ± 1.5 ppb and aflatoxin levels ranged from 0.3 to 132.2 ppb, with 53% of the samples having levels above 15 ppb. The mean fumonisin level was 1.2 ± 0.0 ppm, which is below the 4.0 ppm action threshold for Ghana. Our results show that aflatoxin levels were high in the market maize in Northern Region of Ghana and insects were prevalent, even though grain moisture tended to be relatively low, especially compared to the Middle Belt of Ghana.

Evaluation of plastic and steel bins for protection of stored maize against Insect Infestation in Ghana

Maize is a staple food in Ghana where there is ever increasing demand for its use to also support poultry and livestock production. However, post-harvest loss of maize is high in Ghana. This study evaluated the effectiveness of plastic and steel bins as bulk storage structures to reduce maize post-harvest loss in Ejura, Ghana during the period from February 2016 to January 2017. Maize pre-disinfested with a solar biomass hybrid dryer was stored in the following treatments: i. a white 7-ton plastic bin filled with untreated maize, ii. agreen 7-ton plastic bin filled with untreated maize, iii.a 6-ton Kikapu steel bin filled with untreated maize, iv. six 50-kg polypropylene (PP) bags filled with maize treated with Betallic Super (80 g pirimiphos-methyl and 15 g permethrin per liter as an emulsifiable concentrate (EC)), and v. six 50-kg PP bags filled with untreated maize ascontrol. Moisture content, insect pests, insect damaged kernels (IDK), grain weight loss, aflatoxin and fumonisin levels data were collected monthly. Sitophilus zeamais, Tribolium castaneum, Cathartus quadricollis, and Cryptolestes ferrugineus were the dominant insect species collected from maize samples. At the end of 12 months of storage, % IDK in the control was >17% while IDK values in the other treatments were <3%. Mean grain weight losses of <1% were recorded in the bin treatments. Mycotoxin levels in the control were above the allowable threshold of 15 ppb. Our data suggest that use of plastic and steel bins has potential to reduce post-harvest loss of maize during storage.

On-farm maize insect pest and mycotoxin levels in Ghana: Presentation

Maize post-harvest losses are perennial in Ghana but reliable comparative information on on-farm losses of maize produced in the Middle and Northern Belts of Ghana is lacking. Two studies were conducted from September 2015 to February 2016 to identify factors contributing to on-farm losses of maize in these two Belts. In the Northern Belt, the study was conducted in six communities including Adubiyili, Diari, Pong-Tamale, Savelugu, Toroyili and Zamnayili; and in the Middle Belt, in Ejura, Sekyedumase and Amantin communities. Moisture content, percent weight loss, percent insect damaged kernels (IDK) on numerical basis (%IDKnb) and percent IDK by weight basis (%IDKwb), insect pest abundance, and mycotoxin levels were estimated. Moisture content values of maize at pre-harvest and heaping stages in all nine communities were below 15%. Sitophilus zeamais, Sitotroga cerealella, Cathartus quadricollis, and Carpophilus dimidiatus were found to attack maize onfarm in communities in the Middle Belt, but no adult insect pests were collected on pre-harvested maize in the Northern Belt. The %IDKnb values on-farm in all nine communities were < 2% per 250 g. Mean aflatoxin levels below 15 ppb were obtained from pre-harvested maize in both regions but levels above 15 ppb were obtained from heaped maize on-farm. Fumonisin levels of maize were below 4 ppm on pre-harvested and in heaped maize in both regions. Results show that heaping maize on-farm increases aflatoxin levels beyond the acceptable threshold level and should not be practiced.

Chilled aeration to control pests and maintain grain quality during the summer storage of wheat in north central region of Kansas.

Chilled aeration allows to cool grain, independent of ambient conditions, to safe temperatures where insect, fungi, and spoilage is reduced to the minimum. The objective of this research was to evaluate the advantages of using grain chilling to preserve the quality of grain and reduce post-harvest losses, compared to conventional aeration and storage strategies used during the summer storage of wheat in Central Kansas, U.S.A. The research trials were developed in two 1,350 metric ton (t) steel silos in a Farmer’s Cooperative during the summer and fall of 2015 and 2016. One of the silos was chilled and the other was used as a control managed by the Cooperative. Variables evaluated were: grain temperature, moisture content (MC), grain quality, insect development and reproduction rate. The chilling treatment reduced the grain temperature from 28°C- 39°C to a minimum of 17°C- 17.6°C in less than 250 hours. Grain temperatures below 25°C were not possible during the summer using ambient aeration. Minimum variation of MC was observed in the Chilled silo while ambient aeration reduced the MC by 0.5%. Reproduction rates of RFB and LGB were significantly reduced by chilled temperatures lower than 17°C. Lower temperatures also reduced insects discovered in probe traps and insect damaged kernels (IDK). The energy cost of the grain chiller was between 0.26 US $/t- 0.32 US $/t higher than ambient aeration.

Identification and classification of damaged corn kernels with impact acoustics multi-domain patterns

An impact acoustic signal device was tested with undamaged, insect-damaged, and mildew-damaged corn kernels, and the different signals were compared using ensemble empirical mode decomposition methods. These methods were adopted based on their known superiority in processing of non-stationary signals and in suppressing of mode mixing. Time domain, frequency domain, and Hilbert domain features were extracted from an ensemble empirical mode decomposition of the impact acoustic signals. Four features were extracted from the time domain: the average amplitude change, Wilson amplitude, average absolute value, and peak-to-peak value. Three features were extracted from the frequency domain: the mean square frequency, the root mean square of the power spectrum, and the frequency band variance. The energy of the high-frequency and low-frequency bands and the average values of the envelopes were extracted from the Hilbert domain. Subsequently, these features were used as inputs to a support vector machine which was optimized by particle swarm optimization. The use of hybrid features enabled higher classification accuracy than usage of features in each domain separately. In this study, achieving the classification accuracies were 99.2% for undamaged kernels, 99.6% for insect-damaged kernels and 99.3% for mildew-damaged kernels. These results, based on ensemble empirical mode decomposition and integration of multi-domain features, are encouraging for the potential of an automated inspection system.