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Loss of animal feed due to infestation by Rhyzopertha dominica: Poster
No full textDespite the use of natural food for livestock production, different animal feeds are currently available at the market. Long-term storage of these animal feeds lead to deterioration and contamination by insects. Therefore, it is important that the loss of these animal feeds be determined and methods to control the damage be sought. This study was conducted to determine the loss of eleven types of animal feed commonly used in Sri Lanka due to infestation by Rhyzopertha dominica, a major granivorous insect species. Twenty newly emerged adults of R. dominica were introduced separately to each animal feed: fish feed, rabbit feed, dog feed, cat feed, chick mash, grower mash, layer mash, broiler starter, broiler finisher, bird feed (Bajiri), and rice polish. Each animal feed was maintained either aerated or air tight. These parent adults were maintained for 21 days in the media under ambient environmental conditions (30°C, 65% relative humidity), and then removed. The progeny adults emerged in each feed sample were removed and the weight of the samples was determined at monthly intervals. In general, weight loss of animal feed varied with the feed type, duration of exposure, and aeration condition. Attention needs to be paid to protect those animal feeds that recorded higher losses due to R. dominica during storage.Despite the use of natural food for livestock production, different animal feeds are currently available at the market. Long-term storage of these animal feeds lead to deterioration and contamination by insects. Therefore, it is important that the loss of these animal feeds be determined and methods to control the damage be sought. This study was conducted to determine the loss of eleven types of animal feed commonly used in Sri Lanka due to infestation by Rhyzopertha dominica, a major granivorous insect species. Twenty newly emerged adults of R. dominica were introduced separately to each animal feed: fish feed, rabbit feed, dog feed, cat feed, chick mash, grower mash, layer mash, broiler starter, broiler finisher, bird feed (Bajiri), and rice polish. Each animal feed was maintained either aerated or air tight. These parent adults were maintained for 21 days in the media under ambient environmental conditions (30°C, 65% relative humidity), and then removed. The progeny adults emerged in each feed sample were removed and the weight of the samples was determined at monthly intervals. In general, weight loss of animal feed varied with the feed type, duration of exposure, and aeration condition. Attention needs to be paid to protect those animal feeds that recorded higher losses due to R. dominica during storage
Modelling of population dynamics of insects in any ecosystem with several distributions of insect development: A Review: Presentation
Get PDFPredicting the occurrence of insects with a high accuracy requires the estimation of insect development time and the variation among individuals for each life stage and species under different environmental conditions such as fluctuating temperature, variation of relative humidity, different body sizes and stages of the insects, levels of crowding, and food supply. This review summarized the modeling methods of population dynamics of insects with several distributions of insect development, assumption and prediction accuracy of these developed models, and disadvantages and advantages of these modelling methods. These modeling methods include degree day model, nonlinear model, and distribution delay models. The structure of most common models are cohort, Leslie matrix, simulation, and individual based. The relationships among the modeling assumptions, effects of temperature, and other environmental factors, and structures of the developed models were examined. A new modelling approach such as physiological-biological time scale and chaos theory was suggested.Predicting the occurrence of insects with a high accuracy requires the estimation of insect development time and the variation among individuals for each life stage and species under different environmental conditions such as fluctuating temperature, variation of relative humidity, different body sizes and stages of the insects, levels of crowding, and food supply. This review summarized the modeling methods of population dynamics of insects with several distributions of insect development, assumption and prediction accuracy of these developed models, and disadvantages and advantages of these modelling methods. These modeling methods include degree day model, nonlinear model, and distribution delay models. The structure of most common models are cohort, Leslie matrix, simulation, and individual based. The relationships among the modeling assumptions, effects of temperature, and other environmental factors, and structures of the developed models were examined. A new modelling approach such as physiological-biological time scale and chaos theory was suggested
Effect of delayed mating on reproductive performance of Lasioderma serricorne (F.) (Coleoptera: Anobiidae): Presentation
No full textWith the ban of methyl bromide and the many problems associated with the use of other synthetic chemicals, current research have focused on non-chemical alternatives and integrated pest management approach for the control of stored product insect pests. Mating disruption is one technique being investigated for its effect on stored product insects. In this study, we determined the effect of age at mating on the reproductive rate and longevity of the cigarette beetle, Lasioderma serricorne (Coleoptera: Anobiidae). We disrupted the mating approach by delaying the insects from mating for different time periods in days. Same age virgin male and female cigarette beetles were paired to mate soon after emergence (0 d old), or delayed from mating for 1–14 d. In another experiment, we maintained the age of the male at 0 d old and varied the age of the female from 0– 14 d old and vice versa. Insects were observed daily for longevity and F1 progeny was recorded 7–10 weeks after mating pairs were put together. Progeny production generally decreased with age of adults at mating. The number of F1 progeny produced by same age adults varied from 10 per female to 59 per female. Similarly, the number of progeny decreased the longer one sex was delayed from mating. Findings from this study may provide information for the development of mating disruption techniques that can delay mating and may be effective in keeping populations of L. serricorne below levels that would warrant a control action.With the ban of methyl bromide and the many problems associated with the use of other synthetic chemicals, current research have focused on non-chemical alternatives and integrated pest management approach for the control of stored product insect pests. Mating disruption is one technique being investigated for its effect on stored product insects. In this study, we determined the effect of age at mating on the reproductive rate and longevity of the cigarette beetle, Lasioderma serricorne (Coleoptera: Anobiidae). We disrupted the mating approach by delaying the insects from mating for different time periods in days. Same age virgin male and female cigarette beetles were paired to mate soon after emergence (0 d old), or delayed from mating for 1–14 d. In another experiment, we maintained the age of the male at 0 d old and varied the age of the female from 0– 14 d old and vice versa. Insects were observed daily for longevity and F1 progeny was recorded 7–10 weeks after mating pairs were put together. Progeny production generally decreased with age of adults at mating. The number of F1 progeny produced by same age adults varied from 10 per female to 59 per female. Similarly, the number of progeny decreased the longer one sex was delayed from mating. Findings from this study may provide information for the development of mating disruption techniques that can delay mating and may be effective in keeping populations of L. serricorne below levels that would warrant a control action
Sitotroga cerealella (Olivier) resilience to extreme temperature and desiccation may explain its increasing pest status in changing climates: Poster
Get PDFThe mechanisms underlying Sitotroga cerealella survival under variable and increasing mean thermal and desiccation environments typical under global change is currently unknown. To understand how S. cerealella survives extreme abiotic stressors typical of stored-grain environments, we measured S. cerealella tolerance temperature and desiccation. The results showed that to survive desiccating grain storage environments, S. cerealella relied more on high body water content (BWC) (70.2 ± 3.72%) compared to lipid reserves (9.8± 0.81%). In desiccating environment, S. cerealella showed a reduced water loss rate (0.056mg/h) (equivalent of 1.81% of body water/hour) which would require 19.31 h to reduce the insect body water to its critical minimum (35.23% body water content at death), which is 50.20% of normal initial body water. Similarly S. cerealella exhibited high basal heat tolerance with critical thermal maximum of 46.09 ± 1.042°C and a heat knockdown time of 7.97 ± 1.64 minutes. Basal cold tolerance was relatively compromised (critical thermal minima of 4.52 ± 1.06°C and chill coma recovery time of 5.80 ±1.17 minutes), following 1h at 0°C. We found no significant correlation (P > 0.001) between BWC and the measured thermal tolerance traits. Low water loss rates reported here may be an evolutionary resistance mechanism for desiccation tolerance. Observed abiotic stress tolerance may explain the ubiquitous distribution of S. cerealella in Africa which is likely to enhance its survival and increase its pest status under global change.The mechanisms underlying Sitotroga cerealella survival under variable and increasing mean thermal and desiccation environments typical under global change is currently unknown. To understand how S. cerealella survives extreme abiotic stressors typical of stored-grain environments, we measured S. cerealella tolerance temperature and desiccation. The results showed that to survive desiccating grain storage environments, S. cerealella relied more on high body water content (BWC) (70.2 ± 3.72%) compared to lipid reserves (9.8± 0.81%). In desiccating environment, S. cerealella showed a reduced water loss rate (0.056mg/h) (equivalent of 1.81% of body water/hour) which would require 19.31 h to reduce the insect body water to its critical minimum (35.23% body water content at death), which is 50.20% of normal initial body water. Similarly S. cerealella exhibited high basal heat tolerance with critical thermal maximum of 46.09 ± 1.042°C and a heat knockdown time of 7.97 ± 1.64 minutes. Basal cold tolerance was relatively compromised (critical thermal minima of 4.52 ± 1.06°C and chill coma recovery time of 5.80 ±1.17 minutes), following 1h at 0°C. We found no significant correlation (P > 0.001) between BWC and the measured thermal tolerance traits. Low water loss rates reported here may be an evolutionary resistance mechanism for desiccation tolerance. Observed abiotic stress tolerance may explain the ubiquitous distribution of S. cerealella in Africa which is likely to enhance its survival and increase its pest status under global change
Insects and fungi in stored maize in Angola: Poster
No full textIn underdeveloped countries in Asia and Africa, non-effective post-harvest technologies and sometimes ideal environmental conditions for development of pests like insects, fungi, rodents and birds, can lead to damage of both raw or processed foods. Losses can achieve considerable proportions in dried vegetables used as food products, particularly in underdeveloped countries where food security problems are a daily basis routine. The major goal of the present study was the identification of insects and fungi associated with maize under local storage conditions in the Angola provinces of de Benguela, Bié, Cuando Cubango, Cuanza sul, Huambo, Huíla, Luanda, Malange and Namibe. A wide range of storage methods for cereals were sampled, from small containers of peasants and small farmers up to the large metal containers used by large agricultural companies and Estates. The achieved results will contribute for food security improvement in Angola and for the maintenance and preservation of good and healthy seeds at the traditional farmers’ community level. The insect pests registered from the studied samples were Cryptolestes ferrugineus, Gnatocerus maxillosus, Liposcelis bostrychophila, Oryzaephilus surinamensis, Rhyzopertha dominica, Sitophilus zeamais, Sitotroga cerealella and Tribolium castaneum. The species Prostephanus truncatus was not found in the studied samples. Fungi in the genus Aspergillus, Fusarium and Penicillium were presented at a high incidence in all samples studied, although the relative abundance of different fungi species varied with the sample location.In underdeveloped countries in Asia and Africa, non-effective post-harvest technologies and sometimes ideal environmental conditions for development of pests like insects, fungi, rodents and birds, can lead to damage of both raw or processed foods. Losses can achieve considerable proportions in dried vegetables used as food products, particularly in underdeveloped countries where food security problems are a daily basis routine. The major goal of the present study was the identification of insects and fungi associated with maize under local storage conditions in the Angola provinces of de Benguela, Bié, Cuando Cubango, Cuanza sul, Huambo, Huíla, Luanda, Malange and Namibe. A wide range of storage methods for cereals were sampled, from small containers of peasants and small farmers up to the large metal containers used by large agricultural companies and Estates. The achieved results will contribute for food security improvement in Angola and for the maintenance and preservation of good and healthy seeds at the traditional farmers’ community level. The insect pests registered from the studied samples were Cryptolestes ferrugineus, Gnatocerus maxillosus, Liposcelis bostrychophila, Oryzaephilus surinamensis, Rhyzopertha dominica, Sitophilus zeamais, Sitotroga cerealella and Tribolium castaneum. The species Prostephanus truncatus was not found in the studied samples. Fungi in the genus Aspergillus, Fusarium and Penicillium were presented at a high incidence in all samples studied, although the relative abundance of different fungi species varied with the sample location
Drying ginger and preserving 6-gingerol: Poster
No full textGinger rhizome (Zingiber officinale) is widely used as a spice or as a medicinal plant. The major bioactive compound in fresh ginger rhizome is 6-gingerol and it is known for having a number of physiological effects. This compound is heat-sensitive and during cooking or drying will transform into 6-shogaol. Hence, the 6- gingerol content is used to evaluate the quality of dried ginger. The content of 6-gingerol during drying was measured using HPLC. Several factors that could affect the 6-gingerol content were considered and a predictive model for changes in 6-gingerol has been developed from the experimental data. The predictive model includes a single term drying model that predicts the changes of moisture content during drying. Drying time and relative humidity (ranging from 10% to 40%) impacted 6-gingerol content whereas drying air temperature (ranging from 30ºC to 60ºC) had a lesser effect. It was also found that the 6-gingerol content in fresh rhizomes was highly variable and thus required thorough testing prior to drying to be able to make the prediction more accurate.Ginger rhizome (Zingiber officinale) is widely used as a spice or as a medicinal plant. The major bioactive compound in fresh ginger rhizome is 6-gingerol and it is known for having a number of physiological effects. This compound is heat-sensitive and during cooking or drying will transform into 6-shogaol. Hence, the 6- gingerol content is used to evaluate the quality of dried ginger. The content of 6-gingerol during drying was measured using HPLC. Several factors that could affect the 6-gingerol content were considered and a predictive model for changes in 6-gingerol has been developed from the experimental data. The predictive model includes a single term drying model that predicts the changes of moisture content during drying. Drying time and relative humidity (ranging from 10% to 40%) impacted 6-gingerol content whereas drying air temperature (ranging from 30ºC to 60ºC) had a lesser effect. It was also found that the 6-gingerol content in fresh rhizomes was highly variable and thus required thorough testing prior to drying to be able to make the prediction more accurate
Evaluation of insecticidal efficacy and persistence of Nigerian raw diatomaceous earth against Callosobruchus maculatus (F.) on stored cowpea: Presentation
Get PDFThe insecticidal efficacy and persistence of Nigerian raw diatomaceous earth (DE) were evaluated in the laboratory on cowpea against Callosobruchus maculatus (F.) (Coleoptera: Chrysomelidae). The raw DE was applied to 1.5 kg lots of cowpea seeds at 0 (untreated control), 250, 500, 750, 1000 and 1500 mg/kg, and a commercial DE formulation (Protect-It®) applied at 1000 mg/kg was included in the test as positive (treated) control. The treated cowpea seeds were kept under ambient laboratory conditions (26 - 34°C and 24 - 93% RH. Bioassays were conducted on samples taken from each treatment at the day of storage and every 30 d for 6 consecutive months. Adult C. maculatus were exposed for 3 and 5 d to the samples and adult mortality was assessed over this exposure interval and progeny production and seed damage were assessed after additional 30 d. On freshly treated cowpea, both the raw DE and Protect-It® were highly effective against C. maculatus causing 100% adult mortality following 5 d of exposure. In general, the raw DE was less persistent on cowpea providing complete adult mortality only for two months. Protect-It® on the other hand was stable over the 6- month period of storage causing 95.8 to 100% adult mortality. None of the treatments completely inhibited progeny production after 2-3-moths storage period. The results of this study indicated that Protect-It® may provide suitable protection for 6 months against C. maculatus, but the raw DE in its present state is not suitable for long-term protection against this insect pest.The insecticidal efficacy and persistence of Nigerian raw diatomaceous earth (DE) were evaluated in the laboratory on cowpea against Callosobruchus maculatus (F.) (Coleoptera: Chrysomelidae). The raw DE was applied to 1.5 kg lots of cowpea seeds at 0 (untreated control), 250, 500, 750, 1000 and 1500 mg/kg, and a commercial DE formulation (Protect-It®) applied at 1000 mg/kg was included in the test as positive (treated) control. The treated cowpea seeds were kept under ambient laboratory conditions (26 - 34°C and 24 - 93% RH. Bioassays were conducted on samples taken from each treatment at the day of storage and every 30 d for 6 consecutive months. Adult C. maculatus were exposed for 3 and 5 d to the samples and adult mortality was assessed over this exposure interval and progeny production and seed damage were assessed after additional 30 d. On freshly treated cowpea, both the raw DE and Protect-It® were highly effective against C. maculatus causing 100% adult mortality following 5 d of exposure. In general, the raw DE was less persistent on cowpea providing complete adult mortality only for two months. Protect-It® on the other hand was stable over the 6- month period of storage causing 95.8 to 100% adult mortality. None of the treatments completely inhibited progeny production after 2-3-moths storage period. The results of this study indicated that Protect-It® may provide suitable protection for 6 months against C. maculatus, but the raw DE in its present state is not suitable for long-term protection against this insect pest
Phosphine resistance status in lesser grain borer Rhyzopertha dominica (Fab.) (Coleoptera: Bostrichidae) strains originating from the tropical countries: Presentation
Get PDFStored product beetles that are resistant to the fumigant phosphine (hydrogen phosphide) have been reported for more than 50 years in many places worldwide. The high levels of phosphine resistance in lesser grain borer Rhyzopertha dominica (F.) have been noted from several countries including Bangladesh. This study was designed to evaluate the status of resistance to phosphine in Bangladeshi R. dominica and to verify the possible comparison among other phosphine resistant strains from tropical countries viz. Burkina Faso and Malaysia. The data reported and summarized here showed varied levels of resistance compared to the laboratory phosphine susceptible strain (RDLAB). Rhyzopertha dominica strains originating from Bangladesh (RDBGD) and Burkina Faso (RDBKF) exhibited higher levels of resistance to phosphine compared to the Malaysian strains (RDMAL). Analysis of dose–response data indicated that the RDBGD and RDBKF strains were the most resistant to phosphine under different exposure periods. At LC50, these two strains were more than 80-fold more resistant at all exposures compared to the susceptible strain. Results also revealed that RDBGD and RDBKF strains required a relatively high concentration of 334.94 and 240.081 mg L-1 for 99% mortality. The mean survival time (MST) for the phosphine resistant and susceptible also varied significantly. The maximum MST was recorded for RDBGD and RDBKF strains. The present findings further confirmed that the Bangladeshi originated R. dominica strain contained higher resistance to phosphine compared to strains from other countries. This study could be useful in developing management strategies to prevent stored grain from being infested by resistant strains of R. dominica in tropical countries.Stored product beetles that are resistant to the fumigant phosphine (hydrogen phosphide) have been reported for more than 50 years in many places worldwide. The high levels of phosphine resistance in lesser grain borer Rhyzopertha dominica (F.) have been noted from several countries including Bangladesh. This study was designed to evaluate the status of resistance to phosphine in Bangladeshi R. dominica and to verify the possible comparison among other phosphine resistant strains from tropical countries viz. Burkina Faso and Malaysia. The data reported and summarized here showed varied levels of resistance compared to the laboratory phosphine susceptible strain (RDLAB). Rhyzopertha dominica strains originating from Bangladesh (RDBGD) and Burkina Faso (RDBKF) exhibited higher levels of resistance to phosphine compared to the Malaysian strains (RDMAL). Analysis of dose–response data indicated that the RDBGD and RDBKF strains were the most resistant to phosphine under different exposure periods. At LC50, these two strains were more than 80-fold more resistant at all exposures compared to the susceptible strain. Results also revealed that RDBGD and RDBKF strains required a relatively high concentration of 334.94 and 240.081 mg L-1 for 99% mortality. The mean survival time (MST) for the phosphine resistant and susceptible also varied significantly. The maximum MST was recorded for RDBGD and RDBKF strains. The present findings further confirmed that the Bangladeshi originated R. dominica strain contained higher resistance to phosphine compared to strains from other countries. This study could be useful in developing management strategies to prevent stored grain from being infested by resistant strains of R. dominica in tropical countries