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Raul Narciso C. Guedes - One of the best experts on this subject based on the ideXlab platform.
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Walking activity and dispersal on deltamethrin- and spinosad-treated grains by the Maize Weevil Sitophilus zeamais
Crop Protection, 2019Co-Authors: M. Vélez, Wagner Faria Barbosa, Rodrigo Cupertino Bernardes, Jéssica Cristina Dos Santos, Raul Narciso C. GuedesAbstract:Abstract The Maize Weevil (Sitophilus zeamais) is a serious worldwide pest of stored products frequently requiring control measures to reduce its infestation and minimize grain losses. The fumigant phosphine and insecticides including pyrethroids and organophosphates have been the most used management tools against this stored product pest, but the over-reliance on these chemical products has led to insecticide resistance in Maize Weevil populations. A recent alternative, the actinomycete-based insecticide spinosad, has been considered highly effective against several stored grain pests, including Maize Weevils, and has sparked increasing attention. Nonetheless, the sublethal effects of spinosad have yet to be studied, particularly regarding its potential effect on insect dispersal within contaminated grain masses since exposure may be either enhanced or compromised. Thus, we carried out laboratory experiments using a digital tracking system and commercial insecticide formulations with the objective to assess if deltamethrin- or spinosad-contaminated grains may affect the walking activity and dispersal movements of adult Maize Weevils. The overall activity of groups of Weevils was enhanced with insecticide exposure. However, insecticide exposure did not affect resting time and distance walked, but velocity and number of stops were affected compromising walking in individual walking bioassays. Insecticide avoidance by either irritability and repellence were not detected. Dispersal of adult Maize Weevils on treated grains differed among insecticidal treatments with individuals spending more time at the edges of arenas in non-treated and deltamethrin-treated grains. In contrast, insects on spinosad-treated grains were more evenly distributed within the arena. These findings reinforce the potential of spinosad as an alternative for managing Maize Weevils because this insecticide minimizes the risk of dispersal away from treated grains.
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Spinosad-induced stress on the Maize Weevil Sitophilus zeamais:
Julius-Kühn-Archiv, 2018Co-Authors: Raul Narciso C. Guedes, M. Vélez, Spencer S. WalseAbstract:Although seldom considered, sublethal insecticide exposure may lead to harmful, neutral, or even beneficial responses that may affect (or not) the behavior and fitness of the exposed insects. Intriguingly, little is known about such effects on stored product insect pests and even less is available regarding the bioinsecticide, spinosad. Thus, we assessed the sublethal effects of spinosad on walking, feeding, drinking and mating behaviors of Maize Weevils (Sitophilus zeamais), also assessing their survival, reproductive output, and grain loss compared with Maize Weevils exposed to the pyrethroid deltamethrin (as positive control), and water only (negative control). Both spinosad and deltamethrin were able to effectively control the insects, although the latter caused a faster mortality than the former. Behavioral pattern changes were caused by both insecticides, especially deltamethrin, triggering irritability (i.e., avoidance after contact). Different feeding and drinking responses were also detected with significant avoidance to deltamethrin, but not to spinosad. Maize Weevil couples sublethally exposed to deltamethrin and spinosad exhibited altered reproductive behavior, a likely consequence of their altered activity, but deltamethrin caused greater behavioral changes. Curiously, higher progeny emergence and grain loss were observed in deltamethrin-exposed insects, suggesting that this pyrethroid insecticide elicits hormesis in Maize Weevils that may compromise control efficacy by this compound. In contrast, such effect was not detected with spinosad, which did not elicit avoidance allowing the intended Weevil exposure and control.
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Bidirectional selection of walking velocity, associated behavioral syndrome and reproductive output in the Maize Weevil Sitophilus zeamais
Journal of Pest Science, 2018Co-Authors: Leonardo Morais Turchen, Lírio Cosme, Raul Narciso C. GuedesAbstract:Individual behavioral types (i.e., personality traits) and their interrelations (i.e., behavioral syndrome) are recognized in arthropods and are of ecological and evolutionary importance. This aspect is also important in applied entomology, as distinct personality types may exhibit different fitness consequences. Here, we attempt to understand how within-population variation in a personality trait responds to selection and affects other personality traits. Our main focus was a quantifiable behavioral trait (i.e., walking velocity), its potential association with other personality traits, and how these traits are related to the reproductive output. The Maize Weevil (Sitophilus zeamais), a key pest of stored cereal grains, was used to test these hypotheses, and we detected that walking velocity is amenable to selection in this species. Furthermore, bidirectional selection with regard to walking velocity (i.e., either high or low) had an impact on the behavioral type, thereby allowing the recognition of different behavioral patterns among the strains. The generated multi-dimensional behavioral constructs of personality indicate consistent divergence among the strains with a stronger contribution of the activity dimension. Walking velocity was associated with other behavioral traits, particularly within the activity dimension, indicating the existence of a behavioral syndrome in the Maize Weevil. Furthermore, this behavioral dimension (i.e., activity), and particularly walking velocity, was associated with the reproductive output of Maize Weevil.
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Spinosad- and Deltamethrin-Induced Impact on Mating and Reproductive Output of the Maize Weevil Sitophilus zeamais.
Journal of economic entomology, 2018Co-Authors: M. Vélez, Leonardo Morais Turchen, Lorena L. Botina, Wagner Faria Barbosa, Raul Narciso C. GuedesAbstract:Assessments of acute insecticide toxicity frequently focus on the lethal effects on individual arthropod pest species and populations neglecting the impacts and consequences of sublethal exposure. However, the sublethal effects of insecticides may lead to harmful, neutral, or even beneficial responses that may affect (or not) the behavior and sexual fitness of the exposed insects. Intriguingly, little is known about such effects on stored product insect pests in general and the Maize Weevil in particular. Thus, we assessed the sublethal effects of spinosad and deltamethrin on female mate-searching, mating behavior, progeny emergence, and grain consumption by Maize Weevils. Insecticide exposure did not affect the resting time, number of stops, and duration of mate-searching by female Weevils, but their walking velocity was compromised. Maize Weevil couples sublethally exposed to deltamethrin and spinosad exhibited altered reproductive behavior (walking, interacting, mounting, and copulating), but deltamethrin caused greater impairment. Curiously, higher grain consumption and increased progeny emergence were observed in deltamethrin-exposed insects, suggesting that this pyrethroid insecticide elicits hormesis in Maize Weevils that may compromise control efficacy by this compound. Although spinosad has less of an impact on Weevil reproductive behavior than deltamethrin, this bioinsecticide also benefited Weevil progeny emergence, but did not affect grain consumption. Therefore, our findings suggest caution using either compound, and particularly deltamethrin, for controlling the Maize Weevil, as they may actually favor this species population growth when in sublethal exposure requiring further assessments. The same concern may be valid for other insecticides as well, what deserves future attention.
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Insecticide resistance and size assortative mating in females of the Maize Weevil (Sitophilus zeamais).
Pest management science, 2016Co-Authors: Erick M. G. Cordeiro, Alberto S Correa, Conrado A. Rosi-denadai, Hudson Vaner Ventura Tomé, Raul Narciso C. GuedesAbstract:BACKGROUND Random mating is a common assumption in studies of insecticide resistance evolution, but seldom tested despite its potential consequences. Therefore, the existing evidence of female choice and insecticide resistance in populations of the Maize Weevil (Sitophilus zeamais), a key pest of stored cereals, led to the assessment of mating preferences and their association with insecticide resistance in this species. RESULTS Mixed lines of a Maize Weevil colony were established from field-collected populations, which after 5 months of natural breeding were selected for deltamethrin resistance for five generations, reaching over 100-fold resistance. Mating preference was significantly based on the partner size, measured as body mass (χ2 = 5.83, df = 1, P = 0.016). Susceptible females preferred heavier males for mating (χ2 = 5.83, df = 1, P = 0.015), a trait that was more frequently associated with deltamethrin resistance (χ2 = 7.38, df = 1, P = 0.007). Deltamethrin resistance compromised daily fertility, although the reduced offspring production observed in matings between susceptible females and resistant males was negligible. CONCLUSION Susceptible female Weevils prefer larger (and heavier) males to mate, a trait associated with deltamethrin resistance, favouring the maintenance and spread of the resistant phenotype in the population. © 2016 Society of Chemical Industry
S. W. Munyiri - One of the best experts on this subject based on the ideXlab platform.
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Sources of resistance to the Maize Weevil Sitophilus Zeamais in tropical Maize
Journal of Agricultural Science, 2012Co-Authors: J. K. Mwololo, S. Mugo, Patrick Okori, Tadele Tefera, M. Otim, S. W. MunyiriAbstract:The Maize Weevil, Sitophilus zeamais (Motschulsky) (Coleoptera: Curculionidae), is among the major storage pests that enhance food insecurity among Maize farmers. New sources of resistance to the Maize Weevil are critical in a successful breeding program to address grain damage by postharvest pests. The objective of the study was to evaluate resistance in Maize genotypes to the Maize Weevil, and consequently their value for use in breeding programs. A total of 175 genotypes, including hybrids, landraces, open-pollinated varieties and checks, were tested for resistance to the Maize Weevil. The percentage grain damage, weight loss, flour weight and weight of damaged and undamaged grains were measured. Significant differences (P
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sources of resistance to the Maize Weevil sitophilus zeamais in tropical Maize
The Journal of Agricultural Science, 2012Co-Authors: J. K. Mwololo, S. Mugo, Patrick Okori, Tadele Tefera, M. Otim, S. W. MunyiriAbstract:The Maize Weevil, Sitophilus zeamais (Motschulsky) (Coleoptera: Curculionidae), is among the major storage pests that enhance food insecurity among Maize farmers. New sources of resistance to the Maize Weevil are critical in a successful breeding program to address grain damage by postharvest pests. The objective of the study was to evaluate resistance in Maize genotypes to the Maize Weevil, and consequently their value for use in breeding programs. A total of 175 genotypes, including hybrids, landraces, open-pollinated varieties and checks, were tested for resistance to the Maize Weevil. The percentage grain damage, weight loss, flour weight and weight of damaged and undamaged grains were measured. Significant differences (P <0.001) were observed among the genotypes for all the traits evaluated. The distribution of the genotypes among the different categories of resistance was an indication of the existence of genetic variation. The most resistant genotypes were CKPH08003 and BRAZ 2451 while the most susceptible were PH 3254 and BRAZ 4, among the hybrids and landraces respectively. Genotypes that were superior to the resistant checks were identified. The percentage weight loss and flour weight were identified as the most important insect-resistance traits for discriminating genotypes as evident from the canonical discriminant analysis. Correlation coefficients among the traits evaluated were highly significant. The resistant hybrids identified can be recommended for release and adoption by farmers, whereas the resistant landraces can act as sources of resistance for use in breeding programs.
Wilber Lwande - One of the best experts on this subject based on the ideXlab platform.
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Cleome hirta essential oil as livestock tick (Rhipicephalus appendiculatus) and Maize Weevil (Sitophilus zeamais) repellent
Fitoterapia, 1999Co-Authors: M.w. Ndungu, Sumesh C. Chhabra, Wilber LwandeAbstract:The repellency of the essential oil of the shrub Cleome hirta and of three identified constituents (phytol, (+)-cedrol, n-octacosane) was evaluated against the livestock tick, Rhipicephalus appendiculatus and the Maize Weevil, Sitophillus zeamais. In a tick climbing repellency bioassay, the oil exhibited repellency which, at the highest dose, was comparable to that of the commercial arthropod repellent N,N-diethyltoluamide (DEET). In a Y-tube olfactometer bioassay, the oil showed higher or comparable repellency against S. zeamais relative to DEET at all the doses tested. The potential of C. hirta in livestock tick and Maize Weevil control is discussed.
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Cleome monophylla essential oil and its constituents as tick (Rhipicephalus appendiculatus) and Maize Weevil (Sitophilus zeamais) repellents
Entomologia Experimentalis et Applicata, 1995Co-Authors: M.w. Ndungu, Wilber Lwande, Ahmed Hassanali, Lambert Moreka, Sumesh C. ChhabraAbstract:The repellency of the essential oil of the shrub Cleome monophylla (Family: Capparidaceae) and identified constituents of the oil were evaluated against the livestock tick, Rhipicephalus appendiculatus and the Maize Weevil, Sitophillus zeamais . In a tick climbing repellency bioassay, the oil of C. monophylla exhibited repellency which, at the highest dose, was comparable to that of the commercial arthropod repellent N,N-diethyl toluamide (DEET). In a Y-tube olfactometer bioassay, C. monophylla oil showed higher or comparable repellency against S. zeamais relative to DEET at all the doses tested. 14 Compounds were identified in the C. monophylla oil by GC, GC-MS and coinjection with authentic samples. Terpenolene was found to occur in largest quantity (14%) followed by 1-α-terpeneol (10%), pentacosane (9%), (α+β)-humulene (8%), phytol (5%) and 2-dodecanone (4%). The most repellent components against R. appendiculatus and S. zeamais were 1-α-terpeneol and 2-dodecanone. The overall pattern of repellency activity of the C. monophylla constituents with respect to the two arthropods was, however, different. The potential of C. monophylla in tick and Maize Weevil control is discussed.
Tadele Tefera - One of the best experts on this subject based on the ideXlab platform.
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Sources of resistance to the Maize Weevil Sitophilus Zeamais in tropical Maize
Journal of Agricultural Science, 2012Co-Authors: J. K. Mwololo, S. Mugo, Patrick Okori, Tadele Tefera, M. Otim, S. W. MunyiriAbstract:The Maize Weevil, Sitophilus zeamais (Motschulsky) (Coleoptera: Curculionidae), is among the major storage pests that enhance food insecurity among Maize farmers. New sources of resistance to the Maize Weevil are critical in a successful breeding program to address grain damage by postharvest pests. The objective of the study was to evaluate resistance in Maize genotypes to the Maize Weevil, and consequently their value for use in breeding programs. A total of 175 genotypes, including hybrids, landraces, open-pollinated varieties and checks, were tested for resistance to the Maize Weevil. The percentage grain damage, weight loss, flour weight and weight of damaged and undamaged grains were measured. Significant differences (P
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sources of resistance to the Maize Weevil sitophilus zeamais in tropical Maize
The Journal of Agricultural Science, 2012Co-Authors: J. K. Mwololo, S. Mugo, Patrick Okori, Tadele Tefera, M. Otim, S. W. MunyiriAbstract:The Maize Weevil, Sitophilus zeamais (Motschulsky) (Coleoptera: Curculionidae), is among the major storage pests that enhance food insecurity among Maize farmers. New sources of resistance to the Maize Weevil are critical in a successful breeding program to address grain damage by postharvest pests. The objective of the study was to evaluate resistance in Maize genotypes to the Maize Weevil, and consequently their value for use in breeding programs. A total of 175 genotypes, including hybrids, landraces, open-pollinated varieties and checks, were tested for resistance to the Maize Weevil. The percentage grain damage, weight loss, flour weight and weight of damaged and undamaged grains were measured. Significant differences (P <0.001) were observed among the genotypes for all the traits evaluated. The distribution of the genotypes among the different categories of resistance was an indication of the existence of genetic variation. The most resistant genotypes were CKPH08003 and BRAZ 2451 while the most susceptible were PH 3254 and BRAZ 4, among the hybrids and landraces respectively. Genotypes that were superior to the resistant checks were identified. The percentage weight loss and flour weight were identified as the most important insect-resistance traits for discriminating genotypes as evident from the canonical discriminant analysis. Correlation coefficients among the traits evaluated were highly significant. The resistant hybrids identified can be recommended for release and adoption by farmers, whereas the resistant landraces can act as sources of resistance for use in breeding programs.
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Efficacy of combining Niger seed oil with malathion 5% dust formulation on Maize against the Maize Weevil, Sitophilus zeamais (Coleoptera: Curculionidae)
Journal of Stored Products Research, 2009Co-Authors: Ahmed Ibrahim Yuya, Abraham Tadesse, Ferdu Azerefegne, Tadele TeferaAbstract:Abstract The combined effects of Niger seed oil and malathion, 5% dust, against the Maize Weevil, Sitophilus zeamais , were evaluated to determine the minimum effective rate(s) of the combinations that can provide adequate protection to Maize seed against attack by Weevils. Niger seed oil at the rates of 0%, 10%, 20%, 30%, 40%, 50% and 100% of the recommended application rate, 5 ml kg −1 , was combined with malathion at the respective rates of 100%, 50%, 40%, 30%, 20%, 10% and 0% of the recommended application rate, 0.5 g kg −1 . All combinations provided complete protection to Maize seed from the Maize Weevil up to 90 days after infestation. To determine the residual effects of the treatments, Weevils were reintroduced to the grain that had been treated 90 days previously. In addition to 100% malathion, 10% Niger seed oil + 50% malathion, and 20% Niger seed oil + 40% malathion, were fully effective in controlling S. zeamais for a further 156 days after this re-infestation. Therefore, these combinations could be considered as a potential component in an effort to establish integrated management of the Maize Weevil. Residual performance of both oil and malathion against the Weevils was primarily affected by the dose of malathion, with higher doses of malathion providing greater protection for a longer period. Niger seed oil treatment lowered the level of seed germination at the application rate of 5 ml per kg of Maize.
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Efficacy of Silicosec, filter cake and wood ash against the Maize Weevil, Sitophilus zeamais Motschulsky (Coleoptera: Curculionidae) on three Maize genotypes
Journal of Stored Products Research, 2008Co-Authors: Girma Demissie, Tadele Tefera, Abraham TadesseAbstract:The effectiveness of the diatomaceous earth Silicosec, a mineral industrial filter cake and domestic wood ash, applied at three different rates for the control of the Maize Weevil, Sitophilus zeamais, on three Maize genotypes was determined. Treatment with Silicosec was the most effective followed by filter cake and wood ash. The treatments reduced progeny emergence, percentage grain damage and grain weight losses, but did not affect percentage seed germination. Grain treated with wood ash at all rates resulted in a relatively low mortality 3 days after infestation as compared to other treatments. However, all treatments caused high mortality (97–100%) after 15 days of exposure. Therefore, Silicosec, filter cake and wood ash can be considered as potential components of an integrated pest management strategy against the Maize Weevil. r 2008 Elsevier Ltd. All rights reserved.
J. K. Mwololo - One of the best experts on this subject based on the ideXlab platform.
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Post-harvest evaluation of selected inbred lines to Maize Weevil Sitophilus zeamais resistance.
Journal of Plant Breeding and Crop Science, 2018Co-Authors: S. Khakata, F. N. Mbute, G. N. Chemining'wa, M. Mwimali, J. Karanja, J. Harvey, J. K. MwololoAbstract:Maize Weevil (Sitophilus zeamais Motschulsky) is a major Maize (Zea mays L.) storage insect pest in the tropics which reduces the quantity and quality of Maize hence facilitating establishment of aflatoxin and other mycotoxins. The objective of this study was to evaluate Maize Weevil resistance on selected inbred lines. Twenty eight inbred lines with 2 checks (MTPO701-reistant and Duma 41-susceptible) were used in this experiment. Thirty unsexed adult insects were introduced into 250 ml glass jars with grains of the lines at room temperature. Evaluation of Weevil damage was done at 10, 60 and 120 days after Maize Weevil infestation. Each category of storage period was replicated 4 times and experiment was set at the same time. Data was collected on percent Weevil damage, grain weight loss and number of live and dead Weevils on each inbred line. ANOVA analysis showed significant differences (P ≤ 0.05) on weight loss. The selection of the resistant genotypes was based on percent weight loss after 60 days. Resistant lines selected included KEN2/TZL2.25# and LEPOOL-1/TZL2-2-1. These lines showed resistance to Maize Weevil damage and hence can be stored up to 4 months. At 120 days there was maximum damage and most lines could not be differentiated on the basis of resistance. KEN2/TZL2-2-5# showed consistency in resistance to Maize Weevils at all storage periods. High heritability at 60 days showed that selection for Weevil resistance in these inbred lines is effective and feasible. Results in this study also revealed high, positive and significant correlation relationship between percent damage, weight loss and live Weevils. The Maize Weevil resistant lines can be used to improve resistance of high yielding varieties in breeding programmes. Key words: Inbred lines, Maize, post-harvest, resistance, Sitophillus zeamais.
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Sources of resistance to the Maize Weevil Sitophilus Zeamais in tropical Maize
Journal of Agricultural Science, 2012Co-Authors: J. K. Mwololo, S. Mugo, Patrick Okori, Tadele Tefera, M. Otim, S. W. MunyiriAbstract:The Maize Weevil, Sitophilus zeamais (Motschulsky) (Coleoptera: Curculionidae), is among the major storage pests that enhance food insecurity among Maize farmers. New sources of resistance to the Maize Weevil are critical in a successful breeding program to address grain damage by postharvest pests. The objective of the study was to evaluate resistance in Maize genotypes to the Maize Weevil, and consequently their value for use in breeding programs. A total of 175 genotypes, including hybrids, landraces, open-pollinated varieties and checks, were tested for resistance to the Maize Weevil. The percentage grain damage, weight loss, flour weight and weight of damaged and undamaged grains were measured. Significant differences (P
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sources of resistance to the Maize Weevil sitophilus zeamais in tropical Maize
The Journal of Agricultural Science, 2012Co-Authors: J. K. Mwololo, S. Mugo, Patrick Okori, Tadele Tefera, M. Otim, S. W. MunyiriAbstract:The Maize Weevil, Sitophilus zeamais (Motschulsky) (Coleoptera: Curculionidae), is among the major storage pests that enhance food insecurity among Maize farmers. New sources of resistance to the Maize Weevil are critical in a successful breeding program to address grain damage by postharvest pests. The objective of the study was to evaluate resistance in Maize genotypes to the Maize Weevil, and consequently their value for use in breeding programs. A total of 175 genotypes, including hybrids, landraces, open-pollinated varieties and checks, were tested for resistance to the Maize Weevil. The percentage grain damage, weight loss, flour weight and weight of damaged and undamaged grains were measured. Significant differences (P <0.001) were observed among the genotypes for all the traits evaluated. The distribution of the genotypes among the different categories of resistance was an indication of the existence of genetic variation. The most resistant genotypes were CKPH08003 and BRAZ 2451 while the most susceptible were PH 3254 and BRAZ 4, among the hybrids and landraces respectively. Genotypes that were superior to the resistant checks were identified. The percentage weight loss and flour weight were identified as the most important insect-resistance traits for discriminating genotypes as evident from the canonical discriminant analysis. Correlation coefficients among the traits evaluated were highly significant. The resistant hybrids identified can be recommended for release and adoption by farmers, whereas the resistant landraces can act as sources of resistance for use in breeding programs.
