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Paul-andré Calatayud - One of the best experts on this subject based on the ideXlab platform.
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draft genome of Busseola fusca the maize stalk borer a major crop pest in sub saharan africa
Genome Biology and Evolution, 2019Co-Authors: Kayla M Hardwick, Paul-andré Calatayud, Awino Maureiq Edith Ojwang, Francesca Stomeo, Solomon Maina, Gladys BichangaAbstract:The maize stalk borer, Busseola fusca, is an important Lepidopteran pest of cereal crops in Central, East, and Southern Africa. Crop losses due to B. fusca feeding activity vary by region, but can result in total crop loss in areas with high levels of infestation. Genomic resources provide critical insight into the biology of pest species and can allow for the development of effective management tools and strategies to mitigate their impact on agriculture. To this end, we sequenced, assembled, and annotated the genome of B. fusca. The total assembled genome size was 492.9 Mb with 19,417 annotated protein-coding genes. Using a comparative approach, we identified a putative expansion in the Chorion gene family, which is involved in the formation of the egg shell structure. Our analysis revealed high repeat content within the B. fusca genome, with LTR sequences comprising the majority of the repetitive sequence. We hope genomic resources will provide a foundation for future work aimed at developing an integrated pest management strategy to reduce B. fusca's impact on food security.
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Assortments of Digestive Enzymes Induced in First Instar Larvae of Busseola fusca Feeding on Different Plants
International Journal of Insect Science, 2019Co-Authors: G. Juma, Paul-andré CalatayudAbstract:The stem borer Busseola fusca (Fuller) (Lepidoptera: Noctuidae) is an important pest of maize and sorghum in sub-Saharan Africa. This insect has oligophagous feeding habits, feeding mostly on maize...
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influence of plant silicon in Busseola fusca lepidoptera noctuidae larvae poaceae interactions
Bulletin of Entomological Research, 2015Co-Authors: G. Juma, G. Magoma, Jean Fran??ois Silvain, Peter Ahuya, G Ongamo, Le B Ru, Paul-andré CalatayudAbstract:The noctuid stem borer Busseola fusca is an important pest of maize and sorghum in Sub-Saharan Africa. The presence of this species occurred mostly on cultivated than on wild habitats. Busseola fusca is oligophagous having a narrow range of a wild grass species. This might be due, in part, to differences in silicon (Si) content in plant tissues between cultivated and wild grasses. In the present study, we have tested this hypothesis by studying the survival and the relative growth rate (RGR) expressed as daily weight gains of B. fusca larvae on maize and six wild host plants, mostly present in the natural habitat where B. fusca occurred, and correlated with their Si contents. Survival and RGR of B. fusca larvae were considerably higher on maize and wild sorghum than on the other grass species, and they were negatively related to plant Si content. This was corroborated with results on RGR from artificial diets amended with increasing levels of Si. In addition, if Si was added to maize growing substrate B. fusca larval growth was significantly reduced confirming the involvement of Si in B. fusca larvae – Poaceae interactions. The results provide insight into the possible mechanisms of oligophagy of B. fusca and provide a correlative support for a physical role of plant endogenous Si in impeding feeding of B. fusca larvae.
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ecology of the african maize stalk borer Busseola fusca lepidoptera noctuidae with special reference to insect plant interactions
Insects, 2014Co-Authors: Paul-andré Calatayud, Johnnie Van Den Berg, Bruno Le Ru, F SchulthessAbstract:Busseola fusca (Lepidoptera: Noctuidae) is an important pest of maize and sorghum in sub-Saharan Africa. One century after its first description by Fuller in 1901, inaccurate information based on earlier reports are still propagated on its distribution (e.g., absent from the lower altitudes in East Africa) and host plant range (e.g., feeding on a large range of wild grass species). This review provides updated information on the biology, distribution and genetics of B. fusca with emphasis on insect-plant interactions. Related to this, new avenues of stem borer management are proposed.
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importance of the experimental setup in research on attractiveness of odours in moths an example with Busseola fusca
Entomologia Experimentalis Et Applicata, 2014Co-Authors: Paul-andré Calatayud, Peter Ahuya, Le B RuAbstract:Wind tunnel and Y-tube olfactometer studies are useful for demonstrating the responsiveness of male moths to sex pheromones. However, in the cereal stem borer, Busseola fusca (Fuller) (Lepidoptera: Noctuidae), wind tunnel bioassays yielded poor results when the behavioural responses of females to plant odours were tested. We demonstrated that for B. fusca females, the Y-tube olfactometer was better suited for measuring the attractiveness of plant odours, compared with the wind tunnel. In particular, we showed B. fusca preference for odours of a host over a non-host plant species using this apparatus. Behavioural responses for B. fusca after host finding are also discussed.
J Van Den Berg - One of the best experts on this subject based on the ideXlab platform.
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resistance status of Busseola fusca lepidoptera noctuidae populations to single and stacked gene bt maize in south africa
Journal of Economic Entomology, 2019Co-Authors: E Strydom, Annemie Erasmus, H Du Plessis, J Van Den BergAbstract:Transgenic Bt maize expressing Cry insecticidal δ-endotoxins of Bacillus thuringiensis has been cultivated in South Africa for the control of Busseola fusca since 1998. Busseola fusca is resistant to Cry1Ab Bt maize at many localities throughout the maize production region. Pre-release evaluation (1994-1996) of the inherent susceptibility and post-release assessments (1998-2011) of resistance status of B. fusca focused on a limited number of pest populations. This study reports the current levels of susceptibility of 10 B. fusca populations evaluated between 2013 and 2017 and compared this data with previously reported data on the survival of this pest on Bt maize, including data of pre-release evaluations done during 1994 and 1995. Larval feeding bioassays in which plant tissue of maize events expressing either Cry1Ab or Cry1A.105+Cry2Ab2 (stacked event) proteins were conducted and survival and different life history parameters recorded. Results show a shift in levels of susceptibility of B. fusca to Bt maize. Pre-release evaluation of the single-gene event showed very low larval survival on Bt maize leaf tissue while studies 10 yr later and the current study reported survival of up to 40% and 100% on Cry1Ab maize, respectively. While no larvae completed their life cycle on the stacked event, higher LT50 values in this study indicate a shift in susceptibility of B. fusca to the stacked-gene event and highlight the importance of baseline information and monitoring of pest populations for their susceptibility to Bt maize.
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Genetic hitchhiking and resistance evolution to transgenic Bt toxins: insights from the African stalk borer Busseola fusca (Noctuidae)
Heredity, 2017Co-Authors: P Campagne, C Capdevielle-dulac, R Pasquet, S J Cornell, M Kruger, J-f Silvain, B Lerü, J Van Den BergAbstract:Since transgenic crops expressing Bacillus thuringiensis ( Bt ) toxins were first released, resistance evolution leading to failure in control of pests populations has been observed in a number of species. Field resistance of the moth Busseola fusca was acknowledged 8 years after Bt maize was introduced in South Africa. Since then, field resistance of this corn borer has been observed at several locations, raising questions about the nature, distribution and dynamics of the resistance trait. Using genetic markers, our study identified four outlier loci clearly associated with resistance. In addition, genetic structure at neutral loci reflected extensive gene flow among populations. A realistically parameterised model suggests that resistance could travel in space at speed of several kilometres a year. Markers at outlier loci delineated a geographic region associated with resistance spread. This was an area of approximately 100 km radius, including the location where resistance was first reported. Controlled crosses corroborated these findings and showed significant differences of progeny survival on Bt plants depending on the origin of the resistant parent. Last, our study suggests diverse resistance mutations, which would explain the widespread occurrence of resistant larvae in Bt fields across the main area of maize production in South Africa.
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the effect of temperature on the development and reproduction of Busseola fusca lepidoptera noctuidae
Bulletin of Entomological Research, 2017Co-Authors: J Glatz, H Du Plessis, J Van Den BergAbstract:The effect of temperature on the reproduction and development of Busseola fusca was studied under laboratory conditions. Single male-female pairs were confined to oviposition chambers kept at 15, 20, 26 and 30 ± 1°C and a 14L:10D photoperiod. Data on reproduction parameters were captured daily. Oviposition occurred at all the mentioned temperatures but no fertility was recorded at 30°C. The total number of eggs laid per female moth was between 300 and 400 and the optimum temperature for oviposition and fertility was between 20 and 26°C. Larval development was studied at five different temperature regimes, i.e. 15, 18, 20, 26 and 30 ± 1°C and a 14L:10D photoperiod. The most favourable temperature as well as the upper threshold temperature for larval development was between 26 and 30°C. Total development period was 152.6-52.6 days, respectively, at 15°C, and 26-30°C. The thermal constants for B. fusca was 99.50, 536.48, 246.25 and 893.66°D and lower temperature thresholds were 10.36, 8.14, 8.99 and 8.84°C, for completion of the egg, larval, pupal and egg-to-adult stages, respectively. Results on the thermal constants and lower and upper threshold temperatures of B. fusca can be used to predict the impact of climate change on the distribution and population growth of this pest.
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ecological genetics and host range expansion by Busseola fusca lepidoptera noctuidae
Environmental Entomology, 2015Co-Authors: Y Assefa, J Van Den Berg, D E Conlong, L A MartinAbstract:The host plant range of pests can have important consequences for its evolution, and plays a critical role in the emergence and spread of a new pest outbreak. This study addresses the ecological genetics of the indigenous African maize stem borer, Busseola fusca (Fuller) (Lepidoptera: Noctuidae), in an attempt to investigate the evolutionary forces that may be involved in the recent host range expansion and establishment of this species in Ethiopian and southern African sugarcane. We used populations from Ethiopia, Zimbabwe, and South Africa to examine whether the host range expansion patterns shared by the Ethiopian and the southern African populations of B. fusca have evolved independently. Base-pair differences in the cytochrome oxidase I (COI) gene were used to characterize haplotype diversity and phylogenetic relationships. There were seven haplotypes among the 30 sequenced individuals collected on four host plant species from 17 localities in the four countries. Of the seven COI haplotypes identified, the two major ones occurred in both sugarcane and maize. Genetic analyses revealed no detectable genetic differentiation between southern African B. fusca populations from maize and sugarcane (FST = 0.019; P = 0.24). However, there was strong evidence of variation in genetic composition between populations of the pest from different geographic regions (FST = 0.948; P < 0.001). The main implication of these findings is that the B. fusca populations in maize in southern Africa are more likely to shift to sugarcane, suggesting that ecological opportunity is an important factor in host plant range expansion by a pest.
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no fitness costs associated with resistance of Busseola fusca lepidoptera noctuidae to genetically modified bt maize
Crop Protection, 2014Co-Authors: Marlene Kruger, J B J Van Rensburg, J Van Den BergAbstract:Abstract A concern regarding planting of Bt crops is that their widespread cultivation could lead to evolution of insect resistance to Bt toxins. In South Africa, the noctuid maize stem borer ( Busseola fusca [Fuller]), is resistant to Bt maize ( Zea mays L.; MON810) which produces Cry1Ab protein. The presence of fitness costs in resistant populations could be a valuable component of resistance management since the non-Bt maize refuge may select against resistance. The aim of the study was to determine if there are fitness costs associated with Bt resistance of B . fusca . Life history parameters were compared between individuals of a Bt maize resistant B. fusca population when feeding on Bt or non-Bt maize. Similar comparisons were done using a control population. Field collected larvae as well as their F 1 -generation were used in the study. The following parameters were compared: pupal mass, moth longevity, fecundity, fertility, larval mass and survival, and sex ratio. Except for LT50-values, no fitness costs were associated with the resistance trait in the highly resistant B. fusca population. The absence of fitness costs and presence of resistant populations may promote the use of a multi-gene strategy which would be expected to impact negatively on fitness.
J B J Van Rensburg - One of the best experts on this subject based on the ideXlab platform.
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Recurrent selection for resistance in maize to the African stalk borer, Busseola fusca (Fuller)
The South African Journal of Plant and Soil, 2020Co-Authors: J B J Van Rensburg, J. KlopperAbstract:Stem borer resistant inbred lines Mp704 and Mp706 of Mississippi origin were used as donor parents in a recurrent selection programme, to develop locally adapted germplasm with improved resistance to the stalk borer Busseola fusca. The segregating progenies of crosses between resistant and susceptible lines were planted ear-to-row, with selection based on the incidence of leaf feeding damage and stunting, following artificial infestation of plants with neonate larvae. Resistance derived from the two sources was combined after two cycles of selection, which resulted in high levels of resistance being achieved over a relatively short period. Combining ability for yield was evaluated at the S3 level of inbreeding, using 1137TN as tester. Compared with commercial hybrids, a number of test crosses were identified with superior yield under conditions of stalk borer infestation and comparative yields in the absence of attack. Characterization data were obtained on 42 lines intended for release.
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no fitness costs associated with resistance of Busseola fusca lepidoptera noctuidae to genetically modified bt maize
Crop Protection, 2014Co-Authors: Marlene Kruger, J B J Van Rensburg, J Van Den BergAbstract:Abstract A concern regarding planting of Bt crops is that their widespread cultivation could lead to evolution of insect resistance to Bt toxins. In South Africa, the noctuid maize stem borer ( Busseola fusca [Fuller]), is resistant to Bt maize ( Zea mays L.; MON810) which produces Cry1Ab protein. The presence of fitness costs in resistant populations could be a valuable component of resistance management since the non-Bt maize refuge may select against resistance. The aim of the study was to determine if there are fitness costs associated with Bt resistance of B . fusca . Life history parameters were compared between individuals of a Bt maize resistant B. fusca population when feeding on Bt or non-Bt maize. Similar comparisons were done using a control population. Field collected larvae as well as their F 1 -generation were used in the study. The following parameters were compared: pupal mass, moth longevity, fecundity, fertility, larval mass and survival, and sex ratio. Except for LT50-values, no fitness costs were associated with the resistance trait in the highly resistant B. fusca population. The absence of fitness costs and presence of resistant populations may promote the use of a multi-gene strategy which would be expected to impact negatively on fitness.
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the influence of rainfall on the seasonal abundance and flight activity of the maize stalk borer Busseola fusca in south africa
The South African Journal of Plant and Soil, 2013Co-Authors: J B J Van Rensburg, J H Giliomee, G D J Van Rensburg, M C WaltersAbstract:This study attempts to demonstrate the extent to which seasonal fluctuations in the number of Busseola fusca (Fuller) moths can be explained by precipitation data. Daily flight activity is shown to be enhanced by cool, humid conditions and restricted by rain. Humidity was shown experimentally to be of importance in the survival of moths under laboratory conditions. It is suspected that the observed relationship between seasonal moth numbers and rainfall is an indirect one and that survival of moths is rather determined by the direct influence of humidity. More serious infestations can therefore be expected during years with favourable rains.
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resistance to bt maize in Busseola fusca lepidoptera noctuidae from vaalharts south africa
Environmental Entomology, 2011Co-Authors: Marlene Kruger, J B J Van Rensburg, J Van Den BergAbstract:ABSTRACT The first report of resistance of the maize stem borer [Busseola fusca (Fuller)] to Bt maize (MON810) was made in the Christiana area of South Africa during 2007. The objective of this study was to evaluate the status of resistance of other populations of B. fusca to Bt maize. One greenhouse and two laboratory studies were conducted. B. fusca populations were collected on Bt maize as well as the adjacent refugia (conventional maize and non-Bt maize) in the Vaalharts area, 50 km from the Christiana site. Control populations were collected from sites where Bt maize was not planted. In the greenhouse study 720 potted plants were each artificially infested with 10 neonate larvae of the F1-generation after the field collected populations were reared through to adults. Numbers of live larvae and larval mass per plant were determined at regular intervals over a 35-d period. Larvae of the Christiana conventional population (Bt-susceptible) on Bt maize (CHR08ConBt) and Bethal conventional population (Bt-s...
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a review of research achievements on maize stem borer Busseola fusca fuller and diplodia ear rot caused by stenocarpella maydis berk sutton
The South African Journal of Plant and Soil, 2010Co-Authors: J B J Van Rensburg, B C FlettAbstract:Research that focused on maize production on the central Highveld of South Africa was traditionally, since the early twentieth century, dealt with by the Department of Agriculture at Potchefstroom. During the 1970s the Highveld Region at Potchefstroom assigned a group of researchers with an interest in maize to a unit termed the Summer Grain Centre that in 1992 became part of the Agricultural Research Council’s Grain Crops Institute. Members of this group in particular gave research attention to various aspects of crop protection in maize, including the soil insect complex, the maize stem borer complex, maize streak disease, the ear rot complex and various leaf diseases. This paper deals with research progress on the African stem borer, Busseola fusca, and ear rot caused by Stenocarpella maydis. The emphasis is on research with a practical application rather than that of an academic nature.
Brigitte Frerot - One of the best experts on this subject based on the ideXlab platform.
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host plants and reproductive behaviour in the african maize stemborer Busseola fusca fuller 1901 lepidoptera noctuidae
Annales De La Societe Entomologique De France, 2013Co-Authors: Anneemmanuelle Felix, Tassadit Smail, Brigitte FrerotAbstract:Summary Busseola fusca Fuller (Lepidoptera: Noctuidae) is the major pest on maize and sorghum crops in sub-Saharan Africa. As a specialised phytophagous insect, survival of B. fusca larvae depends on the presence of the cultivated host plants. Taking into account recent evidence of host-plant presence acting on pheromone perception and production in Lepidoptera, we investigated the effect of different host and non-host plants on reproductive behaviour in B. fusca: female calling behaviour and male attraction by female. Results showed that both behaviours did not change in presence of plants, whether they are larvae host plant or oviposition repellent plant. Native host associated mating remains unknown for this species, but results are likely to favour the hypothesis that mating behaviour is not related to the presence of cultivated or putative native host plants.
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dissemination of entomopathogenic fungi using Busseola fusca male as vector
Biological Control, 2011Co-Authors: Nguya K Maniania, Paul-andré Calatayud, Brigitte Frerot, Peter Ahuya, Anneemmanuelle Felix, Bruno Le Ru, Elizabeth OunaAbstract:The stem borer, Busseola fusca (Fuller), is an important pest of maize Zea mays L. and sorghum Sorghum bicolor (L.) in eastern and southern Africa. To control this pest, biological control methods including the use of entomopathogenic fungi are being considered. The pathogenicity of one isolate of Metarhizium anisopliae (Metsch.) Sorok. and one isolate of Beauveria bassiana Bals. (Vuill.) were first tested on different developmental stages of B. fusca including eggs, neonate, 2nd and 3rd-instar larvae. Both fungal isolates were pathogenic to all the stages tested. However, differences in mortality were observed among larvae that hatched from treated egg masses. Experiments were conducted thereafter to test whether B. fusca males could serve as a vector for fungal conidia to contaminate B. fusca females and subsequently eggs and larvae. Results demonstrated that B. fusca males successfully transferred inoculum to females during copulation, which in turn transmitted it to the eggs they laid on maize plants, resulting in the decrease of leaf damages.
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variability in pheromone communication among different haplotype populations of Busseola fusca
Journal of Chemical Ecology, 2009Co-Authors: Paul-andré Calatayud, Le B Ru, Jeanfrancois Silvain, A E Felix, G Genestier, Christian Malosse, Brigitte FrerotAbstract:The relationship between pheromone composition and mitochondrial haplotype clades was investigated by coupling DNA analyses with pheromone identification and male mate searching behavior among different geographic populations of Busseola fusca. The within-population variations in pheromone blend were as great as those observed between geographic populations, suggesting that the female sex pheromone blend was not the basis of reproductive isolation between the geographic clades. Furthermore, while data from wind tunnel experiments demonstrated that most of the tested males were sensitive to small variations in pheromone mixture, there was considerable within-population variability in the observed response. The study identified a new pheromone component, (Z)-11-hexadecen-1-yl acetate, which when added to the currently used three-component synthetic blend resulted in significantly higher traps catches. The new recommended blend for monitoring flight phenology and for timing control measures for optimal efficacy of B. fusca is (Z)-11-tetradecen-1-yl acetate (62%), (E)-11-tetradecen-1-yl acetate (15%), (Z)-9-tetradecen-1-yl acetate (13%), and (Z)-11-hexadecen-1-yl acetate (10%).
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Differences in mate acceptance and host plant recognition between wild and laboratory‐reared Busseola fusca (Fuller)
Journal of Applied Entomology, 2008Co-Authors: Paul-andré Calatayud, G. Juma, G. Magoma, Nicolas Faure, Jean Fran??ois Silvain, Peter G N Njagi, Sabine Calatayud, Stéphane Dupas, Brigitte FrerotAbstract:The present study was aimed at characterizing differences in mate acceptance and host plant recognition between Busseola fusca (Lep.: Noctuidae) reared for several generations under laboratory conditions and wild conspecifics, directly collected from maize stems in the field. The mating success was significantly higher in laboratory reared when compared with the wild B. fusca population. Oviposition on artificial stems was significantly higher for laboratory-reared insects than for the wild ones. Moreover, unlike adults of the wild strain, laboratory-reared B. fusca showed no preference to oviposit on surrogate stems impregnated with maize extracts. Long-range attraction to the host plant was significantly lower for laboratory-reared insects. Furthermore, the polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) analysis of mitochondrial DNA showed that the wild type and laboratory populations belonged to the same genetic strain, indicating that these differences between the populations were mainly phenotypic.
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importance of plant physical cues in host acceptance for oviposition by Busseola fusca
Entomologia Experimentalis Et Applicata, 2008Co-Authors: Paul-andré Calatayud, Jean Fran??ois Silvain, Peter Ahuya, Le B Ru, A Wanjoya, Brigitte FrerotAbstract:Plant and surrogate stems exhibiting specific combinations of physical cues were used to determine which plant-related stimuli influence the oviposition of Busseola fusca (Fuller) (Lepidoptera: Noctuidae). The number of eggs and egg batches laid per female increased with an increase in diameter of both natural and artificial stems. Direct observations of the oviposition behaviour (walking, antennating, and sweeping with the ovipositor) indicated that the female moths preferred oviposition supports with a large diameter and non-pubescent or smooth surfaces over pubescent or rough ones. Pubescence and rough surfaces significantly affected the behavioural steps leading to oviposition by interfering with the ovipositor sweep process necessary to find a suitable oviposition site. Furthermore, more eggs and egg batches were laid on soft than rigid supports. The rigidity of the support affected the proper insertion of the ovipositor for egg deposition. Our results underline the importance of physical stimuli in B. fusca ’s choice of an oviposition site, which may facilitate the identification of potential host plants or preferred oviposition sites on a plant for this species.
Bruno Le Ru - One of the best experts on this subject based on the ideXlab platform.
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ecology of the african maize stalk borer Busseola fusca lepidoptera noctuidae with special reference to insect plant interactions
Insects, 2014Co-Authors: Paul-andré Calatayud, Johnnie Van Den Berg, Bruno Le Ru, F SchulthessAbstract:Busseola fusca (Lepidoptera: Noctuidae) is an important pest of maize and sorghum in sub-Saharan Africa. One century after its first description by Fuller in 1901, inaccurate information based on earlier reports are still propagated on its distribution (e.g., absent from the lower altitudes in East Africa) and host plant range (e.g., feeding on a large range of wild grass species). This review provides updated information on the biology, distribution and genetics of B. fusca with emphasis on insect-plant interactions. Related to this, new avenues of stem borer management are proposed.
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dominant inheritance of field evolved resistance to bt corn in Busseola fusca
PLOS ONE, 2013Co-Authors: Pascal Campagne, Marlene Kruger, Bruno Le Ru, Remy S Pasquet, Johnnie Van Den BergAbstract:Transgenic crops expressing Bacillus thuringiensis (Bt) toxins have been adopted worldwide, notably in developing countries. In spite of their success in controlling target pests while allowing a substantial reduction of insecticide use, the sustainable control of these pest populations is threatened by the evolution of resistance. The implementation of the “high dose/refuge” strategy for managing insect resistance in transgenic crops aims at delaying the evolution of resistance to Bt crops in pest populations by promoting survival of susceptible insects. However, a crucial condition for the “high dose/refuge” strategy to be efficient is that the inheritance of resistance should be functionally recessive. Busseola fusca developed high levels of resistance to the Bt toxin Cry 1Ab expressed in Bt corn in South Africa. To test whether the inheritance of B. fusca resistance to the Bt toxin could be considered recessive we performed controlled crosses with this pest and evaluated its survival on Bt and non-Bt corn. Results show that resistance of B. fusca to Bt corn is dominant, which refutes the hypothesis of recessive inheritance. Survival on Bt corn was not lower than on non-Bt corn for both resistant larvae and the F1 progeny from resistant × susceptible parents. Hence, resistance management strategies of B. fusca to Bt corn must address non-recessive resistance.
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genetic structure and origin of Busseola fusca populations in cameroon
Entomologia Experimentalis Et Applicata, 2012Co-Authors: Stéphane Dupas, Bruno Le Ru, Michel Sezonlin, Rose Ndemah, Georg Goergen, Jeanfrancois SilvainAbstract:The cereal stem borer Busseola fusca Fuller (Lepidoptera: Noctuidae) is a species endemic to sub-Saharan Africa. It is a major pest of maize and cultivated sorghum, the main cereal crops on the African mainland. Previous studies using mitochondrial markers revealed the presence of three clades of haplotypes (W, KI, KII) among B. fusca populations. Previous preliminary studies based on a few B. fusca individuals collected from three localities within the Guineo-Congolian rain forest in Cameroon demonstrated a matching with clade KII, a fairly surprising result because the putative centre of origin of that clade is located 3 000 km away in East Africa. To check this finding, 120 individuals of B. fusca covering several Cameroonian sites belonging to both Guineo-Congolian rain forest and Afromontane vegetation mosaics were collected. Comparison of cytochrome b sequences using the same marker revealed low mitochondrial diversity (h = 0.483 ± 0.054, π = 0.073 ± 0.061%). Moreover, molecular diversity in the Guineo-Congolian rain forest zone was lower than that in Afromontane vegetation, which is therefore thought to be the likely starting point for the colonization of other zones in Cameroon. The study showed a moderate but significant structuring between populations (ΦST = 0.034, P<0.001) as well as within and among the two Cameroonian phytogeographical groups considered (ΦSC = 0.000 and ΦCT = 0.051, respectively, both P<0.001). Nested clade phylogeographic analysis indicated that all Cameroonian clades with significant geographical associations were interpreted as a phenomenon of contiguous range expansion. All results suggest that the Cameroonian population of B. fusca is relatively recent and originates from the recent geographical expansion of clade KII.
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dissemination of entomopathogenic fungi using Busseola fusca male as vector
Biological Control, 2011Co-Authors: Nguya K Maniania, Paul-andré Calatayud, Brigitte Frerot, Peter Ahuya, Anneemmanuelle Felix, Bruno Le Ru, Elizabeth OunaAbstract:The stem borer, Busseola fusca (Fuller), is an important pest of maize Zea mays L. and sorghum Sorghum bicolor (L.) in eastern and southern Africa. To control this pest, biological control methods including the use of entomopathogenic fungi are being considered. The pathogenicity of one isolate of Metarhizium anisopliae (Metsch.) Sorok. and one isolate of Beauveria bassiana Bals. (Vuill.) were first tested on different developmental stages of B. fusca including eggs, neonate, 2nd and 3rd-instar larvae. Both fungal isolates were pathogenic to all the stages tested. However, differences in mortality were observed among larvae that hatched from treated egg masses. Experiments were conducted thereafter to test whether B. fusca males could serve as a vector for fungal conidia to contaminate B. fusca females and subsequently eggs and larvae. Results demonstrated that B. fusca males successfully transferred inoculum to females during copulation, which in turn transmitted it to the eggs they laid on maize plants, resulting in the decrease of leaf damages.
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distribution of chemo and mechanoreceptors on the antennae and maxillae of Busseola fusca larvae
Entomologia Experimentalis Et Applicata, 2008Co-Authors: G. Juma, G. Magoma, Peter G N Njagi, Peter Ahuya, Bruno Le Ru, M Chimtawi, Jeanfrancois SilvainAbstract:The stem borer Busseola fusca (Fuller) (Lepidoptera: Noctuidae) is a major pest of maize, Zea mays L., and sorghum, Sorghum bicolor (L.) Moench (both Poaceae), in sub-Saharan Africa. Like in many other lepidopteran insects, the success of B. fusca in recognizing and colonizing a limited variety of plants is based on the interaction between its sensory systems and the physicochemical characteristics of its immediate environment. The sensilla on the maxillary galeae of B. fusca larvae are typical of Lepidoptera and comprise two uniporous styloconic sensilla, which are contact chemoreceptors, three basiconic sensilla, and two aporous sensilla chaetica. The maxillary palp is two-segmented and has eight small basiconic sensilla at the tip, which were also found to be gustatory. The antennae of B. fusca larvae are short and simple. The sensilla of the antenna are composed of two aporous sensilla chaetica, three multiporous cone-shaped basiconic sensilla, three small basiconic sensilla, and one aporous styloconic sensillum. The basiconic sensillum located on the third antennal segment displayed a contact chemoreception response. The other basiconic sensilla did not show any action potential activity in tip-recording tests. The significant and positive dose-response curve obtained for the antennal basiconic sensillum with sucrose indicated for the first time the presence of gustatory chemoreceptors on the antennae of a lepidopteran larva.
