Capacités de discrimination des femelles de quatre souches de Callosobruchus maculatus Fab. (Coléoptera : Chrysomelidae, Bruchinae) pour la localisation de l’hôte et la ponte aux dépens d’hôtes secondaires

L’objectif de cette étude est de savoir comment les femelles de quatre souches de Callosobruchus maculatus F., localisent leur hôte, distribuent les oeufs sur des graines de taille différente dans des conditions de libre choix, de semi choix et de non choix. Ainsi, des couples de C. maculatus ont été transférés du niébé, Vigna unguiculata (L.) Walp. (Fabaceae), et maintenus sur les graines de deux variétés de voandzou, Vigna subterranea (L.) Verdc. (Fabaceae), et du pois d’angole, Cajanus cajan (L.) Millsp (Fabaceae), trois ans durant. La capacité des femelles à reconnaître les odeurs de ces quatre types de graines a été testée à l’aide d’un olfactomètre et dans un dispositif tridimensionnel. Elles ont été ensuite mises en contact avec les différentes graines pour la ponte. Dans l’olfatomètre, lorsqu’elles ont le choix entre l’air pur et l’air provenant de leurs hôtes d’origine, elles sont significativement attirées par l’air odorant. Quand les femelles issues des souches du voandzou ou du pois d’angole ont le choix entre le niébé et leur plante d’origine, elles préfèrent le niébé. Dans le dispositif tridimensionnel, quand les femelles issues du voandzou ou du pois d’angole ont un libre choix entre les quatre types de graines, elles (> 30%) préfèrent leurs plantes hôtes d’origine. Les odeurs dégagées par les graines semblent contribuer à l’orientation des femelles vers ces graines. C. maculatus utilisent des signaux chimiques dans la localisation de leurs hôtes. Ceci entraînerait ou stimulerait l’utilisation des répulsifs et attractants dans la gestion intégrée des insectes de stocks.Mots clés: Capacités de discrimination, localisation, ponte, C. maculatus, plantes hôtes secondaire

Using contextual clues to infer EFL word meanings

Abstract: The present exploratory study investigates the use of contextual clues to infer unknown/unfamiliar words meanings through reading. It involves two classroom observers and a sample of 55 secondary school EFL students. The students’ sample is composed of 1ère A students from Lycée Provincial Dimdolobsom de Boussé, in ‘la Région du Plateau Central’, Burkina Faso. These students have spent at least six years in the learning of English as a foreign language. This sample is obtained through a convenient and purposive sampling technique by considering all the students in the classroom. A classroom observation protocol and a semi-structured interview are used as data collection instruments. The teaching materials are 14 reading comprehension texts containing unknown/unfamiliar words and 14 vocabulary lesson plans based on reading. The data are analysed using qualitative and quantitative approaches. Some data are first processed manually and the SPSS 17.0 (2008) is deployed for others. The results indicate that the students approve learning EFL vocabulary using contextual clues. They also reveal important strengths and weaknesses with pedagogical implication regarding the use of contextual clues to infer the meanings of unknown/unfamiliar words through reading. Keywords: Contextual Clues, Vocabulary Teaching/Learning, Reading Comprehension, English as a Foreign Language (EFL), Word Meaning Inferencing, Unknown/Unfamiliar words

Evaluation of different options: host plant resistance, weed management, fertilization for the development of an integrated pest management strategy for the sweet potato weevil in Burkina Faso

The sweet potato weevil (SPW) (Cylas puncticollis) is a destructive pest feeding on the sweet potato in Burkina Faso. This weevil causes severe damage to the tuber, and the infested tuber is unsuitable for human consumption or animal feed. This problem calls for effective control management, especially for non-chemical approaches. A field experiment was carried out from 2012 to 2015 with the aim to develop management methods. Different control methods, including host-plant resistance, weeds management and crop fertilization, were tested. The results showed that two varieties, Zappalo-1 and Resisto were free of any SPW damage (0%). Similarly, when plots were not weeded tubers of the BF11 variety were free of any SPW damage (0%). Finally, the combination of manure and mineral fertilizer significantly reduced the damage due to the SPW to score as low as 1 compare to 3.5 in the absence of manure. From the current study, it can be concluded that an integrated approach combining resistant varieties, good weeding practices and fertilizer application could be implemented to control the SPW in Burkina Faso

Feeding preferences of the legume pod borer Maruca vitrata (Lepidoptera: Crambidae) larvae and suitability of different flower parts for larval development

With the advent of transgenic Bacillus thuringiensis (Bt)-cowpea, there is a need to identify the feeding preferences of Maruca vitrata Fab. to determine in which component of the plant the expression of the toxin needs to be the highest to ensure the greatest efficacy of insecticidal Bt proteins. In the current study, we examined the feeding preferences of M. vitrata larvae in a naturally infested cowpea field. We also tested, in the laboratory, the suitability of different flower components for the larval development of M. vitrata. Our results indicate that in the field, all types of flowers, regardless of their age, were infested with M. vitrata larvae. The reproductive organs, in the flowers, were the preferred feeding diet for the larvae. Laboratory bioassays confirmed that the reproductive organs were the optimal tissues for M. vitrata larval development. The implications of these findings for transgenic Bt-cowpea are discussed

Effects of Maruca vitrata multi-nucleopolyhedrovirus and neem oil, Azadirachta indica Juss on the eggs of the cowpea pod borer, Maruca vitrata Fabricius (Lepidoptera: Crambidae)

Cowpea, Vigna unguiculata (L.) Walp., is the most cultivated and consumed legume in West Africa and is typically attacked by several insect pests, including Maruca vitrata, leading to reduced yields. This study assessed under laboratory conditions the efficacy of neem oil and M. vitrata multi-nucleopolyhedrovirus (MaviMNPV) against M. vitrata eggs as alternatives to second generation pesticides. Hatching and mortality rates after biopesticide application of neem oil, MaviMNPV, and the two in combination reduced the egg viability by 89%, 84% and 91%, respectively. Moreover, the combination of MaviMNPV and neem oil induced 100% mortality among the hatched larvae, compared to 60% and 100% alone, respectively. Implications for using these biopesticides are discussed within an integrated pest management (IPM) context

Effects of PICS bags on insect pests of sorghum during long-term storage in Burkina Faso

The PICS bags, originally developed for cowpea storage, were evaluated for sorghum (Sorghum bicolor) preservation. Batches of 25 kg of sorghum grain were stored in 50 kg PICS or polypropylene (PP) bags under ambient conditions for 12 months and assessed for the presence of insect pests and their damage, seed viability and, oxygen and carbon dioxide variations. The grain was incubated for 35 days to assess whether any insects would emerge. After six months of storage, oxygen levels decreased in the PICS bags compared to polypropylene bags. After 12 months of storage, only two pests, Rhyzopertha dominica and Sitophilus zeamais were found in the PICS bags. However, in PP bags there were additional pests including Tribolium castaneum and Oryzeaphilus mercator and Xylocoris flavipes. Grain weight loss and damage caused by these insects in the PP bags were significantly higher compared to those stored in PICS bags. Germination rates of sorghum grains stored in PP bags decreased significantly while no changes were observed in grains stored in PICS bags when compared to the initial germination. After the incubation post storage period, there was a resurgence of R. dominica in sorghum grains from PICS bags but the population levels were significantly lower compared to polypropylene bags. PICS bags preserved the quality and viability of stored sorghum grains and protected it from key insect pests. The PICS technology is effective for long-term sorghum storage but the potential resurgence of insects in low-oxygen environment calls for further research

Differential regulation of myeloid leukemias by the bone marrow microenvironment

Like their normal hematopoietic stem cell counterparts, leukemia stem cells (LSC) in chronic myelogenous leukemia (CML) and acute myeloid leukemia (AML) are presumed to reside in specific niches in the bone marrow microenvironment (BMM)1, and may be the cause of relapse following chemotherapy.2 Targeting the niche is a novel strategy to eliminate persistent and drug-resistant LSC. CD443,4 and IL-65 have been implicated previously in the LSC niche. Transforming growth factor (TGF)-β1 is released during bone remodeling6 and plays a role in maintenance of CML LSCs7, but a role for TGF-β1 from the BMM has not been defined. Here, we show that alteration of the BMM by osteoblastic cell-specific activation of the parathyroid hormone (PTH) receptor8,9 attenuates BCR-ABL1-induced CML-like myeloproliferative neoplasia (MPN)10 but enhances MLL-AF9-induced AML11 in mouse transplantation models, possibly through opposing effects of increased TGF-β1 on the respective LSC. PTH treatment caused a 15-fold decrease in LSCs in wildtype mice with CML-like MPN, and reduced engraftment of immune deficient mice with primary human CML cells. These results demonstrate that LSC niches in chronic and acute myeloid leukemias are distinct, and suggest that modulation of the BMM by PTH may be a feasible strategy to reduce LSC, a prerequisite for the cure of CML