Repellent activity of Cymbopogon citratus and Tagetes minuta and their specific volatiles against Megalurothrips sjostedti

Cowpea is an important source of protein for people in Africa. However, the crop suffers major damage and yield losses due to bean flower thrips, Megalurothrips sjostedti Trybom (Thysanoptera: Thripidae). Although companion plants are known to reduce the damage caused by insect pests, the role of their volatiles in repelling pests from target plants has been the subject of few investigations. Here, we used the Y‐tube olfactometer experiments and chemical analyses to investigate the effect of volatiles from cowpea flowers and two companion plants; lemongrass, Cymbopogon citratus and Mexican marigold, Tagetes minuta on the olfactory responses of M. sjostedti. The results revealed that M. sjostedti males and females were repelled by the volatiles from freshly cut leaves of C. citratus. The combination of freshly cut leaves of C. citratus and cowpea flower was repellent to females but not to males. The female thrips, but not males, were repelled by the volatiles from the vegetative stage of T. minuta. Fifty‐four compounds were identified in the volatiles from two herbal plants. Among the major compounds, citral and a 4‐component blend comprised of dihydrotagetone, (Z)‐3‐hexenyl acetate, limonene and (Z)‐β‐ocimene repelled females but dihydrotagetone alone attracted females. While myrcene combined with cowpea flower volatiles enhanced the attraction of females M. sjostedti, when tested alone was not attractive. These results highlight the potential of volatiles from C. citratus and T. minuta to repel M. sjostedti females. The use of these plants as companion plants in a cowpea cropping system could reduce M. sjostedti infestation

Behavioural responses of bean flower thrips (Megalurothrips sjostedti) to vegetative and floral volatiles from different cowpea cultivars

Bean flower thrips (Megalurothrips sjostedti) is a key pest of cowpea (Vigna unguicalata) in Africa. To better understand the interaction of M. sjostedti to cowpea cultivars to improve management efforts, we investigated the repellent properties of volatiles of four cowpea cultivars, namely Ex-Luanda, Machakos, Ken Kunde 1 and Katumani 80 at different phenological stages. Bioassays were conducted to study host preference and gas chromatography–mass spectrometry for chemical analysis of volatiles. Our results showed no significant preference of females M. sjostedti for any cowpea cultivars tested in preference assays. However, in olfactometer, the volatiles emitted during the vegetative stage of only Ex-Luanda, Machakos and Katumani 80 cultivars were repellent to females, while only Ken Kunde 1 was repellent to males. Volatiles from flowers of Ken Kunde 1 were attractive to females, whereas volatiles from the flowers of Katumani 80 were repellent, respectively. Ex-Luanda and Machakos elicited neutral response. Flowers of Machakos 66 and Ex-Luanda cultivars were repellent to males, while Katumani 80 and Ken Kunde 1 were neutral. The volatile analysis showed that (E)-β-ocimene and 1-octen-3-ol were unique to the volatile profile of Katumani 80 flowers. Previous study showed that (E)-2-hexenal and hexanal were only abundant in the vegetative stage of Katumani 80. (E)-2-hexenal was repellent to the females at a concentration of 0.01% but not at 1%. Hexanal, (E)-β-ocimene and 1-octen-3-ol elicited a neutral response from females at 0.01% and 1%. Our study indicates that (E)-2-hexenal could be useful in the development of semiochemical-based repellent tools for M. sjostedti management

The most frequent Mycobacterium tuberculosis complex families in mali (2006–2016) based on spoligotyping

Background: To identify strains of Mycobacterium tuberculosis complex (MTBc) circulating in Bamako region during the past 10 years. Methods: From 2006 to 2016, we conducted a cross-sectional study to identify with spoligotyping, clinical isolates from tuberculosis (TB)-infected patients at different stages of their treatments in Bamako, Mali. Results: Among the 904 suspected TB patients included in the study and thereafter tested in our BSL-3 laboratory, 492 (54.4%) had MTBc and therefore underwent spoligotyping. Overall, three subspecies, i.e., MTB T1 (31.9%) and MTB LAM10 (15.3%) from lineage 4 and M. africanum 2 (16.8%) from lineage 6 were the leading causes of TB in Bamako region during the past 10 years. Other spoligotypes such as MTB T3, MTB Haarlem 2, MTB EAI3, and MTB family 33 were also commonly seen from 2010 to 2016. Conclusion: This study showed a high genetic diversity of strains isolated in Bamako region and highlights that M. tuberculosis T1 strain was the most prevalent. Furthermore, the data indicate an increasing proportion of primary drug resistance overtime in Bamako

Patients infected with Mycobacterium africanum versus Mycobacterium tuberculosis possess distinct intestinal microbiota.

BACKGROUND:Mycobacterium tuberculosis complex (MTBC), the causative agent of tuberculosis (TB), is composed of eight subspecies. TB in West Africa, in contrast to other geographical regions, is caused by Mycobacterium africanum (MAF) in addition to M. tuberculosis (MTB), with both infections presenting similar symptoms. Nevertheless, MAF is considered to be hypovirulent in comparison with MTB and less likely to progress to active disease. In this study, we asked whether MAF and MTB infected patients possess distinct intestinal microbiomes and characterized how these microbiota communities are affected by anti-tuberculosis therapy (ATT). Additionally, we assessed if the changes in microbiota composition following infection correlate with pathogen induced alterations in host blood-gene expression. METHODS:A longitudinal, clinical study of MAF infected, MTB infected patients assessed at diagnosis and two months after start of ATT, and healthy, endemic controls was conducted to compare compositions of the fecal microbiome as determined by 16S rRNA sequencing. A blood transcriptome analysis was also performed on a subset of subjects in each group by microarray and the results cross-compared with the same individual's microbiota composition. FINDINGS:MAF participants have distinct microbiomes compared with MTB patients, displaying decreased diversity and increases in Enterobacteriaceae with respect to healthy participants not observed in the latter patient group. Interestingly, this observed elevation in Enterobacteriaceae positively correlated with enhanced inflammatory gene expression in peripheral blood and was reversed after initiation of ATT. INTERPRETATION:Our findings indicate that MAF and MTB have distinct associations with the gut microbiome that may be reflective of the differential susceptibility of West Africans to these two co-endemic infections either as biomarkers or as a contributing determinant