Compounds associated with infection by the root-knot Nematode, Meloidogyne javanica influence the ability of infective juveniles to recognize host plants

Plant root chemistry is altered by parasitism of plant parasitic nematodes (PPN). Here, we 2 investigated the influence of the infective stage juveniles (J2) of Meloidogyne javanica in 3 inducing tomato (Solanum lycopersicum) root volatiles, and chemotactic effect on conspecifics. 4 In olfactometer assays, J2 avoided roots of 2-day infected plants but preferred 7-day infected 5 tomato compared to healthy plants. Chemical analysis showed a two- to seven-fold increase in 6 the amounts of monoterpenes emitted from tomato roots infected with M. javanica relative to 7 healthy roots. In further bioassays, the monoterpenes β-pinene, (+)-(2)-carene, α-phellandrene, 8 and β-phellandrene differentially attracted (51-87%) J2 relative to control. Concurrent reduction 9 and increase in the levels of methyl salicylate and (Z)-methyl dihydrojasmonate, respectively, in 10 the root volatiles reduced J2 responses. These results demonstrate that the host plant can alter its 11 root volatile composition to inhibit PPN attack. The observed plant-produced inhibition of J2 12 warrants further investigation as a potential management tool for growers

Repellency and composition of essential oils of selected ethnobotanical plants used in Western Kenya against bites of Anopheles gambiae Sensu Stricto

The essential oils of Ocimum gratissimum Linn, Hyptis suaveolens (L) Poit and Vitex keniensis, which are used traditionally in Western Kenya for personal and space protection against mosquito bites, were screened for repellence against Anopheles gambiae Sensu Stricto. Essential oils were extracted from their leaves by hydrodistillation, characterised by gas chromatography linked with mass spectrophotometer and electroantennogram detectors. The repellency of the oils and their selected blends was studied by the reduction in probing and feeding on the human arm. The oils showed promising repellency for Anopheles gambiae, O. gratissimum (RD50 = 2.77 × 10-5 mg cm-2, 95% CI), Vitex keniensis (RD = 5.68 × 10-5 mg cm-2) and Hyptis suaveolens (6.27× 10-5 mg cm-2) as compared to that of DEET (control) RD = 1.25×10-5 mg cm-2). The bioactive constituents of each oil were identified by Gas chromatography-linked with Mass spectrometry and Electroantennography. Some compounds were confirmed by co-injections of the oil with available authentic standards. The results provide a scientific rationale for the traditional use of these plants in repelling disease vectors and other biting insects, and lay down some useful groundwork for downstream development of more effective products for personal and space protection

Rethinking HIV prevention to prepare for oral PrEP implementation for young African women

Introduction: HIV incidence remains high among young women in sub-Saharan Africa in spite of scale-up of HIV testing, behavioural interventions, antiretroviral treatment and medical male circumcision. There is a critical need to critique past approaches and learn about the most effective implementation of evidence-based HIV prevention strategies, particularly emerging interventions such as pre-exposure prophylaxis (PrEP). Discussion Women in sub-Saharan Africa are at increased risk of HIV during adolescence and into their 20s, in part due to contextual factors including gender norms and relationship dynamics, and limited access to reproductive and sexual health services. We reviewed behavioural, behavioural economic and biomedical approaches to HIV prevention for young African women, with a particular focus on the barriers, opportunities and implications for implementing PrEP in this group. Behavioural interventions have had limited impact in part due to not effectively addressing the context, broader sexual norms and expectations, and structural factors that increase risk and vulnerability. Of biomedical HIV prevention strategies that have been tested, daily oral PrEP has the greatest evidence for protection, although adherence was low in two placebo-controlled trials in young African women. Given high efficacy and effectiveness in other populations, demonstration projects of open-label PrEP in young African women are needed to determine the most effective delivery models and whether women at substantial risk are motivated and able to use oral PrEP with sufficient adherence to achieve HIV prevention benefits. Conclusions: Social marketing, adherence support and behavioural economic interventions should be evaluated as part of PrEP demonstration projects among young African women in terms of their effectiveness in increasing demand and optimizing uptake and effective use of PrEP. Lessons learned through evaluations of implementation strategies for delivering oral PrEP, a first-generation biomedical HIV prevention product, will inform development of new and less user-dependent PrEP formulations and delivery of an expanding choice of prevention options in HIV prevention programmes for young African women