Field margins and botanical insecticides enhance Lablab purpureus yield by reducing aphid pests and supporting natural enemies.

Botanical insecticides offer an environmentally benign insect pest management option for field crops with reduced impacts on natural enemies of pests and pollinators while botanically rich field margins can augment their abundance. Here, we evaluated the non-target effects on natural enemies and pest control efficacy on bean aphids in Lablab of three neem- and pyrethrum-based botanical insecticides (Pyerin75EC®, Nimbecidine® and Pyeneem 20EC®) and determine the influence of florally rich field margin vegetation on the recovery of beneficial insects after treatment. The botanical insecticides were applied at the early and late vegetative growth stages. Data were collected on aphids (abundance, damage severity and percent incidence) and natural enemy (abundance) both at pre-spraying and post-spraying alongside Lablab bean yield. The efficacy of botanical insecticides was similar to a synthetic pesticide control and reduced aphid abundance by 88% compared with the untreated control. However, the number of natural enemies was 34% higher in botanical insecticide-treated plots than in plots treated with synthetic insecticide indicating that plant-based treatments were less harmful to beneficial insects. The presence of field margin vegetation increased further the number of parasitic wasps and tachinid flies by 16% and 20%, respectively. This indicated that non-crop habitats can enhance recovery in beneficial insect populations and that botanical insecticides integrate effectively with conservation biological control strategies. Higher grain yields of 2.55-3.04 and 2.95-3.23 t/ha were recorded for both botanical insecticide and synthetic insecticide in the presence of florally enhanced field margins in consecutive cropping seasons. Overall, these data demonstrated that commercial botanical insecticides together with florally rich field margins offer an integrated, environmentally benign and sustainable alternative to synthetic insecticides for insect pest management and increased productivity of the orphan crop legume, Lablab.

Tracking Antimicrobial Resistance Determinants in Diarrheal Pathogens: A Cross-Institutional Pilot Study.

Infectious diarrhea affects over four billion individuals annually and causes over a million deaths each year. Though not typically prescribed for treatment of uncomplicated diarrheal disease, antimicrobials serve as a critical part of the armamentarium used to treat severe or persistent cases. Due to widespread over- and misuse of antimicrobials, there has been an alarming increase in global resistance, for which a standardized methodology for geographic surveillance would be highly beneficial. To demonstrate that a standardized methodology could be used to provide molecular surveillance of antimicrobial resistance (AMR) genes, we initiated a pilot study to test 130 diarrheal pathogens (Campylobacter spp., Escherichia coli, Salmonella, and Shigella spp.) from the USA, Peru, Egypt, Cambodia, and Kenya for the presence/absence of over 200 AMR determinants. We detected a total of 55 different determinants conferring resistance to ten different categories of antimicrobials: genes detected in ≥ 25 samples included blaTEM, tet(A), tet(B), mac(A), mac(B), aadA1/A2, strA, strB, sul1, sul2, qacEΔ1, cmr, and dfrA1. The number of determinants per strain ranged from none (several Campylobacter spp. strains) to sixteen, with isolates from Egypt harboring a wider variety and greater number of genes per isolate than other sites. Two samples harbored carbapenemase genes, blaOXA-48 or blaNDM. Genes conferring resistance to azithromycin (ere(A), mph(A)/mph(K), erm(B)), a first-line therapeutic for severe diarrhea, were detected in over 10% of all Enterobacteriaceae tested: these included >25% of the Enterobacteriaceae from Egypt and Kenya. Forty-six percent of the Egyptian Enterobacteriaceae harbored genes encoding CTX-M-1 or CTX-M-9 families of extended-spectrum ß-lactamases. Overall, the data provide cross-comparable resistome information to establish regional trends in support of international surveillance activities and potentially guide geospatially informed medical care.

Surveillance for enteric pathogens in a case-control study of acute diarrhea in Western Kenya.

BACKGROUND: Acute diarrhea remains a major public health problem in East African nations such as Kenya. Surveillance for a broad range of enteric pathogens is necessary to accurately predict the frequency of pathogens and potential changes in antibiotic resistance patterns. METHOD: Stool samples were collected from September 2009 to September 2011; 193 and 239 samples, from age-matched cases and asymptomatic controls, were collected, respectively, from Kericho and Kisumu District Hospitals in western Kenya. Bacterial pathogens were identified by conventional microbiological methods; antibiotic susceptibility of bacterial isolates was ascertained using the MicroScan WalkAway 40 Plus. An enzyme immunoassay kit was used to detect rotavirus, and ova and parasite examination was conducted by microscopy and an enzyme immunoassay. RESULTS: Rotavirus (10.2% and 10.5%) and Shigella (11% and 8%) were isolated significantly more often in the cases than the controls from Kericho and Kisumu District Hospitals respectively. The diarrheagenic Escherichia coli, Campylobacter jejuni and Salmonella were found most often in the cases while Giardia lamblia and Entamoeba histolytica/E. dispar were found more often in the controls. Most pathogens were isolated from children under 5 years old. More than 50% of the Shigella, Salmonella and diarrheagenic E. coli isolates were multidrug resistant to ampicillin, tetracycline and trimethoprim/sulfamethoxazole with several enteroaggregative and enterotoxigenic E. coli isolates producing extended-spectrum beta-lactamases. CONCLUSION: Accurate epidemiologic information on acute diarrheal illness in Kenya will be critical for augmenting existing diarrhea management policies in terms of treatment and to strengthen future community awareness and health promotion programs.

Shoot epicatechin and epigallocatechin contents respond to water stress in tea [Camellia sinensis (L.) O. Kuntze].

An experiment was conducted to determine the association of tea catechins to water stress in tea, with the objective of determining their suitability as indicators for predicting drought tolerance in tea (Camellia sinensis). The study consisted of six tea clones (BBK 35, TRFK 6/8, TRFK 76/1, TRFK 395/2, TRFK 31/30, and TRFK 311/287) and four levels of soil water content (38, 30, 22, and 14% v/v), which were arranged in a complete randomized design and replicated 3 times. The treatments were maintained for a period of 12 weeks. Tea shoots were sampled for catechin analysis during the 6th week of water treatment, in which fresh shoots with two leaves and a bud were plucked and steamed for 2 min, and dried at 70 degrees C to constant weight. Subsequently, the samples were ground and analyzed for catechins using an HPLC system. The total catechins showed significant correlation with shoot growth (r=0.65, P=0.006), soil water content (r=0.54, P=0.0066), and water stress index (r=0.67, P=0.0004). The epicatechin (EC) correlated with shoot growth (r=0.58, P=0.0032), soil water content (r=0.62, P=0.0014), and water stress index (r=0.63, P=0.0010). Similarly, epigallocatechin (EGC) correlated with shoot growth (r=0.65, P=0.0006), soil water content (r=0.50, P=0.0133), and water stress index (r=0.60, P=0.0021). However, epigallocatechin gallate (EGCg) and epicatechin gallate (ECG) showed no significant response to changes in soil water content. The shoot contents of EC and EGC in the six clones showed varied responses, with a distinct pattern in the water-stress tolerant clones (TRFK 6/8 and TRFK 31/30). The results suggest a potential use for EC and EGC as indicators in predicting drought tolerance in tea.

Polyphenols as potential indicators for drought tolerance in tea (Camellia sinensis L.).

Plant polyphenols have gained prominence in quality of plant products and in human health. An experiment was conducted to determine the association of tea polyphenols with water stress and their suitability as indicators for drought tolerance. The experiment was conducted in a 'rain-out' shelter, and consisted of six tea clones (BBK 35, TRFK 6/8, TRFK 76/1, TRFK 395/2, TRFK 31/30, and TRFK 311/287) and four levels of soil water contents (38, 30, 22, and 14% v/v), which were maintained for a period of 12 weeks. The treatments were arranged in a completely randomized design and replicated three times. Plant growth was monitored over 6 weeks, and a water stress index was calculated to determine water-stress tolerant clones. Total polyphenols in tea shoots was analyzed and a regression analysis done. The results indicate that declining soil water content (SWC) reduced both growth and content of polyphenols in tea. Tolerant clones maintained a high polyphenol content at low SWC, and also showed less fluctuation in phenolics when subjected to changes in SWC. There was significant (P<0.001) correlation of total polyphenol content with shoot growth and WSI of tea, and a linear relationship (r2=0.97) between SWC for tea and both, water stress index and shoot polyphenol content. We report that there is a potential to use polyphenols as indicators for selection of drought-tolerant tea cultivars.