Ethnobotanical survey and evaluation of traditional mosquito repellent plants of Dai people in Xishuangbanna, Yunnan Province, China.

ETHNOPHARMACOLOGICAL RELEVANCE: Dengue is one of the most important pervasive diseases in many regions of the world, including China. There is an urgent need for new repellents, including plant derivatives, due to the resistance, toxicity, and non-degradability of synthetic insecticides. Traditional plant-based remedies may provide potential avenues for developing new strategies. AIMS OF THE STUDY: The aims of this study were to 1) document the traditional mosquitoes repellent plants used by the Dai people of Xishuangbanna, China; 2) screen out new efficient mosquito repellent plants as candidates for further study. MATERIALS AND METHODS: During the period August 2016 to July 2017, five field surveys were conducted in 16 villages of Xishuangbanna. A total of 81 informants (44 males and 37 females) were interviewed using semi-structured questions to collect detailed information on the plants they use to prevent mosquito bites. Ten plants with higher popularity and larger resource were collected and extracts were prepared by hydro-distillation or with petroleum ether. Extracts were tested for adult Aedes albopictus repellency using a human-bait cage. Firstly, repellency was determined as the Minimum Effective Dosage (MED) per minute at which 1% of the mosquito bite through the treated cloth. Secondly, five plant extracts with lower MEDs were tested the repellent longevity of different concentrations. RESULTS: Eighteen plants were documented as being used in traditional remedies against mosquitoes. The methods for controlling mosquitoes were diverse: direct burning was used for most plants (16 species), followed by smearing (5 species), and placing (5 species). Laboratory analyses confirmed that ten plants did exhibit mosquito repellent activity. Of them, Artemisia indica, Nicotiana tabacum, Blumea balsamifera, Vitex trifolia, and Chromolaena odorata showed good mosquito repellency with MEDs of 0.015, 0.061, 0.090, 0.090, and 0.105 mg/cm2, respectively. The protection rate provided by A. indica is also the highest among five plants. Although it provides complete protection time of only 30 min at 0.45 mg/cm2 concentration, its repellency within 2 h is not significantly different from that of DEET. CONCLUSION: Dai villagers in Xishuangbanna have a rich, diverse and scientific knowledge of plant-based mosquito repellents. Laboratory experiments screened out several plants as candidates for mosquito repellents, of which Artemisia indica was the most promising candidate plant.

Contact irritant dermatitis in Kenya.

Kenya is one of the British Army's main training areas outside of the UK and the flora and fauna present the physicians with several challenges. A 22 year old infantry soldier presented with a vesicular, linear painful rash across his chest caused by the chemical excreted from the Staphylinid or rove beetle, known locally as the Nairobi fly. Treatment included topical antibiotic and steroid creams to good effect. This report highlights the recognition, treatment and complications of the Nairobi Fly.