Field Evaluation of Deet, Repel Care®, and Three Plant-Based Essential Oil Repellents Against Mosquitoes, Black Flies (Diptera: Simuliidae), and Land Leeches (Arhynchobdellida: Haemadipsidae) in Thailand

Abstract

Diethyl methyl benzamide, or deet, a commercial plant-based repellent (Repel Care), and essential ils from 3 species of plants (finger root rhizomes, guava leaves, and turmeric rhizomes), steam distillated and formulated as insect repellents, were evaluated in the field on human volunteers against hematophagous mosquitoes, black flies, and land leeches in Thailand. Field trials were conducted against wild mosquitoes in Bang Bua Thong District, Nonthaburi Province, and in the Thap Lan National Park Headquarters, Nadee District, Pranchinburi Province; anthroophilic black flies (Diptera: Simuliidae) at the Forestry Fire Control Station in Doi Inthanon National Park, Chomthong district, Chiang Mai Province; and land leeches (Arhynchobdellida: Haemadipsidae) in the Khao Yai National Park, Pak Chong District, Nakhon Ratchasima Province. The 3 experimental plant-based essential oil formulations as well as Repel Care and deet provided complete protection from mosquito landing and biting for up to 9 h (duration of the experiment). Similar results were obtained with the 5 products against black flies, providing 100% protection for 9 h but 96-82% protection after 10 and 11 h posttreatment. The 5 repellent products also provided 100% protection against land leeches for at least 8 h. Thi is the 1st report of repellency of plant-based repellents against black flies and land leeches in Thailand. The identification and availability of inexpensive sources of plant-based oils, i.e., finger root rhizomes, guava leaves, and turmeric rhizomes providing long-lasting repellency against blood-sucking organisms are promising leads into commercial production of relatively safe and effective repellents.

“Singing in the Tube”—audiovisual assay of plant oil repellent activity against mosquitoes (Culex pipiens)

“…Especially, plant essential oils have been proposed for mosquito control and repelling (Boschitz and Grunewald 1994, Amer and Mehlhorn 2006, Tawatsin et al 2006a, 2006b. In addition, a recent study suggested the use of chitosan-based elicitors for the induction of insect-repelling activity (Wongchai et al 2013).…”

“…Therefore, new repellents would be helpful. Notably, plant seed kernel extracts and essential oils have been proposed for mosquito control and repelling (Boschitz and Grunewald 1994, Amer and Mehlhorn 2006, Tawatsin et al 2006a, 2006b. Testing plant materials, we searched for an assay with simple generally available equipment and potential of automation.…”

Role of Plant Biopesticides in Managing Vectors of Communicable Diseases

“…In Thailand, essential oils extracted from B. rotunda , P. guajava , and C. longa and one commercial plant-based repellent (containing turmeric oil 5 % and eucalyptus oil 4.5 %) were tested on human volunteers against blackfl ies ( S. nigrogilvum 99 % of the fl ies collected). All four plant-based repellents gave 100 % protection from the bites of blackfl ies for 9 h, protection decreasing to 93 and 90 % after 10 and 11 h of application of the repellents (Tawatsin et al 2006b ). The extent and duration of protection was the same for deet and the plant products.…”

“…aegypti and Ae. albopictus ) mosquitoes (Tawatsin et al 2006b ). The four plant oils, fi ngerroot, Boesenbergia rotunda (10 %); guava, P. guajava (10 %); turmeric, C. longa (10 %); and a commercial product Repel Care 9.5 % (turmeric oil 5 % and E. citriodora oil 4.5 %), were compared with deet.…”

“…In Malaysia, Kirton ( 2005 ) revealed that a commercial spray containing 40 % (w/w) Citriodiol, an extract of the leaves of C. citriodora (or E. citriodora ) and primarily consists of PMD, showed excellent repellency against land leeches, mostly Haemadipsa sylvestris , when applied on the footwear and trouser legs (tucked into socks). Later, three plant-based repellents derived from essential oil of B. rotunda (10 %), P. guajava (10 %), and C. longa (10 %) and one commercial repellent (containing turmeric oil 5 % and eucalyptus oil 4.5 %) as mentioned previously by Tawatsin et al ( 2006b ) and deet (10 %) were tested on human volunteers against land leeches in national park in Thailand. The volunteers walked for 10 min along the trail in each hour interval through the walking trail and collected attached land leeches on both legs (one treated with repellent and the other untreated as control).…”