Present and future potential of plant-derived products to control arthropods of veterinary and medical significance

The use of synthetic pesticides and repellents to target pests of veterinary and medical significance is becoming increasingly problematic. One alternative approach employs the bioactive attributes of plant-derived products (PDPs). These are particularly attractive on the grounds of low mammalian toxicity, short environmental persistence and complex chemistries that should limit development of pest resistance against them. Several pesticides and repellents based on PDPs are already available, and in some cases widely utilised, in modern pest management. Many more have a long history of traditional use in poorer areas of the globe where access to synthetic pesticides is often limited. Preliminary studies support that PDPs could be more widely used to target numerous medical and veterinary pests, with modes of action often specific to invertebrates. Though their current and future potential appears significant, development and deployment of PDPs to target veterinary and medical pests is not without issue. Variable efficacy is widely recognised as a restraint to PDPs for pest control. Identifying and developing natural bioactive PDP components in place of chemically less-stable raw or 'whole’ products seems to be the most popular solution to this problem. A limited residual activity, often due to photosensitivity or high volatility, is a further drawback in some cases (though potentially advantageous in others). Nevertheless, encapsulation technologies and other slow-release mechanisms offer strong potential to improve residual activity where needed. The current review provides a summary of existing use and future potential of PDPs against ectoparasites of veterinary and medical significance. Four main types of PDP are considered (pyrethrum, neem, essential oils and plant extracts) for their pesticidal, growth regulating and repellent or deterrent properties. An overview of existing use and research for each is provided, with direction to more extensive reviews given in many sections. Sections to highlight potential issues, modes of action and emerging and future potential are also included

Wirkung verschiedener Insektizide und Repellentien gegen den Gemeinen Birnenblattsauger (Cacopsylla pyri)

The efficacy of different insecticides (neem, pyrethrin, spinosad, and rotenone) and a repellent (kaolin) applied with different strategies (single or repeated applications) against the over-wintering pear suckers (Cacopsylla pyri) and nymphs of the first generation was tested in a field trial in Switzerland in spring 2003. Rotenone, the only admitted product in Swiss organic agriculture, showed good effects. But, since Rotenone is toxic for non-target insects we looked for an alternative. The application of spinosad (Audienz) in combination with rape oil (Telmion) as well as the application of pyrethrum showed similar efficacy as rotenone. Neem had no or a very low impact on the pear sucker populations. The repellent kaolin (Surround® WP) showed the best efficacy against the European pear sucker: triple application of kaolin before blossom was most efficient. Since kaolin is not toxic for beneficials this product might be an alternative to rotenone

Alternative protection of potatoes in organic farming

There were tested water extracts from Syringa vulgaris and Pyrethrum parthenium. They did not prove signincant differences ofdecrease of the air attack ofColorado potato beetle (Leptinotarsa decemlineata), the activity ofeggs -laying and the occurrence oflarvae in comparison to the control. Interesting trends oflower-eggs lying and a lower larvae occurrence were discovered. The liquid spray against the late blight (Phytophthora infestans) did not signincantly decrease neither occurrence oflate blight or the yield. The production of the bio-potatoes is only 0,2% of all potatoes production in the Czech Republic. The aim of this experiment was to try alternative methods of regulation of Colorado potato beetle and late blight (the biggest harmful! organisms ofpotatoes). For biological agriculture could be also suitable water extracts. These are possible to use as protection of potatoes against unfavorable factors (Colorado potate beetle and late blight) and increase yield and quality ofproduction

Effects of autumn kaolin, pyrethrin, and ladybird larvae (Adalia bipunctata) applications on the spring populations of the rosy apple aphid (Dysaphis plantaginea) in an on-farm apple orchard (cv. Topaz)

Effects of different strategies (insecticide treatment, physical barrier, biocontrol) to control autumn forms of Dysaphis plantaginea. Question 1: Efficacy of pyrethrum, kaolin, and larvae of A. bipunctata to control Dysaphis plantaginea. Question 2: Date of application and number of applications for a valuable efficacy

New N-alkylamides from Anacyclus pyrethrum

The roots of Anacyclus pyrethrum DC (Asteraceae) are frequently used in traditional medicine e.g. as aphrodisiac [1]. Depending on the extraction method and solvent, different yields of N-alkylamide constituents can be found, possibly resulting in alterations in biological effects and toxicity. Therefore, analytical profiling of the bio-active N-alkylamides in these plant preparations is an inevitable quality parameter, with liquid chromatography-electrospray mass spectrometry (HPLC/ESI-MS) as recommended technique for comprehensive analysis of alkylamides in plant extracts [2-4].An N-alkylamide profiling from an ethanolic Anacyclus pyrethrum root extract was performed using a gradient reversed phase HPLC/ESI-MS method on an embedded polar column. MS1 and MS2 fragmentation data were used for identification purposes, while UV was used for quantification. Thirteen N-alkylamides (five N-isobutylamides, three N-methyl isobutylamides, four tyramides and one 2-phenylethylamide) were detected. Five of are novel compounds, which have never been identified in Anacyclus pyrethrum or other plants: Acknowledgements: Institute for the Promotion of Innovation through Science and Technology in Flanders (IWT-Vlaanderen) (no. 091257) and the All India Council for Technical Education, New Delhi, India. References: 1. Sharma, V., Thakur, M., Chauhan, N., Dixit, V. 2010 Planta Med 76:1214-1214. 2. Sharma, V., Boonen, J., Chauhan, N., Thakur, M. De Spiegeleer, B., Dixit, V. 2011 Phytomedicine, In press. 3. Kartal, M., Kan, Y., Gulpinar, A. R. 2007 Planta Med 73:253. 4. Boonen, J., Baert, B., Burvenich, C., Blondeel, P., De Saeger, S., De Spiegeleer, B. 2010 J Pharmaceut Biomed 53:243-249

Survey on the control methods of Bactrocera oleae (Gmelin) in organic olive groves producing oil and table olives in Sicily

In Sicily there are several organic farms producing olive oil and the number of farms has grown in the last years. The control methods of Bactrocera oleae (Gmelin) used by Sicilian organic farms were surveyed in 2004 and 2005. After a bibliographic search on internet and by personal contacts, a sample of 30 organic farms in Sicily was chosen; 23 farms produce bottled extra-virgin oil and 7 produce table olives. Then farms were contacted by phone, some of them visited and olive growers were interviewed. For each farm were put together data about: interventions vs. the olive fruit fly, altitude, surface of the olive grove, olive cultivar, irrigation method, harvesting period, milling procedure, product destination and production results in 2005 and in the previous years. From collected data we can say that obtaining oils of excellent quality and table olives of good quality in organic farming is surely possible; the early harvesting and a quick milling (for the oil) let to obtain good results. The most used interventions are: mass trapping with ammonium carbonate, pheromone and pyrethroids, bottled-traps baited with sardines, yellow sticky traps, sprays with kaolin, Bordeaux mixture or pyrethrum, but there is more than one third of sampled oil producers not using any control method except early harvesting and a quick milling. Unfortunately the organic farms producing table olives in Sicily are very few, perhaps because, differently from olive oil producers, table olive plantings are almost all young and the experience of growers in such organic cultivation is not strong. Also these growers prefer to use mass trapping to control olive fruit fly, but best results were achieved by farmers spraying kaolin, rotenone or copper hydroxide

A Systematic Review of Mosquito Coils and Passive Emanators: Defining Recommendations for Spatial Repellency Testing Methodologies.

Mosquito coils, vaporizer mats and emanators confer protection against mosquito bites through the spatial action of emanated vapor or airborne pyrethroid particles. These products dominate the pest control market; therefore, it is vital to characterize mosquito responses elicited by the chemical actives and their potential for disease prevention. The aim of this review was to determine effects of mosquito coils and emanators on mosquito responses that reduce human-vector contact and to propose scientific consensus on terminologies and methodologies used for evaluation of product formats that could contain spatial chemical actives, including indoor residual spraying (IRS), long lasting insecticide treated nets (LLINs) and insecticide treated materials (ITMs). PubMed, (National Centre for Biotechnology Information (NCBI), U.S. National Library of Medicine, NIH), MEDLINE, LILAC, Cochrane library, IBECS and Armed Forces Pest Management Board Literature Retrieval System search engines were used to identify studies of pyrethroid based coils and emanators with key-words "Mosquito coils" "Mosquito emanators" and "Spatial repellents". It was concluded that there is need to improve statistical reporting of studies, and reach consensus in the methodologies and terminologies used through standardized testing guidelines. Despite differing evaluation methodologies, data showed that coils and emanators induce mortality, deterrence, repellency as well as reduce the ability of mosquitoes to feed on humans. Available data on efficacy outdoors, dose-response relationships and effective distance of coils and emanators is inadequate for developing a target product profile (TPP), which will be required for such chemicals before optimized implementation can occur for maximum benefits in disease control

Nematicidal activity of plant extracts against the root-knot nematode, Meloidogyne incognita

Nematicidal activity of extracts from plants was assayed against Meloidogyne incognita. In laboratory assays extracts from tobacco (Nicotiana tabacum L), clove (Syzygium aromaticum L), betelvine (Piper betle L), and sweet flag (Acorus calamus L) were most effective in killing the nematode, with an EC50 that was 5-10 times lower than the EC50 of the synthetic pesticides chlorpyrifos, carbosulfan and deltamethrin. The shapes of the dead nematodes differed in a characteristic way, and groups of pesticides and plant extracts could clearly be distinguished based on this phenomenon, which may be an indicator for the modes of action of the tested pesticides. In a greenhouse bioassay clove bud and betelvine were tested as mulch. Experiments revealed that the total number of live nematodes on roots of pepper plants treated with mulch of the clove bud was 7% of that of the controls and did not differ significantly from that of plants treated with the recommended synthetic pesticide carbofuran. The application of clove buds as a botanical pesticide for future use against nematodes is highly promising since clove is the 6th major plant grown on Bangka Island, and the market value of clove has decreased sharply over the last year

N-alkylamides : from plant to brain

Background: Plant N-alkylamides (NAAs) are bio-active compounds with a broad functional spectrum. In order to reach their pharmacodynamic targets, they have to overcome several barriers of the body in the absorption phase. The permeability kinetics of spilanthol (a diene NAA) and pellitorine (a triene NAA) across these barriers (i.e. skin, oral/gut mucosa, blood-brain barrier) were investigated. Methods: The skin and oral mucosa permeability were investigated using human skin and pig mucosa in an ex vivo in vitro Franz diffusion cell set-up. The gut absorption characteristics were examined using the in vitro Caco-2 cell monolayer test system. The initial blood-brain barrier transport kinetics were investigated in an in vivo mice model using multiple time regression and efflux experiments. Quantification of both NAAs was conducted using HPLC-UV and bio-analytical UPLC-MS methods. Results: We demonstrated that spilanthol and pellitorine are able to penetrate the skin after topical administration. It is likely that spilanthol and pellitorine can pass the endothelial gut as they easily pass the Caco-2 cells in the monolayer model. It has been shown that spilanthol also crosses the oral mucosa as well as the blood-brain barrier. Conclusion: It was demonstrated that NAAs pass various physiological barriers i.e. the skin, oral and gut mucosa, and after having reached the systemic circulation, also the blood-brain barrier. As such, NAAs are cosmenutriceuticals which can be active in the brain

Mosquito Abundance, Bed net Coverage and Other Factors Associated with Variations in Sporozoite Infectivity Rates in Four Villages of Rural Tanzania.

Entomological surveys are of great importance in decision-making processes regarding malaria control strategies because they help to identify associations between vector abundance both species-specific ecology and disease intervention factors associated with malaria transmission. Sporozoite infectivity rates, mosquito host blood meal source, bed net coverage and mosquito abundance were assessed in this study. A longitudinal survey was conducted in four villages in two regions of Tanzania. Malaria vectors were sampled using the CDC light trap and pyrethrum spray catch methods. In each village, ten paired houses were selected for mosquitoes sampling. Sampling was done in fortnight case and study was undertaken for six months in both Kilimanjaro (Northern Tanzania) and Dodoma (Central Tanzania) regions. A total of 6,883 mosquitoes were collected including: 5,628 (81.8%) Anopheles arabiensis, 1,100 (15.9%) Culex quinquefasciatus, 89 (1.4%) Anopheles funestus, and 66 (0.9%) Anopheles gambiae s.s. Of the total mosquitoes collected 3,861 were captured by CDC light trap and 3,022 by the pyrethrum spray catch method. The overall light trap: spray catch ratio was 1.3:1. Mosquito densities per room were 96.5 and 75.5 for light trap and pyrethrum spray catch respectively. Mosquito infectivity rates between villages that have high proportion of bed net owners and those without bed nets was significant (P < 0.001) and there was a significant difference in sporozoite rates between households with and without bed nets in these four villages (P < 0.001). Malaria remains a major problem in the study areas characterized as low transmission sites. Further studies are required to establish the annual entomological inoculation rates and to observe the annual parasitaemia dynamics in these communities. Outdoor mosquitoes collection should also be considered