Arthropods are dangerous vectors of agents of deadly diseases, which may hit as epidemics or pandemics in the increasing world population of humans and animals. Among them, ticks transmit more pathogen species than any other group of blood-feeding arthropods worldwide. Thus, the effective and eco-friendly control of tick vectors in a constantly changing environment is a crucial challenge. A number of novel routes have been attempted to prevent and control tick-borne diseases, including the development of (i) vaccines against viruses vectored by ticks; (ii) pheromone-based control tools, with special reference to the “lure and kill” techniques; (iii) biological control programmes relying on ticks’ natural enemies and pathogens; and (iv) the integrated pest management practices aimed at reducing tick interactions with livestock. However, the extensive employment of acaricides and tick repellents still remains the two most effective and ready-to-use strategies. Unfortunately, the first one is limited by the rapid development of resistance in ticks, as well as by serious environmental concerns. On the other hand, the exploitation of plants as sources of effective tick repellents is often promising. Here, we reviewed current knowledge concerning the effectiveness of plant extracts as acaricides or repellents against tick vectors of public health importance, with special reference to Ixodes ricinus, Ixodes persulcatus, Amblyomma cajennense, Haemaphysalis bispinosa, Haemaphysalis longicornis, Hyalomma anatolicum, Hyalomma marginatum rufipes, Rhipicephalus appendiculatus, Rhipicephalus (Boophilus) microplus, Rhipicephalus pulchellus, Rhipicephalus sanguineus and Rhipicephalus turanicus. Eighty-three plant species from 35 botanical families were selected. The most frequent botanical families exploited as sources of acaricides and repellents against ticks were Asteraceae (15 % of the selected studies), Fabaceae (9 %), Lamiaceae (10 %), Meliaceae (5 %), Solanaceae (6 %) and Verbenaceae (5 %). Regression equation analyses showed that the literature grew by approximately 20 % per year (period: 2005–2015). Lastly, in the final section, insights for future research are discussed. We focused on some caveats for future data collection and analysis. Current critical points mainly deal with (a) not uniform methods used, which prevent proper comparison of the results; (b) inaccurate tested concentrations, frequently 100 % concentration corresponded to the gross extract, where the exact amounts of extracted substances are unknown; and (c) not homogeneous size of tested tick instars and species. Overall, the knowledge summarized in this review may be helpful for comparative screening among extensive numbers of plant-borne preparations, in order to develop newer and safer tick control tools.

Tick repellents and acaricides of botanical origin: a green roadmap to control tick-borne diseases?

Potentiality of plants as source of insecticide principles

Exploitation of chemical, herbal and nanoformulated acaricides to control the cattle tick, Rhipicephalus (Boophilus) microplus - A review.

The chemical composition of essential oil of leaves of Piper aduncum L., growing wild in a fragment of the Atlantic Rainforest biome in northeastern Brazil, was determined through gas chromatography-mass spectrometry. The acaricidal activity and repellency of the essential oil and its components [dillapiole (0.28 g/ml), α-humulene (0.016 g/ml), (E)-nerolidol (0.0007 g/ml) and β-caryophyllene (0.0021 g/ml)] were evaluated in the laboratory against adults of Tetranychus urticae Koch. The mites were more susceptible to the oil in fumigation tests (LC50 = 0.01 μl/l of air) than in contact test with closed Petri dish (LC50 = 7.17 μl/ml); mortality was reduced by approximately 50 % in the latter test. The repellent action of the oil and toxicity by fumigation and contact did not differ significantly from the positive control (eugenol). The repellent activity was attributed to the components (E)-nerolidol, α-humulene and β-caryophyllene, whereas toxicity by fumigation and contact was attributed to β-caryophyllene. The effect of Piper oil and the role of its components regarding host plant preference with a two-choice leaf disk test are also discussed.

Acaricidal activity and repellency of essential oil from Piper aduncum and its components against Tetranychus urticae

The anthelmintic effect of plant extracts on Haemonchus contortus and Strongyloides venezuelensis.

Toxicity of Piper aduncum L. (Piperales: Piperaceae) from the Amazon forest for the cattle tick Rhipicephalus (Boophilus) microplus (Acari: Ixodidae).

This study describes the life cycle of Agrotis malefida Guenee, 1852 (Noctuidae: Noctuinae) under laboratory conditions. The insects were reared in a controlled environment (25 ± 1oC, 70 ± 10% RH and 14 hours photo phase) and observed daily. The larvae were fed Greene's artificial diet and adults were offered a 10% sucrose solution. The viability and duration of immature stages were assessed. The experiment initiated with 2,410 eggs. Larvae were isolated shortly after hatching. Longevity, pre-, post- and oviposition, fecundity and fertility of 13 adult couples were also evaluated. The viability of eggs, larvae, pupae and pre-pupae was 96.72, 91.25, 78.37 and 95.26%, respectively. The average duration of egg, larva, pre-pupa, pupa and adult was 7.93, 54.26, 61.61, 37.43 and 12.85 days, respectively. The immature stage of A. malefida lasted an average of 161.29 days, ranging from 102 to 227 days. The life cycle of A. malefida is much longer than that of congeners. The mean fecundity was 1,696.77 eggs and fertility 1,641.15 larvae per female. Under the conditions in which the study was conducted, the biotic potential of A. malefida was of 606,666.59 individuals/female/year. The results also indicated that this species goes through larval (pre-pupae) and pupal diapause.

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Francine Albrecht

Papers

Toxicity of Piper aduncum L. (Piperales: Piperaceae) from the Amazon forest for the cattle tick Rhipicephalus (Boophilus) microplus (Acari: Ixodidae).

Life cycle of Agrotis malefida (Lepidoptera: Noctuidae): a diapausing cutworm