Mosquito and tick repellency of two Anthemis essential oils from Saudi Arabia

Assessment of Cota altissima (L.) J. Gay for phytochemical composition and antioxidant, anti-inflammatory, antidiabetic and antimicrobial activities

Phytochemical profiles of essential oil (EO), fatty acids, and n-hexane (CAH), diethyl ether (CAD), ethyl acetate (CAE) and methanol extracts (CAM) of Cota altissima L. J. Gay (syn. Anthemis altissima L.) were investigated as well as their antioxidant, anti-inflammatory, antidiabetic and antimicrobial activites. The essential oil was characterized by the content of acetophenone (35.8%) and β-caryophyllene (10.3%) by GC-MS/FID. Linoleic and oleic acid were found as main fatty acids. The major constituents of the extracts were found to be 5-caffeoylquinic acid, 3,5-dicaffeoylquinic acid, isorhamnetin glucoside, quercetin and quercetin glucoside by LC-MS/MS. Antioxidant activities of the extracts were determined by scavenging of DPPH and ABTS free radicals. Also, the inhibitory effects on lipoxygenase and α-glucosidase enzymes were determined. Antimicrobial activity was evaluated against Gram positive, Gram negative bacteria and yeast pathogens. CAM showed the highest antioxidant activity against DPPH and ABTS radicals with IC₅₀ values of 126.60 and 144.40 μg/mL, respectively. In the anti-inflammatory activity, CAE demonstrated the highest antilipoxygenase activity with an IC₅₀ value of 105.40 μg/mL, whereas, CAD showed the best inhibition of α-glucosidase with an IC₅₀ value of 396.40 μg/mL in the antidiabetic activity. CAH was effective against Staphylococcus aureus at MIC = 312.5 µg/mL. This is the first report on antidiabetic, anti-inflammatory and antimicrobial activities of different extracts of C. altissima.

Blue Tansy Essential Oil: Chemical Composition, Repellent Activity Against Aedes aegypti and Attractant Activity for Ceratitis capitata

Blue tansy essential oil (BTEO) ( Tanacetum annuum L.) was analyzed by GC-MS and GC-FID using two different capillary column stationary phases. Sabinene (14.0%), camphor (13.6%), myrcene (8.0%), β-pinene (7.7%), and chamazulene (6.9%) were the main components using an SE52 column (non-polar). On a polar CW20M phase column, sabinene (15.1%), camphor (14.4%), α-phellandrene (7.9%), β-pinene (7.7%), and myrcene (6.9%) were the most abundant compounds. To assess the oil for potential applications in integrated pest management strategies, behavioral bioassays were conducted to test for repellency against yellow fever mosquito Aedes aegypti, and for attractant activity for Mediterranean fruit fly Ceratitis capitata. Results showed that BTEO was not effective in repelling Ae. aegypti (minimum effective dosage [MED]: 0.625 ± 0.109 mg/cm2 compared with the standard insect repellent DEET (N,N-diethyl-3-methylbenzamide). In assays with male C. capitata, BTEO displayed mild attraction compared with two positive controls (essential oils from tea tree Melaleuca alternifolia and African ginger bush Tetradenia riparia). Additional studies are needed to identify the specific attractant chemicals in BTEO and to determine if they confer a synergistic effect when combined with other known attractants for C. capitata. To the best of our knowledge, this study represents the first investigation of BTEO for repellency against the mosquito vector Ae. aegypti and for attractancy to C. capitata, a major agricultural pest worldwide.

Botanical acaricides and repellents in tick control: current status and future directions

Ticks are obligate blood-sucking ectoparasites and notorious as vectors of a great diversity of, in many instances, zoonotic pathogens which can cause considerable damage to animal and human health. The most commonly used approach for the control of ticks is the application of synthetic acaricides. However, the negative impacts of synthetic acaricides on the treated animals and the environment, in addition to its documented role in the development of resistance has led to the search for safer and more environmentally friendly alternative methods without compromising efficacy. An emerging promising approach for the control of ticks which has attracted much attention in recent years is the use of botanicals. Indeed, botanicals have been widely reported to show diverse effects and great potential as tick repellent and control. Although several excellent reviews have previously focused on this topic, studies on the exploration and application of botanicals to control ticks have expanded rapidly. Herein, we provide an update on the current understanding and status of botanical acaricides and repellents in tick control using recently published articles between 2017 and 2019. We also discuss the challenges and future directions in the application of botanicals in tick control, with a view of providing important clues for designing new integrated tick control methods.

Isopentyl Butanoate: Aggregation Pheromone of the Brown Spiny Bug, Clavigralla tomentosicollis (Hemiptera: Coreidae), and Kairomone for the Egg Parasitoid Gryon sp. (Hymenoptera: Scelionidae)

The brown spiny bug, Clavigralla tomentosicollis Stål (Hemiptera: Coreidae) is a key pest of leguminous crops in many countries in Africa, causing significant yield losses especially in cowpea, pigeon pea and common beans. Although C. tomentosicollis uses olfaction to aggregate, little is known about the identity of the aggregation pheromone. This study aimed to identify the aggregation pheromone of C. tomentosicollis and to test its potential role in the behavior of its egg parasitoid, Gryon sp. In Y-tube olfactometer bioassays, only male volatiles strongly attracted both sexes of C. tomentosicollis. Coupled gas chromatography/electroantennographic detection (GC/EAD) and GC/mass spectrometry were used to identify antennally-active compounds from male volatiles. Antennae of both sexes detected identical components including a male-specific component, identified as isopentyl butanoate, which was also detected by antenna of the egg parasitoid. In olfactometer bioassays, both sexes of C. tomentosicollis and the egg parasitoid responded to isopentyl butanoate. These results suggest that isopentyl butanoate serves as an aggregation pheromone for both sexes of C. tomentosicollis and a useful kairomone to attract the parasitoid in the management of C. tomentosicollis.