Origanum majorana Essential Oil-A Review of Its Chemical Profile and Pesticide Activity.

Origanum majorana is a medicinal and aromatic plant that belongs to the Lamiaceae family. It is cultivated in several parts of the world and, due to its splendid aroma and taste, is widely used for culinary purposes and in perfumes. The essential oil of the plant, to which is attributed its aroma, contains many secondary metabolites with valuable biological activity. One of them is the pesticide activity, which has attracted much interest. Given the necessity of replacing synthetic pesticides, essential oils are studied in an attempt to find naturally derived products. Thus, the aim of this review paper is to discuss the chemical profile of O. majorana essential oil and to present data regarding its insecticidal, repellent and fumigant activity. Data were collected from 1992 to 2022. Databases, including PubMed, Google Scholar, ScienceDirect and Scopus, were used for the research, and keywords, including O. majorana, sweet marjoram, essential oil, volatiles, pesticide, insecticide and repellent activity, were used. The results of this review paper indicate that O. majorana essential oil can be an alternative agent to manage pests. However, still, much research should be conducted to evaluate its toxicity against beneficial insects and to ensure its safety for human health.

Farming practices and biodiversity: Evidence from a Mediterranean semi-extensive system on the island of Lemnos (North Aegean, Greece).

The management of agroecosystems affects biodiversity at all levels from genetic to food-web complexity. Low-input farming systems support higher levels of genetic, species and habitat diversity than high-input, industrial ones. In Greece, as in other Mediterranean countries, the role of traditional farming practices has been underlined in studies concerning conservation in agricultural landscapes. With this study, we aim to provide evidence for the potential of semi-extensive farming for biodiversity conservation at landscape-scale, focusing on Lemnos, a medium-sized island in the North Aegean. Evidence was gathered by species- and community-level local-scale surveys on various trophic levels (vascular plants, arthropods, birds). The surveys took place in 2018 and 2019 in 25 sampling areas comprising 106 plots of 100 m2 (vascular plants, arthropods) and 57 points where bird species were recorded. The plots were classified into three landscape types: mosaic agriculture, mixed rangelands and uniform rangelands. The relevés of Lemnos farmlands were assigned to plant communities of 18 phytosociological alliances, grouped into 12 classes. The most abundant arthropods were Coleoptera, Chilopoda, and Hymenoptera, followed by Opiliones and Isopoda, while 133 different bird species were recorded in total, including the recording for the first time on the island of five species. Farming on Lemnos is rather extensive compared to most agricultural landscapes of Europe. Our approach has demonstrated that, given the geographic characteristics of the area, the measured data reveal very high biodiversity. Our explorative findings suggest that moderate seasonal grazing, the mixed habitat mosaic with ecotones, fallow and stubble fields at the landscape scale, and the small size of fields, the kinds of crop, and farm-scale crop diversification, like mixed cultivation and crop rotation, are key practices supporting this diversity. These explorative findings are considered as a first step providing the baseline for future assessments. A wider effort, for systematic evaluation of the impacts of farming practices to biodiversity, is required, as part of a subsidized agri-environmental scheme and/or through a market-oriented product certification system for the area.

Predator size affects the intensity of mutual interference in a predatory mirid.

Interference competition occurs when access to an available resource is negatively affected by interactions with other individuals, where mutual interference involves individuals of the same species. The interactive phenomena among individuals may be size-dependent, since body size is a major factor that may alter prey consumption rates and ultimately the dynamics and structure of food webs.A study was initiated in order to evaluate the effect of mutual interference in the prey-specific attack rates and handling times of same size class predators, incorporating variation in consumer size. For this purpose, laboratory functional response experiments were conducted using same age predators, that is, newly hatched (first instar) or mature (fifth instar) nymphs of the polyphagous mirid predator Macrolophus pygmaeus preying on Ephestia kuehniella (Lepidoptera: Pyralidae) eggs.The experiments involved four predator density treatments, that is, one, two, three, or four predators of same age, that is, either first- or fifth-instar nymphs, which were exposed to several prey densities. The Crowley-Martin model, which allows for interference competition between foraging predators, was used to fit the data.The results showed that mutual interference between predator's nymphs may occur that affect their foraging efficiency. The values of the attack rate coefficient were dependent on the predator density and for the first-instar nymphs were significantly lower at the highest predator density than the lower predator densities, whereas for the fifth-instar nymphs in all density treatments were significantly lower to that of the individual foragers' ones.These results indicate that mutual interference is more intense for larger predators and is more obvious at low prey densities where the competition level is higher. The wider use of predator-dependent functional response models will help toward a mechanistic understanding of intraspecific interactions and its consequences on the stability and structure of food webs.