Herbivory enhances leaky sex expression in the dioecious herb Mercurialis annua

Plant reproductive traits are widely understood to be responsive to the selective pressures exerted by pollinators, but there is also increasing evidence for an important role of antagonists such as herbivores in shaping these traits. Many dioecious species show leaky sex expression, with males and females occasionally producing flowers of the opposite sex. Here we show that leaky sex expression in both males and females of the wind-pollinated dioecious herb Mercurialis annua (Euphorbiaceae) is enhanced in response to simulated herbivory, increasing the probability and the degree of leakiness in both sexes. We also found that leakiness was greater in larger females but not in larger males. We discuss hypotheses for a possible functional link between herbivory and leaky sex expression, and consider what herbivory-induced leakiness might imply for the evolutionary ecology of plant reproductive systems, especially the breakdown of dioecy and the evolution of hermaphroditism.

Phytochemicals, Antioxidant Attributes and Larvicidal Activity of Mercurialis annua L. (Euphorbiaceae) Leaf Extracts against Tribolium confusum (Du Val) Larvae (Coleoptera; Tenebrionidae)

This study reports the link between larvicidal activity and the phytochemical composition of male and female leaf extracts of Mercurialis annua L. (M. annua) from four Tunisian regions: Bizerte, Jandouba, Nabeul and Beja. Their antioxidant activity was evaluated using DPPH (2, 2-diphenyl-1-picrylhydrazyl) assays. Phenolic compounds were identified and quantified using liquid chromatography coupled with a UV detector and mass spectrometry (LC-UV-ESI/MS). Higher antioxidant activity (AOA) was found in the leaves of male plant extracts than of female ones. The leaves of male and female plant extracts from Bizerte exhibited the highest AOA: 22.04 and 22.78 mg Trolox equivalent/g dry matter (mg TE/g DM), respectively. For both sexes, plant extracts from Beja had the lowest AOA with 19.71 and 19.67 mg TE/g DM for male and female plants, respectively. Some phenolic compounds such as narcissin, gallocatechin, rutin, epigallocatechin and epicatechin were identified and quantified using LC-MS, which highlighted the abundance of narcissin and rutin in the male leaves of M. annua. We noted that the interaction between the sex of plants and the provenance had a significant effect on TFC (F = 6.63; p = 0.004) and AOA (F = 6.53; p = 0.004) assays, but there was no interaction between sex and origins for TPC (F = 1.76; p = 0.19). The larvicidal activity of aqueous leaf extracts of M. annua against Tribolium confusum (Du Val) (T. confusum), an insect pest of flour and cereal seeds, showed that the mortality could reach 100% after 48 h of exposure in the Bizerte region. The LC50 values for the leaf extract were low in Bizerte, with 0.003 and 0.009 g/mL for male and female plants, respectively, succeeded by Jandouba, which displayed 0.006 and 0.024 g/mL for male and female plants, respectively. Nabeul showed 0.025 g/mL for male plants and 0.046 g/mL for female plants and Beja showed 0.037 and 0.072 g/mL for male and female plants, respectively. This is the first time that a study has revealed a negative correlation between the antioxidant activity and the larvicidal activity of the leaf extracts of M. annua with the following correlation coefficients of Perason: r = −0.975 and r = −0.760 for male and female plants, respectively.

Floristic findings in the Kabardino-Balkar Republic (Central Caucasus)

The article presents information on floristic findings in the Kabardino-Balkari Republic. As a result of expedition research in 2020-2021 and inventory studies in the Herbarium of the Tembotov Institute of Ecology of Mountain Territories RAS, we revealed nine species new to the Kabardino-Balkar Republic and new locations of ten vascular plants species. Species new to the region flora were Carex acuta, Genista angustifolia, Amorpha fruticosa, Ambrosia psilostachya, Mercurialis annua, Echinocystis lobata, Phlomis majkopensis, Cleistogenes squarrosa, Bidens frondosa. New locations of seven species were identified for the Balkarskiy floristic region. These were three native species (Carex flacca subsp. erythrostachys, C. songorica, Eriophorum latifolium) and four alien species (Oenothera biennis, Elsholtzia ciliata, Sigesbeckia orientalis, Bidens frondosa). Carex elongata, Genista angustifolia, Ambrosia psilostachya, Mercurialis annua, Cleistogenes squarrosa, Amaranthus albus and alien species Acer negundo were revealed for the Tsentralno-Elbrusskiy and Kabardinskiy floristic regions, respectively. We also found the alien species Amorpha fruticosa, Echinocystis lobata and rare steppe species Phlomis majkopensis, Glaucium corniculatum in the Tursko-Sunzhensky floristic region. We provided data on floristic findings indicating the coordinates of the locations, species habitat preferences, and distribution in the Caucasus according to earlier literary sources.