No abstract

Introduction The steep population decline of the emblematic monarch butterfly is caused mainly by the reduction of food sources for caterpillars and adults, as well as disturbance in its overwintering forests. Although feeding at the overwintering sites in Mexico has long been considered unimportant, observations show that butterflies feed inside and outside of their forests on sunny days. Nectaring close to the hibernation colonies may be relevant for their conservation, as their reserves decline faster in disturbed forests. However, there are no systematic studies on nectar sources in the Monarch Butterfly Biosphere Reserve, Michoacán, Mexico. Aims In this study, we identified and quantified the main plant species visited by butterflies for nectaring in the Reserve. Methods We collected systematic observational data on the flora and butterfly visits in three sanctuaries, around colonies formed between February and March of the 2019–2020 season. Results Butterflies fed on 29 plant species from 10 families. Most had white, yellow or blue flowers, were somewhat synanthropic and had their main flowering season in winter. The most visited species were Salvia mexicana and S. plurispicata, which were also the most abundant. By individual plant, Prunus serotina, Crataegus mexicana, Buddleja sessiliflora, Verbesina oncophora and Roldana albonervia were the most visited. Discussion/Implications for insect conservation The results point to possible interventions in support of the butterflies. The visited species are generally easy to encourage or cultivate and could be promoted in the surrounding agricultural areas.

Ectomycorrhiza is a mutualistic symbiosis of paramount importance in the functioning of forest ecosystems. Therefore, inoculation with ectomycorrhizal fungi, particularly edible species, has gained enormous relevance in the production of forest trees with economic importance. However, due to technical difficulties for the cultivation of ectomycorrhizal basidiomata associated with their host trees, factors influencing basidiomata formation have not been fully understood. This study evaluated the effect of two light wavelengths on the production of basidiomata of two edible ectomycorrhizal mushroom species (Hebeloma leucosarx and Laccaria bicolor) associated with two neo-tropical trees, Pinus montezumae and Pinus greggii. The two fungal species evaluated are widely used as food and sold in traditional markets in México. In general, the type of light differentially influenced the basidioma formation of these fungi in association with host seedlings in greenhouse during six years. Increased basidioma formation of H. leucosarx was observed associated with trees growing in pots covered with yellow filters with a wavelength of ~590 nm compared with those covered with red filters with a wavelength of ~660 nm. Meanwhile, the opposite trend was observed in basidiomata of L. bicolor. The host tree species influenced the formation of basidiomata. Hebeloma leucosarx produced more basidiomata in association with P. montezumae than with P. greggii. In addition, a description of basidiomata formation from very young stages previous to senescence is provided for both mycobionts. To our knowledge, this is the first record of the effect of light wavelengths on the production of basidiomata of edible ectomycorrhizal mushrooms, demonstrating that this phenomenon is more complex than previously believed.

No abstract

Mexico’s basin is one of the most altered in the country, owing to the presence of the megalopolis of Mexico City. Lake Texcoco, which had the basin’s biggest extension, dried up almost completely. The basin’s evolution over time led in the formation of a megabasin in which water is transported from one source to another to serve the urban region and subsequently drained to prevent flooding. The major hydrotechnical works in Mexico Basin have been interpreted as a solution to the problem of flooding in Mexico City, but they were actually part of a much larger strategy of territorial appropriation by the Spanish colonists. The ecological imbalance that has resulted has sparked a variety of social issues. For the purpose of analyzing the environmental transformation of Lake Texcoco over the last 500 years, actors and processes that influenced specific moments in the country’s history were identified; these elements showed the inexorable relationship between the lake and Mexico City. Subsequently, they were grouped by periods with similar trends in terms of the way in which society relates to and appropriates the natural environment of the lake. It was found that the critical moment for the desiccation of Lake Texcoco occurred during the Spanish colonial historical period as part of the redesign of the city; from then on, the same environmental imaginary prevailed century after century, shaped by social and economic factors. This study contributes to the literature on how urbanization affects natural resources by making an original theoretical contribution through an analysis based on political ecology, and it adds to the literature on how people use the prevailing federal area of the lake.