Liometopum Apiculatum Research Articles

Productive Characteristics, Nesting Substrates, and Colonies of the Escamolera Ant (Liometopum apiculatum M.) in Zacatecas, Mexico

Objective: The objective of this study was to connect measurements, weights, and production of escamoles with nesting substrates, foraging paths, nest types, and colony sizes of the escamolera ant. Design/Methodology/Approach: The data about nests, colonies, and larvae were gathered during morning and evening field walks, with the support of escamoles harvesters. The basic statistics of the data were estimated (N = 59 nests/colonies) and analyzed with the Kruskal-Wallis H test. In addition, the Mann-Whitney U test was used to determine the differences per nest type. Results: The highest production of escamoles was recorded in the Prosopis laevigata substrate (x=551.08 g/N=1), while the lowest production was recorded in the Echinocereus stramineus substrate (x=228.31 g/N=4). The length and width of the larvae (N=1,100 larvae) were similar in all the substrates. The weight of the larvae varied from 0.09 g, in the Prosopis levigata substrate, to 0.16 g, in the dry palm (Yucca spp.) substrate; therefore, 11,111 and 6,250 larvae are required, respectively, to obtain 1 kg of escamoles. Study Limitations/Implications: The information of this study is limited to a single harvesting region. Findings/Conclusions: The low escamoles production indicates that its harvesting must comply with a regulatory framework and a better organization, in order to guarantee the continuous presence of Liometopum apiculatum colonies.

Effects of Eight Years of Collecting on the Persistence of Liometopum apiculatum Ant Nests in Rangelands of Charcas, San Luis Potosí, Mexico

In Mexico, the pupae of the reproductive castes of the ant Liometopum apiculatum, escamoles, are highly valued in traditional and gourmet cuisine in the country’s central region. Escamoles are collected during the dry season of the year. The recommended collecting process is to open the ant nest by removing soil until the rearing chamber and the trabeculae with attached escamoles are found. A well-managed ant nest can be collected repeatedly for approximately 12 to 40 years. In Charcas municipality, San Luis Potosí, Mexico, 400 ant nests were located and checked under two land tenure conditions: the Laguna Seca private ranch and the Pocitos communal ejido. The exploitation of escamoles on both tenures was characterized by recording the number of dead and live ant nests. This work evaluated the condition of the ant nests registered in 2012 after eight years. The hypothesis was that ant nests’ survival would be greater in the private than in the communal land. The percentage of living ant nests on the ejido decreased by 35.67%. In contrast, on the ranch, it was 26.88%. The percentage of relocated ant nests was lower on the ejido, 37.43%, compared to the ranch, which was 48.1%. The number of dead ant nests on the ejido increased to 33.51% and on the ranch 15.0%. As predicted by the hypothesis, ant nest survival was higher on the private ranch than on the communal ejido lands because of stronger control of the extraction process.

Volatile organic compounds in the habitat of the escamolera ant (Liometopum apiculatum Mayr) in Zacatecas, Mexico

Volatile organic compounds (VOCs) take part in the biological processes of insects; however, these compounds have not been determined for genus Liometopum. The objective of this study was to identify the variability of the VOCs found in the Liometopum apiculatum habitat during the exploitation season. During the 2017 preseason and season, 35 air samples were collected from the nests of five L. apiculatum colonies established in crassicaule scrub vegetation; additionally, another 35 samples were taken from their foraging sites. Using a gas chromatograph with an electronic nose detector, the VOCs were identified with the Kovats index. In addition, a principal component analysis (PCA) was carried out to evaluate the intensity variability per season. Fourty-eight VOCs were identified in the L. apiculatum habitat. The most significant VOCs included: saturated hydrocarbon (17%), aldehydes (17%), alcohols (15%), and esters (10%). PCA accounted for 79.5% (PC1=53.8 and PC2=25.7) of the intensity variability of the VOCs in the habitat between seasons. The escamol season was characterized by the 3-methyl-3-sulfonyl butan-1-ol, 2-Methylbutanoic acid, and trimethylamine. This profile of the VOCs in the L. apiculatum habitat is a pioneer work and has future implications for the conservation and sustainable exploitation of the escamolera ant.

Herbivory in Myrtillocactus geometrizans (Cactaceae): Do Parasitoids Provide Indirect Defense or a Direct Advantage?

Plants respond to herbivory in diverse, complex ways, ranging from avoidance or tolerance to indirect defense mechanisms such as attracting natural enemies of herbivores, i.e., parasitoids or predators, to strengthen their defense. Defense provided by parasitoids to cultivated plants is well documented and is used in biological control programs. However, its effectiveness on wild plants under natural conditions has been little studied. Such is the case of the cactus Myrtilllocactus geometrizans (known in Mexico as garambullo), which is consumed by the soft-scale insect Toumeyella martinezae (herbivore) which, in turn, is host to the parasitoid wasp Mexidalgus toumeyellus, and mutualist with the ant Liometopum apiculatum, that tenders and protects it. This study explores the role of the parasitoid as an indirect defense, by examining its effect on both the herbivore and the plant, and how this interaction is affected by the presence of the mutualistic ant. We found that scales adversely affect the cactus' growth, flower, and fruit production, as well as its progeny's performance, as seedlings from scale-infested garambullo plants were shorter, and it also favors the presence of fungus (sooty mold). The parasitoid responded positively to herbivore abundance, but the presence of ants reduced the intensity of parasitism. Our results show that parasitoids can function as an indirect defense, but their effectiveness is reduced by the presence of the herbivore's mutualistic ant.

Edible insect harvest in Pinos, Zacatecas, Mexico

Objective: To identify the exploitation and generation of economic income derived from the harvest ofescamol (Liometopum apiculatum Mayr), white worm (Aegiale hesperiaris W) and red worm (Comadiaredtenbacheri H), during an annual season.Design/Methodology: Surveys were applied to n=593 edible insect harvesters in n= 18 ruralcommunities, local authorities (ejido commissaries, auxiliary judges), buyers (intermediaries), andrepresentatives of the stockpiling company DELIZAC. The interviews were conducted in harvesting zones(field), at the time of the delivery of the product (stockpiling), and in the homes of harvesters selected assample in Pinos, Zacatecas, Mexico.Results: The prices per kilogram of escamol and white worm, during the 2020 seasons, was US$15.00,and for the red worm, US$25.00. The harvest of edible insects was 34.6 tons with an economic spill ofUS$572,800.00 showing a per capita average income of US$965.90.Study Limitations/Implications: The results of this study can be used to propose techniques that favorthe conservation, management, and sustainable exploitation of the three species of edible insects forinhabitants of the rural zones in central-northern Mexico.Conclusions: The harvest of edible insects in Pinos, Zacatecas, generates important economic income. Ofthe harvesters, 78.9 % were men, 13.7 % adult women, and 7.4 % children. Most of the harvestinglocalities lack permits to carry out the exploitation.

Phylogeny, evolution, and classification of the ant genus Lasius, the tribe Lasiini and the subfamily Formicinae (Hymenoptera: Formicidae)

AbstractWithin the Formicidae, the higher classification of nearly all subfamilies has been recently revised given the findings of molecular phylogenetics. Here, we integrate morphology and molecular data to holistically address the evolution, classification, and identification of the ant genus Lasius, its tribe Lasiini, and their subfamily Formicinae. We find that the crown Lasiini originated around the end of the Cretaceous on the Eurasian continent and is divisible into four morphologically distinct clades: Cladomyrma, the Lasius genus group, the Prenolepis genus group, and a previously undetected lineage we name Metalasius gen.nov., with one extant species M. myrmidon comb. nov. and one fossil species, †M. pumilus comb. nov. The crown of the Lasius genus group is considerably younger than that of the Prenolepis genus group, indicating that extinction has played a major role in the evolution of the former clade. Lasius itself is divided into two well‐supported monophyletic groups, which are approximately equally speciose. We present evidence that temporary social parasitism and fungiculture arose twice independently in Lasius. In addition, we recover the paraphyly of three Lasius subgenera and propose replacing all subgenera with an informal species group classification: Lasius = Acanthomyops syn.rev., = Austrolasius syn.nov., = Cautolasius syn.nov., = Chthonolasius syn.nov., = Dendrolasius syn.nov. Total‐evidence analysis reveals that the Baltic‐region amber fossil species †Lasius pumilus and †Pseudolasius boreus are misplaced to genus; we, therefore, create Sussuido gen. nov. to accomodate †S. boreus comb. nov. and transfer †L. pumilus to Metalasius. Further, we transfer †Sussudio and †Glaphyromyrmex out of the Lasiini, considering the former to be incertae sedis in the subfamily, and the latter a member of the Formicini (tribal transfer). Two final taxonomic actions are deemed necessary: synonymy of Lasius escamole with Liometopum apiculatum syn.nov. (subfamilial transfer), and transfer of Paratrechina kohli to Anoplolepis (tribal transfer, forming A. kohli comb.nov.).ZooBank Article LSID: urn:lsid:zoobank.org:pub:016059BA‐33C3‐43B2‐ADAD‐6807DC5CB6D8Author ZooBank LSIDs: Borowiec: urn:lsid:zoobank.org:author:411B711F‐605B‐4C4B‐ABDB‐D4D96075CE48. Boudinot: urn:lsid:zoobank.org:author:919F03B0‐60BA‐4379‐964D‐A56EB582E16D. Prebus: urn:lsid:zoobank.org:author:1A6494C7‐795E‐455C‐B66F‐7F6C32F76584

Does ant-plant mutualism have spillover effects on the non-partner ant community?

Mutualism benefits partner species, and theory predicts these partnerships can affect the abundance, diversity, and composition of partner and non‐partner species. We used 16 years of monitoring data to determine the ant partner species of tree cholla cacti (Cylindropuntia imbricata), which reward ants with extrafloral nectar in exchange for anti‐herbivore defense. These long‐term data revealed one dominant ant partner (Liometopum apiculatum) and two less common partners (Crematogaster opuntiae and Forelius pruinosus). We then used short‐term characterization of the terrestrial ant community by pitfall trapping to sample partner and non‐partner ant species across ten plots of varying cactus density. We found that the dominant ant partner tended a higher proportion cacti in plots of higher cactus density, and was also found at higher occurrence within the pitfall traps in higher density plots, suggesting a strong positive feedback that promotes ant partner occurrence where plant partners are available. Despite the strong association and increased partner occurrence, ant community‐wide effects from this mutualism appear limited. Of the common ant species, the occurrence of a single non‐partner ant species was negatively associated with cactus density and with the increased presence of L. apiculatum. Additionally, the composition and diversity of the ant community in our plots were insensitive to cactus density variation, indicating that positive effects of the mutualism on the dominant ant partner did not have cascading impacts on the ant community. This study provides novel evidence that exclusive mutualisms, even those with a strong positive feedback, may be limited in the scope of their community‐level effects.

DETERMINATION OF THE CONSERVATION STATUS OF THE “ESCAMOLERA” ANT (Liometopum apiculatum MAYR) IN MEXICO BY THE SPECIES RISK ASSESSEMENT METHODOLOGY – MER

The larvae and pupae of Liometopum apiculatum, an ant species known as “escamolera” (Lap), are valued for their flavour and nutritional value. Currently demand at restaurants trade, high price and other factors have threatened their populations. However, in Mexico there is no risk assessment for this species. Therefore, information was compiled to evaluate the conservation status of L apiculatum. The species Risk Assessment Methodology (MER) of Appendix I in the Mexican Standard NOM-059-SEMARNAT-2010 determines the risk category of a species based on scores of four criteria and places a species as “Extinct in the wild, subject to special protection, threatened or in danger of extinction”. In this study, the related scores were, for Criterion A (taxon distributional area), 3 points (restricted distribution); Criterion B (habitat status regarding its natural development), 1 point (apt, or not limiting); Criterion C (biological vulnerability), 1 point (low vulnerability); and criterion D (impact of human activity on the taxon) scored 3 points (medium impact). The sum of the scores of the four MER criteria indicated that Lap (the escamolera ant) should be placed in the category of Subject to special protection (SSP). This information shall be used to design management and conservation policies for edible insects in Mexico.

Inclusion of typical Mexican ingredients in canned escamoles (Liometopum apiculatum): thermophysical and physicochemical properties

Escamoles are the larvae of the antLiometopum apiculatum and have been consumed in Mexico since pre-Hispanic times. Currently, they are one of the most consumed insects in Mexico because of their organoleptic and nutritional characteristics. Escamoles are rich in protein, unsaturated fatty acids, including oleic, linoleic, linolenic, and arachidic acid, as well as vitamin A, thiamine, riboflavin, and niacin. Escamoles, however, have a shelf life of five days at 4 °C. Canning is an alternative process for increasing their shelf life and creating new products. Therefore, the objective of this study was to include traditional Mexican food ingredients for creating new canned escamoles products, as well as to determine and validate the canning time. Four canned escamoles products were obtained according to an official Mexican regulation using the following ingredients: mole, adobo, butter, Mexican mix, and tamarind sauce. Cylindrical cans with a diameter of 68 mm and height of 76 mm were used in all experiments. The sterilisation process was performed with saturated steam at 121 °C. The process time was calculated with a graphic method and validated by a microbiological test. Additionally, thermophysical properties, chemical composition, lipid oxidation, structural changes, and sensory evaluation were determined after the canning process. The process time (P<0.05) of products varied between 13 to 38 min. The microbiological tests were negative in all experiments. The chemical composition and thermophysical properties of products (P<0.05) were dependent on the ingredient used. The escamoles structure remained intact after the canning process. The hedonic scale for escamoles in the Mexican mix and in butter was 5.0, equivalent to ‘like slightly’. For the products in mole and tamarind sauce, the score was 4.0, meaning ‘neither like nor dislike’. The inclusion of Mexican gastronomic ingredients in canned escamoles allowed designing new products without damaging the nutritional and sensory characteristics of escamoles.

Biodegradation of recalcitrant compounds and phthalates by culturable bacteria isolated from Liometopum apiculatum microbiota.

Liometopum apiculatum is a species of ants widely distributed in arid and semi-arid ecosystems where there is a relative food shortage compared with tropical ecosystems. L. apiculatum has established an ecological balance involving symbiotic interactions, which have allowed them to survive through mechanisms that are still unknown. Therefore, the aim of this study was to explore the metabolic potential of isolated bacteria from L. apiculatum using enzymatic activity assay and substrate assimilation. Results revealed a complex bacteria consortium belonging to Proteobacteria, Firmicutes, and Actinobacteria phylum. Most of the isolated bacteria showed activities associated with biopolymers degradation, from them Exiguobacterium and B. simplex showed the highest amylolytic activity (27 U/mg protein), while A. johnsonii and B. pumulis showed the highest cellulolytic and xylanolytic activities (1 and 2.9 U/mg protein, respectively). By other hand, some microorganisms such as S. ficaria, E. asburiae, P. agglomerans, A. johnsonii, S. rubidaea, S. marcescens, S. warneri, and M. hydrocarbonoxydans were able to grow up to 1000mg/L of phthalates esters. These results not only revealed the important contribution of the symbionts in L apiculatum ants feeding habits, but also have shown a promising source of enzymes with potential biotechnological applications such as lignocellulosic biomass hydrolysis and bioremediation processes.

Amplitud forrajera de la hormiga escamolera (Liometopum apiculatum Mayr, Hymenoptera: Formicidae) en una zona semiárida del altiplano zacatecano

En México, la hormiga escamolera (Liometopum apiculatum Mayr) es un recurso natural económicamente importante. Sin embargo, sus colonias son sobre utilizadas. Tanto su hábitat como su actividad forrajera son aspectos poco estudiados. El objetivo de este estudio fue determinar la amplitud forrajera de L. apiculatum y las variables del hábitat que la definen en Villa González Ortega, Zacatecas, México. Durante 2014, se localizaron 31 colonias de L. apiculatum. La amplitud forrajera de la hormiga se determinó mediante la identificación de los caminos de forrajeo, sus distancias desde el nido a los sitios de forrajeo y sus azimuts. Las variables del hábitat que más se asociaron con la amplitud forrajera se determinaron con índices de Frecuencia de observación (Fo), análisis cladístico (AC) y análisis de correspondencia canónica (ACC). La hormiga escamolera forrajeó en un área de tamaño promedio de 1 565.65 ± 535.63 m2 y las variables que más explicaron esta superficie forrajera fueron la presencia de Agave salmiana, Yucca spp., Prosopis spp., Acacia farnesiana, suelo desnudo, material leñoso y cobertura de arbustos. Este estudio, sobre la amplitud forrajera de la hormiga escamolera, proporciona información para el diseño de estrategias de manejo y conservación de sus poblaciones y hábitats en México.

Extrafloral nectaries of Cylindropuntia imbricata (Cactaceae) in the southern Chihuahuan Desert: anatomy and interaction with ants

Cylindropuntia imbricata is a common cactus species from North American deserts that has extrafloral nectaries (EFNs). We assessed: (i) the anatomical structure of the EFNs of C. imbricata to determine whether they are vascularized or not, and (ii) whether water availability in the soil and soil temperature are related to the abundance of ants visiting C. imbricata. The study site was in San Luis Potosi, Mexico, in the southern Chihuahuan Desert. EFNs of C. imbricata are vascularized, so they have a constant flow of resources and can produce nectar even when the plant experiences periods of drought, although perhaps less nectar. The availability of water was the most vital factor as a regulator of the interaction between the EFNs of C. imbricata and the ants. Irrigation increased the abundance of visitor ants, with the main species being Liometopum apiculatum, Crematogaster opuntiae and Pseudomyrmex pallidus, with L. apiculatum the most abundant species of them. The present work is the first to investigate the anatomy of the EFNs of C. imbricata and the first to demonstrate their functional relevance in cacti.

Nutritional content of Liometopum apiculatum Mayr larvae (“escamoles”) by vegetation type in north-central Mexico

Abstract In Mexico the ant Liometopum apiculatum is an important insect nutritionally, economically and ecologically. Their larvae (“escamoles”) contain proteins, lipids, vitamins and minerals, the concentrations of which may be related with the type of vegetation where the ant forages. The objective of this study was to evaluate the content of macro and micro nutrients of L. apiculatum larvae collected in three types of vegetation in north-central Mexico. We determined content of moisture, crude protein, total lipids, crude fiber, ash, and nitrogen-free extract. The amino acids were analyzed by cationic Exchange chromatography with acid hydrolysis and fatty acids by gas chromatography and solvent extraction with sodium methoxide. The effect of vegetation type on nutrient content was determined with an ANOVA and Sheffe comparison of means (P

The proteome map of the escamolera ant (Liometopum apiculatum Mayr) larvae reveals immunogenic proteins and several hexamerin proteoforms

The larvae of escamolera ant (Liometopum apiculatum Mayr) have been considered a delicacy since Pre-Hispanic times. The increased demand for this stew has led to massive collection of ant nests. Yet biological aspects of L. apiculatum larvae remain unknown, and mapping the proteome of this species is important for understanding its biological characteristics. Two-dimensional gel electrophoresis (2-DE) followed by liquid chromatography-tandem mass spectrometry (LC-MS/MS) analysis was used to characterize the larvae proteome profile. From 380 protein spots analyzed, 174 were identified by LC-MS/MS and homology search against the Hymenoptera subset of the NCBInr protein database using the Mascot search engine. Peptide de novo sequencing and homology-based alignment allowed the identification of 36 additional protein spots. Identified proteins were classified by cellular location, molecular function, and biological process according to the Gene Ontology annotation. Immunity- and defense-related proteins were identified including PPIases, FK506, PEBP, and chitinases. Several hexamerin proteoforms were identified and the cDNA of the most abundant protein detected in the 2-DE map was isolated and characterized. L. apiculatum hexamerin (LaHEX, GeneBank accession no. MH256667) contains an open reading frame of 2199 bp encoding a polypeptide of 733 amino acid residues with a calculated molecular mass of 82.41 kDa. LaHEX protein is more similar to HEX110 than HEX70 from Apis mellifera. Down-regulation of LaHEX was observed throughout ant development. This work represents the first proteome map as well as the first hexamerin characterized from L. apiculatum larvae.

Microbiota of edible Liometopum apiculatum ant larvae reveals potential functions related to their nutritional value

Edible insects, due to their high nutritive value, are currently considered as a potential renewable source for food and feed production. Liometopum apiculatum ants are widely distributed in arid and semi-arid ecosystems and their larvae (escamoles) are considered as a delicacy, however the microbial importance in L. apiculatum nutritional ecology is unknown. The aim of this research was to characterize the microorganisms associated with both L. apiculatum larvae and the reproductive adult ants using the 16S rRNA gene sequencing and culturomics approaches. The obligate endosymbionts were also investigated through microscopic analysis. The most abundant Phylum identified by sequencing in the larvae was Firmicutes while in adult ants was Proteobacteria. Interestingly, the culturomics results showed 15 genera corresponding to the bacteria identified by sequencing analysis. Particularly, it was observed a large population of nitrogen-fixing bacteria, which could be linked with the high protein content in escamoles. Endosymbionts were detected in bacteoriocytes, these bacteria are related with vitamins and essential amino acids biosynthesis, and both compounds contributing to the high nutritional value of escamoles. This is the first report of the microorganisms present in the escamolera ant ensuring their safety as food and opening new areas of nutritional ecological and food processing.

Efectos del sitio y la condición de agostadero en la densidad de hormigueros de escamoles (Liometopum apiculatum Mayr)

El efecto de la condición de agostadero en la densidad de hormigueros de la hormiga de escamoles (Liometopum apiculatum Mayr) se evaluó en tres sitios diferentes (favorable, regular y desfavorable), en un espacio dividido en dos patrones contrastantes de aprovechamiento y régimen de tenencia comunal (ejido) y privada (rancho) en Charcas, San Luis Potosí, México. La vegetación se midió utilizando el método de cuadrantes centrados en un punto, espaciados sobre transectos; en cada cuadrante se midió el individuo más próximo al punto correspondiente a cada estrato de la vegetación y se registró la distancia al hormiguero más cercano (si existía). Las especies se agruparon de acuerdo con su valor forrajero (deseables, menos deseables e indeseables) y, mediante estimaciones de densidad y biomasa volumétrica, los grupos se contrastaron con un análisis tabular y estadístico descriptivo. La superficie del suelo se evaluó con el método de líneas de intercepción en la proporción de cobertura basal viva y muerta (mantillo), suelo desnudo, rocas, caminos de hormigas y heces. La densidad más alta de los hormigueros (14·ha-1) se registró en el sitio favorable del rancho (mejor condición de agostadero). Con base en la información registrada se encontraron diferencias en la densidad de hormigueros entre sitios de agostaderos contiguos, lo cual a su vez es alterado severamente por la condición de los mismos.

Influence of environmental conditions on insect reproduction and chemical composition of escamoles (Liometopum apiculatum M)

Escamoles, ant eggs (Liometopum apiculatum M), are edible insects consumed in great numbers and appreciated for their sensory characteristics, but not for their nutritional value. In Mexico, they reproduce in arid and semi-arid zones of Mexico and several states (Puebla, Tlaxcala, Hidalgo). Samples were gathered to determine reproduction conditions and perform an insect analysis to generate data composition in macronutrients, on dry basis, according to AOAC methods. The obtained data were: proteins: 42.12-50.63%; lipids: 30.27-34.96%; minerals: 6.53-7.85%; fibres: 1.91-2.56%; and soluble carbohydrates: 6.80-18.27%. Entomological material was collected in spring 2014, 3 nests for each zone, all from different altitudes and agroclimatic regions. Samples were representative for the insect supply in the areas studied. Insects are high in proteins and lipids, compared with most of the commonly consumed food, due to their high content of fatty acids; they must be refrigerated for later consumption. Minerals are moderated. Fibre and soluble carbohydrate levels are low, but an excess of proteins can be converted into carbohydrates via gluconeogenesis. Escamoles reproduce once a year in the spring, but sometimes one nest can provide escamoles eggs twice in the same season, once at the beginning and again at the end, depending on the biotic and abiotic conditions of their environment. Escamoles are a good source of nutrients; however, some rural people sell them to obtain extra income rather than consume them to improve their nutritional condition and welfare.

Consumption of Escamoles (Liometopum apiculatum M.): A Source of Vitamins A and E

Consumption of Escamoles (Liometopum apiculatum M.): A Source of Vitamins A and E

Structural and physicochemical changes due to proteolytic deterioration of escamoles (Liometopum apiculatum) a traditional Mexican food

Entomophagy or consumption of insects has significantly increased worldwide, either for pleasure or to satisfy the food needs in developing countries. There are approximately 2,000 species of edible insects distributed in 120 countries. From these 2,000 species, about 540 are located in Mexico; one of the most consumed are the escamoles. Escamoles are larvae and pupae of the ant Liometopum apiculatum. Escamoles are nutritious because of their high content of protein, fat, carbohydrates and vitamin. However, during storage the quality of escamoles changes rapidly which affects the acceptability by the consumer. This loss of quality is probably a result of proteolytic activity of endogenous proteases. Therefore, the objectives of this study were to identify the classes of proteases in escamoles as well as to evaluate the effect of proteolytic activity on physicochemical and structural changes during storage. Proteases identification was conducted using specific inhibitors; structural changes, texture, and proteolytic activity were monitored at different days of storage. The highest proteolytic activities (P<0.05) were observed at pH 8, 9 and 10 and at 37 and 50 °C. Proteases were mainly inhibited by iodoacetic acid and soybean trypsin inhibitor showing that cysteine and serine proteases were dominant. High proteolytic activity, significant (P<0.05) reduction in texture and weight loss was observed during storage. The deterioration of escamoles was evident in analyses of images, where initial structure was lost during storage. These results indicate that different groups of proteases are associated with rapid deterioration of escamoles.

Balancing anti‐herbivore benefits and anti‐pollinator costs of defensive mutualists

Quantifying costs and benefits of ostensibly mutualistic interactions is an important step toward understanding their evolutionary trajectories. In food‐for‐protection interactions between ants and extrafloral nectar (EFN)‐bearing plants, tending by aggressive ants may deter herbivores, but it may also deter pollinators. The fitness costs of pollinator deterrence are not straightforward for long‐lived iteroparous plants, because reproductive vital rates often contribute weakly to fitness relative to growth and survival (vital rates that may be enhanced by ant defense). We used field manipulations of ant and pollinator activity and demographic modeling to examine how pollination costs of ant defense translate to plant fitness, given the benefits of ant defense elsewhere in the plant life cycle. We contrasted the net fitness effects of alternative ant partner species. Our work focused on the tree cholla cactus, Opuntia imbricata, an EFN‐bearing plant associated with two ant species (Crematogaster opuntiae and Liometopum apiculatum) that differ in quality of defense against insect herbivores. We found that ant defense imposed pollination costs, despite evidence for ant‐repellent floral volatiles and temporal partitioning of ant and pollinator activity. The two partner species similarly reduced pollinator visitation and seed mass, and one (C. opuntiae) additionally reduced seed number. We used the experimental data and other long‐term demographic data to parameterize an integral projection model that integrated costs and benefits of ant defense over the complete plant life cycle. Model results indicated that the pollination costs of L. apiculatum were balanced by beneficial effects on growth, leading to a net fitness effect that was neutral to positive. By contrast, pollination costs outweighed benefits for C. opuntiae, the weaker defender, rendering this species a reproductive parasite. Thus, we infer that pollination costs destabilize mutualism with one partner species, but are offset by strong defensive benefits provided by the other, leading to contrasting selective pressures imposed by alternative associations. Accounting for ontogenetic turnover in ant partner identity indicated that most plants avoid the parasitic effects of C. opuntiae by associating nonrandomly with L. apiculatum at reproductive life stages. Our results highlight the value of a demographic approach to quantifying the costs and benefits of mutualism.