Where might be many tropical insects?

Baorisa hieroglyphica  
Photo: Sanjay Sondhi
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Global invasion history of the agricultural pest butterfly Pieris rapae revealed with genomics and citizen science

Ryan et al., 2019

 Over the last few thousand years, the seemingly inconspicuous cabbage white butterfly, Pieris rapae, has become one of the most abundant and destructive butterflies in the world. Here, we assessed variation at thousands of genetic markers from butterflies collected across 32 countries by over 150 volunteer scientists and citizens to reconstruct the global spread of this agricultural pest. Our results suggest this butterfly spread out from eastern Europe to occupy every continent except South America and Antarctica, with the timing of many of these events coinciding with human activities—migration, trade, and the development of crop cultivars that serve as food plants for the butterfly larvae. Interestingly, many of these invasions were hugely successful despite repeated losses of genetic diversity.

he small cabbage white butterfly, Pieris rapae, is a major agricultural pest of cruciferous crops and has been introduced to every continent except South America and Antarctica as a result of human activities. In an effort to reconstruct the near-global invasion history of P. rapae, we developed a citizen science project, the “Pieris Project,” and successfully amassed thousands of specimens from 32 countries worldwide. We then generated and analyzed nuclear (double-digest restriction site-associated DNA fragment procedure [ddRAD]) and mitochondrial DNA sequence data for these samples to reconstruct and compare different global invasion history scenarios. Our results bolster historical accounts of the global spread and timing of P. rapae introductions. We provide molecular evidence supporting the hypothesis that the ongoing divergence of the European and Asian subspecies of P. rapae (∼1,200 y B.P.) coincides with the diversification of brassicaceous crops and the development of human trade routes such as the Silk Route (Silk Road). The further spread of P. rapae over the last ∼160 y was facilitated by human movement and trade, resulting in an almost linear series of at least 4 founding events, with each introduced population going through a severe bottleneck and serving as the source for the next introduction. Management efforts of this agricultural pest may need to consider the current existence of multiple genetically distinct populations. Finally, the international success of the Pieris Project demonstrates the power of the public to aid scientists in collections-based research addressing important questions in invasion biology, and in ecology and evolutionary biology more broadly.

Global invasion history and patterns of genetic structure and diversity of P. rapae. (A) Genetic ancestry assignments based on the program ADMIXTURE. (B) Rooted neighbor-joining tree based on Nei’s genetic distance. (C) Among population genetic differentiation based on Weir and Cockerham’s F_ST, New Zealand and Australia are treated separately. (D) Graphical illustration of divergence scenario chosen in ABC-RF analysis. (E) Geographic representation of divergence scenario with the highest likelihood based on ABC-RF analysis; points are colored based on their population assignment using ADMIXTURE as in A, and dates represent median estimates from ABC-RF analysis. All analyses are based on 558 individuals genotyped for 17,917 ddRADseq SNPs. Explore these data further through interactive data visualizations

https://www.pnas.org/content/116/40/20015

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El afecto por algo imaginado es el más fuerte de todos

Spinoza
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Honey bees as bioindicators of changing global agricultural landscapes 
Tyler P, Quigley, Gro V Amdam and Gyan H Harwood

Agricultural landscapes are under pressure from climate change, needs for increased productivity, and changing consumer demand.

Land management decisions will affect ecologically important organisms that live on agricultural land and in surrounding areas.

Honey bees can be useful bioindicators to detect and track changes in agricultural landscape quality at spatial and temporal scales.

There is a growing need to understand relationships between agricultural intensification and global change. Monitoring solutions, however, often do not include pollinator communities that are of importance to ecosystem integrity. Here, we put forth the honey bee as an economical and broadly available bioindicator that can be used to assess and track changes in the quality of agricultural ecosystems. We detail a variety of simple, low-cost procedures that can be deployed within honey bee hives to gain generalizable information about ecosystem quality at multiple scales, and discuss the potential of the honey bee system in both environmental and ecological bioindication.

https://bit.ly/2m6VyEe
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Landscape connectivity explains interaction network patterns at multiple scales 
Santos et al., 2019.

Under a metacommunity framework, the spatial configuration of habitat fragments could determine local community structure. Yet, quantifying fragment connectivity is challenging, as it depends on multiple variables at several geographical scales. We assessed the extent to which fragment connectivity and area explain patterns in interaction structure among four herbivore guilds and their host plants in a metacommunity. We propose an integrative connectivity metric including geographic distance, neighbouring fragment area and similarity in resource composition as an extension of Hanski's classic metric. We then used non‐linear models to assess whether fragment connectivity and area predicted link richness and similarity in link composition. We found that link richness was always negatively related to connectivity but at different geographic scales depending on the herbivore guild. In contrast, while link composition was also related to connectivity, the direction and strength of this relationship varied among herbivore guilds and type of link composition (qualitative or quantitative). Furthermore, focal fragment area was not an important determinant of interaction diversity in local communities. Our findings emphasize resource similarity as a novel dimension of fragment connectivity relevant in explaining interaction diversity patterns in natural trophic networks.

https://bit.ly/2k48IkO 
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Caligo memnon hind wing

Maíz Azul 
Foto: https://www.foodnavigator-latam.com/

Coevolution Creates Complex Mosaics across Large Landscapes 
Fernande et al., 2019.

The spatial distribution of populations can influence the evolutionary outcome of species interactions. The variation in direction and strength of selection across local communities creates geographic selection mosaics that, when combined with gene flow and genomic processes such as genome duplication or hybridization, can fuel ongoing coevolution. A fundamental problem to solve is how coevolution proceeds when many populations that vary in their ecological outcomes are connected across large landscapes. Here we use a lattice model to explore this problem. Our results show that the complex interrelationships among the elements of the geographic mosaic of coevolution can lead to the formation of clusters of populations with similar phenotypes that are larger than expected by local selection. Our results indicate that neither the spatial distribution of phenotypes nor the spatial differences in magnitude and direction of selection alone dictate coevolutionary dynamics: the geographic mosaic of coevolution affects formation of phenotypic clusters, which in turn affect the spatial and temporal dynamics of coevolution. Because the formation of large phenotypic clusters depends on gene flow, we predict that current habitat fragmentation will change the outcomes of geographic mosaics, coupling spatial patterns in selection and phenotypes.

 https://bit.ly/2ZiBVHz
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Utricularia gibba, a freshwater carnivorous plant 
Photo: Igor Siwanowicz
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A global synthesis reveals biodiversity-mediated benefits for crop production       

Dainese et al., 2019

Human land use threatens global biodiversity and compromises multiple ecosystem functions critical to food production. Whether crop yield–related ecosystem services can be maintained by a few dominant species or rely on high richness remains unclear. Using a global database from 89 studies (with 1475 locations), we partition the relative importance of species richness, abundance, and dominance for pollination; biological pest control; and final yields in the context of ongoing land-use change. Pollinator and enemy richness directly supported ecosystem services in addition to and independent of abundance and dominance. Up to 50% of the negative effects of landscape simplification on ecosystem services was due to richness losses of service-providing organisms, with negative consequences for crop yields. Maintaining the biodiversity of ecosystem service providers is therefore vital to sustain the flow of key agroecosystem benefits to society.

Distribution of analyzed studies and effects of richness on ecosystem services provisioning.(A) Map showing the size (number of crop fields sampled) and location of the 89 studies (further details of studies are given in table S1). (B) Global effect of pollinator richness on pollination (n = 821 fields of 52 studies). (C) Global effect of natural enemy richness on pest control (n = 654 fields of 37 studies). The thick line in each plot represents the median of the posterior distribution of the model. Light gray lines represent 1000 random draws from the posterior. The lines are included to depict uncertainty of the modeled relationship.

https://advances.sciencemag.org/content/5/10/eaax0121

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Los campos de trigo no me recuerdan nada y eso me pone triste.

El principito, Antoine de Saint-Exupéry.

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Written in the Trees: The Roots of Arborglyphs 

"Since earliest times, trees – symbolically anchored in the earth and stretched towards the cosmos – have been inherently connected with human identity.”

Words and symbols carved onto a living tree are sometimes described as ‘arborglyphs’ (derived from arbor ‘tree’; glyphein ‘to carve’), but some people think of it vandalism or ‘tree graffiti’. Whatever the name, tree writing is driven by multifarious social and cultural factors; love, solitude, rivalry, identity, artistry, boredom, or downright bragging.

Arborglyphs are present across many cultures. In Australia the Gamilaroi and Wiradjuri peoples carved ceremonial trees to connect with ancestors. The Scorpion Tree of the Chumash people is thought to be an astrological tool whilst the Moriori people on Chatham Islands carved symbols of the natural world and faces of their ancestors into kopi trees.

As agriculture developed over time carved trees become landscape noticeboards, trail-markers or shelter. For global romantics, the gesture of carving a lover’s initials into a tree appeared as far back as Ovid’s Heroides:

‘The beech trees guard my name, cut there by you;
and I read ‘Oenone’, written there by your knife.
And as the trunk grows, my name grows the same;
grow, and rise straight, in honour of my name!’


https://bit.ly/2yXWCxm
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Utsutsunaki tsumami gokoro no kocho kana

Nothing actual,
the feeling of holding in my fingers
a butterfly.
 
Yosa Buson
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Stick insect eggs
James Robertson 
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Mapping the dynamics of research networks in ecology and evolution using co-citation analysis (1975–2015)  
Reale et al., 2019.

In this paper we used a co-citation network analysis to quantify and illustrate the dynamic patterns of research in ecology and evolution over 40 years (1975–2014). We addressed questions about the historical patterns of development of these two fields. Have ecology and evolution always formed a coherent body of literature? What ideas have motivated research activity in subfields, and how long have these ideas attracted the attention of the scientific community? Contrary to what we expected, we did not observe any trend towards a stronger integration of ecology and evolution into one big cluster that would suggest the existence of a single community. Three main bodies of literature have stayed relatively stable over time: population/community ecology, evolutionary ecology, and population/quantitative genetics. Other fields disappeared, emerged or mutated over time. Besides, research organization has shifted from a taxon-oriented structure to a concept-oriented one over the years, with researchers working on the same topics but on different taxa showing more interactions.

https://ecoevorxiv.org/dpef4/
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Measuring What Matters: Actionable Information for Conservation Biocontrol in Multifunctional Landscapes 
Chaplin-Kramer et al., 2019

Despite decades of study, conservation biocontrol via manipulation of landscape elements has not become a mainstream strategy for pest control. Meanwhile, conservation groups and governments rarely consider the impacts of land management on pest control, and growers can even fear that conservation biocontrol strategies may exacerbate pest problems. By finding leverage points among these actors, there may be opportunities to align them to promote more widespread adoption of conservation biological control at the landscape-scale. But are ecologists measuring the right things and presenting the right evidence to enable such alignment? We articulate key concerns of growers, conservation groups, and governments with regards to implementing conservation biological control at the landscape scale and argue that if ecologists want to gain more traction, we need to reconsider what we measure, for what goals, and for which audiences. A wider set of landscape objectives that ecologists should consider in our measurements include risk management for growers and co-benefits of multifunctional landscapes for public actors. Ecologists need to shift our paradigm toward longer-term, dynamic measurements, and build cross-disciplinary understanding with socioeconomic and behavioral sciences, to enable better integration of the objectives of these diverse actors that will be necessary for landscape management for conservation biocontrol to achieve its full potential.

https://bit.ly/31nyEb3

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Venezuela 
Arbuckle Bros. Coffee Company, 1889. 3 x 5. Chromolithograph by Donaldson Brothers.

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Las mariposas tienen una gracia encantadora pero también son las criaturas más efímeras que existen. Nacidas quién sabe dónde, buscan dulcemente algunas pocas cosas y luego desaparecen silenciosamente en alguna parte. 

Haruki Murakami
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The geographic scaling of biotic interactions 
Miguel B. Araújo Alejandro Rozenfeld

A central tenet of ecology and biogeography is that the broad outlines of species ranges are determined by climate, whereas the effects of biotic interactions are manifested at local scales. While the first proposition is supported by ample evidence, the second is still a matter of controversy. To address this question, we develop a mathematical model that predicts the spatial overlap, i.e. co‐occurrence, between pairs of species subject to all possible types of interactions. We then identify the scale of resolution in which predicted range overlaps are lost. We found that co‐occurrence arising from positive interactions, such as mutualism (+/+) and commensalism (+/0), are manifested across scales. Negative interactions, such as competition (−/−) and amensalism (−/0), generate checkerboard patterns of co‐occurrence that are discernible at finer resolutions but that are lost and increasing scales of resolution. Scale dependence in consumer–resource interactions (+/−) depends on the strength of positive dependencies between species. If the net positive effect is greater than the net negative effect, then interactions scale up similarly to positive interactions. Our results challenge the widely held view that climate alone is sufficient to characterize species distributions at broad scales, but also demonstrate that the spatial signature of competition is unlikely to be discernible beyond local and regional scales.

Expected co‐occurrence across biotic‐interaction space. Colours on the top graph indicate the intensity of the predicted co‐occurrence between species A (y axis) and B (x axis), where increasing gradients of red indicate increased co‐occurrence and increasing gradients of blue indicate decreased co‐occurrence. The light gray line indicates the portion of biotic‐interaction space where co‐occurrence between two species is no different than expected with the null model. The numbers on the y and x axes represent interactions (I) of varying signal (+, −, 0) and strength (≥ 0 ≤ 1). The lower scatter diagrams provide examples of simulated distributions of species A (black) and B (gray), with their respective co‐occurrence (red), for interactions of varying sign and strength. Both species have prevalence ρ= 0.3.

https://bit.ly/32ZDmNU

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The Isle of Fisherwoman 

https://bit.ly/2XJ16Hj
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The man has made the Earth a hell for animals. 

Arthur Schopenhauer
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Sauromatum guttatum parenchyma cell, coloured transmission electron micrograph.   Note the cell wall, nucleus with nucleolus, amyloplast with starch grains and mitochondria.

https://buff.ly/2LRfh5J  

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Effectiveness of agri‐environmental management on pollinators is moderated more by ecological contrast than by landscape structure or land‐use intensity 
Marja et al., 2019.

Agri‐environment management (AEM) started in the 1980s in Europe to mitigate biodiversity decline, but the effectiveness of AEM has been questioned. We hypothesize that this is caused by a lack of a large enough ecological contrast between AEM and non‐treated control sites. The effectiveness of AEM may be moderated by landscape structure and land‐use intensity. Here, we examined the influence of local ecological contrast, landscape structure and regional land‐use intensity on AEM effectiveness in a meta‐analysis of 62 European pollinator studies. We found that ecological contrast was most important in determining the effectiveness of AEM, but landscape structure and regional land‐use intensity played also a role. In conclusion, the most successful way to enhance AEM effectiveness for pollinators is to implement measures that result in a large ecological improvement at a local scale, which exhibit a strong contrast to conventional practices in simple landscapes of intensive land‐use regions.

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https://onlinelibrary.wiley.com/doi/pdf/10.1111/ele.13339
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The beauty of a flower comes from its roots

Ralph Waldo Emerson
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A global synthesis reveals biodiversity-mediated benefits for crop production      
Dainese et al., 2019.

Human land use threatens global biodiversity and compromises multiple ecosystem functions critical to food production. Whether crop yield–related ecosystem services can be maintained by a few dominant species or rely on high richness remains unclear. Using a global database from 89 studies (with 1475 locations), we partition the relative importance of species richness, abundance, and dominance for pollination; biological pest control; and final yields in the context of ongoing land-use change. Pollinator and enemy richness directly supported ecosystem services in addition to and independent of abundance and dominance. Up to 50% of the negative effects of landscape simplification on ecosystem services was due to richness losses of service-providing organisms, with negative consequences for crop yields. Maintaining the biodiversity of ecosystem service providers is therefore vital to sustain the flow of key agroecosystem benefits to society.

Distribution of analyzed studies and effects of richness on ecosystem services provisioning. (A) Map showing the size (number of crop fields sampled) and location of the 89 studies (further details of studies are given in table S1). (B) Global effect of pollinator richness on pollination (n = 821 fields of 52 studies). (C) Global effect of natural enemy richness on pest control (n = 654 fields of 37 studies). The thick line in each plot represents the median of the posterior distribution of the model. Light gray lines represent 1000 random draws from the posterior. The lines are included to depict uncertainty of the modeled relationship.

https://advances.sciencemag.org/content/5/10/eaax0121/tab-pdf
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Santa Cruz, Bolivia 

Deforestation for the expansion of mechanized agriculture and cattle ranching (17°23'15.7"S, 60°33'43.6"W)
Via: Anne-Marie Clark

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There's a whisper on the night-wind, there's a star agleam to guide us, 
And the Wild is calling, calling . . . let us go. 

Robert William Service
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A mutualistic interaction between Streptomyces bacteria, strawberry plants and pollinating bees      

Kim et al., 2019.

Microbes can establish mutualistic interactions with plants and insects. Here we track the movement of an endophytic strain of Streptomyces bacteria throughout a managed strawberry ecosystem. We show that a Streptomyces isolate found in the rhizosphere and on flowers protects both the plant and pollinating honeybees from pathogens (phytopathogenic fungus Botrytis cinerea and pathogenic bacteria, respectively). The pollinators can transfer the Streptomyces bacteria among flowers and plants, and Streptomyces can move into the plant vascular bundle from the flowers and from the rhizosphere. Our results present a tripartite mutualism between Streptomyces, plant and pollinator partners.

Microbial diversity of strawberry flowers and pollen. a Pyrosequencing of microbes in strawberry flowers (n = 9, 13 independent experiments) and b pollen (n = 2, 9 independent experiments). Taxonomic assignment was conducted at the family level with the Silva database (http://www.arb-silva.de/) and a cutoff of 97% similarity. Flower and pollen samples were collected from November 2013 (0 week) to March 2014 (24 week). Heatmap of hierarchical clustering of bacterial communities by 16S rRNA region. c Flower samples and d pollen samples. Heatmap color (purple to yellow) displayed from low to high abundance of each OTU. e Beta diversity tree (Minkowski distance) of samples with gray mold disease incidence. f Venn diagram of common OTU numbers in flower and pollen samples during the period of low gray mold disease incidence. g Gray mold incidence over a growing season as related to Streptomyces OTU read numbers. Gray mold incidence, bars represent standard error of nine blocks, each block contains 150 plants. Star (*) indicates statistically significant differences between disease incidence and OTU numbers of Streptomyces globisporus NRRL B-2872, which is identical to SP6C4 and SF7B6 by t-test (P value < 0.05). Bars represent standard error. a, b, e, f, g Source data are provided as a Source Data file.

https://www.nature.com/articles/s41467-019-12785-3

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El Sol
Alan Friedman
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Rain downpours affect survival and development of insect herbivores: the specter of climate change?
Chen et al., 2019.

Changes in the frequency, duration and intensity of rainfall events are among the abiotic effects predicted under anthropogenic global warming. Heavy downpours may profoundly affect the development and survival of small organisms such as insects. Here, we examined direct (physically on the insects) and indirect (plant‐mediated) effects of simulated downpours on the performance of caterpillars of two lepidopteran herbivores (Plutella xylostella and Pieris brassicae) feeding on black mustard (Brassica nigra) plants. Host plants were exposed to different rainfall regimes both before and while caterpillars were feeding on the plants in an attempt to separate direct and indirect (plant‐mediated) effects of rainfall on insect survival and development. In two independent experiments, downpours were simulated as a single long (20 min) or as three short (5 min) daily events. Downpours had a strong negative direct effect on the survival of P. xylostella, but not on that of P. brassicae. Direct effects of downpours consistently increased development time of both herbivore species, whereas effects on body mass depended on herbivore species and downpour frequency. Caterpillar disturbance by rain and recorded microclimatic cooling by 5 °C may explain extended immature development. Indirect, plant‐mediated effects of downpours on the herbivores were generally small, despite the fact that sugar concentrations were reduced and herbivore induction of secondary metabolites (glucosinolates) was enhanced in plants exposed to rain. Changes in the frequency of precipitation events due to climate change may impact the survival and development of insect herbivores differentially. Broader effects of downpours on insects and other arthropods up the food chain could seriously impair and disrupt trophic interactions, ultimately destabilizing communities.

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https://esajournals.onlinelibrary.wiley.com/doi/10.1002/ecy.2819

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Maíz Fresa

Mazorcas de 5 a 8 centímetros, granos de color rojo oscuro. Es utilizado para hacer palomitas y también como ornamento.

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Philippe Descola 
Naturaleza-Cultura

Some theoretical notes on agrobiodiversity: spatial heterogeneity and population interactions 

Diego Griffon & Maria-Josefina Hernandez

Ecological interactions are fundamental in ecological pest management, and these interactions form networks. The properties of these networks, where interactions of all possible nature (positive, neutral, negative) coexist, are key for management, but little is known about them. The main reasons for this lack of knowledge are the difficulties in obtaining empirical evidence. These problems may be partially bypassed using a theoretical approach. Here, by means of mathematical models that represent networks of ecological interactions in agroecosystems, we characterize some architectural features that promote the self-regulation of population densities in these networks. The results show that the key features are: spatial heterogeneity and a high proportion of positive interactions.

Biodiversity and spatial heterogeneity strongly benefit agricultural landscapes. Among others, these benefits are related to population regulation of organisms that feed on cultivated plants (Duflot et al. 2015; Fahrig et al. 2011; Letourneau et al. 2011; Rusch et al. 2016, 2010; Tscharntke et al. 2002, 2012; Vandermeer 1989). However, there is a need for further theoretical development to help us understand the processes behind these empirical observations, particularly from a mechanistic point of view. In a very general sense, in the agroecological literature it is proposed that increasing agricultural biodiversity involves an increase in the number of trophic interactions of the ecological community, which in turn promotes the stability of the whole system (Altieri 1983; Altieri and Nicholls 2000, 2004; Nicholls and Altieri 2002). On the other hand, we acknowledge that the ecological evidence concerning the relationship between the number of species (richness) and the number of trophic interactions in natural ecosystems is ambiguous (Hall and Raffaelli 1997) and, that from a theoretical point of view, the relationship between complexity and stability is an issue far from resolved (Allesina and Tang 2015; Bersier 2007; Ings et al. 2009; Namba 2015). However, when it comes to contrasting a monoculture with a multidiverse agroecosystem, these topics may have clearer answers (Griffon and Hernández 2014; Griffon and Rodríguez 2017; Rusch et al. 2016, 2010; Tscharntke et al. 2012).

In a conventional monoculture, the system is explicitly designed and managed to reduce as much as possible the unplanned associated biodiversity(typically by using insecticides, herbicides, etc.). Paradoxically this may contribute(among other things) to the long term establishment of phytophagous organisms in the system, eradicating at the same time their biological controllers (Jonsson et al. 2015; Landis, Wratten, and Gurr 2000; Levins and Vandermeer 1990). In this type of farming system most species are related directly to one (the monoculture) by a victim-exploiter relationship (i.e., predation, parasitism, parasitoidism and herbivory), where the monoculture species (the crop) typically plays the role of the victim. So, the system has a star-like architecture (i.e., many nodes connected to a central hub) with the monoculture in the center (Griffon and Torres-Alruiz 2008), which is a structure that favours the occurrence of pest situations and crops losses (Griffon and Hernández 2014; Griffon and Rodríguez 2017).

Alternatives to the ecological oversimplification of monocultures are companion crops. One of the aims of this cropping strategy is the population regulation of phytophagous and phytopathogenic species by means of ecological interactions (Altieri and Nicholls 2004). The success of this approach not only depends on the occurrence of a more complex trophic web, but also on the occurrence of other ecological interactions (competition, mutualism, amensalism and commensalism) that together make up the ecological network system, i.e., a network consisting of all types of ecological interactions (Ings et al. 2009). We have very little information on the structure of ecological networks (Pocock et al. 2012) and we also lack knowledge on how ecological networks promote the regulation of phytophagous population densities. Given the need of information, coupled with the difficulty and effort involved in achieving it in the field, this paper addresses the issue from a theoretical perspective. In order to do this, we build and numerically evaluate mathematical models that simulate networks of hypothetical ecological interactions associated with agricultural ecosystems. This is done with the objective of finding patterns that can provide guidelines on architectural features associated with self-regulation in populations.

Another related topic must be considered. There is abundant field information that shows the positive effects of spatial heterogeneity (Batáry et al. 2011; Duflot et al. 2015; Fahrig 2013; Fahrig et al. 2011, 2015; Jonsson et al. 2015; Landis, Wratten, and Gurr 2000; Rusch et al. 2016; Tscharntke et al. 2012; Tuck et al. 2014) on the maintenance of associated agricultural biodiversity (sensu Vandermeer and Perfecto 1995; Altieri et al. 2005). In some cases, space heterogeneity may even play a more important role than intra-farm diversity in the regulation of phytophagous population densities (Fahrig et al. 2011, 2015). But surely the two components (intra and inter farm diversity) relate synergistically.

For the spatial heterogeneity to have a positive effect on the internal dynamics of agroecosystems it is necessary, on the one hand, an insidefarm design that attracts biological controllers (e.g., flower strips or beetle banks) (Altieri, Ponti, and Nicholls 2005; Nicholls and Altieri 2002) and on the other, the existence of nearby sources of organisms with enough internal complexity to provide the necessary control agents (Rusch et al. 2016, 2010; Tscharntke et al. 2012).

So, metapopulation and metacommunity dynamics seem to be crucial for the long term survival of species in heterogeneous environments (Alfonzo et al. 2009; Aberg et al. 1995; Cantrell, Cosner, and Fagan 1998; Delin and Andren 1999; Griffon, Alfonzo, and Hernandez 2010; Griffon and Hernández 2014; Gustafson and Gardner 1996; Perfecto, Vandermeer, and Wright 2009; Sisk, Haddad, and Ehrlich 1997; Tejat et al. 2002; Vandermeer and Carvajal 2001; Vandermeer and Perfecto 2007). In general terms, the spatial structure of populations, along with processes of dispersal, migration and colonization, allows the emergence of dynamics that make possible the persistence and coexistence of species (Hanski 1994, 1998; Hanski and Gilpin 1997; Hanski et al. 1996; Leibold et al. 2004). Thus, spatial heterogeneity may enhance the configuration of the complex ecological networks needed for a successful ecological pest management program (Batáry et al. 2011; Fahrig et al. 2011; Rusch et al. 2016, 2010; Tejat et al. 2002; Tscharntke et al. 2002, 2012). For this reason, in the mathematical approach used here we also include the effect of spatial heterogeneity on population dynamics.

In short, the objective of this work is to find architectural features that promote the self-regulation of population densities in ecological networks associated to agroecosystems. To do this, we built mathematical models that represent ecological networks, both for a single community and for metacommunitarian systems. We must make clear that whenever we say ‘ecological network’, we are considering the potential presence of ‘all’ types of interactions, i.e., competition, mutualism, victim-exploiter, amensalism and commensalism.

Species survivals. Initial richness, for six different initial conditions (defined in Fig 3). Blue: survival percentage in one community (no spatial heterogeneity). Grey: survival percentage of one community in a metacommunitarian background. The curves are averages of 40 simulations for each initial condition.

Uniform perturbation (example). A persistent network obtained under the 20:10:10:60 initial condition is perturbed by a little increase in the densities of each population. Left: dynamics after the perturbation. Two populations reach very low (but non zero) densities. Right: network before and after the perturbation. Notice that both networks are the same.

The more relevant results of the models evaluated and discussed in this article can be summarized as follows: (i) The conditions under which persistent networks are obtained after the iterative process are very restricted. However, when persistent  networks are obtained, they are fundamentally resilient to perturbations. (ii) Mutualistic (and positive in general) interactions have an important and extensive effect under certain (very specific) conditions. (iii) Spatial heterogeneity increases the possibility of persistence in hypothetical communities. (iv) Ecological interactions that somehow have been neglected in the past (commensalism and amensalism, the forgotten sisters), may be: 1- More frequent than generally thought, and 2- Important for the persistence of communities.

https://bit.ly/2YPVlTO

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Caterpillar proleg with circle of gripping hooks in red
Photo: Karin Panser
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O insects
don't you complain too!
this autumn

Issa, 1820
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Turning toxic - The Bayer-Monsanto merger

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La simplicidad es la máxima sofisticación.

Leonardo Da Vinci
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Göbekli Tepe

Göbekli Tepe 
Un lugar significativo en la historia de la agricultura según Yuval Noah Harari.

"En 1995, los arqueólogos empezaron a excavar una localidad del sudeste de Turquía llamada Göbekli Tepe. En el estrato más antiguo no descubrieron ninguna señal de una aldea, de casas o de actividades diarias. Sin embargo, encontraron estructuras columnares monumentales decoradas con grabados espectaculares. Cada columna de piedra pesaba hasta 7 toneladas y alcanzaba una altura de 5 metros. En una cantera cercana encontraron una columna a medio cincelar que pesaba 50 toneladas. En total, descubrieron más de 10 estructuras monumentales, la mayor de las cuales medía casi 30 metros.

Los arqueólogos están familiarizados con estas estructuras monumentales de localidades de todo el mundo; el ejemplo más conocido es Stonehenge, en Gran Bretaña. Pero cuando estudiaron Göbekli Tepe descubrieron algo sorprendente. Stonehenge se remonta a 2500 a.C., y fue construido por una sociedad agrícola desarrollada. Las estructuras de Göbekli Tepe están datadas hacia 9500 a.C., y todos los indicios disponibles señalan que fueron construidas por cazadores-recolectores. La comunidad arqueológica no daba crédito a estos hallazgos, pero una prueba tras otra confirmaron la fecha temprana de las estructuras y la sociedad preagrícola de sus constructores. Las capacidades de los antiguos cazadores-recolectores, y la complejidad de sus culturas, parece que fueron mucho más impresionantes de lo que se sospechaba en un principio.

¿Por qué habría de construir estructuras de este tipo una sociedad de cazadores-recolectores? No tenían ningún propósito utilitario evidente. No eran ni mataderos de mamuts ni lugares en los que resguardarse de la lluvia o esconderse de los leones. Esto nos deja con la teoría de que fueron construidas con algún propósito cultural misterioso que los arqueólogos se esfuerzan en descifrar. Fuera lo que fuese, los cazadores-recolectores creyeron que valía la pena dedicarles una enorme cantidad de esfuerzo y de tiempo. La única manera de construir Göbekli Tepe era que miles de cazadores-recolectores pertenecientes a bandas y tribus diferentes cooperaran a lo largo de un período de tiempo prolongado. Solo un sistema religioso o ideológico complejo podía sostener tales empresas.

Göbekli Tepe contenía otro secreto sensacional. Durante muchos años, los genetistas han estado siguiendo la pista del trigo domesticado. Descubrimientos recientes indican que al menos una variante domesticada (el trigo carraón) se originó en las colinas de Karacadag, a unos 30 kilómetros de Göbekli Tepe.

Es difícil que esto sea una coincidencia. Es probable que el centro cultural de Göbekli Tepe estuviera de algún modo relacionado con la domesticación inicial del trigo por la humanidad y de la humanidad por el trigo. Con el fin de dar de comer a las gentes que construyeron y usaron las estructuras monumentales, se necesitaban cantidades de alimento particularmente grandes. Bien pudiera ser que los cazadores-recolectores pasaran de recolectar trigo silvestre a un cultivo intensivo de trigo, no para aumentar sus recursos alimentarios normales, sino más bien para sostener la construcción y el funcionamiento de un templo. En la imagen convencional, los pioneros primero construían una aldea y, cuando esta prosperaba, establecían un templo en el centro de la misma. Pero Göbekli Tepe sugiere que primero pudo haberse construido el templo, y que posteriormente a su alrededor creció una aldea."

Yuval Noah Harari. Sapiens: De animales a dioses: Una breve historia de la humanidad.  https://amzn.to/2Oqd3M2 
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