Symbiomes: when symbionts go to the congress

Symbiosis plays a very important role in the origin, organization and evolution of life and it is now evident that we live in a symbiotic world, where the key characteristic of the biological systems is to establish associations and connections with other organisms. The practical implications of this new approach are enormous, and largely unexplored and rwe have to dissect the different aspects of the interaction of the microbiota with the host in humans and other model systems through the interdisciplinary effort of experts from different fields including molecular and cellular biology, microbiology, immunology, computational biology, bioinformatics, genetics, population genetics, and epidemiology.

In order to facilitate interactions among scientists involved in the study of microbiomes, Claudio Donati (Fondazione Edmund Mach, Italy), Duccio Cavalieri (Fondazione Edmund Mach, Italy) and Marco Soriani (Novartis Vaccies and Diagnostics) organize a meeting to provide a discussion forum for experts in these different fields to foster new ideas for interdisciplinary research.

The conference, entitled Symbiomes: system biology of host-microbiome interactions, will cover different topics including:

  1. The healthy human commensal flora and its alterations
  2. Homeostasis between microbiota and immune system
  3. An ecological perspective of host-microbe interactions
  4. Environmental metagenonmics
  5. Soil and plant microbiome
  6. Therapeutic and prentive manipulation of microbiota
  7. Foresight

The conference will be held at Polonia Castle (Dom Polonii) in Pultusk, Poland in days 5-10 june 2015.

A Christmas Aphid

Originally posted on Don't Forget the Roundabouts:

A few weeks ago I was contacted by a researcher from the One Show.  They were interested in the possibility of doing a festive piece about what people bring into the house with them on Christmas trees with the idea that George McGavin would shake a Christmas tree over a piece of white paper and tell the audience all about the insects that fell out;  a typical media “how gross nature” is piece.

The researcher was somewhat disappointed when I told her that being winter  that there would be relatively little hiding in the tree, especially if it was a commercially reared cut tree bought from a garden centre or other retail outlet.  Cut Christmas trees in the UK tend to be harvested from October onwards so the chances are that your tree has lain about for at least a month before you bring it into your house and by…

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Neonicotinoids? An unacceptable danger for biodiversity

Neonicotinoids and fipronil are currently highly used insecticides applied in different cases, including seed coating,
bathing, foliar spray applications and trunk injection. These compounds are commonly used for insect pest management since they are very effective due to their disruption of the neural transmission in the central nervous system of organisms. Indeed, neonicotinoids bind to the nicotinic acetylcholine receptor (nAChR) , whereas fipronil inhibits the GABA receptor. Both pesticides produce lethal and a wide range of sublethal adverse impacts and even low-dose exposure over extended periods of time can culminate into substantial effects.

According to literature data, neonicotinoids and fipronil can have negative effects on physiology and survival for a wide range of non-target invertebrates in terrestrial, aquatic, wetland, marine and benthic habitats, but their effects on non-target species has been frequently debated.

A definitive reply could come from The Worldwide Integrated Assessment of the Impact of Systemic Pesticides on Biodiversity and Ecosystems (WIA), the most comprehensive study of neonics ever undertaken that examined over 800 scientific studies spanning the last five years.

The conclusionspublished in the international journal Environmental Science and Pollution Researchclearly indicate that:

Overall, the existing literature clearly shows that present-day levels of pollution with neonicotinoids and fipronil caused by authorized uses (i.e. following label rates and applying compounds as intended) frequently exceed the lowest observed adverse effect concentrations for a wide range of non-target species and are thus likely to have a wide range of negative biological and ecological impacts. The combination of prophylactic use, persistence, mobility, systemic properties and chronic toxicity is predicted to result in substantial impacts on biodiversity and ecosystem functioning. The body of evidence reviewed in this Worldwide Integrated Assessment indicates that the present scale
of use of neonicotinoids and fipronil is not a sustainable pest management approach and compromises the actions of numerous stakeholders in maintaining and supporting biodiversity and subsequently the ecological functions and services the diverse organisms perform.

At present pesticides represent the first defense line in the field, whereas these chemicals need to become the last resort in the chain of preferred options that need be applied first. In particular, preferred options should include organic farming, diversifying and altering crops and their rotations, inter-row planting, planting timing, tillage and irrigation, using less sensitive crop species in infested areas, using trap crops, applying biological
control agents, and selective use of alternative reduced-risk insecticides.



further-readingFurther reading:

Gibbons, D., Morrissey, C., & Mineau, P. (2014). A review of the direct and indirect effects of neonicotinoids and fipronil on vertebrate wildlife Environmental Science and Pollution Research DOI: 10.1007/s11356-014-3180-5

J. P. van der Sluijs, V. Amaral-Rogers, L. P. Belzunces, M. F. I. J. Bijleveld van Lexmond, & et al. (2014). Conclusions of the Worldwide Integrated Assessment on the risks of neonicotinoids and fipronil to biodiversity and ecosystemfunctioning Environmental Science and Pollution Research : 10.1007/s11356-014-3229-5

How do parasitoids respond to defended hosts?

Originally posted on Parasite Ecology:

Last week, I talked about the new Godzilla movie and how I thought that the MUTOs should have been parasitoids.  This week, let’s talk about some awesome, real life parasitoids: parasitoid wasps (Aphidius ervi).

Quickly, the life cycle works like this: the female wasp finds an aphid nymph, she stabs the aphid with her ovipositor, and then she typically lays one egg inside the aphid.  After one day, the egg hatches into a larval parasitoid, and the larva hangs out inside the aphid while eating the aphid’s innards.  After about one week of this, the aphid dies.  Actually, the aphid’s corpse becomes a “mummy,” and the larva pupates inside the mummy before eventually emerging as an adult parasitoid.  Mating happens, and then the female wasps go off to infect more aphids.

But here’s an interesting complication: some aphids are protected by bacterial symbionts (Hamiltonella defensa). …

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Listening to plants to reduce the use of pesticides

More than 40 years ago James Mallet published in Trends in Ecology and Evolution a paper entitled “The Evolution of insecticide resistance: have the insects won?”  where he stated at the end of the paper:

The insects have won for the moment in tropical malaria control, and they seem to be winning in cotton, among a number of other crops. Pest susceptibility is a valuable natural resource that has been overexploited. Better management of this susceptibility resource will require a better knowledge of the ecology and population genetics of insects, as well as the political will to make resistance management strategies work.

I’m not sure that insects won, but I’m sure that we are not winning this battle so that… what is the future of insect control? In the last decades we used different kinds of insecticides that were costly not only for farmers, but also four our health and for the environment where we live. The World Health Organization estimates that there are 3 million cases of pesticide poisoning each year and up to 220,000 deaths, primarily in developing countries. Children, for instance, are particularly vulnerable to the harmful effects of pesticides and even very low levels of exposure during development may have adverse health effects.

At the same time more than 500 crop pest insects already evolved resistance to conventional insecticides. Mosquitoes that are capable of transmitting malaria are now resistant to virtually all pesticides used against them. Many populations of the corn earworm, which attacks many agricultural crops worldwide including corn, cotton, tomatoes, tobacco, and peanuts, are resistant to multiple pesticides. Lastly, the green peach aphid Myzus persicae is resistant to more insecticides than any other insects and it should merit a gold medal for insecticide resistance since  M. persicae indeed has a documented resistance to 71 synthetic chemical insecticides.

So… what is the future for insect control in the field? Pesticides represented a significant progress in controlling pests, but there is another way. It involves listening to plants, which have fought this battle much longer than we have!

A nice summary of this “new way” has been recently published in an intriguing editorial by entitled “Listen to the plants” by Kat McGowan. As she wrote, plants are talking to bugs in a language we can try to understand:

When a caterpillar or a beetle starts chewing on a leaf, the plant responds by synthesizing its own defense chemicals in an attempt to drive away the insect. It also releases a chemical plume into the air, a message that can be intercepted by creatures nearby. Other plants respond to these alerts by producing their own chemical weapons, substances that repel leaf-eating insects. Predators that eat plant pests also detect the signals, using them like beacons to locate their prey.

The first evidences that plants might be able to communicate with one another came more than 40 years ago, now we have to crack the plant code so that we can understand when a plant could be damaged and make plants less attractive for pest crop. At the same time, as McGowan wrote:

Plants aren’t the only ones listening to these messages. Predatory bugs and caterpillar parasites sniff out the emissions of a plant being eaten, and like Batman responding to a bat signal in the night sky, swoop in for the rescue. 

ResearchBlogging.orgA proof of the results we could obtain understanding the plant language comes from the “push-pull” system developed by the  International Center of Insect Physiology and Ecology in Kenya in collaboration with Rothamsted Research, the most famous agricultural research station in the world (here a free report on this method). According to this strategy, farmers  use some plants whose emissions repel pest crop insects, keeping them away from the grains. Then they “pull” insects using plants that  attract them increasing the field yields in view of the reduced damages due to insects.

Genetically engineered sentinel plants could be stationed in fields like canaries in the coal mine—the first to get attacked and the first to raise the alarm, so valuable crops get a head start on making their own defenses. Crops that naturally produce pest-attracting volatiles could instead be genetically silenced, a way of cloaking them so that the bugs don’t even know they’re there.

Plants coexisted with pest crop insects since long time so that we have to understand how they detect their enemies and recruit their protectors. By understanding how the crops that feed us deploy their own defenses, we can turn plants into our allies by learning to speak their language.


Further reading:

Hassanali, A., Herren, H., Khan, Z., Pickett, J., & Woodcock, C. (2008). Integrated pest management: the push-pull approach for controlling insect pests and weeds of cereals, and its potential for other agricultural systems including animal husbandry Philosophical Transactions of the Royal Society B: Biological Sciences, 363 (1491), 611-621 DOI: 10.1098/rstb.2007.2173

Pickett JA, Woodcock CM, Midega CA, & Khan ZR (2014). Push-pull farming systems. Current opinion in biotechnology, 26, 125-32 PMID: 24445079

Sobhy, I., Erb, M., Lou, Y., & Turlings, T. (2014). The prospect of applying chemical elicitors and plant strengtheners to enhance the biological control of crop pests Philosophical Transactions of the Royal Society B: Biological Sciences, 369 (1639), 20120283-20120283 DOI: 10.1098/rstb.2012.0283

Peñaflor, M., & Bento, J. (2013). Herbivore-Induced Plant Volatiles to Enhance Biological Control in Agriculture Neotropical Entomology, 42 (4), 331-343 DOI: 10.1007/s13744-013-0147-z

At the origin of the aphid-ant mutualism

Several hemipteran species are involved in mutualistic relationships with ants so that aphids produce honeydew, a sweet waste product enriched in sugar and aminoacids, that ants collect as a supply for their diet. In return, ants defend hemipterans from natural enemies, such as ladybirds and parassitoid wasps.

IMG_2277_2A well-studied example is the aphid-ant mutualism and about 60% of the aphid species is involved in a mutualistic relationship with ants, called myrmecophily. The strength of this mutualism is highly variable in aphids and, as reported in the aphid genus Chaitophorus, the mutualism may be obligate, facultative or non-existent at all suggesting that myrmecophily is an evolutionarily labile trait in aphids.

About ten years ago, Alexander W. Shingleton and colleagues published in the journal Molecular Phylogenetics and Evolution the first aphid phylogeny reconstructed specifically to elucidate the evolutionary pattern of ant tending amongst a group of homopterans. According to their data, myrmecophily has been apparently gained and lost at least five times in the genus Chaitophorus.

This high rate of evolutionary change in ant–aphid interactions suggests that this mutualism is not due to co-evolutionary adaptations so that aphids can be in touch with different ant species and in literature there are very few examples of aphids being wholly dependent on a single species of ant. In some cases, aphids seem to be in symbiosis with a single ant species, but this is more a consequence of the relatively low diversity of ants rather than a dependence of the aphids on that particular ant species. As Shingleton suggested in 2003:

This tolerance of aphids for a wide variety of ant mutualists may relate to their extremely specific diet. Most aphids are mono- or oligophagous, showing a high degree of host specificity. A mutualistic monophagous aphid that also associates with only one or two species of ants will doubly limit its ability to colonise new host plants, as it will not only be restricted to plants of a certain species, but also to plants located near the nest of the mutualist ant. This may be selectively disadvantageous and limit the strength of the relationship between any one species of ant and aphid,

ants_aphids_sugar by Charles ChienInterestingly, although almost all aphids produce honeydew, are susceptible to predation and co-occur in the same habitats as ants, some species only established a mutualism with ants so that it is intriguing to understand the origin of such a symbiotic relationship.

At this regard, Shingleton et al. suggested in 2005 that the pattern of ant mutualism among aphids may be explained by differences in feeding position on their host plants so that there was a strong association between feeding on woody parts of the host plant and ant tending. According to this hypothesis, ant tending may therefore be one method of escaping interspecific competition by allowing an aphid to feed at a site unavailable to untended species. This means that if you feed yourself in a risky place, you need some protection and ants can help you. As Shingleton suggested in 2005:

It follows that aphids feeding on deeper phloem elements have evolved additional traits to better attract ants, as an evolutionary response to tending. Several of these traits have been identified. For example, tended aphids appear to adjust the quality and quantity of their honeydew to successfully attract ants. In particular, tended aphids increase the honeydew concentration of melezitose, a trisacharide particularly attractive to ants. There is evidence that such adjustments incur costs to the aphids, which are likely to increase if there is competition between aphid species for ant partners. We suggest that only in species feeding on deeper phloem elements will the costs of these traits be outweighed by the benefits of protection from predators.

The natural history of the Chaitophorus–ant mutualism suggests therefore that it is ‘easy’ for an aphid lineage to gain or lose tending. Ants can be induced to tend even non-myrmecophilic species such as C. tremulae if there is no other available source of carbohydrates, although they prefer to tend myrmeophilic species such as C. populeti when given a choice. The pattern of myrmecophily amongst the Chaitophorus species may be better understood as a hierarchy of ant preference, with different species varying in attractiveness to ants. Ant preference may in turn be influenced by honeydew quality, quantity, and availability. Host plant species, feeding position on the host plant, and competition with other aphids for the attention of ants may all influence whether an aphid species is actually tended or not. The pattern of myrmecophily amongst the aphids may therefore depend on a number of subtle differences between species.


Shingleton, A., & Stern, D. (2003). Molecular phylogenetic evidence for multiple gains or losses of ant mutualism within the aphid genus Chaitophorus Molecular Phylogenetics and Evolution, 26 (1), 26-35 DOI: 10.1016/S1055-7903(02)00328-7
Shingleton, A., Stern, D., & Foster, W. (2005). The origin of a mutualism: a morphological trait promoting the evolution of ant-aphid mutualisms. Evolution, 59 (4) DOI: 10.1554/04-584

Aphids from Fukushima: a chromosomal-based resistance to radionuclides?

In mid-March 2011, the Fukushima Nuclear Power Plant exploded releasing into the atmosphere several radionuclides, including iodine-131, cesium-137, and strontium-90. Several researchers and governmental agencies started to evaluate the levels of radionuclides accumulated in wild animals and plants in the Fukushima area assessing that several birds and insects had a significant negative correlation between densities and background radiation level. A. Hiyama et al. (2012) reported for instance that the lycaenid butterfly Zizeeria maha that emerged in 2011 in contaminated areas exhibited morphological abnormalities and that these abnormalities were inherited by the next generation, which exhibited a higher proportion of abnormalities than the first generation.

Further intriguing data have been published in aphids by Shin-ichi Akimoto from the  Hokkaido University,  who collected closed galls of Tetraneura aphid species from leaves of Ulmus davidiana var. japonica at a point 32 km from the Fukushima Daiichi Nuclear Power Plant and inspected the morphology of the gall formers at the first stadium. As he wrote in a paper published in Ecology and Evolution:

I report frequent occurrences of morphological abnormalities and mortalities in two gall-forming aphids in the Fukushima area by comparing them with other populations in uncontaminated areas. Although investigation is limited to one site in Fukushima, the results from two species corroborate the possibility of an initial, detrimental impact of fallout.

According to the published results, more than 10% of the Tetraneura sorini galls collected at 32 km from Fukushima Daiichi in spring 2012  exhibited morphological abnormalities, including some highly malformed individuals (as evident in the figure below from the Akinoto’ paper). The proportions of abnormalities were significantly higher in Fukushima than in the control areas. Similarly, about 6% of the T. nigriabdominalis galls exhibited morphological abnormalities.Interestingly only 0.37% of the aphids showed abnormalities in the second generation suggesting that abnormalities found in the first generation were not inherited. These results suggest that radioactive contamination had deleterious effects on aphid embryogenesis in eggs deposited on the bark surface, but a negligible influence on the second generation produced in closed galls.



Quite surprisingly, the malformed individual with the bifurcated abdomen successfully reached adulthood and developed embryos in her abdomen suggesting that even if external radiation was responsible for this malformation, some cells were free from the adverse effects of radiation. Similarly, the low level of abnormality in the second generations indicates that radionuclides may not have penetrated a closed gall or that a sort of radiation tolerance is present in aphids.

Even if Authors did not referred to the aphid chromosomes, this paper prompted a question? What about their chromosomes? As I revised (together with G.C. Manicardi and R.L. Blackman in Biological Reviews) aphids possess holocentric chromosomes and this could be intriguing after a damage due to radiation. Indeed, according to literature data, radionuclides can induce double-strand DNA breaks that in monocentric chromosomes bring to chromosomal fragments that cannot be properly inherited by cells due to their inability to attach to spindle microtubules. In contrast, fragments of holocentric chromosomes, could properly segregate and be stably maintained since they have microtubule attachments sites along their entire length. This could be the basis of the radiation tolerance of aphids!

As we summarized in Current Genomics:

The ability of stabilizing double-strand DNA breaks observed in holocentric chromosomes might have arisen as a defense mechanism against the production of chemicals able to induce DNA damages by several plants. Nicotine, for instance, is a naturally occurring alkaloid found primarily in members of the solanaceous plant family (including Nicotiana tabacum) that cause replication fork stress bringing to different DNA damages, including chromosomal fragmentations. Similar effects have been also reported by other plant-produced molecules, such as caffeine and ethanol. In view of these effects, the presence of holocentric chromosome in phytophagous insects, such as aphids and lepidopteran species, could be a response to the clastogenic effects of some molecules produced by the plant tissue during the insect feeding.

It seems therefore that a defence mechanism that aphids evolved against plant clastogens helped them also to survive to human-induces damages!!!! Differently from what reported in some old movies (such as Them) where some insects become big due to mutations caused by radiation exposure, it seems that aphids could survive us also after a nuclear accident!!!




Hiyama, A., Nohara, C., Kinjo, S., Taira, W., Gima, S., Tanahara, A., & Otaki, J. (2012). The biological impacts of the Fukushima nuclear accident on the pale grass blue butterfly Scientific Reports, 2 DOI: 10.1038/srep00570

Akimoto, S. (2014). Morphological abnormalities in gall-forming aphids in a radiation-contaminated area near Fukushima Daiichi: selective impact of fallout? Ecology and Evolution, 4 (4), 355-369 DOI: 10.1002/ece3.949

Manicardi GC, Mandrioli M, & Blackman RL (2014). The cytogenetic architecture of the aphid genome. Biological reviews of the Cambridge Philosophical Society PMID: 24593177

Mandrioli M, & Manicardi GC (2012). Unlocking holocentric chromosomes: new perspectives from comparative and functional genomics? Current genomics, 13 (5), 343-9 PMID: 23372420