Tag Archives: mosquito

News Roundup: Autumn 2015.

Disease eradications, Bee vaccinations and Entomophagy- catch up on all the latest entomological news stories you might have missed!

Risks of Eating Insects

The European Food Safety Authority (EFSA) have recently published a report on using insects as a protein source for animal feed and human consumption. It found that edible insects could contain biological and chemical contaminants, depending on how the large scale insect farms were managed.

With an estimated global population of 9 billion by 2050, using insects as a high quality source of protein as feed (for chickens, for example) could give a much needed food conversion rate (lower levels of initial energy and water required). Insect meat is also a quality source of fat, fibre, minerals and vitamins.

It is estimated that insects such as flies, moths, mealworms and crickets/locust already form the diet of at least 2 billion people. There is still clearly a way to go until western cultures can adopt new foodstuffs and a better understanding of the hazards of eating insects is required for the next step.

GM Mosquitoes trial reduced Dengue by 95%

A trial where scientists released thousands of ‘friendly’ Aedes aegypti mosquitoes infected with a bacteria that will intended to suppress dengue fever has yielded positive results. The theory was that the genetically modified yellow fever carrying mosquitos breed with the existing population and become the dominant type, thus eliminating the disease spreading variants.

The results of the Oxitec trial in Brazil found that the disease carrying mosquito number were reduced by 95%, well below the disease transmission threshold. The control was species-specific, and the Oxitec male mosquitoes mate with the naturally occurring females of the population and their offspring die before they can transmit the disease.

New methods of pest control like this are crucial as Aedes aegypti is developing resistance to insecticides and removal of breeding sites leads to them re invading the following year from neighbouring habitats that are inaccessible to us. There is also no vaccine or specific medication currently for dengue, chikungunya or zika virus (3 debilitating mosquito-borne diseases) so the development of new methods is crucial.

Honeybees give each other Vaccinations

Once a disease takes hold of a hive, the workers of a honeybee colony become disorientated and fail to forage to feed their sisters and brood. Luckily bees naturally immunize their young against certain diseases found in their environment, and scientists have recently discovered how exactly they do this.

The latest research suggests that the queen is fed on royal jelly from pollen infected with bacteria, and these are digested in the gut and stored in the queen’s fat body. Pieces of the bacteria are then bound to vitellogenin (a blood protein) and this is carried via blood to supply developing eggs with immunity.

The industries relying on honeybees colonies and the pollination service could benefit if a similar vaccine was produced for other bee diseases- like american foul brood. The discovery of vitellogenin, the carrier of immune-priming signals, could have implications for other animals that pass on immunity to their young.

Wasps are an indicator for environmental decline

A decline in wasps is thought to be a reaction to the increased harm of pesticides on wasps, and their food resource. Wasps play a key role in ecosystems (a ‘keystone species’), and taking them out would cause many systems in an ecosystem to collapse- for example dead insects and detritus would accumulate, with pestilent flies possibly taking advantage of this and proliferating.

A possible decline in wasps that might go unnoticed is what’s called a ‘shifting baseline syndrome’, meaning that small declines in number each year might go unnoticed, despite a reduction in 50% of population over 20 years (for example).

For the 2 most recognizable species of social wasp, Vespula germanica and Vespula vulgaris, there have been reported losses in number and this has been attributed to a reduction in their food resources- wasps are carnivorous during colony development (eating dead insects, aphids, etc.) and take advantage of sugar foods (such as fermenting fruit) late in the season. The decline of wasps could therefore be a signal that insects lower in the food chain are vanishing too and endangering whole systems. Environmental decline should be indicated by more than just a decline in wasps, though!

Further Reading:

Entomophagy http://www.bbc.co.uk/news/science-environment-34476742

Dengue Mosquitos http://entomologytoday.org/2015/07/03/genetically-engineered-mosquitoes-reduce-population-by-95-percent/

Honeybee Immunization http://entomologytoday.org/2015/08/03/researchers-discover-key-to-bee-vaccination/

Wasps and Ecosystems http://www.independent.co.uk/voices/nature-studies-fewer-wasps-to-swat-is-a-sign-of-an-ecosystem-in-serious-trouble-a6680881.html


Release of GM Mosquitoes to fight Dengue Fever in Brazil


In Rio de Janeiro, scientists have released thousands of mosquitoes infected with a bacteria that will hopefully suppress dengue fever. The theory is that the genetically modified yellow fever mosquitos (Aedes aegypti) will breed with the existing population and become the dominant type, thus eliminating the disease spreading variants.

Dengue is one of the most widespread and rapidly spreading mosquito-borne diseases in the world, with a 30-fold increase in global incidence over the past 50 years. So far Aedes aegypti have proved difficult to control with insecticides and more traditional methods. However it was discovered that A. aegypti transinfected with the wMel strain of Wolbachia showed limited dengue virus (DENV) replication. Virus-blocking persists in Wolbachia-infected mosquitoes after their release and establishment (like a vaccine). This, coupled with the ability of Wolbachia to both induce pathogen interferences and spread into mosquito vector population (i.e. become dominant) makes them ideal bio-control agents.

To achieve population suppression of Aedes aegypti using the RIDL system (Release of Insects carrying a Dominant Lethal), a large number of male mosquitos need to be released. This requires mass rearing techniques to obtain the highest quality males. RIDL is effective and an environmentally safe method of controlling mosquitoes, with no knock on effect to non-target organisms such as natural enemies.

Brazil leads the world in the number of dengue cases, with 3.2 million cases and 800 deaths reported in the 2009-14 period. Brazil has released around 11 million males in the 2012 programme, and part of the programme is also taking place in Australia, Vietnam and Indonesia.

Bian, G., Zhou, G., Lu, P., & Xi, Z. (2013). Replacing a native Wolbachia with a novel strain results in an increase in endosymbiont load and resistance to dengue virus in a mosquito vector. PLoS neglected tropical diseases, 7(6), e2250.
Carvalho, D. O., Nimmo, D., Naish, N., McKemey, A. R., Gray, P., Wilke, A. B., … & Capurro, M. L. (2014). Mass production of genetically modified Aedes aegypti for field releases in Brazil. JoVE (Journal of Visualized Experiments), (83), e3579-e3579.
Frentiu, F. D., Zakir, T., Walker, T., Popovici, J., Pyke, A. T., van den Hurk, A., … & O’Neill, S. L. (2014). Limited Dengue Virus Replication in Field-Collected Aedes aegypti Mosquitoes Infected with Wolbachia. PLoS neglected tropical diseases, 8(2), e2688.
Peter, R., & Scott, O. N. (2014, September). Using Wolbachia infections to control dengue transmission. In 8th Cuban Congress on Microbiology and Parasitology, 5th National Congress on Tropical Medicine and 5th International Symposium on HIV/aids infection in Cuba.