For the love of dog

Like many others, I am a dog lover. They are a most amazing creature which has fitted into human society greater than any other animal. From personal companions to dogs which work from herding to guard dogs and seeing eye dogs. While we take the domestic dog to our hearts we often treat their cousins with less care, and ever more suspicion.

At least fifteen thousand years ago we began to take grey wolves into our villages and homes. Since then we have selectively bred them into a range of breeds of varying shapes and sizes as well as to enhance certain senses. While they may have an incredibly diverse set of appearances they are all the same species, Canis familiaris or Canis lupis familiaris.

They are in the family Canidae along with dingoes, wolves, dhole, and foxes. Sadly many of these species are hunted for sport in spite of their closeness to an animal we seem to cherish. So I thought I’d have a quick look at a few things about canids.

With dogs integrating so well into human society they also exhibit some of our behaviour, such as imperative pointing. This is when someone or something indicates to another the location of something they desire but can not access, usually by gesturing or eye movement. It has been widely observed in primates such as chimpanzees, gorilla, and orangutans in captivity, as well as toddlers.

A small study at the Wolf Science Centre in Austria has shown that, like dogs, wolves are capable of this imperative pointing behaviour to indicate the location of food to humans when it is out of their reach. Wolves don’t pick up this behaviour until a later stage in development but display it without training, this would indicate it is a skill derived from working in a pack in the wild. During this study though they had both co-operative and competitive ones, where the competitive humans would take the food after it being indicated to them. While both wolves and dogs would still indicate the food locations to competitive humans they would do so far less emphatically than with the co-operative humans.

For about four thousand years the adorable bandicoots of mainland Australia have had to avoid being prey for the dingo. This period of time has given the bandicoot the survival knowledge to avoid yards where domesticated dogs live. Dogs were introduced to both mainland Australia and Tasmania around two hundred years ago. This doesn’t appear to have been enough time for the Tasmanian bandicoots to have gained a natural avoidance of property where dogs are located. Cats were also introduced to Australia and Tasmania at the same time as the domesticated dog, but bandicoots, either mainland or Tasmanian do not avoid properties where these are homed.

The domesticated dog is also one of the most successful killers of humanity, only mosquitos, humans and snakes cause the death of more people in the animal kingdom. It’s estimated at around twenty-five thousand people per year, although many die by rabies contracted during the attack, while the wolf is roughly the cause of ten deaths per year. People still insist on hunting wolves, as well as other less dangerous canids. So why not extend this love of dogs to other canids, although best done at a distance, it probably wont hurt you.

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Rabbits, pets or pests

Rabbits are a common sight in the countryside and in peoples back gardens. Some are a childs adorable companion while others are seen as a pest, vermin to be removed or destroyed.

Over the years there have been many ways in which authorities have attempted to curb the spread of rabbits. Australia is a country which has had some of the worst problems of what can be termed an invasive species. In response to the spread of rabbits they infected the population with myxomatosis in 1950. The disease, which causes tumours to grow around the eyes and genitals, depleted their population from around 600 million to 100 million in 2 years. Other countries followed suit in an attempt to curb the species.

The release of myxomatosis in France in 1952 had a knock on effect as the disease spread into Spain. The drop in rabbit population caused by this led to decline in the population of the Iberian lynx (Lynx pardinus). L. pardinus is a rabbit specialist relying heaving on the European rabbit as a food source.

Rabbit proof fencing is a much more humane way of controlling populations and habitats. While the introduction of fencing can prove to be incredibly traumatic to populations initially, as they learn to cope with a more restricted environment, in time the population will adapt to the new limitations and return to normal behaviours. In contrast shooting is also seen as a possible way of limiting the rabbit populations, while a headshot to an individual rabbit may not be traumatic for the individual, assuming instantanous death, it can be highly traumatic for the surround rabbits with trauma increasig as subsequant rabbits are culled. Chest shots are seen as even more traumatic as likliehood of gaining a kill shot is decreased from that of aiming for the head.

While it is true that the rabbit can cause serious ecological issues as an invasive species, the moethods which are used to try and reduce their populations are horrendous at time. Their cost to agriculture and markets can be equally staggering with an estimated AU$130m to the Australian wool industry due to competition over grazing. Their does seem to be a reasonable solution in using rabbit proof fencing though, a high cost initially as well as trauma for the creatures until they adapt to the new range, but this may protect grazing land for the animals we intend it for.

Regardless of how we adapt to protect our own interests, it would be nice to do so by causing as little harm as possible. In the end some people will still think of them as pests and/or food, while others will always see them as adoreable pets.

European bumblebees finding success in Patagonia

It has at times been common practice to introduce species to a new area. Generally to remove pests or enhance production in some way. In the 80s and 90s European bumble bees were transported to South American, Patagonia to be precise, in order to aid with pollination of crops. Well used bee populations can increase the economic benefits of crops significantly. but it seems that the bees are doing just a little too well. Reports from a serious of surveys conducted between 2004 and 2012 shows an increasing spread of Bombus terrestris and Bombus ruderatus across the region.

B. ruderatus were collected from colonies in New Zealand where it had previously been introduced in the 19th century and B. terrestris are thought to have been collected from Mt. Carmel region of Israel and introduced in 1998 to Chile. Since their introduction they have both thrived in their new environment, with B. terrestris in particular making a significant invasion effort. While B. ruderatus has seemingly entrenched itself in Chile and the east side of the Andes B. terrestris has now reached the Atlantic coast near Comodoro Rivadavia. It has completely replaced the native Bombus dahlbomii and has become the dominant species everywhere it has spread. Even B. ruderatus numbers have declined once B. terrestris arrived in locations they were more dominant.

They don’t appear to be spreading alone though, parasites have gone with them. Most notably Crithidia bombi, thought to have been brought across with B. ruderatus, are using their primary hosts B. terrestris to great success since their introduction.

It is not entirely understood what is causing the native population of B. dahlbomii to retreat so drastically in the face of the invaders, it is possible that the parasites are having a significant effect but this is hard to prove. It is also possible that B. terrestris are just merely out competing the indigenous species for resources but this is also thought to be unlikely. Whatever the case there is a serious issue pertaining to the introduction of these species which look likely to continue their expansion throughout South America.

There is a history of bad consequences resulting from introducing species into a new environment for one reason or another. The cane toad was introduced to many places in order to control pests, but its voracious appetite for anything it could eat and the success at which it managed it saw them becoming the pests they were meant to destroy. Another story is of rabbits in Australia, among many others, they may all have started out with good intentions but a lack of foresight has seen greater problems emerging in many places.

Reference:

Schmid-Hempel, R, Eckhardt, M, Goulson, D, Heinzmann, D, Lange, C, Plischuk, S, Escudero, L, Salathé, R, Scriven, J, & Schmid-Hempel, P 2014, ‘The invasion of southern South America by imported bumblebees and associated parasites’, Journal Of Animal Ecology, 83, 4, pp. 823-837

The devil is in the genes…

While searching through topics for a university project I came across details on the Australia Zoo website of a horrific disease spreading through the populations of Tasmanian devils known as Devil Facial Tumour Disease (DFTD).  First described in 1996 this cancer is one of the very few instances where it is transmissible, meaning it can be passed on to others members of the species if tumorous tissue is transferred into the targets body.  This can occur due to the low diversity in their genetics, especially the Major Histocompatibility Complex (MHC), which means that the devils own immune system is unable to detect the tumour as foreign tissue and reject it.  This may not seem like such a problem until you take into account the social behaviour of the devils, which includes regular biting in social interactions and is thought to be the means of transfer and has led to the spread of the disease across 70% of Tasmania and has wreaked havoc on devil populations.

The cancer forms tumours over the face and throat of the devils and commonly results in a long and drawn out death by starvation over 6-12 months, although other causes of death are possible for infected devils.  The spread of the disease is believed to be frequency dependent rather than population dependent which means that even a rapid loss of numbers in a population would not halt the progress of the disease, which rules out culling as a viable method of controlling its spread.  There is some hope though, at West Pencil Pine in west Tasmania the spread of the disease has apparently slowed, with several hypotheses for the cause of this.  The first is that there may be a slightly more diverse HMC genotype allowing for an immune response to foreign tissue, it is also possible a less virulent strain of the cancer may exist and finally a less agonistic social interaction in the devils in western Tasmania leading to less biting.

DFTD has led the Tasmanian devil to go from abundance to the brink of extinction in around 20 years, and lists it among the extremely limited number of species which are affected by a transmissible form of cancer.  Conservation work is incredibly important due to the devils being the largest remaining carnivorous marsupial after the Tasmanian tiger went extinct in 1933.  Thankfully there are attempts to protect the species by Australia Zoo with the support of The Mark Webber Foundation and others, the latest information seems to be found on the save the Tasmanian devil website for those who are interested.

The remaining two forms of transmissible cancer attacks dogs and Syrian hamsters. The dogs are affected by canine transmissible venereal tumour (CTVT) which is passed on during copulation and mutes immune responses allowing it to propagate. While the Syrian hamsters are subjected to a similar problem to that of the devils with their own lack of genetic diversity allowing the infection to occur after being transmitted between hamsters by mosquitos.

Bees, pesticides and unfinished business

Last year I spent a significant amount of time looking into neonicotinoid pesticides and their effects on bees through agricultural use for my dissertation. I found it fascinating but in hindsight it was probably far too big a topic for the project, especially in the way I had to write it. So I thought I’d briefly go over it and then possibly put more in depth posts regarding it and future developments in later posts.

Bees are brilliant creatures; with many different species they are one of the most prominent pollinating insects in the world. They are not alone in being useful pollinators but they are seen as being of great importance to agriculture with around 80% of crops in Europe benefiting from some interaction with bee species[1].

Neonicotinoid pesticides, also known as chloroncotinyls, are a range of systemic pesticides first developed by Shell in the 80’s and later by Bayer and Syngenta in Europe. Designed to target the post-synaptic nicotinic acetylcholine receptors (nAChRs)[2] located in the insects central nervous system. They are ubiquitous in agriculture due to their high toxicity to target species and limited effect on other species.

There have been many laboratory studies into the effect these pesticides have on bees with some varying results but some worrying results have been shown and linked to the process known as colony collapse disorder (CCD). CCD occurs when drones fail to return to the hive after foraging trips. There have also been other effects noted, such as a reduction in the production of queens in bumble bees (Bombus terrestris) after being dosed with imidacloprid as well as notable reduction in weight compared to the control group [3].

Honey bees (Apis mellifera) are by far the most studied species due to their importance with apiculture as well as agricultural pollination. In 2000 it was estimated the value of the agricultural yield enhanced by honey bee pollination was around $14.6 billion[4]. This shows how important it is to understand how detrimental external factors can be on pollinators. The Proboscis Extension Response/Reflex (PER) assay is a test to indicate memory and learning due to the proboscis response to a stimulation of the antennae. In A. mellifera saw hits to learning performance and reflex responses in winter and summer bees [5].

In Brazil it has been shown that neonicotinoids directly affect the development of the area known as the mushroom body in the brain of native stingless bees (M. quadrifasciata anthidioides), this area is important for memory retention especially regarding the areas outside of the hive. This could lead to problems with the bees ability to return to the hive once it has flown a sufficient distance on foraging trips. It was also noted there was some effect on the walking behaviour of the bees after several days exposure with less steps being taken compared to the control groups[6].

As if these weren’t enough problems it is thought that disturbances to growth and larval development make bees susceptible to further indirect effects. Varroa mites are one of these issues, which have also been suggested as a prominent cause for CCD, it is believed due to the decreased size and extended period of development as a larvae allows the varroa mite a greater chance of attacking the young and reducing the size of the brood[7]. A gut pathogen called Nosema ceranae has also been noted having an increase in occurrence with bees that have been exposed to pesticides and fungicides, including imidacloprid [9].

These are just a few examples of the studies looking at problems for bees. Because these studies are primarily done in a laboratory of severely restricted semi field tests it has been said that they are unrepresentative of the exposure bees receive in the wild, this is to an extent a valid point which was used to try and avoid a temporary ban on the pesticides by the EU last year in favour of increased field studies which they felt would prove a lack of connection between neonicotinoid pesticides and detrimental effects on bee populations.

A study by the Food and Environment Research Agency (FERA) which was used as a basis for the UK governments decision on whether to support a temporary ban pulled up a striking issue with plausibility of extensive field trials. During their experiments they noticed that the bees would travel for significant distances in attempts to forage for pollen even if there was a substantial supply right next to their hives, when examining the bees they discovered a variety of neonicotinoids and pesticides from several other fields in the control group which realistically invalidated the results[9]. Essentially this would indicate without a ban on neonicotinoids for all but research it would be all but impossible to control the factors effectively enough to prove whether they were truly an issue to be tackled.

In the end I concluded that there is a definite need for further research, and the ban was essential to making that research effective. It is too important an issue to be left with poor and incomplete information to base decisions on, especially when the current research is not entirely conclusive. I’ll be looking forward to reading more over the coming months and years and writing further on the progress made in new studies.

1. Grimm, M., Sedy, K., Süßenbacher, E. & Riss, A., 2012. Existing scientific evidence of the effects of neonicotinoid pesticides on bees, Brussels: EU Directorate-General for internal policies.

2. Jeschke, P. & Nauen, R., 2008. Neonicotinoids – from zero to hero in insecticide chemistry. Pest Management Science, Volume 64, pp. 1084-1098.

3. Whitehorn, P., O’Connor, S., Wackers, F. & Goulson, D., 2012. Neonicotinoid pesticide reduces bumble bee growth and queen production. Science, Volume 336, pp. 351-352.

4. Morse, R. & Calderone, N., 2000. The value of honey bees as pollinators of U.S. crops in 2000. Bee culture.

5. Decourtye, A., Lacassie, E. & Pham-Delegue, 2003. Learning performances of honeybees (Apis mellifer L) are differently affected by imidacloprid according to season. Pest management science, Volume 59, pp. 269-278.

6. Tome, H.V.V. Martins, G.F. Lima, M.A.P. Campos, A.O. Guedes, R.N.C., 2012. Imidacloprid-induced impairment of mushroom bodies and behavior of the native stingless bee Melipona quadrifasciata anthidioides. PLoS ONE, 7(6).

7. Wu, J., Anelli, C. & Sheppard, W., 2011. Sub-lethal effects of pesticide residuses in brood comb on worker honey bee (Apis mellifera) development and longevity. PLoS ONE, 6(2).

8. Pettis, J.S. Lichtenberg, E.M. Andree, M. Stitzinger, J. Rose, R. vanEngelsdrop, D., 2013. Crop pollination exposes honey bees to pesticides which alters their succeptibility to the gut pathogen Nosema ceranae. PLOS ONE, 8(7).

9. Thompson, H. Harrington, P. Wilkins, S. Pietravalle, S. Sweet, D. Jones, A., 2013. Effects of neonicotinoid seed treatments on bumble bee colonies under field conditions, s.l.: The Food and Environment Research Agency.