Sunday, April 21, 2019

No one likes mosquitos - not even the tadpoles


Biocontrol of mosquito larvae by three species of Anuran tadpoles


Anopheles vagus is a major vector of Plasmodium vivex, the malarial parasite that infects a large portion of the population of India. Given that mosquito larvae and anuran tadpoles share a similar habitat in the early stages of development, and that some predation of larvae by tadpoles has been observed in the past, this study sought to determine whether native tadpoles would be an effective means of controlling the mosquito population.

            The researchers collected eggs from three anuran different species, Duttaphrynus melanostictus, Polypedates maculatus and Microhyla ornata, and raised the tadpoles in separate enclosures and fed them boiled spinach and algae collected from the source pond. The tadpoles were then separated into two feeding stages – initial and late feeding. From there, each group was separated into starved and fed, in which the tadpoles were either provided or deprived of food prior to the introduction of mosquito larvae.
            Interestingly enough, there was no occurrence of predation by the tadpoles on the mosquito larvae. However, there was multiple instances of cannibalism among conspecifics after roughly 36 hours after the introduction of the larvae and by 48 hours, 20% of tadpoles had been partially or fully consumed.
            The apparent lack of predation by the tadpoles suggests that these species of anurans may not be effective means of biocontrol for the mosquito population in Oshida. There are a few explanations as to why these anurans may not be feeding on mosquito larvae. It is possible that mosquito larvae are not a food source in their natural habitat and that tadpoles either prefer alternative food sources or not exposed to the larvae much at all. Additionally, the oral morphology of these species may not allow for them to feasibly ingest the larvae, despite the existing evidence of some herbivorous tadpoles feeding on larvae.  
            It may be the case that competition is more a driving force between the populations of mosquito larvae and tadpoles than predation. It is speculated, though not supported yet, that a higher population of anuran tadpoles would negatively effect the population of mosquito larvae and therefore, the population of the disease-carrying adult. If there is research done that supports this, there would then be greater motivation to preserve anuran habitat and maintain the population of the tadpoles, as to decrease the prevalence of malaria in these areas. 

2 comments:

Allison Welch said...

Interesting article. I wonder if this varies among species of anurans/mosquitos, as well as how each interacts with other species that do prey on mosquito larvae (e.g., mosquitofish).

Anonymous said...

I second Doctor Welch. I was not surprised about the cannibalism amongst the tadpoles due to previous discussion in class, but I was surprised that cannibalism occurred over predation on the mosquito larvae!

What was your inspiration for your BlogPost title?

I personally have a love/hate relationship with mosquitoes. On the humanitarian end, they spread so much devastating disease to swaths of people; while on the environmental end, not only are they a valuable member of the tree of life but they are also one of the primary reasons that humans have not yet destroyed all of the rainforests, serving as mother nature's royal guards in a poetic sense.