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:
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).
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.
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