This study investigated whether tadpoles of the bromeliad-dwelling frog Phyllodytes luteolus are able to prey on mosquito larvae. The researchers collected P. luteolus tadpoles and mosquito larvae from bromeliads in restinga areas in Brazil. They defined size categories for tadpoles and larvae and conducted experiments pairing one tadpole with five larvae. Larger tadpoles preyed on larvae of any size, while smaller tadpoles mostly preyed on smaller larvae. Larger tadpoles were also more developed and efficient predators. The results provide evidence that P. luteolus tadpoles can physically prey on mosquito larvae and their predatory effectiveness increases with size. The study highlights the potential

1. Are tadpoles of the bromeliad-dwelling frog
Phyllodytes luteolus able to prey
on mosquito larvae?
Aila S. Salinas; Renan N. Costa; Victor G.D Orrico; Mirco Solé
Universidade Estadual de Santa Cruz, Rodovia Jorge Amado, km 16, Ilhéus, Bahia, Brasil
Email: msole@uesc.br
INTRODUCTION
Biological control often happens
naturally and is considered the best way to
control mosquito populations reducing
ecological impacts and side effects to
humans (1). Experimental studies have
shown that tadpoles of some species are
effective in regulating mosquito larvae
populations by predation or competition.
Phyllodytes luteolus is a bromeligenous
hylid, their tadpoles develop in bromeliad
axils filled with water. Despite the
knowledge on the controlling effect of
mosquito larvae populations by tadpoles, no
species has been studied in Brazil yet. Our
aim is to assess if P. luteolus tadpoles are
physically able to prey on mosquito larvae.
METHODS
RESULTS
DISCUSSION
REFERENCES
Bowatte G, et al. 2013. Tadpoles as dengue mosquito (Aedes aegypti) egg predators. Biol Control. 67(3):469-474.
Murugan K, et al. 2015. Predation by Asian bullfrog tadpoles, Hoplobatrachus tigerinus,against the dengue vector, Aedes aegypti, in an aquatic environment treated with mosquitocidal nanoparticles. Parasitol Res. 114: 3601-3610.
Fig 2. Differences between stages per category of tadpole size: large tadpoles are more
developed than small and medium, however these do not differ from each other.
Note: bold values: P<0.05.
Fig 1. Predation rates of mosquito larvae by tadpoles accordingly to size categories:
Tadpole size/Mosquito larvae size: L/S - Large/Small; L/M - Large/Medium; L/L -
Large/Large; M/S - Medium/Small; M/M - Medium/Medium; M/L - Medium/Large; S/S -
Small/Small; S/M - Small/Medium; S/L - Small/Large).
Treatment L/S L/M L/L M/S M/M M/L S/S S/M S/L
F 4.333 3.750 4.250 2.250 1.818 1.461 1.272 1.166 4.166
L/S
L/M 0.963
L/L 1.000 0.985
M/S 0.002 0.083 0.004
M/M 0.000 0.008 0.000 0.995
M/L 0.000 0.000 0.000 0.804 0.998
S/S 0.000 0.000 0.000 0.616 0.981 0.999
S/M 0.000 0.000 0.000 0.445 0.938 0.999 1.000
S/L 0.000 0.000 0.000 0.012 0.153 0.468 0.767 0.857
Table 2.
Post- hoc Tukey test results. (Tadpole size/Larvae size. L: large; M: medium; S: small.)
We collected Phyllodytes luteolus
tadpoles and mosquito larvae from
bromeliads found in two restinga areas
located in Ilhéus. Before starting the
experiment, tadpoles and mosquito larvae
were acclimated for 48 hr in independent
storage tanks. We used only the total length
as a variable to define size categories of
tadpoles and mosquito larvae. We also
evaluated the developmental stage of
tadpoles according to Gosner (1960).
Predator-prey experiment
In each experimental unit we added one
tadpole that was acclimated for 48 hr. We
added five mosquito larvae into each experi-
Size categories Mean TL (mm) SD Range (mm) Individuals
Size A
Small 9.24 1.38 6.05 - 10.09 35
Medium 14.56 1.55 12.10 - 17.01 36
Large 20.03 2.66 19.17 - 29.28 38
Size B
Small 0.32 0.02 0.25 - 0.38 15
Medium 0.48 0.02 0.42 - 0.50 15
Large 0.59 0.04 0.53 - 0.59 15
)
Table 1. Size categories for tadpoles (A) and mosquito larvae (B). (TL: Total Length;
SD: Standard Deviation)
mental unit accordingly to the size categories
previously defined. We replicated each
treatment 12 times, totaling 108 experimental
units. The experiment was conducted during
four days and we checked the predation of
mosquito larvae every 24 hr.
Statistical analyses
We performed a One-way ANOVA to
evaluate the difference of overall predation
rates of mosquito larvae among treatments.
We applied a post-hoc Tukey test to verify if
larger tadpoles were able to prey on different
sizes of mosquito larvae. We also applied a
Kruskall-Wallis test to evaluate if the
developmental stage of tadpoles differed
among treatments
Our study provides strong evidence for
predatory behavior and relation between
body size, development stage and predatory
effectiveness. We observed that the tadpoles
of Phyllodytes luteolus were physically able
to prey on mosquito larvae. As expected,
larger tadpoles were more developed
(according to Gosner scale), and they
managed to prey mosquito larvae of any
size, while small tadpoles predated mostly
small larvae, suggesting that body size may
directly influence predatory capacity and
efficiency of tadpoles. Additionally,
predation was slower and less efficient in
small tadpoles than in medium and large
tadpoles.
Tadpoles of some species are
considered active predators of all larval
instars of A. aegypti, (2), highlighting the
importance of biologic control. Concordant
findings suggest that tadpoles of different
species, which use different habitats around
the world, may significantly control
mosquito larvae populations and reduces
mosquito-borne disease spread.
Tadpoles and mosquito larvae feed on
various types of organic matter, debris,
bacteria and protozoa. We would like to
emphasize the need to conserve bromeliads,
which are essential for the growth and
survival of P. luteolus tadpoles, so that they
can reach a larger size and be able to control
mosquito larvae more efficiently.