of malathion on the demography of Daphnia pulex Leydig
Diaphanosoma birgei Korinek (Cladocera)
Bravo-Hern?ndez1, S.S.S. Sarma2* and S. Nandini2
en Ciencias del Mar y Limnolog?a, Universidad Nacional Aut?noma de M?xico,
Mexico City, 04510, Mexico
Nacional Aut?noma de M?xico, Campus Iztacala. Av. De los Barrios #1, Col. Los
Estado de M?xico. C.P. 54090, Mexico
Author E-mail: firstname.lastname@example.org
19 October 2012
20 July 2013
05 September 2013
is a common pesticide used to control insects in agricultural, domestic and
industrial sectors in different parts of the world. In this work we evaluated
the effects of sublethal concentrations of malathion on the survivorship and
reproductive variables of two cladoceran species Daphnia pulex and Diaphanosoma
birgei using standard life table demography method. Based on preliminary
tests, we selected four sub-lethal concentrations of malathion for each
cladoceran species. For D. pulex, the malathion concentrations were 0.
225, 0.45, 0.9 and 1.8ng l-1 and for D. birgei, these were 0.0281,
0.0562, 0.1125, 0.225ng l-1.Our results showed that in general, Daphnia
pulex was less sensitive than Diaphanosoma birgei to malathion.
The average lifespan of Daphnia pulex in controls was about 19 days
while under similar conditions, that of D. birgei was about 21 days. For
either cladoceran species, increased pesticide concentration resulted in
decreased survival; this was more evident in the treatment containing the
highest concentration of malathion (0.225 ng l-1) for D. birgei.
Fecundity of D. pulex and D. birgei also decreased with
increase in the concentration of malathion. For a given cladoceran species,
compared to controls, the gross reproductive, net reproductive rates and the
population growth rate significantly decreased due to malathion. Compared to
the survivorship variables (age-specific survival, life expectancy and
average lifespan), the reproductive parameters (gross reproductive rate, net
reproductive rate and the rate of population increase) of the two cladoceran
species were decreased by the pesticide.
history, Lifespan, Pesticide, Zooplankton
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