  Simulating the population dynamics of a stage-structured population requires
the knowledge of the biodemographic functions characterizing the species,
namely development, mortality and fecundity. In general, development and
fecundity can satisfactorily be estimated starting from literature data.
Unfortunately, this is often not the case of the mortality function, because of
the lack of experimental data. To overcome this problem we estimate the
mortality rate function from field data on the abundance of the species. The
mortality is expressed as a linear combination of cubic splines and the
estimation method allows to determine its coefficients taking into account the
observations measurement error. Moreover, the variability in the estimate is
quantified by means of the confidence bands for both mortality and dynamics.
The presented method allows to obtain a more flexible shape for the mortality
rate functions compared with previous methods applied to the same pest. The
method is applied to the case of Lobesia botrana, the main pest in the European
vineyards, with abundance data collected in a location in the North of Italy
for five consecutive years. Data collected over three years are used to
estimate the mortality and to analyze the variability in the estimate and its
effects on the population dynamics. Other two datasets are used to validate the
model simulating the dynamics using the estimated mortality.
