Modelling the mortality of Hylotrupes bajulus (L.) larvae exposed to anoxic treatment for disinfestation of wooden art objects

Experiments were conducted to quantify the effect of several variables on
the mortality of insects exposed to an anoxic treatment in order to generate a model
linking mortality to these variables. This study aims to explore the possible interest
of using such a model to determine the characteristics of treatment (especially
duration) needed to guarantee insect mortality with a given level of probability.
Trials were performed on Hylotrupes bajulus larvae, which is a widespread species
known for its high tolerance to anoxic conditions. The studied variables are the
initial mass of the larvae, the treatment temperature (21, 30 and 40 C), the treatment
duration (four durations for each temperature tested) and whether the larva is
held in wood or in a petri dish (directly exposed to anoxic atmosphere) during the
experiment. It was found that, while the last variable is not correlated with mortality,
treatment duration and temperature are significantly and positively correlated
with it. Larvae with higher body mass were also shown to have a better resistance to
the treatment. Based on these results, a model including insect initial mass, treatment
temperature and duration, together with the interaction between these two
variables, was determined. This relatively simple model appeared to be a useful tool
in overcoming the difficulty in defining the modalities for anoxic treatment in order
to reach a given level of mortality.