Impacts of sex, age, and
desiccation on cuticular
hydrocarbon profiles of Anopheles
gambiae pupae

Abstract

CHC analysis of
female and male pupae show dimethylalkanes are present in female pupae shells but not in male
shells. Branched hydrocarbons such as dimethylalkanes decrease the melting point of the lipid layer
making it more “liquid like” (Menzel et al., 2019). This in part may explain the differences seen with
eclosion success rates between sexes. However, more research is needed to determine the
mechanisms at play. This study confirms that pupal CHCs in An. gambiae change depending on the
age and sex of the pupae. However, changes in salinity and how long the pupae are desiccating for
has a negligible impact on the CHC composition. This highlights the reduced plasticity of pupal CHCs
to react to environmental stresses when compared to the adults (Wagoner et al., 2014b), possibly
suggesting a greater vulnerability in the pupal life stage to environmental stresses and perhaps
insecticides (insecticides were not directly tested in this study but it can be inferred due to strong
links between reduced CHC plasticity and vulnerability to insecticides (Adams et al., 2021). Hence,
targeting An. gambiae pupae may prove to be more effective in the ongoing fight to reduce vector
transmission. However, more research is required, such as if the reduced plasticity is a result of
biological factors or reduced time for the pupae to react to environmental stresses due to the short
time frame of the pupal life stage.
This study quantifies the CHC differences with An. gambiae pupae within different climatic
scenarios, such as drought. This study shows a discrepancy in eclosion success rates between male
and female pupae under desiccation conditions and aims to provide a theory behind the discrepancy
using CHCs as a framework.