Efficacy of the Sterile Insect Technique in the presence of inaccessible areas: A study using two-patch models

TL;DR

This study models the effectiveness of the Sterile Insect Technique (SIT) in controlling mosquito populations across accessible and inaccessible areas, highlighting how release strategies and migration influence eradication success.

Contribution

The paper introduces a two-patch model incorporating diffusion between areas, analyzing how different release strategies affect SIT efficacy in inaccessible zones.

Findings

Exceeding a threshold number of sterile males leads to population extinction.

Migration between patches influences the success of SIT.

Periodic releases can be effective if above a certain threshold.

Abstract

The Sterile Insect Technique (SIT) is one of the sustainable strategies for the control of disease vectors, which consists of releasing sterilized males that will mate with the wild females, resulting in a reduction and, eventually a local elimination, of the wild population. The implementation of the SIT in the field can become problematic when there are inaccessible areas where the release of sterile insects cannot be carried out directly, and the migration of wild insects from these areas to the treated zone may influence the efficacy of this technique. However, we can also take advantage of the movement of sterile individuals to control the wild population in these unreachable places. In this paper, we derive a two-patch model for Aedes mosquitoes where we consider the discrete diffusion between the treated area and the inaccessible zone. We investigate two different release strategies (constant and impulsive periodic releases), and by using the monotonicity of the model, we show that if the number of released sterile males exceeds some threshold, the technique succeeds in driving the whole population in both areas to extinction. This threshold depends on not only the biological parameters of the population but also the diffusion between the two patches.