# Re-mating consequences on the efficiency of the sterile insect technique

Marine A. Courtois, Taha Belkhayate, Crésus Kounoudji, Frédéric Grognard, Suzanne Touzeau, Ludovic Mailleret, Louise van Oudenhove

► To cite this version:

Marine A. Courtois, Taha Belkhayate, Crésus Kounoudji, Frédéric Grognard, Suzanne Touzeau, et al. Re-mating consequences on the efficiency of the sterile insect technique. DSABNS - 15th Conference on Dynamical Systems Applied to Biology and Natural Sciences, Feb 2024, Caparica, Portugal. hal-04452111

HAL Id: hal-04452111

https://hal.inrae.fr/hal-04452111

Submitted on 12 Feb 2024

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# Re-mating consequences on the efficiency of the sterile insect technique

Marine A. Courtois, Taha Belkhayate, Crésus Kounoudji, Frédéric Grognard, Suzanne Touzeau, Ludovic Mailleret, Louise van Oudenhove

► To cite this version:

Marine A. Courtois, Taha Belkhayate, Crésus Kounoudji, Frédéric Grognard, Suzanne Touzeau, et al. Re-mating consequences on the efficiency of the sterile insect technique. DSABNS - 15th Conference on Dynamical Systems Applied to Biology and Natural Sciences, Feb 2024, Caparica, Portugal. hal-04452111

HAL Id: hal-04452111

https://hal.inrae.fr/hal-04452111v1

Submitted on 12 Feb 2024

HAL is a multi-disciplinary open access
archive for the deposit and dissemination of sci-
entific research documents, whether they are pub-
lished or not. The documents may come from
teaching and research institutions in France or
abroad, or from public or private research centers.

L'archive ouverte pluridisciplinaire HAL, est
destinée au dépôt et à la diffusion de documents
scientifiques de niveau recherche, publiés ou non,
émanant des établissements d'enseignement et de
recherche français ou étrangers, des laboratoires
publics ou privés.

<figure><img src="image_1.png" /></figure>

Distributed under a Creative Commons Attribution 4.0 International License
RE-MATING CONSEQUENCES ON THE EFFICIENCY OF THE STERILE INSECT TECHNIQUE

Marine Courtois*<fnref n="1" />, Taha Belkhayate<fnref n="1" />, Crésus Kounoudji<fnref n="1" />, Frédéric Grognard<fnref n="2" />, Suzanne Touzeau<fnref n="1" />,<fnref n="2" />, Ludovic Mailleret<fnref n="1" />,<fnref n="2" /> and Louise van Oudenhove<fnref n="1" />

marine.courtois@inrae.fr (*presenter)

frédéric.grognard@inria.fr,suzanne.touzeau@inrae.fr

ludovic.mailleret@inrae.fr, louise.vanoudenhove@inrae.fr

The Sterile Insect Technique (SIT) is a biological control technique based on mass-rearing, sterilization, and releases of the pest species targeted for population control. Sterile males are released to dilute wild population, so that wild females are more likely to encounter and mate with a sterile male rather than a wild male, thus reducing the number of offspring in the next generation. However, if wild females tend to re-mate, the effectiveness of SIT may be compromised.

The influence of re-mating, i.e. the ability of a female to be inseminated several times, was studied using a model based on differential equations with continuous releases. In the model, the population is structured into larvae, sterile and wild males, and three female stages: unmated, mated with sterile males, and mated with wild males. Sterile matings with sterile males produce no offspring, as opposed to fertile matings with fertile males. We compared a situation in which females mate only once in their lifetime with one in which they can mate and then re-mate after a certain period of time, called the refractory period. Situations in which the refractory periods associated with sterile and fertile matings are not equal have been studied.

The analytical study of the re-mating model revealed a dependency between the existence of infestation equilibria, limiting control capabilities where they exist, and the length of refractory periods. Thus, if the refractory period associated with sterile matings is short, larger releases are needed to control the population. If this refractory period is long, sterile matings will make females unavailable for some time, in addition to the dilution effect of the releases, thus increasing the effectiveness of SIT compared to the previous case. The study highlights the impact of reproduction processes on SIT control effectiveness, and more generally the need for a thorough understanding of the ecology and biology of the target pest.

<footnote n="1">¹Université Côte d'Azur, INRAE, CNRS, ISA, France</footnote>

<footnote n="2">²Université Côte d'Azur, Inria, INRAE, CNRS, Macbes, France</footnote>
RE-MATING CONSEQUENCES ON THE EFFICIENCY OF THE STERILE INSECT TECHNIQUE

Marine Courtois*<fnref n="1" />, Taha Belkhayate<fnref n="1" />, Crésus Kounoudji<fnref n="1" />, Frédéric Grognard<fnref n="2" />, Suzanne Touzeau<fnref n="1" />,<fnref n="2" />, Ludovic Mailleret<fnref n="1" />,<fnref n="2" /> and Louise van Oudenhove<fnref n="1" />

marine.courtois@inrae.fr (*presenter)

frederic.grognard@inria.fr,suzanne.touzeau@inrae.fr

ludovic.mailleret@inrae.fr, louise.vanoudenhove@inrae.fr

The Sterile Insect Technique (SIT) is a biological control technique based on mass-rearing, sterilization, and releases of the pest species targeted for population control. Sterile males are released to dilute wild population, so that wild females are more likely to encounter and mate with a sterile male rather than a wild male, thus reducing the number of offspring in the next generation. However, if wild females tend to re-mate, the effectiveness of SIT may be compromised.

The influence of re-mating, i.e. the ability of a female to be inseminated several times, was studied using a model based on differential equations with continuous releases. In the model, the population is structured into larvae, sterile and wild males, and three female stages: unmated, mated with sterile males, and mated with wild males. Sterile matings with sterile males produce no offspring, as opposed to fertile matings with fertile males. We compared a situation in which females mate only once in their lifetime with one in which they can mate and then re-mate after a certain period of time, called the refractory period. Situations in which the refractory periods associated with sterile and fertile matings are not equal have been studied.

The analytical study of the re-mating model revealed a dependency between the existence of infestation equilibria, limiting control capabilities where they exist, and the length of refractory periods. Thus, if the refractory period associated with sterile matings is short, larger releases are needed to control the population. If this refractory period is long, sterile matings will make females unavailable for some time, in addition to the dilution effect of the releases, thus increasing the effectiveness of SIT compared to the previous case. The study highlights the impact of reproduction processes on SIT control effectiveness, and more generally the need for a thorough understanding of the ecology and biology of the target pest.

<footnote n="1">¹Université Côte d'Azur, INRAE, CNRS, ISA, France</footnote>

<footnote n="2">²Université Côte d'Azur, Inria, INRAE, CNRS, Macbes, France</footnote>