Keywords: Sex Separation

Advances in male sex separation for the support of mosquito control programs

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Duman-Scheel M,  Frontiers in Insect Science,  6. 2026-03-09 09:05:10.
Several mosquito control technologies, including the sterile insect technique (SIT), the incompatible insect technique (IIT), and a variety of genetic technologies are emerging as promising solutions for combatting insecticide resistance and the spread of vector-borne diseases. These approaches involve mass releases of male mosquitoes in an effort to suppress mosquito populations in an eco-friendly manner. At small scale, male mosquito selection can be achieved through the use of mechanical separation techniques, but such methods are not sufficient for scaled implementation of emerging mosquito population control technologies. This review discusses mechanical, genetic, and automated mosquito sex sorting techniques that have emerged to address the need for scaled male mosquito production, as well as the potential contributions of RNA interference (RNAi) to facilitate this process. One RNAi method utilizes the oral delivery of yeast expressing interfering RNA targeting genes required for female larval survival. The yeast, which can be incorporated into normal insect larval diets, enables male sex selection during larval rearing in mosquitoes and could easily be extended to other insects. RNAi-mediated sex-sorting technologies, in combination with mechanical, genetic, and automated sorting technologies, could facilitate the scaled production of adult males in support of global insect population suppression efforts.

Generating cisgenic sexing strains in insect pests

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Davydova, S., Liu, J., Kandul, N.P. et al.,  Communications Biology,  2026-02-05 18:20:56.
Insect pest population control via sterile insect technique markedly benefits from separation by sex prior to release. To simplify this process, traditional genetics has been deployed to develop genetic sexing strains (GSSs) for several disease vectors and agricultural pests of vast economic significance, although very few are applied in the field due to associated fitness costs and instability. In this study, we generated a method to engineer cisgenic GSS (CGSS) in insects. We use CRISPR/Cas9-mediated homology-directed repair to seamlessly translocate a sex-specific alternatively spliced intron into a dominant phenotypic gene generating a genetically stable strain that enables sex-sorting by eye. To achieve this feat, we use Ceratitis capitata as our model and relied on the sex-specifically spliced intron of its endogenous transformer gene, which we seamlessly inserted a copy into the pupal colouration white pupae gene. This minimal modification resulted in the generation of a homozygous strain we term IMPERIAL that was genetically and phenotypically stable where all female pupae are brown while male pupae are white with overall good fitness. By minimally editing the genome, our novel CGSS approach can be applied to other pests that may aid more efficient and economically suitable pest control.

Bisexual releases are as effective as male-only releases to control Drosophila suzukii with the sterile insect technique

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Alexandra Labbetoul, Simon Fellous,  Pest Management Science,  2026-01-23 10:16:56.
The sterile insect technique (SIT) suppresses insect reproduction by repeatedly releasing sterile insects and allowing them to mate with insects of the same species in the wild. While the classical SIT relies on sterile males mating with wild females, there is a debate regarding the risks and benefits of releasing sterile females along with the sterile males (i.e. bisexual releases). In a replicated cage experiment, we compared the effect of unisexual and bisexual sterile releases of Drosophila suzukii on induced sterility. To ensure field-realism, fertile females - wild-F0 freshly emerged from field-collected sweet-cherries - were placed in cages with artificial vegetation and plastic berries. The proportion of fertile females that produced offspring was not significantly different in unisexual and bisexual treatment (45% and 46%, respectively). Excluding females that had not mated (i.e. no sperm in the spermathecae) from the analysis had no influence. These results suggest the release of sterile females does not always affect the efficacy of the SIT. Even though additional phenomena may arise when scaling up from cages to the field, we conclude that sorting females with genetic constructs or robotic systems is probably dispensable in D. suzukii SIT, at least when deployed in confined farming systems.

Color-coded mosquitoes safely enables male-only releases to combat Dengue and Zika

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Joshua Shavit,  The Brighter Side of News,  2026-01-16 11:13:48.
Across much of the world, a tiny striped insect shapes whether families stay healthy or get sick. The Asian tiger mosquito carries Dengue, Zika and Chikungunya, and traditional control efforts often struggle to keep up. A new genetic trick that literally changes how these mosquitoes look could help tip the balance in your favor. Only female mosquitoes bite and pass on viruses. Males drink nectar, not blood. Many modern control programs release large numbers of males that are sterile or carry a trait that reduces survival in the next generation. When those males mate with wild females, fewer disease-carrying offspring survive. There is one big catch. These programs must release only males. If too many females slip through, they will still bite, still spread disease and may even weaken the program. Today, most facilities separate sexes by size during the pupal stage. That work is tedious, hard to automate and far from perfect. Researchers led by Doron Zaada and Prof. Philippos Papathanos at the Hebrew University of Jerusalem set out to remove that bottleneck. Their idea was simple and bold. Make male and female mosquitoes so visually different that machines, or even the human eye, can sort them at a glance. The team focused on Aedes albopictus, also known as the Asian tiger mosquito. It is aggressive, invasive and a major target for control programs worldwide. In their study, the scientists describe a “Genetic Sexing Strain” that turns sex into a visible trait. They used CRISPR gene editing to break a gene called yellow that controls dark pigment in the mosquito body. When this gene is disrupted, the insects turn pale, almost albino. The group then restored normal dark pigmentation only in males by linking a working copy of the yellow gene to nix, a sex-determining gene. Nix acts like a master switch. When it turns on in a mosquito, the insect develops as a fertile male, even if it started out genetically female. By tying yellow to nix, the team created a line in which all males are dark and all females remain pale. “This produces an engineered sex-linked trait in mosquitoes that uses the insect’s own genes,” said Prof. Papathanos. “By understanding and controlling the sex determination pathway, we were able to create a system were males and females are visually different at the genetic level.”

Spot the males: New gene-editing method could transform mosquito control

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Robert Egan,  Phys.org,  2025-12-17 11:22:04.
Researchers have developed a new "color-coded" genetic method that makes it easy to distinguish male and female mosquitoes. This innovation can help solve a major bottleneck in mosquito control strategies that rely on releasing only sterile males. The approach uses gene editing to produce dark males and pale females, offering a practical and safer alternative to current sex-separation techniques. A new study led by Doron Zaada and Prof. Philippos Papathanos from the Department of Entomology at Hebrew University, introduces a powerful genetic approach for separating male and female mosquitoes, an essential step for large-scale mosquito control programs aimed at reducing the spread of infectious diseases such as Dengue, Zika, and Chikungunya. Mosquito control strategies based on the mass release of males rely on the complete removal of females, which bite and transmit disease. Existing separation methods, largely based on size differences at the pupal stage, are labor-intensive, difficult to scale, and prone to letting biting females slip through. This new study presents a genetically engineered "Genetic Sexing Strain" (GSS) of the Asian tiger mosquito (Aedes albopictus) that allows sexes to be sorted automatically based on visible pigmentation.