[Investigations on the incompatibility in theCulex pipiens-complex]

Area of Science:

• Reproductive biology
• Genetics
• Developmental biology

Context:

• Crosses between different geographical populations of the mosquito Culex pipiens exhibit varying degrees of reproductive compatibility.
• Incompatible crosses result in high embryo lethality (99.9%) with only a small fraction developing into fertile diploid females.

Purpose:

• To investigate the mechanisms underlying reproductive incompatibility in Culex pipiens.
• To determine the role of sperm in fertilization and embryo development in incompatible crosses.
• To characterize the developmental pathways of embryos in incompatible crosses, including parthenogenesis and ploidy.

Summary:

• Three crossing types were identified: normal offspring, reduced offspring, and almost total incompatibility.
• Incompatible crosses trigger induced meiotic parthenogenesis, where sperm enters the egg but does not fuse with the pronucleus.
• The majority of embryos develop as haploid from the activated egg's pronucleus, with diploidy restored in rare cases through meiotic alterations.

Impact:

• This research provides insights into the genetic and cytological basis of reproductive isolation in insects.
• Understanding these mechanisms is crucial for studying speciation processes and vector control strategies for Culex pipiens.
• The findings highlight the complex interplay between sperm, egg, and meiotic processes in determining reproductive success.